A system for the synthesis of gel ZnO nanorods (gel ZnO NRs) for the degradation of methylene blue

Abstract

A system for the synthesis of gel-ZnO nanorods (gel-ZnO NRs), consisting of: a) a colloid solution preparation unit for the production of a ZnO nanorod colloid solution, wherein the colloid solution preparation unit is configured to mix prepared ZnO nanorod (NR) in double distilled water; b) a biopolymer addition module for incorporating agar biopolymer into the colloidal ZnO solution nanorod (NR); c) a heating and mixing device configured to heat and stir the combined solution, the heating and mixing device comprising a magnetic stirrer for continuous stirring to form a suspension of a biopolymer-enriched colloidal ZnO NR solution; d) a cooling system for bringing the solution to ambient temperature, whereby solid gel material -ZnO NR is obtained after cooling; and e) a cutting device for forming thin slices of the synthesized gel ZnO-NRs, the cutting device comprising blades for cutting the material.

Description

FIELD OF THE INVENTION

[0001] The present disclosure relates to a system for synthesizing Gel-ZnO nanorods (Gel-ZnO NRs) for degrading methylene blue. BACKGROUND OF THE INVENTION

[0002] Water pollution from industrial dyes is a major global environmental challenge, as thousands of commercial dyes cause significant ecological damage. Conventional water treatment methods such as biological processes, chemical precipitation, and membrane filtration often fail to effectively remove these persistent organic pollutants. Photocatalytic degradation using semiconductor nanomaterials has emerged as a promising alternative, offering a more sustainable and environmentally friendly approach to water purification.

[0003] Zinc oxide (ZnO) nanoparticles have attracted particular attention due to their exceptional photocatalytic properties, including high electron mobility and unique semiconductor properties. Conventional ZnO nanoparticles have limited effectiveness in harnessing solar radiation and are typically only effective under UV light. To overcome this challenge, researchers have investigated innovative approaches such as nanorod formation and biopolymer immobilization to improve the photocatalytic efficiency of the material.

[0004] The development of gel-encapsulated ZnO nanorods represents a significant advance in water treatment technology. By incorporating ZnO nanorods into an agar biopolymer matrix, researchers have developed a novel photocatalyst that overcomes several challenges in dye degradation. This approach not only improves photocatalytic performance but also provides a practical solution for removing harmful dyes from water, with the added benefits of easy catalyst separation and multiple use potential. The method offers a promising strategy for curbing water pollution caused by industrial dyes and potentially protecting human health and environmental ecosystems. SUMMARY OF THE INVENTION

[0005] The present disclosure relates to a system for synthesizing gel-ZnO nanorods (gel-ZnO NRs) for methylene blue degradation. The invention provides a system for synthesizing gel-ZnO nanorods using an integrated approach that combines precise preparation of colloidal solutions, biopolymer integration, controlled heating and mixing, specialized cooling, and advanced cutting techniques. The system enables the production of a novel photocatalytic material through the systematic combination of ZnO nanorods with agar-biopolymer, resulting in a unique, thin-cut catalyst that enables efficient dye degradation through a streamlined, reproducible manufacturing process.

[0006] The present disclosure is intended to provide a system for synthesizing Gel-ZnO nanorods (Gel-ZnO NRs).The system consists of: a colloidal solution preparation unit for producing a ZnO nanorod colloidal solution, wherein the colloidal solution preparation unit is configured to mix prepared ZnO nanorod (NR) in double-distilled water; a biopolymer addition module for incorporating agar biopolymer into the colloidal solution of ZnO nanorod (NR); a heating and mixing device configured to heat and stir the combined solution, wherein the heating and mixing device comprises a magnetic stirrer for continuously stirring to form a suspension of biopolymer-added colloidal ZnO NR solution; a cooling system for bringing the solution to ambient temperature, obtaining solid material of gel-ZnO NR after cooling; and a cutting device for forming thin slices of the synthesized gel-ZnO NRs, wherein the cutting device comprises blades for cutting the material.

[0007] An object of the present disclosure is to provide a system for synthesizing Gel-ZnO nanorods (Gel-ZnO NRs) for degrading methylene blue.

[0008] Another object of the present disclosure is to provide a modular system that covers each phase of gel-ZnO nanorod synthesis, from the initial preparation of the colloidal solution to the final material processing.

[0009] Another object of the present disclosure is to provide a systematic method for incorporating agar biopolymer into ZnO colloidal nanorod solutions with optimal concentration and uniform distribution.

[0010] Another object of the present disclosure is to develop a special heating and cooling system that allows precise temperature control during the gel-ZnO nanorod synthesis process.

[0011] Another objective of the present disclosure is to develop an integrated cutting and processing unit capable of producing uniform, thin slices of gel-ZnO nanorods for photocatalytic applications.

[0012] Another objective of the present disclosure is to create a reproducible manufacturing system that enables consistent production of gel ZnO nanorods with controlled morphology and photocatalytic properties.

[0013] To further clarify the advantages and features of the present disclosure, a more detailed description of the invention will be given with reference to specific embodiments thereof, which are illustrated in the accompanying drawings. It should be noted that these drawings represent only typical embodiments of the invention and are therefore not to be considered limiting its scope. The invention will be described and explained in additional detail and in greater detail with reference to the accompanying drawings. SHORT DESCRIPTION OF THE FIGURE

[0014] These and other features, aspects, and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying drawings, in which like characters represent like parts throughout. Where: Fig. 1 shows a block diagram of a system for synthesizing Gel-ZnO nanorods (Gel-ZnO NRs) according to an embodiment of the present disclosure.

[0015] Furthermore, those skilled in the art will appreciate that elements in the drawings are shown for convenience and may not necessarily be drawn to scale. For example, the flowcharts illustrate the method by key steps to enhance understanding of aspects of the present disclosure. Furthermore, with respect to device construction, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawing may show only the specific details relevant to understanding embodiments of the present disclosure in order not to clutter the drawings with details that would be readily apparent to those skilled in the art who would benefit from the description herein. DETAILED DESCRIPTION:

[0016] To facilitate an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and described in specific language. It is to be understood, however, that no limitation on the scope of the invention is intended thereby, since such changes and further modifications of the illustrated system, and such further applications of the principles of the invention as illustrated therein, are contemplated as would normally occur to one skilled in the art to which the invention pertains.

[0017] It will be understood by one skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be limiting thereof.

[0018] References in this specification to "one aspect," "another aspect," or similar language mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Therefore, occurrences of the phrase "in one embodiment," "in another embodiment," and similar language throughout this specification may or may not all refer to the same embodiment.

[0019] The terms "comprises," "comprising," or other variations thereof are intended to cover non-exclusive inclusion, such that a process or method comprising a list of steps not only includes those steps, but may also include other steps not expressly listed or inherent in such process or method. Likewise, one or more devices or subsystems or elements or structures or components preceded by "comprises...a" does not preclude, without further limitation, the existence of other devices or other subsystems or other elements or other structures or other components or additional devices or additional subsystems or additional elements or additional structures or additional components.

[0020] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The system, methods, and examples provided herein are for illustrative purposes only and should not be considered limiting.

[0021] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0022] Fig. 1 shows a block diagram of a system (100) for synthesizing Gel-ZnO nanorods (Gel-ZnO NRs) according to an embodiment of the present disclosure.

[0023] In relation to Fig.1, the system (100) comprises: a colloidal solution preparation unit (102) for preparing a ZnO nanorod colloidal solution, wherein the colloidal solution preparation unit (102) is configured to mix prepared ZnO nanorod (NR) in double-distilled water; a biopolymer addition module (104) for introducing agar biopolymer into the colloidal solution of ZnO nanorod (NR); a heating and mixing device (106) configured to heat and stir the combined solution, wherein the heating and mixing device (106) comprises a magnetic stirrer (106a) for continuously stirring to form a suspension of a biopolymer-added colloidal ZnO NR solution; a cooling system (108) for bringing the solution to ambient temperature, wherein, after cooling, solid material of gel-ZnO NR is obtained;and a cutting device (110) for forming thin slices of the synthesized Gel-ZnO NRs, wherein the cutting device (110) comprises blades (110a) for cutting the material.;

[0024] In one embodiment, the colloidal solution preparation unit (102) comprises: an ultrasonic irradiation chamber (102a); and a mixing vessel (102b), wherein the ultrasonic irradiation chamber (102a) facilitates ultrasonic irradiation of the colloidal solution of ZnO NR.

[0025] In one embodiment, the biopolymer integration module (104) is configured to add 1.55 g of agar biopolymer to 30 ml of colloidal solution to form a 5.5 w / v% suspension.

[0026] In one embodiment, the heating and mixing device (106) is configured to a) heat the combined solution to above 70°C, b) stir vigorously during heating, and c) produce a clear, viscous solution.

[0027] In one embodiment, the cooling system (108) is configured to cool the solution to an ambient temperature below 20°C.

[0028] In one embodiment, the cutting device (110) comprises: a) a cutting mechanism (110b) for producing thin slices of the solidified gel ZnO NRs; b) a precision cutting platform (110c); and c) a collecting mechanism (110d) for collecting the thin slices.

[0029] In one embodiment, the system (100) further comprises a photocatalyst preparation module (112) configured to prepare the thin slices of gel-ZnO NRs for dye degradation processes.

[0030] The present invention relates to a system for the synthesis of gel-ZnO nanorods by combining a colloidal solution of ZnO NR with a biopolymer. The proposed system comprises components related to the integration of biopolymers, controlled heating and mixing, special cooling, and advanced cutting techniques. The system enables the production of a novel photocatalytic material through the systematic combination of ZnO nanorods with agar-biopolymer, resulting in a unique, thin-cut catalyst that enables efficient dye degradation through a streamlined, reproducible manufacturing process.

[0031] For the synthesis of Gel-ZnO NRs, ZnO NRs were first synthesized. The synthesis of ZnO NRs and Gel-ZnO NRs was carried out using different methods. ZnO NRs were prepared using a hydrothermal technique, while Gel-ZnO NRs were synthesized using a modified, simple immobilization mechanism. A colloidal solution containing 0.33% ZnO NRs was prepared by dispersing 0.1 g of ZnO NRs in 30 ml of double-distilled water under ultrasonic irradiation. Subsequently, 1.55 g of agar biopolymer was added to this colloidal solution to create a 5.5 w / v% suspension by vigorous stirring. The solution was then heated to a temperature above 70 °C until it transformed into a clear, viscous solution. The mixture was then cooled to ambient temperature, more precisely below 20 °C, resulting in a shiny solid, which was called Gel-ZnO NRs.This shiny solid was then cut into thin slices. Finally, the required amounts of these thin gel-ZnO NRs slices were used as an environmentally friendly photocatalyst for the degradation of MB dye.

[0032] The fabricated nanorod is subjected to an evaluation of its photocatalytic performance. The absorption intensity of the degraded MB is measured in water under the exposure to natural sunlight for various periods of time. The performance evaluation is performed by dissolving a total of 20 mg of the photocatalyst (gel-ZnO NRs) in 100 ml of an aqueous methylene blue solution (MB) with a concentration of 1×10 -5M. The solution was magnetically stirred in the dark for five minutes to establish an adsorption / desorption equilibrium between the MB molecules and the surface of the gel-ZnO NRs photocatalyst. After this step, the suspension was exposed to natural sunlight, and 5 ml samples were taken at specific intervals, for example, after 15, 30, 45, 60, 75, 90, 105, and 120 minutes. The collected samples were simply filtered and then analyzed using UV-visible absorption spectroscopy by measuring the absorption changes at a wavelength of 663 nm. The percentage degradation was calculated using the following formula: Deterioration(%)=A0−AtA0×100

[0033] Here, A o represent the initial absorbance of MB before solar irradiation, and A t is the absorbance of the solution after solar irradiation at time t (in minutes).

[0034] The prepared nanorods were subjected to characterization, where structural, morphological, and photophysical properties of Gel-ZnO NRs were investigated using XRD, SEM-EDX, FTIR, UV-visible absorption, and fluorescence spectroscopy. The absorption spectra of MB, ZnO NRs, and Gel-ZnO NRs were analyzed using a Shimadzu UV-3600 UV-VIS-NIR spectrophotometer with a 1.0 cm quartz cell at room temperature. Concentration fluctuations for MB, methyl orange (MO), and methyl red (MR) solutions were also investigated over different time periods. Fluorescence spectra of MB, ZnO NRs, and Gel-ZnO NRs in combination with MB were recorded using a PC-based spectrofluorophotometer. X-ray diffraction (XRD) patterns of ZnO NRs and gel-ZnO NRs were measured using a Rigaku Ultima IV system with CuK α radiation (λ = 1.5406 Å).

[0035] The functional groups present in ZnO NRs, gel-ZnO NRs, and agar were analyzed using a Fourier transform infrared spectrometer (FTIR) (JASCO Model 4600, Japan). The morphological properties of ZnO NRs and gel-ZnO NRs were investigated using a JEOL JSM-IT 200 scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX). The contact angles for ZnO NRs, gel-ZnO NRs, and gel-ZnO NRs with MB were measured using a manually operated, low-cost contact angle meter. The pH of all solutions was measured using a digital pH meter with a combined glass electrode.

[0036] The invention presents the characterization and photocatalytic properties of ZnO nanorods (ZnO NRs) and gel-encapsulated ZnO nanorods (gel-ZnO NRs). X-ray diffraction (XRD) analysis of ZnO NRs revealed sharp and well-defined peaks, confirming high crystallinity and purity. ZnO NRs have a hexagonal crystal structure with the space group P63mc and lattice constants a = b = 3.22 A° and c = 5.20 A°. The XRD peaks for ZnO NRs and gel-ZnO NRs appeared at slightly different 2-θ values ​​(31.73, 34.36, 36.21, 47.47, 56.52, 62.75, 66.29, 67.85, 68.99, 72.43, and 76.85, corresponding to the lattice planes of

[100] ,

[002] ,

[101] ,

[102] ,

[110] ,

[103] ,

[200] ,

[112] ,

[201] ,

[004] , and

[202] ), indicating a slight structural shift due to the ZnO encapsulated in the agar. Crystal size calculations using the Scherrer equation showed that ZnO NRs had a crystal size of 64.3 nm, while Gel-ZnO NRs had a reduced size of 18 nm due to the incorporation of ZnO into agar gel.

[0037] The morphology of ZnO NRs and gel-ZnO NRs was analyzed using scanning electron microscopy (SEM). ZnO NRs exhibited a nanorod-like morphology with lengths of approximately 400 nm and diameters of 100 nm. In contrast, gel-ZnO NRs retained a similar nanorod structure but were embedded in agar gel and exhibited lengths of approximately 500 nm and diameters of 120 nm. This gel encapsulation increased their photocatalytic efficiency in degrading methylene blue (MB) dye.

[0038] Elemental analysis using energy-dispersive X-ray spectroscopy (EDX) revealed the presence of zinc and oxygen in ZnO NRs. An additional carbon peak was observed in Gel-ZnO NRs, confirming the presence of agar gel. Elemental mapping also revealed the spatial distribution of zinc, oxygen, and carbon in Gel-ZnO NRs, providing evidence for the successful encapsulation of ZnO in the agar matrix.

[0039] Fourier transform infrared spectroscopy (FTIR) was used to identify functional groups and obtain bonding information. The characteristic peaks for metal oxide bonds, hydroxyl groups, and glycosidic bonds were observed, confirming the presence of agar-associated functional groups in gel-ZnO NRs.

[0040] UV spectroscopy revealed distinct absorption peaks for ZnO NRs and gel-ZnO NRs, with the latter exhibiting a slight red shift due to agar encapsulation. ZnO NRs exhibited a peak at 280 nm, while gel-ZnO NRs shifted to 290 nm. A broad peak of 360–450 nm in ZnO NRs, attributed to electron transitions, was suppressed in gel-ZnO NRs due to the influence of the biopolymer. The absorption behavior of methylene blue (MB) was also investigated and highlighted distinct bands, including the key band at 663 nm, which was used for degradation studies.

[0041] Fluorescence spectra showed that gel-ZnO NRs exhibit red-shifted excitation peaks compared to ZnO NRs, likely due to the influence of agar. The emission spectra showed characteristic bands associated with exciton emissions and defect states. Inclusion of ZnO NRs in agar reduced electron-hole recombination and further red-shifted defect-related emission peaks.

[0042] Experiments with different catalyst loadings revealed an optimal amount of 20 mg for maximum photocatalytic efficiency. Higher loadings above this limit led to light blocking and limited efficiency. Likewise, different dye concentrations showed that the MB degradation efficiency at 1×10 -5 M, with higher concentrations resulting in reduced efficiency due to hindrance to photon absorption.

[0043] Gel-ZnO NRs demonstrated superior photocatalytic performance compared to ZnO NRs under UV, visible, and natural sunlight. MB showed the highest degradation among the dyes studied, with Gel-ZnO NRs degrading MB by up to 94% under natural sunlight within 120 minutes. This efficiency exceeded the values ​​achieved under UV and visible light, demonstrating the effectiveness of the more environmentally friendly catalyst under natural sunlight.

[0044] The degradation of MB was attributed to a two-step mechanism involving adsorption and subsequent charge-transfer processes. Adsorption studies confirmed a significant accumulation of MB on the catalyst surface due to hydrogen bonding and interactions with agar. The second step involved photogenerated electron-hole pairs, which caused oxidative degradation, as supported by fluorescence quenching results.

[0045] The degradation process followed pseudo-first-order kinetics under all light sources. Natural sunlight enabled the fastest degradation rate (2.4 × 10 -2 min -1 ) and thus exceeded visible (3×10 -3 min -1 ) and UV light (1×10 -4 min -1 ). The high correlation with the Langmuir-Hinshelwood model further confirmed the kinetic analysis.

[0046] The above results of this invention clearly demonstrate that the synthesized gel-ZnO NRs offer a more environmentally friendly and efficient alternative for photocatalytic dye degradation, especially under natural sunlight. Their easy removability, shortened degradation time, and improved performance make them a promising candidate for wastewater treatment applications. The results underscore their potential in addressing environmental problems associated with organic dye pollutants.

[0047] The drawings and the foregoing description provide examples of embodiments. Those skilled in the art will recognize that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be separated into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of the processes described herein may be changed and are not limited to the manner described herein. Furthermore, the actions of any flowchart need not be implemented in the order shown; nor do all actions necessarily need to be performed. Also, those actions that are not dependent on other actions may be performed in parallel with the other actions. The scope of the embodiments is in no way limited by these specific examples.Numerous variations, whether explicitly stated in the specification or not, such as differences in structure, dimensions, and material use, are possible. The scope of the embodiments is at least as broad as indicated in the following claims.

[0048] Advantages, other benefits, and solutions to problems have been described above with reference to specific embodiments. However, the advantages, benefits, solutions to problems, and any components that may cause an advantage or solution to occur or become more apparent are not to be construed as a critical, required, or essential feature or component of any or all of the claims. REFERENCES 100 A system for the synthesis of gel-Zno nanorods (Gel-Zno NRs). 102 Plant for the production of colloidal solutions 102a Ultrasound irradiation chamber 102b Mixing vessel 104 Biopolymer addition module 106 Heating and mixing devices 108 Cooling system 110 Cutting device 110a blades 110b cutting mechanism 110c precision cutting platform 110d confiscation mechanism

Claims

[1] A system for the synthesis of Gel-ZnO nanorods (Gel-ZnO NRs) consisting of: a) a colloid solution preparation unit for preparing a ZnO nanorod colloid solution, wherein the colloid solution preparation unit is configured to mix prepared ZnO nanorod (NR) in double distilled water; b) a biopolymer addition module for incorporating agar biopolymer into the colloidal ZnO solution nanorod (NR); c) a heating and mixing device configured to heat and stir the combined solution, the heating and mixing device comprising a magnetic stirrer for continuous stirring to form a suspension of a biopolymer-added colloidal ZnO NR solution; d) a cooling system for bringing the solution to ambient temperature, whereby after cooling solid material of Gel -ZnO NR is obtained; and e) a cutting device for forming thin slices of the synthesized gel-ZnO NRs, wherein the cutting device comprises blades for cutting the material. [2] The system according to claim 1, wherein the colloidal solution preparation unit comprises: an ultrasonic irradiation chamber; and a mixing vessel, wherein the ultrasonic irradiation chamber facilitates ultrasonic irradiation of the colloidal solution of ZnO NR. [3] The system of claim 1, wherein the biopolymer integration module is configured to add 1.55 g of agar biopolymer to 30 ml of colloidal solution to form a 5.5 w / v% suspension. [4] The system of claim 1, wherein the heating and mixing device is configured to: a) heat the combined solution to above 70°C; b) stir vigorously during heating; and c) produce a clear, viscous solution. [5] The system of claim 1, wherein the cooling system is configured to cool the solution to an ambient temperature below 20°C. [6] The system of claim 1, wherein the cutting device comprises: a) a cutting mechanism for producing thin slices of the solidified gel ZnO NRs; b) a precision cutting platform; and c) a collecting mechanism for collecting the thin slices. [7] The system of claim 1, further comprising a photocatalyst preparation module configured to prepare the thin sheets of gel-ZnO NRs for dye degradation processes.

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