Photocatalytic composite material, preparation method and application thereof, and industrial wastewater habitat reconstruction method

Abstract

The invention provides a photocatalytic composite material, a preparation method and application thereof, and an industrial wastewater habitat reconstruction method, and relates to the technical field of wastewater treatment. The photocatalytic composite material comprises a fiber fabric substrate, a conductive layer compounded on the fiber surface of the fiber fabric substrate, and a photocatalyst loaded on the conductive layer, wherein the photocatalyst comprises nitrogen-doped titanium dioxide loaded single-walled carbon nanotubes and nitrogen-doped titanium dioxide. The photocatalytic composite material can reduce the toxicity stress of a water body, improve underwater light physical conditions to enable plants to obtain more light energy, self-organize and optimize relative abundance among microbial populations and related paths and functions to enable the plants to obtain a healthy habitat, and finally realize the improvement of biomass. According to the method disclosed by the invention, the biomass amplification of the submerged plants is promoted across ecological niche through chemical-physical-microorganism multi-dimensional habitat optimization by utilizing photocatalysis mediation, and a theoretical basis and a technical support are provided for ecological treatment of industrial wastewater and carbon sequestration of aquatic plants.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a photocatalytic composite material, its preparation method and application, and a method for reconstructing industrial wastewater habitat. Background Technology

[0002] Aquatic vegetation plays a crucial role in mitigating greenhouse gas emissions, maintaining ecosystem stability, and serving as a potential source of raw materials for clean energy production. However, with accelerated industrialization and rapid economic development, the discharge of industrial wastewater has increased significantly, severely impacting the growth of aquatic vegetation and even leading to plant death. Industrial wastewater typically contains complex mixed pollutants, including organic pollutants, heavy metals, and recalcitrant compounds. These substances can inhibit key metabolic, physiological, and developmental processes in aquatic organisms. For example, humic substances contain various reactive chemical groups, such as quinone structures, polycyclic aromatic hydrocarbons, and redox-active functional groups (such as phenolic structural units), and their phytotoxicity is positively correlated with the degree of humification. These toxic substances can inhibit photosynthesis through multiple pathways, thus causing acute and chronic stress to aquatic plants, such as reducing underwater light transmittance, disrupting the photosynthetic electron transport chain, and interfering with beneficial plant-microbe interactions. Long-term exposure to these stressors often leads to a decrease in the growth rate of aquatic plants or even death.

[0003] From the perspective of ecological restoration and promoting plant growth, the treatment of industrial wastewater is not merely a matter of reducing single chemical indicators, but rather a systemic issue of habitat restoration. Traditional industrial wastewater treatment technologies have significant ecological limitations: some conventional methods, such as simply adding algaecides and flocculants, while rapidly reducing organic matter levels, come at the cost of sacrificing the function of the aquatic ecosystem, plunging the receiving water body into a state of multiple stresses. For example, the destruction of functional microbial communities may further lead to the collapse of microbial metabolic networks, causing imbalances in material cycling and energy flow, or inducing toxicity to aquatic animals, ultimately trapping plants in a vicious cycle of growth stagnation—loss of ecological function—decreased system resilience. Therefore, traditional industrial wastewater treatment technologies have failed to escape the narrow perspective of end-of-pipe pollutant reduction and currently lack systemic restoration technologies that take into account multiple dimensions of habitat. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a photocatalytic composite material, its preparation method and application, and a method for reconstructing industrial wastewater habitats. Using the photocatalytic composite material provided by this invention to treat industrial wastewater can achieve multi-dimensional restoration through physical, chemical, and biological processes, restoring aquatic habitats and increasing the biomass of submerged plants.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: The present invention provides a photocatalytic composite material comprising a fiber fabric substrate, a conductive layer composited on the fiber surface of the fiber fabric substrate, and a photocatalyst supported on the conductive layer, wherein the photocatalyst comprises nitrogen-doped titanium dioxide supported on single-walled carbon nanotubes and nitrogen-doped titanium dioxide.

[0006] Preferably, the conductive agent in the conductive layer is a single-walled carbon nanotube.

[0007] Preferably, the mass of nitrogen-doped titanium dioxide in the nitrogen-doped titanium dioxide-supported single-walled carbon nanotubes is 70-80% of the total mass of nitrogen-doped titanium dioxide in the photocatalytic composite material; the loading amount of the photocatalyst on the fiber fabric substrate is 0.05-0.3 mg / cm³. 2 .

[0008] This invention provides a method for preparing the photocatalytic composite material described above, comprising the following steps: The photocatalyst is obtained by hydrothermal reaction of nitrogen-doped nano-titanium dioxide, carboxylated single-walled carbon nanotubes, and water. The photocatalyst comprises single-walled carbon nanotubes supported on nitrogen-doped titanium dioxide and nitrogen-doped titanium dioxide. The mass ratio of nitrogen-doped nano-titanium dioxide to carboxylated single-walled carbon nanotubes is (1.2~1.8):(0~0.0012), and the mass of carboxylated single-walled carbon nanotubes is not 0. After impregnating the fiber fabric substrate in a dispersion of conductive agent, it is heated and cured to obtain a fiber fabric substrate with a conductive layer. The fiber fabric substrate with the conductive layer is impregnated in the dispersion of the photocatalyst and then heated and cured to obtain the photocatalytic composite material.

[0009] Preferably, the nitrogen-doped nano-titanium dioxide has a particle size of 5-10 nm and the nitrogen atomic percentage in the nitrogen-doped nano-titanium dioxide is 1-5%.

[0010] Preferably, the mass ratio of the nitrogen-doped nano-titanium dioxide to the carboxylated single-walled carbon nanotubes is 1.5:0.0004.

[0011] Preferably, the hydrothermal reaction is carried out under microwave irradiation, the temperature of the hydrothermal reaction is 120~170℃, the holding time is 5~20min, and the power of the microwave irradiation is 1500W.

[0012] Preferably, the mass fraction of the conductive agent in the dispersion of the conductive agent is 0.4‰; and the concentration of the photocatalyst in the dispersion of the photocatalyst is 2.5 g / L.

[0013] This invention provides the application of the photocatalytic composite material described in the above technical solutions or the photocatalytic composite material prepared by the above technical solutions in industrial wastewater treatment.

[0014] This invention provides a method for reconstructing industrial wastewater habitats, comprising the following steps: A photocatalytic composite material is applied to industrial wastewater to treat the wastewater under light conditions; the industrial wastewater contains submerged plants and microorganisms; the photocatalytic composite material is the photocatalytic composite material described in the above technical solution or the photocatalytic composite material prepared by the preparation method described in the above technical solution.

[0015] This invention provides a photocatalytic composite material, comprising a fiber fabric substrate, a conductive layer composited on the fiber surface of the fiber fabric substrate, and a photocatalyst loaded on the conductive layer. The photocatalyst comprises nitrogen-doped titanium dioxide-supported single-walled carbon nanotubes and nitrogen-doped titanium dioxide. In this invention, the single-walled carbon nanotubes supported on nitrogen-doped titanium dioxide (denoted as titanium dioxide@carbon nanotubes) are conductive, capable of transferring photogenerated electrons generated by titanium dioxide. This prevents the recombination of photogenerated electrons and holes, improving the reaction efficiency. Moreover, single-walled carbon nanotubes are wire materials, allowing electrons to be transferred along "nanowires," constructing long-range, directional electron transport paths, which can significantly reduce electron-hole recombination. Furthermore, individual nitrogen-doped titanium dioxide particles not combined with carbon nanotubes (denoted as titanium dioxide monomers) can provide superoxide radicals, which, as substrates, are transferred to titanium dioxide@carbon nanotubes to enhance the generation of milder and longer-lived non-radical reactive oxygen species—singlet oxygen. The varying strengths of singlet oxygen and hydroxyl radicals (generated by titanium dioxide and carbon nanotubes) can better reconstruct industrial wastewater. Compared with the prior art, the present invention has the following beneficial effects: The photocatalytic composite material provided by this invention can effectively improve the habitat of industrial wastewater under sunlight, significantly degrade organic pollutants, reduce the proportion of toxic components and the degree of aroma in the water to reduce toxic stress, improve underwater photophysical conditions to allow plants to obtain more light energy, and self-organize and optimize the relative abundance, related pathways and functions among microbial populations, enabling plants to obtain a healthy habitat. Ultimately, this results in increased biomass (plant length, dry weight) and restored Rubisco enzyme activity and PSII fluorescence parameters to normal levels. This invention, through the aforementioned photocatalytic composite material, utilizes photocatalysis to promote the expansion of submerged plant biomass across ecological niches through multi-dimensional habitat optimization via a "chemical-physical-microbial" approach, providing a theoretical basis and technical support for the ecological treatment of industrial wastewater and carbon sequestration by aquatic plants.

[0016] The results of the embodiments show that the solar-responsive photocatalytic composite material provided by the present invention can achieve the degradation of organic pollutants, improvement of optical parameters, and reduction of cyanobacterial dominance; microbial analysis revealed the downregulation of antioxidant genes and the upregulation of metabolic genes, proving the optimization of habitat microbial function; the biomass of submerged plants increased significantly (stem length 2.87 times / dry weight 1.84 times) and the activity of photosynthetic enzymes recovered, reflecting the improvement of carbon fixation capacity; the PLS-PM model elucidates that photocatalysis promotes plant growth across ecological niches through microbial community reconstruction and hydrochemical regulation, with microorganisms being the key driving factor. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the experiment on promoting the growth of large submerged plants in the embodiments. Figure 2 The photocatalytic performance (RhB removal) of photocatalysts obtained with different CNT addition amounts, reaction temperatures, and reaction times was evaluated. Figure 2 In the figure, a represents the photocatalytic performance of four catalysts with different CNT contents, b represents the kinetic fitting curves of four catalysts prepared with different CNT addition amounts, c represents the photocatalytic performance of four catalysts prepared at different reaction temperatures, d represents the kinetic fitting curves of four catalysts prepared at different reaction temperatures, e represents the photocatalytic performance of four catalysts prepared at different reaction times, f represents the kinetic fitting curves of four catalysts prepared at different reaction times, g represents a comparison of the photocatalytic performance of TC-55-10-1, P25 and nitrogen-doped TiO2, h represents the kinetic fitting curves of TC-55-10-1, P25 and nitrogen-doped TiO2, and i represents a radar chart comparing multiple parameters of different TiO2 carbon catalysts. Figure 3 The diagram shows the structural characterization of the synthesized catalyst TC (TC-55-10-1). Figure 3 In the image, a is the XRD pattern of the synthesized catalysts TC, SWCNT, and nitrogen-doped TiO2; b is the diffuse reflectance DRS (inset shows the appearance of the catalyst dispersion sample in the beaker); c is the Tauc pattern; d is the VB-XPS pattern (inset is a local magnification of the energy range from 1.6 eV to 3.8 eV); e is the FTIR pattern; f is the PL spectrum of nitrogen-doped TiO2 and TC; g is the TEM image of nitrogen-doped TiO2; h is the TEM image of SWCNT; and i is the TEM image of catalyst TC. Figure 4 The image shows the degradation effect of Rhodamine B (RhB) on PET fabric immobilized with TC-55-10-1. Figure 4In the figure, a represents the results of fifty cycles of degradation test of RhB dye on TC functional fabric; b represents the contact mode FTIR spectra of the fabric before (B50) and after (A50) cycle test; c~e represent the TEM images of TC fabric before cycle test, with c~e corresponding to fiber, C distribution, and Ti distribution respectively; f~h represent the TEM images of TC fabric after test, with f~h corresponding to fiber, C distribution, and Ti distribution respectively; i represents the treatment efficiency of TC fabric on humic acid and humic acid-PAM mixture under simulated sunlight irradiation; j represents the treatment efficiency of TC fabric on industrial wastewater under simulated sunlight irradiation; and k represents the aquatic biological safety test and evaluation results of Daphnia davidii. Figure 5 This image shows the effect of water treatment on TC / PET fabrics. Figure 5 a) shows the 3D-EEM results of the raw water at W-1; b) shows the 3D-EEM results of the water treated with PET fabric; c) shows the 3D-EEM results of the water treated with TC / PET fabric at W0; d) shows the change in absorbance (Abs) at 420 nm, and the inset shows photographs of the TC / PET treatment group and the PET blank group under sunlight; e~i show the changes in water quality chemical indicators during the photocatalytic pretreatment stage (W-1 to W0), e corresponds to E2 / E3, f corresponds to E4 / E6, g corresponds to TOC and IC, h corresponds to COD, and i corresponds to B / C; Figure 6 This image shows the microbial community profiles of the biofilm layer (W) near the light-receiving surface of the fabric under photocatalytic (T) and blank (B) fabric treatments, and on the leaf surface (L) during plant cultivation. Figure 6 In the diagram, a represents the microbial diversity index; b represents the Venn diagram of phylum-level distribution; c represents the relative abundance of phylum-level microbial communities; and d represents the heatmap of genus-level bacterial communities. Figure 7 Extended error bar analysis of predicted microbial pathways and functions in water samples (W) and leaf samples (L) from the photocatalytic (T) and control (B) groups (p<0.05). Figure 7 In the diagram, a represents water sample pathway prediction, b represents leaf sample pathway prediction, c represents water sample function prediction, and d represents leaf sample function prediction. Figure 8 The changes in relevant indicators of Ceratophyllum demersum growth after industrial wastewater treatment. Figure 8 In the middle section, a represents the comparison of the appearance and plant length of *Ceratophyllum demersum* under two industrial wastewater treatment environments at time points W0 and W3; b~f represent the comparative trends of length, wet weight, dry weight, Rubisco activity, and chlorophyll fluorescence level between the treatment group and the control group, respectively; and g represents the change in dissolved oxygen level. Figure 9 This study explores the potential mechanism by which TC fabrics enhance the photosynthetic performance of Ceratophyllum demersum through the regulation of the physicochemical-biological microenvironment and microbial community. Figure 9In the middle, a is the partial least squares path model (PLS-PM); b is the band structure and reactive oxygen species (ROS) generation mechanism of the composite material on the surface of the TC / PET fabric device, and the resulting changes in various habitat indicators. Figure 10 XPS spectrum of TC (TC-55-10-1), ROS generation signal of TC, and ROS generation signal of nitrogen-doped TiO2. Figure 10 In the diagram, a~c represent the XPS spectra of TC, where a corresponds to Ti 2p, b to C 1s, and c to O 1s; d~f represent the reactive oxygen species (ROS) generation signals of TC, where d corresponds to hydroxyl radicals, e to superoxide anion radicals, and f to singlet oxygen; g~i represent the ROS generation signals of nitrogen-doped TiO2, where g corresponds to hydroxyl radicals, h to superoxide anion radicals, and i to singlet oxygen XPS spectra. Detailed Implementation

[0018] The present invention provides a photocatalytic composite material comprising a fiber fabric substrate, a conductive layer composited on the fiber surface of the fiber fabric substrate, and a photocatalyst supported on the conductive layer, wherein the photocatalyst comprises nitrogen-doped titanium dioxide supported on single-walled carbon nanotubes and nitrogen-doped titanium dioxide.

[0019] In this invention, the material of the fiber fabric substrate is preferably polymer fiber, more preferably polyethylene terephthalate (PET) fiber. In the embodiments of this invention, the fiber fabric substrate is preferably a hexagonal mesh with a fiber diameter of 130µm, a thickness of 0.5mm, and a mesh diameter of 0.2cm.

[0020] In this invention, the conductive agent in the conductive layer is preferably a single-walled carbon nanotube. The introduction of the conductive agent has the following effects: (1) improving the surface state of the fiber fabric substrate and better combining the photocatalytic material; (2) enhancing the conductivity of the substrate, reducing the electron-hole recombination rate of the photocatalytic material, and improving the reaction efficiency.

[0021] In this invention, the photocatalyst is specifically loaded on both sides of a fiber fabric substrate with a conductive layer. In this invention, the nitrogen-doped titanium dioxide-supported single-walled carbon nanotubes specifically consist of nitrogen-doped titanium dioxide coating the outer surface of the single-walled carbon nanotubes. In this invention, the mass of nitrogen-doped titanium dioxide in the nitrogen-doped titanium dioxide-supported single-walled carbon nanotubes is preferably 70-80% of the total mass of nitrogen-doped titanium dioxide in the photocatalytic composite material; the loading amount of the photocatalyst on the fabric substrate is preferably 0.05-0.3 mg / cm³. 2 More preferably, it is 0.1~0.3 mg / cm³. 2 More preferably, it is 0.1~0.2 mg / cm³. 2In this invention, the nitrogen-doped titanium dioxide-supported single-walled carbon nanotubes are referred to as titanium dioxide@carbon nanotubes, and the nitrogen-doped titanium dioxide without composite single-walled carbon nanotubes is referred to as titanium dioxide monomer.

[0022] In this invention, the introduction of nitrogen into the nitrogen-doped titanium dioxide enhances the material's absorption response to visible light. In this invention, the single-walled carbon nanotubes are one-dimensional carbon materials with electrical conductivity, capable of transferring photogenerated electrons generated by titanium dioxide. This prevents the recombination of photogenerated electrons and holes, improving the reaction efficiency. Furthermore, single-walled carbon nanotubes are wire materials, allowing electrons to be transferred along the "nanowires," constructing long-range, directional electron transport paths, which significantly reduces electron-hole recombination.

[0023] In this invention, the structural design of nitrogen-doped titanium dioxide coated with single-walled carbon nanotubes avoids direct contact between plants and carbon nanotubes in industrial wastewater, helping to reduce the phytotoxicity of the material. Fixing the photocatalyst on a fabric substrate prevents particulate matter from depositing on plant leaves, thus preventing light attenuation and oxidative stress that could damage plant growth. The low-load carbon nanotube design improves electron transfer efficiency and underwater transmittance, providing a crucial material basis for efficient wastewater remediation. Furthermore, individual nitrogen-doped titanium dioxide particles not combined with carbon nanotubes (i.e., titanium dioxide monomers) can provide superoxide radicals, which act as substrates for titanium dioxide@carbon nanotubes to enhance the generation of singlet oxygen. Superoxide is a relatively mild and longer-lived non-radical reactive substance. Unlike hydroxyl radicals, it exhibits some reaction selectivity, primarily attacking electron-rich systems such as double bonds (olefins, aromatic rings) and sulfides, while hydroxyl radicals are non-selective and can react rapidly with almost any organic molecule they encounter (proteins, lipids, DNA). This combination of strong and weak radicals allows for better remodeling of industrial wastewater.

[0024] In this embodiment of the invention, the photocatalytic composite material is also referred to as TC photocatalytic functional fabric (represented as TiO2@SWCNT / PET fabric material).

[0025] The photocatalytic fabric of TiO2@SWCNT / PET provided by this invention, which is responsive to sunlight and environmentally friendly, can effectively transform the industrial wastewater habitat: organic pollutants are significantly degraded (three-dimensional fluorescence intensity decreases by 80%; aromaticity index E4 / E6 decreases by 53.34%), and key optical parameters are improved (Abs). 420The biomass of cyanobacteria decreased by 58.8%, and the dominance of cyanobacteria declined. Microbial community analysis showed that the expression of the antioxidant defense gene (K07393) was downregulated, while the expression of the metabolic activity gene (K00500) was upregulated. Under these optimized conditions, the biomass of the large submerged plant *Ceratophyllum demersum* was significantly increased, with a 2.87-fold increase in plant length and a 1.84-fold increase in dry weight. Partial least squares path model (PLS-PM) results showed that photocatalysis mainly occurred through the reconstruction of the microbial community (0.984). ) and water chemical changes (-0.783) This affects plant growth. It is noteworthy that the direct effect of microbial factors on plant growth (0.911) is significant. Stronger than physical factors (-0.197) These results demonstrate that photocatalysis promotes aquatic carbon sequestration across ecological niches by reshaping microenvironmental conditions, particularly through microbial community reorganization. Using the photocatalytic composite material provided in this invention to treat industrial wastewater allows for the simultaneous achievement of industrial wastewater treatment and carbon neutrality goals, bringing dual benefits to environmental remediation and climate change mitigation.

[0026] This invention provides a method for preparing the photocatalytic composite material described above, comprising the following steps: A photocatalyst is obtained by hydrothermal reaction of nitrogen-doped nano-titanium dioxide, carboxylated single-walled carbon nanotubes, and water. The photocatalyst comprises single-walled carbon nanotubes supported on nitrogen-doped titanium dioxide and nitrogen-doped titanium dioxide. The mass ratio of nitrogen-doped nano-titanium dioxide to carboxylated single-walled carbon nanotubes is (1.2~1.8):(0~0.0012), and the mass of carboxylated single-walled carbon nanotubes is not zero. After impregnating the fiber fabric substrate in a dispersion of conductive agent, it is heated and cured to obtain a fiber fabric substrate with conductive agent. The fiber fabric substrate with the conductive layer is impregnated in the dispersion of the photocatalyst and then heated and cured to obtain the photocatalytic composite material.

[0027] Unless otherwise specified, all raw materials involved in this invention are commercially available products well known in the art.

[0028] The present invention involves mixing nitrogen-doped nano-titanium dioxide, carboxylated single-walled carbon nanotubes, and water to carry out a hydrothermal reaction to obtain the photocatalyst.

[0029] In this invention, the particle size of the nitrogen-doped nano-titanium dioxide is preferably 5-10 nm, and the atomic percentage of nitrogen in the nitrogen-doped nano-titanium dioxide is preferably 1-5%. In this embodiment, the nitrogen-doped nano-titanium dioxide is purchased from Ningbo Jiwei Nanomaterials Technology Co., Ltd., model JWN-TO-A01 (elemental analysis shows that the atomic percentage of nitrogen is approximately 3.5%). In this embodiment, the length of the carboxylated single-walled carbon nanotubes is preferably 1-3 μm, the diameter is preferably 1-2 nm, the carboxyl content is preferably 2.73 wt%, and the specific surface area is preferably >380 m². 2 / g. In this invention, the mass ratio of nitrogen-doped nano-titanium dioxide to carboxylated single-walled carbon nanotubes is (1.2~1.8):(0~0.0012) (the mass of carboxylated single-walled carbon nanotubes is not 0), which can be 1.5:0.0004, 1.5:0.0008, or 1.5:0.0012, preferably 1.5:0.0004. In this invention, if too much carboxylated single-walled carbon nanotubes are added, the proportion of carbon nanotubes in the resulting photocatalytic composite material will be large, which will have a shielding effect, affecting the absorption and conversion of photon energy by titanium dioxide, thereby affecting the reaction efficiency; if too little carboxylated single-walled carbon nanotubes are added, the relative content of titanium dioxide will be large, which cannot effectively transfer electrons, reducing the electron-hole recombination of titanium dioxide itself, which will also affect the reaction efficiency. In this invention, the water is preferably deionized water, and the ratio of nitrogen-doped nano-titanium dioxide to water is preferably (1.2~3)g:(50~500)mL, which can be 1.5g:100mL.

[0030] In this invention, the preferred method for mixing the nitrogen-doped nano-titanium dioxide, carboxylated single-walled carbon nanotubes, and water is as follows: The nitrogen-doped nano-titanium dioxide is added to water for a first mixing to obtain a TiO2 suspension; then, carboxylated single-walled carbon nanotubes are added to the TiO2 suspension for a second mixing. In this invention, both the first and second mixing are preferably performed under ultrasonic conditions. In an embodiment of this invention, the carboxylated single-walled carbon nanotubes are added in the form of a carboxylated single-walled carbon nanotube dispersion, and the mass fraction of the carboxylated single-walled carbon nanotube dispersion is 2‰.

[0031] In this invention, the mixed slurry obtained by mixing nitrogen-doped nano-titanium dioxide, carboxylated single-walled carbon nanotubes and water is transferred to a polytetrafluoroethylene-lined stainless steel autoclave for hydrothermal reaction; the filling rate of the polytetrafluoroethylene-lined stainless steel autoclave is preferably 80% to avoid volume expansion during the hydrothermal process.

[0032] In this invention, the hydrothermal reaction is preferably carried out under microwave irradiation; the temperature of the hydrothermal reaction is 120~170℃, which can be 120, 135, 155 or 170℃, and the holding time is preferably 5~20min, which can be 5, 10, 15 or 20min; the power of the microwave irradiation is preferably 1500W. During the hydrothermal reaction, the hydroxyl-OH groups on the surface of nitrogen-doped nano-titanium dioxide and the carboxyl-COOH groups on the surface of carboxylated carbon nanotubes undergo a condensation reaction to form chemical bonds (generating Ti-OC bonds), causing the titanium dioxide particles to self-assemble and encapsulate on the surface of the carbon nanotubes, forming a structure of single-walled carbon nanotubes supporting nitrogen-doped titanium dioxide (titanium dioxide@carbon nanotube composite), while the unencapsulated nitrogen-doped titanium dioxide is distributed around the periphery of the composite material, forming the photocatalyst. This invention prepares the photocatalyst via a microwave-assisted hydrothermal method, combining the advantages of hydrothermal and microwave reactions. Hydrothermal treatment increases the pressure of the synthesis reaction system, controlling crystal growth to prevent excessive growth (crystal size 5-10 nm), while microwaves improve reaction efficiency and reduce energy consumption (shortening reaction time and lowering reaction temperature). In this invention, the hydrothermal reaction yields an aqueous dispersion containing the photocatalyst.

[0033] The present invention involves impregnating a fiber fabric substrate in a dispersion of a conductive agent and then heating and curing it to obtain a fabric substrate with a conductive agent layer.

[0034] In this invention, the fiber fabric substrate is preferably pretreated before use. The pretreatment preferably includes washing, drying and cutting the fiber fabric substrate in sequence. The washing reagent preferably includes water and anionic surfactant. The drying temperature is preferably 80~120℃. The cutting size can be determined according to actual needs. For example, when used for photocatalytic performance evaluation experiments, the size can be 5cm×5cm. When used for outdoor photodegradation of industrial wastewater, the size can be 19.5cm×14.5cm.

[0035] In this invention, the mass fraction of the conductive agent in the dispersion is preferably 0.4‰, and the dispersion is specifically an aqueous dispersion of the conductive agent. In this invention, the impregnation time is preferably 5 minutes; the heating and curing temperature is preferably 80~150℃, and the time is preferably 5~15 minutes; the impregnation and heating / curing operations can be performed once or multiple times, with the final fabric substrate with the conductive layer having a resistance below 10kΩ.

[0036] After obtaining the fiber fabric substrate with the conductive layer, the present invention impregnates the fiber fabric substrate with the conductive layer in the dispersion of the photocatalyst and then heats and cures it to obtain the photocatalytic composite material.

[0037] In this invention, the concentration of the photocatalyst in the dispersion (specifically, suspension) is preferably 2.5 g / L. In an embodiment of this invention, the dispersion of the photocatalyst is obtained by diluting the aqueous dispersion containing the photocatalyst obtained from the above hydrothermal reaction with water. In this invention, the dispersion of the photocatalyst preferably also includes an aqueous polyurethane resin, preferably Covestro's Impranil® DLI, and the volume of the aqueous polyurethane resin is preferably 1.0% of the volume of the dispersion of the photocatalyst. In this invention, the aqueous polyurethane resin, as an additive, has its own polymer skeleton that can support TiO2 particles, preventing particle aggregation, and also acts as a bonding agent to bind the photocatalyst to the fiber fabric substrate. It also has the characteristics of long-term resistance to outdoor ultraviolet radiation and water immersion, preventing the photocatalyst nanomaterials from detaching.

[0038] In this invention, the steps of impregnating the fiber fabric substrate with the conductive layer in the dispersion of the photocatalyst and then heating and curing it are performed multiple times to ensure that the loading of the photocatalyst on the fiber fabric substrate is 0.05~0.3 mg / cm³. 2 For accuracy, the load is specifically obtained by weighing the fabric before and after impregnation using a balance and calculating based on the area of ​​the fiber fabric. In this invention, the heating and curing temperature is preferably 80~150℃, and the heating and curing time for a single session is preferably 5 minutes; after each impregnation, the impregnated fabric substrate is ultrasonically rinsed to remove loosely bonded particles and excess additives, and then the heating and curing is performed.

[0039] This invention provides the application of the photocatalytic composite material described in the above technical solutions or the photocatalytic composite material prepared by the above technical solutions in industrial wastewater treatment.

[0040] This invention provides a method for reconstructing industrial wastewater habitats, comprising the following steps: A photocatalytic composite material is applied to industrial wastewater to treat the wastewater under light conditions; the industrial wastewater contains submerged plants and microorganisms; the photocatalytic composite material is the photocatalytic composite material described in the above technical solution or the photocatalytic composite material prepared by the preparation method described in the above technical solution.

[0041] In this invention, the industrial wastewater is preferably industrial wastewater mainly polluted by humic substances. In this invention, the method of applying the photocatalytic composite material is preferably to spread the photocatalytic composite material on the water surface. In this invention, the illumination condition is visible light.

[0042] Submerged plants are not only an important biomass resource, but their biological carbon sequestration process is also a crucial carbon sequestration pathway. However, the input of industrial wastewater threatens their survival by altering the chemical, physical, and biological indicators of aquatic habitats. Traditional approaches to industrial wastewater treatment primarily focus on reducing organic components, neglecting the in-situ functional microorganisms and other beneficial components within the wastewater, and potentially causing new ecological disasters. Current ecological treatment technologies mainly address this issue by adding enhanced versions of microorganisms or enzymes, but the sensitivity of industrial wastewater to pH or toxicity limits their effectiveness. Adsorbent methods, on the other hand, suffer from issues such as incomplete pollutant removal and the risk of pollutant transfer. In the context of industrial wastewater, to ensure the smooth progress of submerged plant carbon sequestration, this invention introduces the principle of "ecological restoration" into wastewater treatment, proposing a novel strategy of "photocatalytically mediated industrial wastewater habitat reconstruction." By developing and utilizing TiO2@SWCNT / PET fabric material, pretreatment through sunlight exposure reduced the proportion of toxic components and aromaticity in the water, thus mitigating toxic stress. This improved underwater photophysical conditions, allowing plants to acquire more light energy. Furthermore, it self-organized and optimized the relative abundance, pathways, and functions of microbial populations, resulting in a healthy habitat for the plants. Ultimately, this led to increased biomass (plant length, dry weight) and restored Rubisco enzyme activity and PSII fluorescence parameters to normal levels. The PLS-PM model revealed that photocatalysis directly affected various habitat indicators, primarily impacting microorganisms, and also influenced plant biomass through cross-niche processes. This invention utilizes photocatalytic-mediated treatment to promote submerged plant biomass expansion through multi-dimensional "chemical-physical-microbial" habitat optimization across ecological niches, providing a theoretical basis and technical support for the ecological treatment of industrial wastewater and carbon sequestration by aquatic plants.

[0043] To further illustrate the present invention, the following detailed descriptions, in conjunction with examples, illustrate the photocatalytic composite materials, their preparation methods, applications, and industrial wastewater habitat reconstruction methods provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0044] The chemicals and materials used in the examples are as follows: Nitrogen-doped nano-titanium dioxide (JWN-TO-A01, Ningbo Jiwei Nanomaterials Technology Co., Ltd., China), TiO2 (Aeroxide P25, Evonik, Germany), single-walled carbon nanotubes (carboxylated) aqueous dispersion (2wt‰ TNWDSC, Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, China), C 28 H 31ClN2O3 (Rhodamine B, RhB, ≥99.0%, AR, Aladdin, China), anhydrous ethanol (≥99.0%, water ≤0.005%), polyurethane resin (Impranil® DLI, Covestro, Germany), humic acid (fulvic acid ≥90%, Aladdin, China), (C3H5NO) n (Polyacrylamide, PAM, anionic, M) n =1.6×10 7 The ultrapure water had a conductivity of 18.2 MΩ·cm (Milli-Q, Millipore, USA). Polyester hexagonal mesh (PET, green, fiber diameter = 130µm, thickness = 0.5mm, mesh diameter = 0.2cm) was purchased from Jiangyin Jixing Garment Co., Ltd. Industrial wastewater was provided by Jiangsu Tianbo Packaging Co., Ltd. Healthy and morphologically similar large submerged plants, such as *Ceratophyllum demersum* (Goldfishweed), were also used. Ceratophyllum demersum L. The sample was taken from the Meiliang Lake Bay area of ​​Taihu Lake (longitude 120.219679°E; latitude 31.418187°N).

[0045] Example 1 The preparation of photocatalytic composite materials is as follows: (1) Preparation of photocatalyst (microwave-assisted hydrothermal method): 1.5 g of nitrogen-doped titanium dioxide (JWN-TO-A01, abbreviated as N-TiO2) was uniformly dispersed in 100 mL of deionized water under ultrasonic radiation (KQ-700E, Kunshan Ultrasonic Instrument Co., Ltd., China). 0.2 mL of single-walled carbon nanotube dispersion (2wt‰) was added to the TiO2 suspension, followed by a second ultrasonic treatment to ensure uniform dispersion. The resulting mixed slurry was transferred to a 50 mL polytetrafluoroethylene-lined stainless steel autoclave with a filling rate of 80%. The reaction system was irradiated with microwave (Master, Xinyi, China, power 1500W), the reaction temperature was 155℃, and the reaction time was 10 min, resulting in a gray suspension, i.e., the photocatalyst suspension, denoted as TiO2@SWCNT material, abbreviated as TC material. The TC material prepared in Example 1 is denoted as TC-55-10-1.

[0046] (2) Preparation of photocatalytic composite material (TC photocatalytic functional fabric): The PET hexagonal mesh fabric underwent preliminary treatment: washing with water and anionic surfactant, followed by drying at 120°C. It was then cut into small pieces of the required size (e.g., 5 cm × 5 cm for photocatalytic performance evaluation, and 19.5 cm × 14.5 cm for outdoor photodegradation of industrial wastewater). Single-walled carbon nanotubes (SWCNTs) and TC materials were fixed onto the fabric substrate surface via an impregnation loading / thermosetting scheme. Specifically: the fabric was immersed in a 0.4 wt‰ SWCNT aqueous dispersion (diluted from a 2 wt‰ SWCNT aqueous dispersion) for 5 min, followed by heating and curing at 80°C for 5 min under normal pressure; the resulting fabric substrate composited with SWCNTs was then treated with a 2.5 g / L TC material suspension (containing 1.0 v / v% additive polyurethane resin). After each impregnation, the fabric was ultrasonically washed to remove loosely bonded particles and excess additives, and then dried at 80°C for 5 min, ultimately successfully preparing the functional fabric loaded with the material. The load density of the fabric was obtained by weighing it before and after loading using a balance and calculating it based on the fabric area (the load of TC material on the fabric is 0.24 ± 0.02 mg / cm²). 2 ).

[0047] Examples 2-9 and Comparative Examples The preparation processes of photocatalytic composite materials (TC catalytic functional fabric) in Examples 2-9 and the comparative examples are the same as those in Example 1. The difference from Example 1 is that the amount of single-walled carbon nanotube dispersion, reaction temperature, and reaction time in step (1) of photocatalyst preparation are adjusted according to Table 1, and the rest are the same as in Example 1. The TC materials prepared in Examples 2-9 and the comparative examples are respectively denoted as TC-55-10-2, TC-55-10-3, TC-20-10-1, TC-35-10-1, TC-70-10-1, TC-55-5-1, TC-55-15-1, TC-55-20-1, and TC-55-10-0.

[0048] Table 1 shows the amount of single-walled carbon nanotube dispersion, reaction temperature, and reaction time used in the preparation of photocatalysts in Examples 2-9 and the comparative examples.

[0049] The performance of the photocatalysts and photocatalytic composite materials obtained in each embodiment was tested, as follows: (1) Preparation of glass slide samples for coating hardness testing Polyurethane resin (Impranil® DLI) was added to the TC-55-10-1 sample at ratios of 0 v / v%, 0.27 v / v%, 0.5 v / v%, 1 v / v%, and 2 v / v% to prepare dispersions (TC-55-10-1 concentration in the dispersions was 2.5 g / L). 200 μL of each sample was dropped onto one side of a clean 5 cm × 5 cm × 3 mm glass slide, spread evenly, and then spin-coated using a spin coater (MSC-100T, Kehao, China) at 1000 r / min and 300 m / s. 2 The coating was applied for 10 s under (acceleration) conditions. The coated slide was then placed in an 80°C forced-air oven (GZX-9240MBE, Boxun, China) and heated for 90 s. This coating process was repeated 20 times.

[0050] The addition amounts of polyurethane resin of 0.27%, 0.5%, 1%, and 2% corresponded to coating hardness of 2H, 2H, 3H, and HB, respectively.

[0051] (2) Characterization For the catalyst samples: X-ray diffraction (XRD) patterns were obtained using a diffractometer (AXS D8, Bruker, Germany) with a 2θ scan range of 5–80° and a scan rate of 2° / min. Diffuse reflectance (DRS) spectra of the materials were measured using a UV-Vis-NIR spectrophotometer (UV3600IPLUS, Shimadzu, Japan) in the wavelength range of 200–1600 nm. Valence band X-ray photoelectron spectroscopy (VB-XPS) measurements were performed using an XPS instrument (Nexsa G2, Thermo Scientific, USA). Instrument conditions included a monochromatic Al Kα X-ray source, a 400 μm beam size, a full scan pass energy of 100 eV with a step size of 1.0 eV, and a narrow scan pass energy of 50 eV with a step size of 0.05 eV. Fourier transform infrared (FTIR) spectroscopy was performed using a Fourier transform infrared spectrometer (Nicolet iS10, ThermoFisher Scientific, USA) equipped with a diamond ATR (attenuated total reflectance) accessory. Photoluminescence (PL) analysis was performed on the photocatalyst powder using a fluorescence spectrometer (F-4600, Hitachi, Japan). The morphology and size of the catalyst samples were characterized by transmission electron microscopy (TEM, Tecnai 12, Philips, Netherlands). X-ray photoelectron spectroscopy (XPS) analysis was performed on the core energy level regions of Ti 2p, C 1s, and O 1s using an XPS instrument (Nexsa G2, Thermo Scientific, USA). Instrument conditions included a monochromatic Al Kα X-ray source, a 400 μm beam size, a full scan pass energy of 100 eV with a step size of 1.0 eV, and a narrow scan pass energy of 50 eV with a step size of 0.05 eV. Electron paramagnetic resonance (EPR) spectroscopy was performed using a spectrometer (EMX PLUS, Bruker, Germany) to continuously scan and detect ·OH and ·OH in the magnetic field strength range of 3450–3560 G. 1 O2 and ·O2 - Signal.

[0052] For fabric samples: To evaluate the surface microstructure of the mesh before and after long-term cyclic photodegradation testing, SEM and EDS (JSM-7800 Prime, JEOL, Japan) imaging was used. Infrared testing procedures for the fabric followed the material testing methods. The eco-friendliness of the functional fabric was assessed using an aquatic ecotoxicity monitor (TQEW-DZ-3002, Tianquan, China) by recording the movement behavior of water fleas in circulating water soaking the fabric under LED white light (8 W).

[0053] For water samples: Rhodamine B concentration was monitored at 554 nm in the preparation of standard curves and evaluation of degradation efficiency; while HA (humic acid) dispersion, APAM (anionic polyacrylamide) modified HA dispersion, and industrial wastewater were analyzed at 215 nm. Three-dimensional fluorescence excitation-emission matrix spectrometry (3D-EEMs) of the water samples was measured using a fluorescence spectrophotometer (F-7000, Hitachi, Japan) at excitation wavelengths of 200–600 nm and emission wavelengths of 200–500 nm. Vibrio fischeri assay was performed according to ISO 11348-3:2007.

[0054] (3) Evaluation of photocatalytic performance The absorbance of a series of Rhodamine B (RhB) aqueous solutions of different concentrations was measured at 554 nm to establish a standard calibration curve.

[0055] (3.1) Catalyst: In the photocatalytic degradation performance evaluation, the catalyst and the simulated pollutant RhB were mixed at a mass ratio of m(cat):m(RhB) = 75:1. A 2.5 mg / L RhB solution was used, for example, a typical ratio of 300 mL RhB solution to 3.75 mL of 15 mg / mL TC photocatalytic material suspension. Dark magnetic stirring was performed for 30 minutes before the photocatalytic reaction to ensure adsorption-desorption equilibrium was reached. The light source was a xenon lamp (PLS-SXE300, Perfectlight, China) equipped with a 420 nm cutoff filter to ensure that light below 420 nm was filtered out. The light source was preheated for at least 30 minutes to ensure stable light output. The light intensity at the liquid surface was maintained at 60 mW / cm². 2 Samples were taken every 10 minutes during illumination and centrifuged (H1650, Cence, China) at 8000 r / min for 5 minutes. The supernatant was collected to determine the absorbance. A cold water bath was used to cool the samples during the reaction to reduce evaporation of the reaction solution. The entire test lasted 60 minutes. Comparative tests were also performed on nitrogen-doped TiO2 (JWN-TO-A01), P25 powder, and blank RhB solution.

[0056] (3.2) Fabrics: The procedure was similar to that for glass slide testing. The absorbance of all collected samples was measured at 554 nm using a spectrophotometer (UV5200, Metalash, China). The C0.05 values ​​at each time point were recorded. t / C0 and Ln(C t The / C0) data were plotted as a curve. The photocatalytic removal rate (η) was calculated using the following formula: η = (C0 - C) t ) / C0×100%; Among them, C tC0 represents the endpoint concentration (mg / L) measured at a specific time point, while C0 represents the initial concentration (mg / L) of the sample.

[0057] For photodegradation of fabrics, follow these steps: HA (humic acid): The absorbance of a series of HA aqueous solutions of different concentrations at 215 nm was measured to construct a standard calibration curve. The method is based on a similar procedure to the aforementioned photocatalytic degradation of RhB dyes on fabrics.

[0058] Humic acid-PAM mixture: A humic acid dispersion with a concentration of 30 mg / L was prepared by mixing pure water and humic acid, and then polyacrylamide (PAM) was added to prepare a liquid with a PAM concentration of 25 mg / L, which was used as a simulated wastewater pollutant.

[0059] Industrial wastewater: Wastewater samples were filtered through a 0.22 μm membrane filter before being used for photocatalytic degradation testing. The light source was a xenon lamp simulating sunlight. Performance evaluation was based on absorbance at 215 nm. Since the samples were composite mixtures, absorbance analysis was used instead of concentration analysis; therefore, the concentration term in the formula was replaced with the corresponding absorbance value.

[0060] (4) Goldfish algae growth experiment The initially screened industrial wastewater was transferred to a large intermediate water treatment tank (45 cm × 32 cm × 19 cm deep). TC photocatalytic functional fabric was spread out on the surface of the water in the tank, and an unloaded piece of fabric was placed in another large basin containing the same volume of industrial wastewater as a blank control. Outdoor sunlight treatment was conducted on a rooftop. The experiment began on June 12, 2025, denoted as W-1; the treatment ended on June 18, 2025, denoted as W0. The water treated with sunlight + photocatalytic / non-photocatalytic fabric was transferred to three parallel experimental tanks (29 cm × 16 cm × 15 cm deep) as samples for the corresponding treatment groups. Simultaneously, three tanks of the same size served as blank groups, containing filtered blank control water samples. Healthy, intact-topped (approximately 10 cm long, dry weight 0.4–0.5 g) *Ceratophyllum demersum* (Goldfish Algae) were selected. Ceratophyllum demersum L.The experiment was conducted using cuttings. Six cuttings were evenly arranged in each tank, and their bases were secured with cotton thread. Ceramic planting rings were attached to both ends of the thread for weight, anchoring the base of the plant underwater with the top facing upwards. The entire plant was naturally suspended in the water, forming one group. Three groups of plants were placed in each tank, with six cuttings in each group, for a total of 18 cuttings per tank (3 groups × 6 cuttings / group). Three acclimatization periods of 7 days each were set up: June 18, 2025 (W0) to June 24, 2025; June 25, 2025 (W1) to July 1, 2025; and July 2, 2025 (W2) to July 9, 2025 (W3). CO2 was then introduced to adjust the pH to approximately 6.5 to accelerate plant growth. Based on real-time pH monitoring results, supplemental aeration was performed daily from 8:00 to 10:00 and 14:00 to 16:00, using a pH meter (PHS-3C, Leici, China). Water was added daily to maintain a constant water volume. Sampling was conducted at the initial time point, followed by sampling every 7 days. Samples included both plant material and water samples. Water samples were analyzed for dissolved organic carbon (DOC), chemical oxygen demand (COD), total nitrogen (TN), and NH4+. + -N, NO2 - -N, NO3 - -N, total phosphorus (TP), and dissolved oxygen (DO). Plant sample length, wet weight, dry weight, Rubisco enzyme activity, and chlorophyll fluorescence parameter Fv / Fm were measured. Water quality chemical indicators were tested according to the "Surface Water Environmental Quality Standard" GB3838-2002; dissolved oxygen (DO) was measured using a handheld dissolved oxygen meter (HQ 30d, Hach, USA); Rubisco enzyme activity was measured using a commercial kit (BL1075B, microplate method, Labgic, China); fluorescence parameter levels were assessed using a pulse amplitude modulation (PAM) fluorometer (MINI-PAM-II, Walt, Germany). Absorbance (Abs) values ​​were analyzed within the specified wavelength range using a spectrophotometer (UV-5600PC, Metalash, China) and 1 cm path length quartz cuvettes. On day 20, microbial community samples were collected from the light-receiving surfaces of the photocatalyzed fabric treatment group and the blank fabric treatment group.

[0061] 16S rRNA gene amplification was performed using Phusion® Hot Start Flex 2X Master Mix (NEB, M0536L). PCR reactions were conducted on ice in 0.2 mL tubes with the following components: 2× Master Mix (final concentration 1×), forward primer 341F (final concentration 0.5 μM), reverse primer 805R (final concentration 0.5 μM), and template DNA (volume adjusted according to DNA concentration, with sterile deionized water added to a final reaction volume of 20 μL). The thermal cycling program was performed on an L96G gradient PCR instrument (LongGene, L96G) under the following conditions: initial denaturation at 98℃ for 30 s; 30 cycles (98℃ denaturation for 10 s, 55℃ annealing for 30 s, 72℃ extension for 30 s); and a final extension at 72℃ for 5 min. PCR products were analyzed by 1.5% agarose gel electrophoresis, using a DL2000 DNA Marker (Takara, 3427) as the molecular weight standard. Gel images were acquired using a gel imaging system to confirm successful amplification of the target fragment (approximately 290 bp). Microbial taxa were identified by 16S rRNA gene sequencing, and their functional potential (with a focus on antioxidant and metabolic functions) was predicted using PICRUSt2. Data visualization and statistical analysis were performed using STAMP software (version 9.0, Donovan H. Parks & Robert G. Beiko, Canada).

[0062] (5) Experimental methods and data visualization Figure 1 The workflow of the submerged large-scale plant experiment is demonstrated. Relevant data were visualized and analyzed using Origin (version pro2024b) and R (version 4.5.2).

[0063] The test results are as follows: (1) Photocatalytic performance of TC materials The material preparation parameters were optimized from three dimensions: CNT addition amount, reaction temperature, and reaction time. For example... Figure 2 As shown, Figure 2 The photocatalytic performance (RhB removal) of the photocatalysts obtained with different CNT addition amounts (0 mL, 0.2 mL, 0.4 mL, and 0.6 mL), reaction temperatures, and reaction times was evaluated. Figure 2In the figure, a represents the photocatalytic performance of four catalysts with different CNT contents; b represents the kinetic fitting curves of four catalysts prepared with different CNT addition amounts; c represents the photocatalytic performance of four catalysts prepared at different reaction temperatures (120℃, 135℃, 155℃, and 170℃); d represents the kinetic fitting curves of four catalysts prepared at different reaction temperatures; e represents the photocatalytic performance of four catalysts prepared at different reaction times (5 min, 10 min, 15 min, and 20 min); f represents the kinetic fitting curves of four catalysts prepared at different reaction times; g represents a comparison of the photocatalytic performance of TC-55-10-1, P25, and nitrogen-doped TiO2 (JWN-TO-A01, where N-TiO2 is in g); h represents the kinetic fitting curves of TC-55-10-1, P25, and nitrogen-doped TiO2 (JWN-TO-A01); and i represents a multi-parameter comparison radar chart of different TiO2-carbon catalysts.

[0064] Depend on Figure 2 It can be seen that the photocatalytic efficiency initially increases with the increase of CNT content, and then decreases. The addition dose of 0.2 mL is a turning point, with TC-55-10-1 exhibiting the best photocatalytic performance. With increasing CNT content, the RhB removal efficiencies of TC-55-10-0, TC-55-10-1, TC-55-10-2, and TC-55-10-3 are 96.38%, 99.86%, 97.95%, and 97.45%, respectively. The corresponding reaction rate constants are 0.0608 min⁻¹. -1 0.0888 min -1 0.0707 min -1 and 0.0689 min -1 ,like Figure 2 As shown in Figure b and Table 2, appropriate addition of carbon nanotubes can improve the transfer rate of photogenerated electrons, thereby reducing the catalytic performance inhibition caused by carrier recombination. However, excessive addition of carbon nanotubes can lead to a light-blocking effect, resulting in a decrease in catalytic performance.

[0065] The effect of reaction temperature on catalyst performance was investigated by setting four reaction temperatures: 120℃, 135℃, 155℃, and 170℃. As the temperature increased, the catalytic performance initially improved, then decreased. Figure 2 As shown in Figure c, after 60 minutes, the degradation rates of the four samples were 97.74%, 98.79%, 99.86%, and 91.90%, respectively. Figure 2 As shown in Table 2, the corresponding reaction rate constants are 0.069 min. -1 0.080 min -1 0.0888 min -1 and 0.0427 min-1 Under the test conditions, the catalyst sample prepared at 155℃ exhibited the best photocatalytic performance.

[0066] As the reaction time increases, the catalytic performance of the obtained catalyst shows a trend of first increasing, then decreasing, and then increasing again. For example... Figure 2 As shown in Figure e, after 60 minutes, the RhB removal rates of the four samples were 97.84%, 99.86%, 97.65%, and 98.45%, respectively. The corresponding reaction rate constants were 0.069 min. -1 0.0888 min -1 0.0674 min -1 and 0.0755min -1 ,like Figure 2 As shown in Table 2, under the test conditions, the catalyst sample prepared with a reaction time of 10 min exhibited the best photocatalytic performance. Compared with adjusting the CNT component ratio and reaction temperature, the change in reaction time had a relatively small impact on performance within the study range. Among these three parameters, reaction temperature was determined to be the most influential factor.

[0067] like Figure 2 As shown in g, P25, nitrogen-doped TiO2, and TC-55-10-1 achieve a power output of 60 mW / cm². 2 The degradation efficiencies after irradiation with visible light (λ>420 nm) for 60 minutes were 12.14%, 84.99%, and 99.86%, respectively. Kinetic studies ( Figure 2 The data (h) indicates that the reaction rate constants for the three samples are 0.00219 min⁻¹. -1 0.0313 min -1 and 0.0888 min -1 .

[0068] Furthermore, a comprehensive analysis of various TiO2-carbon binary catalysts reported in the literature was conducted based on four dimensions (catalytic performance, light source, reaction dosage, and processing temperature). A scoring standard was then established (Tables 3 and 4), and a radar chart was constructed. Figure 2 (i) Radar chart scoring rules: (1) Catalyst photodegradation performance: P (removal rate) = 100%, score = 5; 90% < P ≤ 99%, score = 4; 70% < P ≤ 89%, score = 3; 50% < P ≤ 69%, score = 2; P ≤ 49%, score = 1. (2) Light source type: λ ≥ 420nm, score = 5; UV-Vis, score = 4; UV-Vis-IR, score = 3; λ ≤ 400nm, score = 2; NA, score = 1. (3) Catalyst dosage: use the formula score = 5 - log 10(Dosage) Calculate the score by mapping the dosage value to a standardized range of 0 to 5. If the dosage is NA (dosage not specified), then 1 point is awarded. (4) Material synthesis temperature: T≤200℃, 5 points; 200℃<T≤400℃, 4 points; 400℃<T≤600℃, 3 points; 600℃<T≤800℃, 2 points; T>800℃, 1 point. This shows the performance advantage of TiO2-CNT composite material in TiO2-carbon series materials.

[0069] Table 2. Photocatalytic performance of photocatalysts prepared under different conditions

[0070] Table 3 Comparison of conditions and effects of different TiO2-carbon binary catalysts on RhB degradation

[0071] Note: In Table 3, TiO2 / graphdiyne is a titanium oxide / graphdiyne composite material (graphdiyne assembled onto titanium oxide); TiO2@Gr / SERS indicates a graphene shell layer grown on the surface of a 3D urchin-shaped TiO2 core layer on a silicon (Si / SiO2) substrate; TiO2@AC indicates activated carbon material encapsulated in titanium oxide microspheres; AC / TiO2 indicates activated carbon microspheres loaded on the surface of titanium oxide microspheres; CQDs / TiO2NPs indicates carbon quantum dots loaded on the surface of titanium oxide nanospheres.

[0072] Table 4 Summary of radar scores for catalyst formulation parameters based on specified rules

[0073] Figure 3 The diagram shows the structural characterization of the synthesized catalyst TC (TC-55-10-1). Figure 3 In the diagram, 'a' represents the synthesized catalysts TC, SWCNT, and nitrogen-doped TiO2 (JWN-TO-A01). Figure 3 The XRD pattern of the catalyst (as shown in the inset) is as follows: b is the diffuse reflectance DRS (the inset shows the appearance of the catalyst dispersion sample in the beaker), c is the Tauc pattern, d is the VB-XPS pattern (the inset is a local magnification of the energy range from 1.6 eV to 3.8 eV), e is the FTIR pattern, f is the PL spectrum of TiO2 and TC, g is the TEM image of nitrogen-doped TiO2, h is the TEM image of SWCNT, and i is the TEM image of the catalyst TC.

[0074] like Figure 3As shown in Figure a, the XRD pattern of TC-55-10-1 is generally similar to that of nitrogen-doped TiO2, but the difference lies in the fact that TC material exhibits a mixed phase of anatase and brookite, while nitrogen-doped TiO2 is a mixed phase of anatase and rutile. Due to the introduction of CNTs, the overall XRD peak signal of the material is slightly shifted to a lower angle. Furthermore, a broad peak appears in the 10–25° range, which may be due to lattice changes caused by CNT embedding. Figure 3 The DRS data shown in b and c indicate that the band gap energies (Eg) of TiO2 and TC materials are approximately 2.91 eV and 2.60 eV, respectively. Figure 3 The figure shows the VB-XPS spectra of TC material and nitrogen-doped TiO2, indicating that the valence band positions of the two materials are at 2.74 eV and 2.56 eV, respectively. Figure 3 FTIR results from the middle e show that CO-Ti bonds exist in the TC material, corresponding to 1054 cm⁻¹. -1 The peak at that location.

[0075] Figure 3 The PL spectra of TC material and TiO2 shown in Figure f indicate that the addition of CNTs promotes the effective separation of electron-hole pairs, which is confirmed by the decrease in PL intensity. Figure 3 Images g, h, and i in the figure show TEM images of nitrogen-doped TiO2, SWCNTs, and TC materials, respectively. Nitrogen-doped TiO2 consists of short, elliptical particles with a size of 5–10 nm. Most SWCNTs have a diameter of 10–20 nm. For TC materials, the introduction of SWCNTs causes the particles to aggregate on the surface of one-dimensional SWCNTs, forming a columnar structure with a relatively large diameter (100–160 nm), where CNTs form the core and TiO2 forms the coating layer (titanium oxide@carbon nanotubes). The unbound TiO2 particles scattered around the columnar structure indicate the presence of an excess of TiO2, with an excess of 18,000–20,000 particles / μm. 2 The areal density distribution is present around the titanium oxide@carbon nanotube composite material, with titanium oxide monomers distributed at a distance of 50 nm to 100 nm from the titanium oxide@carbon nanotube composite material (titanium oxide monomer particles distributed at a distance of 50 nm to 100 nm from the titanium oxide@carbon nanotube composite material account for 50 to 60% of the excess TiO2), which provides superoxide anion free radicals·O2. - As a substrate, it is transferred to titanium oxide@carbon nanotubes to enhance the generation of singlet oxygen, and titanium oxide@carbon nanotubes have a singlet oxygen content of 5~15 per μm. 2 Areal density distribution. This TiO2 self-assembled SWCNT coating structure design avoids direct contact between plants and SWCNTs, helping to reduce the material's phytotoxicity.

[0076] (2) Pollutant removal performance and aquatic organism safety test of TC immobilized PET fabric To prevent particulate matter from depositing on plant leaves, causing light attenuation and inducing oxidative stress, thereby damaging plant growth, functional fabrics were further prepared through material immobilization. Figure 4 The image shows the degradation effect of Rhodamine B (RhB) on PET fabric immobilized with TC-55-10-1. Figure 4 In the figure, a represents the 50-cycle degradation test results of RhB dye on the TC photocatalytic functional fabric (TC-55-10-1 immobilized PET fabric); b represents the contact mode FTIR spectra of the fabric before (B50) and after (A50) the cycle test; c~e represent the TEM images of the TC fabric before the cycle test, with c~e corresponding to fiber, C distribution, and Ti distribution respectively; f~h represent the TEM images of the TC fabric after the test, with f~h corresponding to fiber, C distribution, and Ti distribution respectively (the scale bar of all TEM images is 50 μm); i represents the treatment efficiency of the TC fabric on humic acid and humic acid-PAM mixture under simulated sunlight irradiation; j represents the treatment efficiency of the TC fabric on industrial wastewater under simulated sunlight irradiation; and k represents the aquatic biological safety test and evaluation results of Daphnia davidii.

[0077] Figure 4 Figure a shows the test results of 50 cycles of Rhodamine B (RhB) dye degradation using TC-55-10-1 fabric. The fabric exhibits stable RhB removal efficiency, with an average removal rate of approximately 32.22%. The slight fluctuations observed may be attributed to a small amount of catalytic material shedding. Figure 4 Figure b shows the FTIR spectra of the fabric before and after the cyclic test. The peak positions of the spectra are almost identical in both states, but the signal intensity of the sample decreases slightly after the test. The infrared (IR) spectra of the functionally coated fabric before and after use are almost the same as those of PET. This is because infrared light directly penetrates the thin TC layer and is absorbed by the underlying PET substrate, thus displaying the characteristic absorption peaks of PET. Therefore, the effect of the thin TC layer on the spectral characteristics of the substrate is negligible. TEM image of the fiber ( Figure 4 (c and f) and carbon element mapping ( Figure 4 Mapping of d and g) and titanium elements ( Figure 4 The results (e and h) show that the carbon and titanium signals in the sample were slightly weakened after the cyclic test, which may be due to the trace amount of material detachment.

[0078] Because the collected industrial wastewater samples contained PAM, and its main component was identified as humic substances by three-dimensional fluorescence spectroscopy, simulated wastewater was prepared for testing. The photocatalytic degradation results of humic acid and humic acid-PAM mixed samples by TC fabric were investigated. Figure 4Figure i) shows that the photocatalytic functional fabric can effectively degrade humic acid from a single pollutant and humic acid from a mixed pollutant containing PAM. After 12 h of treatment, the net degradation rates reached 20.29% and 31.05%, respectively. The functional fabric exhibited better degradation performance for simulated pollutants containing some PAM components, indicating that the functional fabric has certain feasibility for wastewater treatment. The overall photocatalytic degradation performance of the functional fabric on the influent is as follows: Figure 4 As shown in Figure j, after 12 hours of treatment under full-spectrum xenon lamp irradiation, the degradation rate reached 33.59%.

[0079] The eco-safety of TC / PET fabrics is assessed through behavioral toxicity evaluation, using testing platforms such as... Figure 4 As shown in Figure k. The results indicate that, under the experimental conditions, soaking the fabric in water samples had no significant effect on the movement amplitude, speed, and activity range of Daphnia. Algorithm-based analysis by the device showed that the functional fabric exhibited a "harmless" toxicity level to aquatic organisms. The immobilization of the material provides an additional protective layer for ecological safety.

[0080] (3) Experiment on the effect of TC / PET fabric on promoting the growth of submerged large plants (3.1) Changes in photophysical and chemical indicators of water bodies The impact of water quality physicochemical indicators on the growth of submerged macrophytes can be analyzed from multiple dimensions, including changes in the types of major pollutants, organic molecular weight and aromaticity, as well as changes in biodegradability.

[0081] High molecular weight organic compounds (such as humic substances, HS), according to the Stevenson model, are rich in aromatic rings, carboxyl groups, and double bonds, exhibiting high aromaticity and complex structures. Their chromophores can cause browning in water bodies, absorb short-wave visible light and ultraviolet light, thereby reducing the availability of photosynthetically active radiation (PAR), limiting plant light energy capture, reducing plant planting depth, or even leading to localized extinction. According to the Lambert-Beer law, larger molecular weight organic pollutants enhance light scattering, refraction, and reflection, weakening the effective light energy received by plants.

[0082] Figure 5 This image shows the effect of water treatment on TC / PET fabrics. Figure 5In Figure a, the three-dimensional fluorescence (3D-EEM) results of the raw water at W-1 are shown; b, the three-dimensional fluorescence results of the PET fabric-treated water at W0 (denoted as W0-B) are shown; c, the three-dimensional fluorescence results of the TC / PET fabric-treated water at W0 (denoted as W0-T) are shown; d, the change in absorbance (Abs) at 420 nm at W-1 is shown, and the inset shows photographs of the TC / PET treatment group (T group) and the PET blank group (B group) under sunlight; e~i represent the changes in water quality chemical indicators during the photocatalytic pretreatment stage (W-1 to W0), where e corresponds to E2 / E3 (characterizing the average molecular weight of organic pollutants), f corresponds to E4 / E6 (characterizing the degree of benzene ring polymerization), g corresponds to TOC and IC (inorganic carbon), h corresponds to COD, and i corresponds to B / C (i.e., the BOD5 / COD ratio). The fluorescence signal of the wastewater sample ( Figure 5 (a~c) are mainly distributed in EEM regions II–IV and the significant region V dominated by HS. Compared with the original water sample, the fluorescence signals of both the blank and treatment groups decreased, with the treatment group showing the largest decrease; specifically, the peak fluorescence intensity of humic substances in the three-dimensional fluorescence spectrum of the treatment group decreased by about 80%, indicating removal under photocatalysis. Structural indices such as E2 / E3 (characterizing the average molecular weight of organic pollutants) and E4 / E6 (characterizing the degree of benzene ring polymerization) further quantified this process. Figure 5 As shown in Figures e to i, compared to the control group, the E2 / E3 and E4 / E6 indices of the treatment group decreased by 11.30% and 53.34%, respectively, indicating a reduction in high molecular weight and high polymer components, and improved water transparency and light energy utilization, although there were fluctuations due to the replenishment of raw water. Simultaneously, the absorbance at 420 nm, representing HS content, decreased after one week of treatment, consistent with visual observation, suggesting improved transparency, indicating that plants were freed from low light stress and obtained more light energy for growth. Low molecular weight organic matter (<500 Da), especially aromatic compounds containing conjugated or benzene rings (such as ketones, imides, and naphthoquinones), can be directly absorbed by plant roots and may interfere with photosystem II (PSII), causing chemoinhibition; however, these compounds can also be removed through photocatalysis.

[0083] Furthermore, after one week of treatment with TC / PET fabric under sunlight (W-1 to W0), several water quality parameters improved. COD and TN were the main pollutants: at W-1, the raw water COD was 684 mg / L; after pretreatment, the COD of the control group was approximately 668 mg / L, while the COD of the treated group decreased to 634 mg / L, indicating that reducible substances were effectively removed. The BOD5 / COD ratio (B / C, positively correlated with biodegradability) increased from an initial 0.167 to 0.263 in the treated group, while it was 0.184 in the control group. Figure 5The results (i) indicate enhanced biodegradability. The decrease in TC index in the treatment group was mainly due to a reduction in TOC (23.5% in the treatment group, compared to only 3.7% in the control group), while the slight increase in inorganic carbon may be related to mineralization. The overall trend suggests that improved water quality creates favorable conditions for related microorganisms, promoting plant growth across ecological niches. Notably, macromolecular degradation and enhanced biodegradability jointly altered the metabolic functions of microorganisms.

[0084] (3.2) Microbial populations and functions related to plant growth Figure 6 This image shows the microbial community profiles of the biofilm layer (W) near the light-receiving surface of the fabric under photocatalytic (T) and blank (B) fabric treatments, and on the leaf surface (L) during plant cultivation. Figure 6 In the diagram, a represents the microbial diversity index; b represents the Venn diagram of phylum-level distribution; c represents the relative abundance of phylum-level microbial communities; and d represents the heatmap of genus-level bacterial communities.

[0085] Microbial biofilms typically take about 30 days to mature at 20°C, so samples were collected for analysis one month later. Figure 6 Figure a presents the results calculated using the α diversity index, including the Chao index, Shannon index, Simpson index, and Pielou index. These four indices reflect the species richness, overall diversity, dominance, and evenness of aquatic and phyllosphere microbial samples, respectively. These four indices are generally positively correlated with microbial diversity. Fabrics, as carriers, can create conditions for microbial fixation. The microbial richness of group T (979, 7.88, 9.80, and 7.94 for WT; 883, 7.98, 9.91, and 8.16 for LT) was generally higher than that of group B (1109, 6.95, 9.55, and 6.87 for WB; 688, 4.71, 8.54, and 5.00 for LB), except that WT had a slightly lower Chao index (979) than group B (1109).

[0086] Figure 6 The Venn diagram in section b shows that at the phylum level, all samples share 20 microbial taxa. The LB group has the highest total number of species with 28. The WT, WB, and LT groups have 25, 24, and 25 species, respectively. Therefore, the population sizes among the groups are not significantly different.

[0087] like Figure 6 As shown in Figure c, in terms of phylum abundance, almost all samples were dominated by Pseudomonas (…). Pseudomonadota ), Cyanobacteria ( Cyanobacteriota Bacteroidetes ( Bacteroidota ), Pneumatomycetes ( Planctomycetota ) and Actinobacteria ( ActinomycetotaPrimarily aerobic, possessing organic matter metabolism functions. Pseudomonadota It is common in water bodies with high COD pollution. Its relative abundance in fabric biofilm water layer sample W (63.25% for WT, 52.99% for WB) was higher than that in leaf L (43.90% for LT, 39.46% for LB). The photocatalytic fabric group T was also higher than the blank fabric group B. This reveals that the photocatalytic environment positively screened it, possibly because photocatalytic degradation of organic matter provided a more suitable carbon source. Secondly, it may be due to the "micro-aerobic zone" created on the surface of the photocatalytic material by free radicals. Another possibility is that the catalyst loading altered the surface state of the fabric and... Pseudomonadota The adhesion is better. However, the smoother surface of the leaf doesn't adhere as well as to fabric. Higher nitrogen and phosphorus levels in water bodies favor cyanobacteria (…). Cyanobacteriota The growth of [plant species] was inhibited. The abundance of group T (6.80% for WT, 5.96% for LT) was lower than that of group B (17.35% for WB, 8.14% for LB). This difference was particularly pronounced in the W sample, indicating a selective inhibitory effect of photocatalysis. Further cultivation of plants in this water body showed that the abundance of T on the leaves [was significantly reduced]. Cyanobacteriota The abundance was also relatively low, reflecting the positive cross-niche influence of photocatalytic fabrics from microorganisms to leaves. The dominant group was Bacteroidetes (an anaerobic phylum). Bacteroidota ) and Actinobacteria ( Actinomycetota The higher abundance of the species on the leaves of group B suggests that the water in group B may be more anaerobic.

[0088] Figure 6 In the figure, 'd' represents the heatmap analysis results at the genus level. Relative abundance is listed from low to high as blue-orange-red. In industrial wastewater environments, those with organic degradation capabilities... Pannonibacter (0.71%>0.05% for W, 0.32%>0.07% for L), Aquimonas (2.57% > 0.45% for W, 0.84% ​​> 0.27% for L) showed higher relative abundance in group T. Group T of W samples Devosia (1.31% > 0.43%) Achromobacter The abundance of group L (1.81% > 1.51%) is relatively high. The abundance of group T is similar, while the abundance of group T is slightly lower. A similar situation exists for group T. Marivita , Stenotrophomonas Microorganisms such as these were observed. This may indicate that photocatalytic pretreatment of wastewater improves its biodegradability, providing more readily available substrates for such microorganisms. The distribution of degrading microorganisms extends from fabrics to plant leaves.

[0089] Nitrogen transformation related Mesorhizobium and LimnobacterThe relative abundance of nitrogen in group T water samples was higher than that in group B, indicating that group T has better nitrogen transformation capabilities, which is conducive to the growth of nitrogen-utilizing microorganisms and suggests that photocatalysis may enhance nitrogen biotransformation. These microorganisms are also often associated with nitrogen fixation processes that promote plant growth. Notably, when the abundance of the two W samples was not significantly different, the LT sample was associated with nitrogen transformation. Phreatobacter , Fuscovulum The abundance was higher than that of LW. This may be because the pretreatment provided a suitable aquatic habitat for the growth of these microorganisms. Alternatively, these microorganisms may be more sensitive and require a certain distance from photocatalytic stimuli to grow, and plant leaves provide a suitable environment.

[0090] The differences in microbial diversity and populations on the surface and in distant leaves of TC / PET fabrics compared to blank PET fabrics may be due to the different surface physical states resulting from the catalytic materials. These differences include the superhydrophilicity of TiO2 materials under light, the promotion of microbial metabolism by photogenerated electrons, and stress caused by free radicals. These factors may collectively influence the adaptation, succession, enrichment, and interaction behaviors of microorganisms on the surfaces of the two fabrics, thus reflecting differences in abundance and population size. Leaf samples reflect the long-range, cross-niche influence of TC fabrics on microorganisms and plants.

[0091] Figure 7 Extended error bar analysis of predicted microbial pathways and functions in water samples (W) and leaf samples (L) from the photocatalytic (T) and control (B) groups (p<0.05). Figure 7 In the diagram, a represents water sample pathway prediction, b represents leaf sample pathway prediction, c represents water sample function prediction, and d represents leaf sample function prediction.

[0092] like Figure 7 As shown in Figure a, in the aqueous layer (W) of the fabric microbial biofilm, the KO functional pathway of the photocatalytic group (T) was significantly enriched in the lysosomal process-related pathway (ko04142) and the glycosaminoglycan degradation-related pathway (ko00531). The former involves the removal of organic particles and cell debris, while the latter points to the decomposition of complex organic substrates and the release of small molecule nutrients, indicating that the T group microorganisms play a dual role in pollutant purification and microenvironment improvement.

[0093] like Figure 7As shown in Figure b, within the phyllosphere microbiota (L), group T was specifically enriched in the zeatin biosynthesis pathway (ko00908). This pathway is involved in cytokinin production and is a core function of plant growth-promoting microorganisms (PGPB). Furthermore, the enrichment of group T in the atrazine metabolism (ko00791) and phosphorus metabolism (ko00440) pathways further confirms its enhanced pollutant transformation and nutrient activation capabilities. In contrast, group B was mainly enriched in exogenous substance degradation (ko00625) and unsaturated fatty acid metabolism (ko01040), reflecting its passive adaptation to highly polluted environments and lack of direct growth-promoting functions.

[0094] like Figure 7 The results showed that in water sample (W), the functional enrichment of group T exhibited a clear "metabolicly active" characteristic: upregulation of genes related to peptide transport (K03305) and phosphate synthesis (K13831) suggested extracellular polymer degradation and community structure remodeling; enrichment of pollutant degradation (K00500) and DNA repair (K03701) genes corresponded to the purification of aromatic pollutants and the maintenance of genome stability, respectively; and enhanced antioxidant function (K00384) mitigated photocatalytic oxidative damage. In contrast, group B showed enrichment of genes concentrated in stress pathways such as antioxidant response (K01916) and transcriptional regulation (K00375), indicating that the community was under continuous oxidative stress and adaptive regulation.

[0095] Figure 7 In the leaf samples (L) shown in d, group T continued the preference for pollutant metabolism (K00500) accompanied by upregulation of the nucleotide metabolism (K00876) gene, which is consistent with the high activity state of the microorganisms. Group B was mainly enriched with genes related to formic acid metabolism (K00127), basal metabolism (K00010), and nutrient transport (K03457), suggesting a passive transport strategy under anaerobic adaptation, general stress, and resource constraints.

[0096] In summary, photocatalytic treatment (T) significantly reshaped the cross-niche microbial functions of the water-leaf microbiome. The functional advantages of group T in areas such as antioxidant activity, pollutant degradation, nutrient cycling, and stress resistance collectively created a low-toxicity, nutrient-rich microenvironment conducive to plant-microbe symbiosis. In contrast, the singular function and stress bias of group B reflect the survival pressure on the community under non-photocatalytic conditions.

[0097] (3.3) Changes in plant growth-related indicators Figure 8 The changes in relevant indicators of Ceratophyllum demersum growth after industrial wastewater treatment. Figure 8In Figure a, the appearance and plant length of *Ceratophyllum demersum* under two industrial wastewater treatment environments were compared at time points W0 and W3 (the initial plant length of all samples was 5-6 cm, and the red and yellow lines represent the approximate length of plants cultivated in water treated with PET and TC-PET fabrics, respectively, for easy comparison); b-f show the comparative trends of length, wet weight, dry weight, Rubisco activity, and chlorophyll fluorescence level between the treatment group (T) and the blank group (B), respectively; and g shows the change in dissolved oxygen level.

[0098] like Figure 8 As shown in Figure a, both the treated and control groups exhibited browning over time, but the browning was less pronounced in the treated group. This is primarily attributed to the continuous input of pollutants and the time required for photocatalytic oxidation of chromophores (HS). Furthermore, at time point W3, the submerged plant *Ceratophyllum demersum* in the treated group showed significantly bent branches, almost parallel to the water surface, while the control group maintained vertical growth. This significant difference in apparent growth morphology is likely due to the combined effects of water toxicity stress, differences in light transmittance between the treated and untreated water matrices, and differences in the composition and function of the microbial community.

[0099] like Figure 8 As shown in Figures b to d, after 3 weeks of growth (W3), the treatment group was superior to the control group in terms of apparent growth indicators such as branch length, wet weight, and dry weight. Specifically, the branch length in the treatment group increased from 5.510 ± 2.261 cm to 21.340 ± 4.859 cm, while that in the control group increased to 14.793 ± 2.222 cm, with highly significant differences between the two groups (P = 0.00013, P < 0.01), representing increases of approximately 3.87 times and 2.69 times, respectively. Regarding wet weight, the treatment group increased from 0.426 ± 0.287 g to 1.577 ± 0.451 g, while that in the control group increased from 0.426 ± 0.287 g to 1.425 ± 0.331 g, with no significant differences between the groups (P = 0.302, P ≥ 0.05, ns), representing increases of approximately 3.70 times and 3.35 times, respectively. In terms of dry weight, the treatment group increased from 0.062 ± 0.0585 g to 0.176 ± 0.0538 g, while the blank group increased to 0.110 ± 0.0231 g, with extremely significant differences (P = 0.000369, P<0.01), representing increases of approximately 2.84 times and 1.77 times, respectively.

[0100] The inhibitory effect of aquatic biotoxicity on submerged plants can be indirectly reflected by changes in Rubisco enzyme activity and the chlorophyll fluorescence parameter Fv / Fm. Rubisco is a key enzyme in CO2 fixation in green plants, but its catalytic efficiency is relatively low. *Ceratophyllum demersum* (Goldfishweed) Ceratophyllum demersum L.It possesses a CO2 concentration mechanism similar to microalgae, but operates in a simpler way, enabling efficient CO2 fixation and thus showing good potential in biomass production. Fluorescence parameters such as Fv / Fm can serve as indicators of the impact of environmental stress on photosynthetic efficiency; the maximum photochemical quantum yield (Fv / Fm) typically decreases under environmental stress. For submerged plants, Fv / Fm is generally between 0.7 and 0.8.

[0101] However, the trends of these two parameters differed significantly between the treatment and control groups. Regarding Rubisco enzyme activity, the treatment group showed a slight overall decrease compared to the initial value, with the most significant decrease occurring in the first week of the adaptation period, followed by a slight recovery; while the control group showed a gradual decreasing trend. Chlorophyll fluorescence parameters also exhibited a similar trend. For example... Figure 8 As shown in Figures e and f, the Rubisco enzyme activities in the treatment group and the control group decreased from the initial value of 25.467 ± 1.217 ng / min / g to 22.572 ± 0.740 ng / min / g and 16.803 ± 0.828 ng / min / g, respectively, with highly significant differences between the two groups (P = 3.46409 × 10⁻⁶). -18 (P < 0.01). Similarly, the chlorophyll fluorescence parameter Fv / Fm decreased significantly from the initial value of 0.752 ± 0.0388 to 0.713 ± 0.0289 in the treatment group and 0.467 ± 0.0238 in the control group (P = 7.29101 × 10⁻⁶). -21 (P<0.01).

[0102] Dissolved oxygen (DO) levels are a key indicator closely related to green biological photosynthesis. Figure 8 (g). At time point W0, the DO concentration in the treatment group was 9.156 ± 0.02 mg / L, slightly lower than the 13.01 ± 0.67 mg / L in the control group. This may be attributed to the consumption of some DO during the organic matter catalytic treatment. During the acclimatization period from W0 to W1, the DO level in the treatment group rose as early as day 1, while the DO level in the control group remained relatively stable during the first week. This indicates that the aquatic environment in the treatment group was more conducive to the metabolic processes of *Ceratophyllum demersum*. By the end of the third week, the DO level in the treatment group remained at a high level, fluctuating between approximately 18 and 22 mg / L; while the DO level in the control group was approximately 10–15 mg / L and showed a gradual decreasing trend.

[0103] Figure 9 The potential mechanism by which TC fabrics enhance the photosynthetic performance of Ceratophyllum demersum by regulating the physicochemical-biological microenvironment and microbial community was clearly elucidated. Figure 9In a, a partial least squares path model (PLS-PM), with latent variables: textile type (type_textile), water chemistry (w_chem), optical physics (w_physi), microorganisms (w_microb), and submerged plants (plant) (blue / red lines represent positive / negative total effects respectively, observed variables (rectangles) are represented by latent variables (rounded rectangles), solid / dashed lines represent non-significant / significant relationships, path coefficients represent total effects, significance levels: p ≤ 0.001; 0.001 < p ≤ 0.01; 0.01 < p ≤ 0.05; the dominant effect of cyanobacteria is included in w_physi as a light shade); in b, the energy band structure and reactive oxygen species (ROS) generation mechanism of the composite material on the surface of the TC / PET fabric device, as well as various habitat index changes caused thereby, and ultimately the plant index changes.

[0104] Previously, the effects of different textile types (photocatalytic type and blank type) on the water chemistry, underwater light field, and microbial community of Ceratophyllum demersum in industrial wastewater habitats were analyzed. Figure 9 In a, the PLS-PM model was further used to explore the multivariate relationships among water chemistry, physical properties, microorganisms, and plants under the influence of textile type. By assigning categorical variables (photocatalytic fabric [T] as 1 and blank fabric [B] as 0), it was observed that the path coefficients of water chemistry (-0.7831) and physical properties (-0.7702) were negative, indicating that the photocatalytic material reduced these indicators, and the impact on water chemistry was more significant. However, the impact on the potential microbial variable was the strongest (0.9841), indicating that photocatalysis enhanced microbial richness and upregulated the pollutant degradation functional gene K00500, while K07393 reflected a greater stress response of surface microorganisms under the blank fabric. Microorganisms had a strong positive effect on plants (0.9107 ), while water physical and chemical properties had a negative effect, meaning that the reduction of the indicator values could promote plant growth. Therefore, the hierarchy of photocatalysis-mediated habitat changes was: microorganisms > water chemistry > water physical and chemical properties, and the order of beneficial effects on plant biomass was: microorganisms > water physical and chemical properties > water chemistry. These results indicate that photocatalysis improves plant biomass across ecological niches through habitat modification.

[0105] Specifically, Figure 9 In b, it shows the potential mechanism of the TC / PET material to form a "strong - weak" free radical combination under sunlight drive, the impact of the material on the habitat, and the response of plants. According to the Tauc curve ( Figure 3 in c) and the valence band top energy ( Figure 3 in d), the bottom energy of the conduction band (E CB ) were: N-TiO2 - 0.28 eV, TC composite 0.16 eV. The valence band top energy E of TCVB (2.74 eV) higher than ·OH / OH - With a potential of 2.40 eV and H2O / ·OH (2.72 eV), photogenerated holes may oxidize H2O or surface ·OH to generate ·OH. Because the oxidation potential of TC is more positive than that of N-TiO2, it is more likely to generate such free radicals.

[0106] Nitrogen doping introduces an N2p impurity level between the valence and conduction bands of TiO2, potentially providing a shorter transition path for photogenerated electrons. SWCNT-composite nitrogen-doped TiO2 particles primarily affect the configuration of nitrogen-doped TiO2 grown secondary during hydrothermal processes, without introducing new impurity levels. The combined effect of both may accelerate electron migration and promote free radical generation. The alteration of the TiO2 crystal structure by the combination of N doping and SWCNTs, along with the enhanced light absorption by the SWCNT component, may jointly influence the utilization of photon energy in the TC composite material. Monomeric nitrogen-doped TiO2 without SWCNTs, due to its more negative reduction potential, may preferentially reduce dissolved oxygen to O2. - The latter transforms at the conduction band of the TC complex (where the reduction potential is low) into 1 O2.

[0107] • OH has a high oxidation potential and can rapidly decompose pollutants without selectivity, but its lifespan is only on the order of nanoseconds; 1 O2 has a moderate oxidation potential, a lifetime on the order of microseconds, and a greater diffusion range, enabling mild and continuous oxidation and potentially participating in the regulation of biological signals. The coexistence of O2 and O2 provides complementary reactivity, covering targets ranging from highly recalcitrant to moderately reactive, forming a sunlight-driven "strong-weak" free radical output system.

[0108] In industrial wastewater habitats, ·OH may non-selectively degrade organic matter and inactivate pathogenic microorganisms, potentially contributing to water quality improvement. With improved water health, submerged plants and microorganisms may gradually recover their physiological functions in a more suitable environment. Meanwhile, 1 O2 may exert a certain degree of "micro-stimulation" regulation on the microorganisms on the fabric surface, affecting the structure and functional composition of the microbial community.

[0109] The surface chemical states of Ti, C, and O elements in TC materials were analyzed using X-ray photoelectron spectroscopy (XPS). The results are as follows: Figure 10 As shown. The Ti 2p spectrum of TC ( Figure 10 In section a), two characteristic peaks were observed at binding energies of 464.3 eV and 458.6 eV, respectively, belonging to Ti 2p1 / 2 and Ti 2p3 / 2, corresponding to Ti 4+ Status. XPS analysis ( Figure 10(b) also shows several characteristic peaks in the C 1s spectrum: the peak at 288.6 eV belongs to C–OH and C–N groups, the peak at 284.8 eV corresponds to C=O groups, and the peak at 284.7 eV belongs to C–C, C=C, and C–H hydrocarbon structures. In the O 1s spectrum ( Figure 10 In c), the strong peak at 529.9 eV is attributed to the Ti–O bond, while two weaker peaks are observed at 532.0 eV and 531.2 eV, corresponding to the Ti–O–C and C=O groups, respectively.

[0110] Figure 10 d to f and Figure 10 In the image, g to i represent the electron paramagnetic resonance (EPR) spectra of TC and N-TiO2, respectively. Both spectra show hydroxyl radicals (·OH) and singlet oxygen (·OH) generated by TC and N-TiO2. 1 O2) and superoxide anion radicals (·O2) - Characteristic signals of ). Among all the reactive oxygen species (ROS) detected, the number of free radicals generated by TC was significantly higher than that of N-TiO2. Under xenon lamp irradiation, the number of photogenerated electrons (e) in N-TiO2 and the TiO2 component of TC increased significantly. - CB) and holes (h) + Both VB were effectively activated.

[0111] As can be seen from the above embodiments, in order to achieve the ultimate goal of enhancing the proliferation of aquatic organisms in industrial wastewater, this invention integrates the principle of ecological restoration into wastewater treatment and proposes a new strategy of "photocatalytic-mediated industrial wastewater habitat reconstruction". Utilizing the high carrier mobility of single-walled carbon nanotubes (SWCNTs) and the plant compatibility of titanium dioxide (TiO2), a high-performance and eco-friendly TiO2@SWCNT / PET textile material was prepared via microwave hydrothermal synthesis, and passed comprehensive physicochemical and biological safety evaluations at the laboratory scale. To facilitate mechanism analysis, a process flow combining sunlight-driven photocatalytic pretreatment with cultivation of large aquatic plants was designed, and the photocatalytic effect was systematically evaluated from three key dimensions of the submerged plant growth habitat. At the mechanistic level, bandgap analysis elucidated the functional principle of the material, and the partial least squares path modeling (PLS-PM) method was used to quantify the hierarchical impact of photocatalysis on various dimensions of the habitat and their interrelationships. Photocatalysis promoted the growth of submerged plants across ecological niches, with the most significant impact on microbial latent variables, ultimately benefiting plants through microbial mediation. This invention provides engineering inspiration for pollution reduction and carbon emission reduction systems, and offers a strategic technological path to support carbon peaking and carbon neutrality goals.

[0112] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A photocatalytic composite material, characterized in that, The invention includes a fiber fabric substrate, a conductive layer composited on the fiber surface of the fiber fabric substrate, and a photocatalyst supported on the conductive layer. The photocatalyst includes single-walled carbon nanotubes supported on nitrogen-doped titanium dioxide and nitrogen-doped titanium dioxide.

2. The photocatalytic composite material according to claim 1, characterized in that, The conductive agent in the conductive layer is a single-walled carbon nanotube.

3. The photocatalytic composite material according to claim 1 or 2, characterized in that, The mass of nitrogen-doped titanium dioxide in the nitrogen-doped titanium dioxide-supported single-walled carbon nanotubes is 70-80% of the total mass of nitrogen-doped titanium dioxide in the photocatalytic composite material; the loading of the photocatalyst on the fiber fabric substrate is 0.05-0.3 mg / cm³. 2 .

4. A method for preparing the photocatalytic composite material according to any one of claims 1 to 3, characterized in that, Includes the following steps: A photocatalyst is obtained by hydrothermal reaction of nitrogen-doped nano-titanium dioxide, carboxylated single-walled carbon nanotubes, and water. The photocatalyst comprises single-walled carbon nanotubes supported on nitrogen-doped titanium dioxide and nitrogen-doped titanium dioxide. The mass ratio of nitrogen-doped nano-titanium dioxide to carboxylated single-walled carbon nanotubes is (1.2~1.8):(0~0.0012), and the mass of carboxylated single-walled carbon nanotubes is not zero. After impregnating the fiber fabric substrate in a dispersion of conductive agent, it is heated and cured to obtain a fiber fabric substrate with a conductive layer. The fiber fabric substrate with the conductive layer is impregnated in the dispersion of the photocatalyst and then cured by heating to obtain the photocatalytic composite material.

5. The preparation method according to claim 4, characterized in that, The nitrogen-doped nano-titanium dioxide has a particle size of 5-10 nm and an atomic percentage of nitrogen of 1-5%.

6. The preparation method according to claim 4 or 5, characterized in that, The mass ratio of nitrogen-doped nano-titanium dioxide to carboxylated single-walled carbon nanotubes is 1.5:0.0004.

7. The preparation method according to claim 4, characterized in that, The hydrothermal reaction is carried out under microwave irradiation conditions, with a temperature of 120~170℃, a holding time of 5~20min, and a microwave irradiation power of 1500W.

8. The preparation method according to claim 4, characterized in that, The conductive agent dispersion contains 0.4‰ of conductive agent by mass; the photocatalyst dispersion contains 2.5g / L of photocatalyst.

9. The application of the photocatalytic composite material according to any one of claims 1 to 3 or the photocatalytic composite material prepared by the preparation method according to any one of claims 4 to 8 in industrial wastewater treatment.

10. A method for reconstructing industrial wastewater habitat, characterized in that, Includes the following steps: A photocatalytic composite material is applied to industrial wastewater to treat the wastewater under light conditions; the industrial wastewater contains submerged plants and microorganisms; the photocatalytic composite material is the photocatalytic composite material according to any one of claims 1 to 3 or the photocatalytic composite material prepared by the preparation method according to any one of claims 4 to 8.

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