Functionalized amorphous ferronickel layered double hydroxide adsorbent as well as preparation method and application thereof

Abstract

The invention provides a functionalized amorphous ferro-nickel layered double hydroxide adsorbent. The adsorbent is obtained by performing non-crystallization and functional modification on ferro-nickel layered double hydroxide through L-cystine, the adsorbent has an amorphous structure, and the surface of the adsorbent is modified with amino and sulfo functional groups. And the adsorption capacity of the A-NiFe LDH on BuX <-> is more than 1880 mg / g. In addition, in the presence of various electrolyte ions (such as Ca < 2 + >, Mg < 2 + >, SO4 < 2->, H2PO4 <-> and HPO4 < 2->) and humic acid, the material still keeps excellent adsorption performance and selectivity. The invention not only provides a novel adsorption material for efficient removal of xanthate pollutants, but also provides a new thought for non-crystallization and functional design of layered double hydroxides.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of functionalized amorphous nickel-iron layered double hydroxide adsorbent, preparation method and application in degrading pollutant, belong to catalytic technical field. BACKGROUND

[0002] Mining, as an important basic industry of national economy, plays an irreplaceable role in promoting economic and social development. However, a large amount of wastewater produced in the beneficiation process contains various residual flotation reagents, which poses a serious threat to the environment. Among them, potassium butyl xanthate (PBX) is one of the most commonly used collectors in sulfide mineral flotation, which has high biological toxicity and can damage the nervous system and hematopoietic system. Its natural degradation is slow, and the decomposition products such as carbon disulfide (CS2) are still toxic, which can easily cause the increase of chemical oxygen demand (COD) of water body and cause persistent harm to aquatic ecosystems. With the expansion of mineral resources development scale, the discharge of butyl xanthate (BuX - ) beneficiation wastewater is increasing, which not only exacerbates the pressure of water resource shortage, but also seriously restricts the reuse efficiency of wastewater. Therefore, developing efficient, economical and environmentally friendly BuX - deep removal technology has become an important theoretical and practical topic in the field of mine wastewater treatment.

[0003] In recent years, in response to the pollution problem caused by xanthate residues in beneficiation wastewater, various treatment technologies have been widely studied, mainly including photocatalysis, advanced oxidation, micro-electrolysis, biodegradation and adsorption, etc. Among them, although photocatalysis, ozone oxidation, Fenton reaction and micro-electrolysis have shown certain effect in degrading xanthate, they still have problems such as high energy consumption, harsh reaction conditions, high operating cost or possible production of harmful by-products. The biodegradation method has the defect of long bacteria domestication period. Compared with the above methods, adsorption method is considered as a green treatment technology with great application potential because of its simple operation, low energy consumption, high cost-effectiveness and less secondary pollution. At present, a variety of adsorbents have been tried to remove butyl xanthate in wastewater, such as activated carbon, graphene oxide, clay and fumed silica, etc. However, the treatment efficiency of existing adsorbents for high-concentration xanthate wastewater still needs to be improved, and the development of high adsorption capacity materials is still an important goal of current research.

[0004] Layered double hydroxide (LDH) is a kind of layered structure material, and its molecular formula can be expressed as (M 1-x 2+ M x 3+ (OH)2) x+ (A x / n )n- • mH2O, wherein M 2+ may be common: Mg 2+ , Zn 2+ or Ni 2+ , M 3+ may be common: Al 3+ , Ga 3+ , Fe 3+ or Mn 3+ . n - is a non-framework charge-compensating inorganic or organic anion, for example: CO3 2- , Cl - , SO4 2- , RCO2 - . LDH has the characteristics of large theoretical specific surface area, easy synthesis and component diversity, and is considered as one of the potential materials for adsorbing organic anions such as butyl xanthate. However, the original LDH has obvious limitations in actual adsorption application. The original LDH has weak selective adsorption capacity for specific target anions, and is easily affected by the coexisting anions in the actual water body. In addition, the types of functional groups on the material surface are relatively single, and there is a lack of strong interaction sites between the target pollutants, resulting in that the adsorption capacity is usually not ideal.

[0005] To overcome the above problems, the application adopts an L-cystine assisted hydrothermal method to successfully prepare amorphous nickel-iron layered double hydroxide (A-NiFe LDH) with amorphous structure and multiple functional group modification. XRD, SEM, BET and TGA and other means are used to systematically compare the differences between A-NiFe LDH and crystalline LDH in terms of phase, morphology and pore structure. Through a series of adsorption experiments, the influence law of factors such as solution pH, temperature, contact time, initial concentration, coexisting ions and humic acid on the removal effect of BuX - is evaluated. Further combined with FT-IR, XPS and zeta potential and other characterization results, the adsorption mechanism of A-NiFe LDH for BuX - is explained. Through the synergistic strategy of amorphization regulation and functionalization, the adsorption capacity and selectivity of LDH for xanthate pollutants are significantly improved, which provides a new idea for the design and development of high-efficiency adsorbents. SUMMARY

[0006] In view of the above technical problems, the application provides a functionalized amorphous nickel-iron layered double hydroxide adsorbent, which is obtained by amorphization and functionalization modification of nickel-iron layered double hydroxide by L-cystine; the adsorbent has an amorphous structure, and the surface thereof is modified with amino and sulfonic acid functional groups.

[0007] The Fourier transform infrared spectrum of the adsorbent is at 1316 cm -1and 1112 cm -1 corresponding to asymmetric stretching vibration of -SO3 - group and stretching vibration of C-N bond, respectively.

[0008] The specific surface area of the adsorbent is 150 m 2 / g to 170 m 2 / g, preferably 159.58 m 2 / g.

[0009] A preparation method of the functionalized amorphous nickel-iron layered double hydroxide, characterized in that it comprises the following steps: (a) dissolving a nickel source, an iron source and L-cystine in a solvent to form a mixed solution A; (b) mixing the mixed solution A with an alkaline solution B, adjusting the pH to 9.5-10.5, and stirring to obtain a precursor slurry; (c) performing a hydrothermal reaction on the precursor slurry obtained in step (b); (d) performing solid-liquid separation, washing and drying on the product after the hydrothermal reaction to obtain the adsorbent.

[0010] In step (a), the nickel source is nickel nitrate hexahydrate, and the iron source is iron nitrate nonahydrate; the molar ratio of Ni²⁺ in the nickel source to Fe³⁺ in the iron source is (3-5):1, preferably 4:1.

[0011] In step (a), the molar ratio of L-cystine to Fe³⁺ in the iron source is (0.8-1.2):1, preferably 1:1. The temperature of the hydrothermal reaction is 180-220°C, preferably 200°C; and the reaction time is 10-14 hours, preferably 12 hours.

[0012] The application of the functionalized amorphous nickel-iron layered double hydroxide adsorbent in adsorbing and removing xanthate pollutants in water bodies.

[0013] The xanthate pollutants are butyl xanthate, and the adsorption is carried out in a water body with a pH value of 6 to 11.

[0014] A method for treating xanthate-containing wastewater, comprising: adding the functionalized amorphous nickel-iron layered double hydroxide adsorbent to xanthate-containing wastewater, mixing and adsorbing.

[0015] The adsorption capacity of the adsorbent for butyl xanthate in wastewater is not less than 1800 mg / g, preferably 1884.4 mg / g.

[0016] The wastewater contains coexisting substances including one or more of Ca 2+ , Mg 2+ , SO4 2- , H2PO4 - , HPO4 2- , and humic acid; and the presence of the coexisting substances does not significantly affect the adsorption capacity of the adsorbent for xanthate.

[0017] The present application successfully constructs a functional amorphous nickel-iron layered double hydroxide (A-NiFe LDH) through an L-cystine-assisted hydrothermal strategy. Characterization results show that the material has a typical amorphous structure and contains functional groups such as amino groups and sulfonic acid groups. Adsorption experiments show that the adsorption capacity of A-NiFe LDH for BuX - is more than 1880 mg / g, and the adsorption behavior conforms to the Sips isotherm model and the pseudo-second-order kinetics model. Combined with the thermodynamic parameters, it is shown that the adsorption process is a spontaneous and exothermic process occurring on a heterogeneous surface dominated by chemical adsorption. XPS, FT-IR, and zeta potential analysis further confirm that the adsorption mechanism of BuX - on A-NiFe LDH is mainly coordination complexation, and the hydroxyl groups and amino groups in the material synergistically enhance the adsorption effect through hydrogen bonding. In addition, in the presence of various electrolyte ions (such as Ca 2+ , Mg 2+ , SO4 2- , H2PO4 - , and HPO4 2- , etc.) and humic acid, the material still maintains excellent adsorption performance and selectivity. The present application not only provides a new adsorbent material for efficient removal of xanthate pollutants, but also provides a new idea for the amorphization and functionalization design of layered double hydroxides. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Standard absorbance curve of PBX.

[0019] Figure 2 (a-d) Morphology of NiFe LDH, NiFe LDH@BuX - , A-NiFe LDH, and A-NiFe LDH@BuX - .

[0020] Figure 3 (a-d) Energy spectrum of NiFe LDH, NiFe LDH@BuX - , A-NiFe LDH, and A-NiFe LDH@BuX - ; (e) EDS diagram of main elements in A-NiFe LDH.

[0021] Figure 4 NiFe LDH, NiFe LDH@BuX - , A-NiFe LDH and A-NiFe LDH@BuX - XRD patterns (a) and FT-IR spectra (b) of NiFe LDH, A-NiFe LDH, NiFe LDH@BuX and A-NiFe LDH@BuX.

[0022] Figure 5 XPS spectra of A-NiFe LDH and A-NiFe LDH@BuX: (a) full spectra, (b) S 2p, (c) Ni 2p and (d) Fe 2p deconvoluted spectra. -

[0023] Figure 6 XPS spectra of A-NiFe LDH: N 1s (a) and O 1s (c); A-NiFe LDH@BuX - XPS spectra of A-NiFe LDH@BuX: N 1s (b) and O 1s (d).

[0024] Figure 7 N2adsorption-desorption curves and pore size distribution plots of (a) NiFe LDH and (b) A-NiFe LDH.

[0025] Figure 8 TG and DTG curves of (a) NiFe LDH and (b) A-NiFe LDH.

[0026] Figure 9 Adsorption capacity of BuX - on NiFe LDH and A-NiFe LDH at different concentrations; (b) zeta potential of A-NiFe LDH; effect of pH on (c) NiFe LDH and (d) A-NiFe LDH adsorption of BuX - .

[0027] Figure 10 Effect of initial concentration on A-NiFe LDH adsorption of BuX - at (a) 1000 mg / L, (b) 2000 mg / L, (c) 4000 mg / L and (d) 6000 mg / L PBX.

[0028] Figure 11 Effect of initial concentration on A-NiFe LDH adsorption of BuX - at (a) 298 K, (b) 308 K and (c) 318 K.

[0029] Figure 12 Effect of (a) cations, (b) anions and (c) HA on A-NiFe LDH adsorption of BuX - ​Effect of adsorption on A-NiFe LDH. DETAILED DESCRIPTION

[0030] The main reagents used in the experiment are shown in Table 1.

[0031] Table 1 Main reagent information

[0032] The main instrument information used in the experiment is shown in Table 2.

[0033] Table 2 Main instrument information

[0034] Example 1 Preparation of NiFe LDH and A-NiFe LDH NiFe LDH was synthesized by hydrothermal method: 5.8158 g of Ni(NO3)2·6H2O (0.02 mol) and 2.02 g of Fe(NO3)3·9H2O (0.005 mol) were dissolved in 30 mL of deionized water, so that the molar ratio of Ni 2+ :Fe 3+ = 4:1, denoted as A.

[0035] Take 25 mL of 2 mol / L NaOH solution, denoted as B.

[0036] Slowly add A to B, and stir vigorously to make the solution homogenate, and at the same time, adjust the pH of the solution to 10.0 with 2 mol / L NaOH solution. After stirring the solution homogenously for 0.5 h, transfer the solution to a 100 ml reaction kettle, and hydrothermal at 200℃ for 12 h. After the reaction is completed, the product is suction filtered, washed with deionized water and anhydrous ethanol three times respectively, and then dried in a 60℃ oven for 3 hours. Grind and pass through a 200 mesh sieve to obtain the product, denoted as NiFe LDH.

[0037] To prepare A-NiFe LDH, 0.005 mol of L-cysteine was dissolved in 25 ml of 2 mol / L NaOH solution, denoted as C. As above, take A, slowly add A to C, and stir vigorously for 0.5 h. Maintain the pH of the mixed solution at 10.0 with 2 mol / L NaOH solution. Then transfer the solution to a 100 ml reaction kettle for hydrothermal reaction, and the reaction conditions and subsequent treatment are the same as above. The product is denoted as A-NiFe LDH.

[0038] The preparation steps of NiFe LDH and A-NiFe LDH and their respective adsorption of butyl xanthate (BuX - ) are as follows: NiFe LDH adsorbed BuX - After adsorbing BuX (the concentration of PBX was 1000 mg / L), the material was recorded as NiFe LDH@BuX - ; A-NiFe LDH adsorbed BuX - After adsorbing BuX (the concentration of PBX was 1000 mg / L), the material was recorded as A-NiFe LDH@BuX - .

[0039] Characterization and test The micro-morphology and surface elements of the crystal structure of NiFe LDH and A-NiFe LDH and the materials after adsorbing BuX (hereinafter referred to as BuX - ) respectively (recorded as NiFe LDH@BuX - , A-NiFe LDH@BuX - ) were observed by using scanning electron microscope (FE-SEM) and energy dispersive spectrometer (EDS). The crystal phase of NiFe LDH, A-NiFe LDH, NiFe LDH@BuX - and A-NiFe LDH@BuX - was characterized by X-ray diffractometer with copper target as test target material. The surface functional groups and chemical bonds of NiFe LDH, A-NiFe LDH and A-NiFe LDH@BuX - were characterized by Fourier transform infrared spectroscopy (FT-IR) (the sample transmittance was tested in the wave number range of 400-4000 cm -1 , the interval was 0.5 cm -1 ). The thermal stability of NiFe LDH and A-NiFe LDH was determined by thermogravimetric analyzer (TGA) under N2 atmosphere. The adsorption performance index of NiFe LDH and A-NiFe LDH was studied by Brunauer-Emmet-Teller (BET) analysis method based on N2 adsorption-desorption data, and the specific surface area and pore size distribution parameters of the modified materials of NiFe LDH and A-NiFe LDH were obtained by BET and BJH equations. The change of surface electrical properties of A-NiFe LDH was explored by using nanoparticle size and Zeta potential analyzer (Zeta). The pH of organic pollutants was adjusted by using 0.1 mol / L HCl or NH3·H2O solution. The absorbance of BuX - at wavelength 301 nm was determined by ultraviolet visible spectrophotometer (UV-8000). A-NiFe LDH and A-NiFe LDH@BuX -The chemical state and surface chemical composition were analyzed by X-ray photoelectron spectroscopy (XPS).

[0040] BuX - Analysis conditions and plotting of standard curves Quantitative analysis of butyl xanthate was performed using a UV-Vis spectrophotometer. (BuX) - The maximum absorption wavelength is 301 nm. A 100 mg / L potassium butyl xanthate stock solution is preferred. This stock solution is then diluted to prepare potassium butyl xanthate (PBX) standard solutions with concentrations ranging from 0 to 15 mg / L (e.g., 0 mg / L, 2 mg / L, 4 mg / L, 5 mg / L, 8 mg / L, 10 mg / L, 12 mg / L, 15 mg / L). Deionized water is used as a reference solution to measure the absorbance at 301 nm, and a standard absorbance curve is plotted. Figure 1 As shown, the curve fitting equation is used to calculate the concentration of potassium butyl xanthate solution, and then BuX is calculated based on the relative molecular mass ratio. - The concentration.

[0041] NiFe LDH and NiFe LDH@BuX were analyzed by SEM. - , A-NiFe LDH and A-NiFe LDH@BuX - Characterize the morphology, such as Figure 2 As shown, the crystal structure of NiFe LDH mainly exhibits a plate-like structure of a certain thickness, without obvious pores, and the particles are relatively regular and uniform. This typical plate-like structure of NiFe LDH is consistent with literature reports. NiFe LDH@BuX - It maintains a crystal structure similar to NiFe LDH. Conversely, SEM images of A-NiFe LDH do not show a distinct crystal form, but a disordered, bent, fragmented layered structure can still be observed. Overall, A-NiFe LDH is an aggregate formed by the stacking of irregularly shaped and curled fragmented LDH. The amorphous and bent layered structure is due to the fact that the morphology of LDH crystals varies with the physicochemical properties of organic anions and the stacking pattern of hydrocarbon chains. The non-closely packed organic hydrocarbon chains in A-NiFe LDH make it prone to bending or deformation, resulting in its irregular shape. The bending curvature may originate from the hydrophobic interactions between the outer tails of organic anions. These hydrophobic interactions cause nonpolar molecules or groups to aggregate together, avoiding contact with water, which in turn encourages the tails of organic anions to approach each other, forming bent knots.

[0042] Further investigation was conducted on NiFe LDH and NiFe LDH@BuX based on EDS characterization. -, A-NiFe LDH and A-NiFe LDH@BuX - The distribution of components. Figure 3 (e) The surface scan elemental mapping diagram of A-NiFe LDH shows that the six elements C, N, O, S, Fe, and Ni are present and evenly distributed. Figure 3 In (a) and 3(c), compared to NiFe LDH, the percentage of C atoms in A-NiFe LDH increases, and S element is present. Figure 3 In (ad), NiFe LDH@BuX - and A-NiFe LDH@BuX - Compared to NiFe LDH and A-NiFe LDH respectively, the atomic percentages of C and S both increased, indicating that BuX... - Successful adsorption on both materials.

[0043] The NiFe LDH and NiFe LDH@BuX compounds were systematically studied using X-ray diffraction analysis. - , A-NiFe LDH and A-NiFe LDH@BuX - The evolution of crystal phases, such as Figure 4 As shown. For the original NiFe LDH, the diffraction peaks at 11.2°, 22.4°, 33.6°, 34.5°, 38.9°, 46.1°, 59.8°, 61.1°, 64.6°, and 71.2° correspond to the (003), (006), (101), (012), (015), (018), (110), (113), (116), and (119) planes of NiFe LDH (JCPDS: 40-0215), respectively, and no other impurity phases were found, indicating the successful synthesis of the nickel-iron layered double hydroxide. In the adsorption of BuX... - Before and after, the XRD patterns of NiFe LDH maintained the same interplanar spacing, proving that NiFe LDH exhibits the same interplanar spacing in BuX. - Structural integrity during adsorption. Notably, no diffraction peaks were observed in the A-NiFe LDH powder, confirming its amorphous structure. This structure significantly increases the number of active sites on the material surface, thereby enhancing the material's adsorption performance for PBX.

[0044] To study NiFe LDH, A-NiFe LDH and A-NiFe LDH@BuX - Structural characteristics and A-NiFe LDH adsorption of BuX - The relevant roles in the process were investigated, and a systematic analysis of FT-IR and XPS data was conducted. NiFe LDH exhibited a typical peak for LDHs, at 3512 cm⁻¹. -1The broad peak at 1630 cm⁻¹ corresponds to ν(OH) of hydroxyl groups within the layer. -1 The peak at 1354 cm⁻¹ is attributed to the δ(HOH) of interlayer H₂O. -1 The peak at that location corresponds to NO3 in NiFe LDH. - Asymmetric stretching vibration, 1000 cm -1 The following spectral bands represent ν(MO) in NiFeLDH. The infrared spectrum of α-NiFe LDH is at 3437 cm⁻¹. -1 The absorption peak at 1603 cm⁻¹ shows a significant broadening, which is due to the superposition of ν(OH) from the hydroxyl group in the lamellar plate and ν(NH) from the introduced amino group. -1 The peak at this location is compared to 1630 cm⁻¹ in NiFe LDH. -1 The δ(HOH) vibration at this point exhibits a significant redshift and increased intensity, which can be attributed to the enhancement of the hydrogen bond network in A-NiFe LDH by the amino and sulfonic acid groups introduced by L-cysteine, thereby altering the vibrational environment of water molecules. Furthermore, the new peaks appearing at 1316 cm⁻¹ and 1112 cm⁻¹ correspond to -SO₃²⁻, respectively. - Asymmetric stretching vibrations and ν(CN). This result is consistent with the N 1s spectrum in XPS ( Figure 6 (a) At 399.5 eV (C-NH2) and S 2p spectrum ( Figure 3 .5(b)) at 168.7 eV (-SO3) - The spectral peaks at the locations corroborate each other.

[0045] In adsorption of BuX - Afterwards, A-NiFe LDH@BuX - The FT-IR spectrum at 1242 cm⁻¹ -1 and 1018 cm -1 The locations appearing respectively belong to BuX - Characteristic absorption peaks of ν(COC) and ν(CS) in medium. Simultaneously, the S 2p spectrum of XPS ( Figure 5 In (b), the peak areas attributable to CS at 163.2 eV and 164.5 eV increased significantly, and a peak area attributable to S appeared at 161.3 eV. 2- The new peak, jointly confirming BuX - Successfully adsorbed by A-NiFe LDH. Notably, the superimposed peaks of ν(OH) and ν(NH) showed a further red shift after adsorption, indicating that the -OH and -NH2 groups in A-NiFe LDH act as hydrogen bond donors, binding with BuX. -Hydrogen bonds of the type OH···S / NH···S are formed between the more electronegative S or O atoms. This inference is supported by XPS data: after adsorption, the binding energy of the M-OH component in the O 1s spectrum undergoes a positive shift of approximately 0.2 eV. Figure 6 (cd)), the amino signal in N 1s also showed a similar shift ( Figure 6 (ab) indicates that the electron cloud density of the corresponding atoms decreases due to hydrogen bonding.

[0046] Figure 5 (c) shows that the Ni 2p spectrum contains two main peaks located at 855.9 eV and 873.6 eV, respectively. These two peaks correspond to Ni... 2+ Ni 2p 3 / 2 and Ni 2p 1 / 2 track. Figure 5 (d) Fe 2p in A-NiFe LDH 3 / 2 and Fe 2p 1 / 2 The spectral peaks are located at 712.1 eV and 724.8 eV, respectively, both of which correspond to Fe. 3+ .from Figure 5 (cd) shows that the adsorption of BuX - Subsequently, both the Ni 2p and Fe 2p binding energies exhibit positive shifts, which is due to the binding energies of Ni and Fe in LDH to BuX. - Caused by complexation, indicating that the metal site is related to BuX. - There is a complexation effect between them. In summary, A-NiFe LDH has a positive effect on BuX. - The adsorption occurs through complexation and hydrogen bonding.

[0047] The BET analysis results of NiFe LDH and A-NiFe LDH are shown in the figure. Figure 7 According to IUPAC classification, both exhibit Type IV N2 adsorption-desorption isotherms with H3-type hysteresis loops, indicating that the materials possess typical mesoporous structures, with porosity related to the porosity between LDH particles. Detailed parameter comparisons show that the specific surface area of ​​A-NiFe LDH (159.58 m²) is... 2 / g) was significantly higher than that of NiFe LDH (48.01 m 2 / g), its single-point total pore volume (0.55 cm³) 3 The ratio ( / g) was also significantly greater than that of NiFe LDH (0.29cm). 3g). In addition, the lower relative pressure (P / P0) of the loop closing point of A-NiFe LDH indicates the change of pore structure. The increase of specific surface area and single-point total pore volume is mainly attributed to the introduction of L-cystine, which inhibits the ordered growth and stacking of crystals, promotes the formation of loose and defect-rich amorphous aggregate structure, thus exposing more active sites and forming a more extensive mesoporous network, which provides more attachment sites and mass transfer channels for adsorbate ions, resulting in the higher adsorption capacity of A-NiFe LDH for BuX - adsorption performance.

[0048] The TG and DTG curves of NiFe LDH and A-NiFe LDH were studied, as shown in Figure 8 The weight loss of NiFe LDH and A-NiFe LDH in the test temperature range was 32.72% and 31.52%, respectively, which was relatively close. However, there were significant differences in the weight loss process revealed by the DTG curves of the two materials.

[0049] For NiFe LDH, the thermal decomposition showed a typical three-stage process: the first stage (25~250℃) was mainly to lose weakly adsorbed water and interlayer crystallization water, and the layered structure was not affected; the significant weight loss peak in the second stage (250~400℃) corresponded to the removal of hydroxyl groups and the decomposition of interlayer ions; the third stage (above 400℃) was related to the further decomposition of the layer plate skeleton and the possible transformation of spinel phase.

[0050] In contrast, the weight loss behavior of A-NiFe LDH showed a more complex characteristic. In the first stage, the weight loss peak of A-NiFe LDH was advanced to 112.6℃, and the weight loss rate was slightly lower (8.63%), which was due to the fact that in the amorphous LDH structure, water molecules mainly existed in the surface of the particles and the pores formed by their accumulation, which were easy to remove; at the same time, although the amorphous material had a higher specific surface area, the increase of surface adsorbed water was not enough to compensate for the decrease of interlayer water due to the destruction of the layer structure, resulting in a slight decrease in the total weight loss rate. In the second stage, the temperature corresponding to the maximum weight loss rate of A-NiFe LDH shifted to high temperature, combined with FT-IR analysis, this phenomenon may be due to the fact that the introduced functional groups enhance the hydrogen bond interaction within the material (such as: -SO3 - as a hydrogen bond acceptor and forms hydrogen bonds with -OH on the LDH layer plate), thus changing the removal energy barrier of interlayer ions and hydroxyl groups. Above 600℃, the weight loss of A-NiFe LDH may be related to the complete decomposition of residual organic matter and the phase transition of the final inorganic product.

[0051] Example 2 The NiFe LDH and A-NiFe LDH prepared by the above method were used to adsorb BuX - Batch adsorption test: The adsorption experiment used a 50 mL round-bottom centrifuge tube as the reaction vessel. 40 mg NiFe LDH was mixed with A-NiFe LDH and 20 mL PBX solution, and placed in a water bath shaker (SHY-2 rotary water bath constant temperature shaker) at a speed of 220 r / min.

[0052] The pH (6-11) test was conducted as follows: The pH of the above mixed solution was adjusted using 0.1 mol / L NH3·H2O and 0.1 mol / L HCl solutions, and the performance of the BuX test within the pH range of 6-11 was investigated at 298 K. - Adsorption behavior on NiFe LDH and A-NiFe LDH. Results are as follows. Figure 9 As shown in (c–d). The zeta potential test indicates that ( Figure 3 .9(b)), pH of A-NiFe LDH zpc The pH is 7.8. When the solution pH is < 7.8, the A-NiFe LDH surface is positively charged, which is conducive to the adsorption of BuX. - When pH > 7.8, BuX - There is electrostatic repulsion between BuX and the negatively charged A-NiFeLDH surface, but within the tested pH range... - The adsorption capacity on A-NiFe LDH did not decrease significantly, indicating that electrostatic interaction is not the primary adsorption mechanism. In contrast, the adsorption capacity of NiFe LDH decreased significantly with increasing pH. These results suggest that A-NiFe LDH is effective for adsorbing BuX within a pH range of 6-11. - It has a stable removal effect, and its adsorption behavior does not mainly rely on electrostatic interaction.

[0053] Contact time affects adsorption of BuX - Effects: The relationship between adsorption capacity and time was investigated at different initial concentrations at pH 7.8 and 298 K. The results are as follows: Figure 10 As shown in the figure. Experiments show that under the condition of an initial concentration of 6000 mg / L, the adsorption can reach more than 90% of the maximum adsorption capacity within 480 min, and then the rate of increase slows down, finally reaching equilibrium at around 600 min.

[0054] At a concentration of 400 mg / L, adsorption reached stability in 300 min.

[0055] At a concentration of 200 mg / L, adsorption reached stability in 150 min.

[0056] At a concentration of 100 mg / L, adsorption reached stability in 60 min.

[0057] The adsorption process was carried out at constant temperature for a certain time, and then the solid was separated by a 0.45 μm microporous filter membrane. The filtrate was diluted to an appropriate concentration in a colorimetric tube, and the PBX concentration was determined by ultraviolet visible spectrophotometry (UV-8000). Each experiment was repeated at least three times to determine the repeatability and effectiveness of the data. Formulas (1), (2), (3) give the BuX - Expressions of adsorption capacity and adsorption removal rate.

[0058]

[0059] In the above formula, C0(mg / L), C t (mg / L) and C e (mg / L) represent the PBX concentrations at the initial, specified time, and equilibrium states, respectively, Q t (mg / g) and Q e (mg / g) are the adsorption capacities at the specified time and equilibrium, respectively, V (L) is the volume in the batch adsorption experiment, and m (g) is the amount of adsorbent used.

[0060] Example 3 Effect of temperature and initial concentration on adsorption of BuX - : The adsorption behavior of A-NiFe LDH for BuX - in water under different initial concentrations and temperatures is shown in the following chart. The results show that the adsorption capacity increases significantly with the increase of the initial concentration of BuX - , and at a high concentration of 3000 mg / L, the removal rate can still be maintained at more than 95%, showing the excellent high-load adsorption capacity of A-NiFe LDH. The experimental results are consistent with the typical adsorption characteristics: as the initial concentration increases, the available active sites on the surface of the adsorbent are gradually saturated, and finally reach adsorption equilibrium. It is worth noting that as the temperature increases from 298 K to 318 K, the equilibrium adsorption capacity of A-NiFe LDH for BuX - decreases, indicating that the overall adsorption process is exothermic. At 298 K, the maximum adsorption capacity of A-NiFe LDH for BuX - can reach 1884.4 mg / g. Combined with the characterization results of XPS, etc., this temperature effect further supports that the adsorption process is related to the coordination and hydrogen bond synergy, and the decrease in adsorption capacity can be attributed to the weakening of hydrogen bond interaction and the inhibition of BuX - coordination with metal sites (Ni / Fe) due to the increase in temperature.

[0061] Maximum adsorption capacity of BuX⁻ on A-NiFe LDH at different temperatures.

[0062]

[0063] Example 4 Effects of electrolyte ions and humic acid The presence of electrolyte ions and humic acid in actual wastewater environments may affect the effect of A-NiFe LDH on BuX. - The adsorption of dyes was investigated. Four different concentrations (0, 0.01, 0.1, and 1 mol / L) were set up to study the effects of cations and anions on dye adsorption. The adsorption of different anions (Cl...) was studied... - NO3 - SO4 2- H2PO4 - and HPO4 2- Sodium salts are typically used when studying the effects of different cations (Na+). + K + Ca 2+ and Mg 2+ When dealing with the effects of ), chloride salts are typically used.

[0064] The effect of different anions on the adsorption of butyl xanthate by A-NiFe LDH: A 50 mL round-bottom centrifuge tube was used as the reaction vessel. 40 mg of A-NiFe LDH was added to 20 mL of a mixed solution of potassium butyl xanthate (PBX) and various anions. The concentration of PBX in the mixed solution was fixed at 2000 mg / L, and the temperature was 298 K. The anions were Cl-, ... - NO3 - SO4 2- H2PO4 - and HPO4 2- (Four groups of different types of anion mixtures were set up, with anion concentrations of 0M, 0.01M, 0.1M, and 1M in each group). The mixtures were placed in a water bath vibrator (SHY-2 rotary water bath constant temperature vibrator) at a speed of 220 r / min.

[0065] The effect of different cations on the adsorption of butyl xanthate by A-NiFe LDH: A 50 mL round-bottom centrifuge tube was used as the reaction vessel. 40 mg of A-NiFe LDH was added to 20 mL of a mixed solution of PBX and various cations for reaction. The concentration of PBX in the mixed solution was fixed at 2000 mg / L, and the temperature was 298 K. The cations were Na+, Na+, and Na+. + K + Ca 2 + and Mg 2+(Four groups of different types of cation mixture solutions were set up, with cation concentrations of 0M, 0.01M, 0.1M, and 1M in each group). The solutions were placed in a water bath vibrator (SHY-2 rotary water bath constant temperature vibrator) at a speed of 220 r / min.

[0066] Humic acid (HA) on BuX - Adsorption effect experiment: 50 mL round-bottom centrifuge tubes were used as reaction vessels. 40 mg of A-NiFe LDH was added to a mixed solution of PBX and HA for reaction. The concentration of PBX in the mixed solution was fixed at 2000 mg / L. The concentrations of HA in the different mixed solutions were 0 mg / L, 5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L and 30 mg / L, respectively. The temperature was 298 K and the pH was not adjusted.

[0067] Figure 12 Describes the situation in cations (Na) + K + Ca 2+ and Mg 2+ ), anion (Cl) - NO3 - SO4 2- H2PO4 - and HPO4 2- BuX in the presence of humic acid - Adsorption on A-NiFe LDH. For example... Figure 12 As shown in (ab), common electrolyte ions did not significantly affect the adsorption of BuX⁻, indicating that A-NiFe LDH has high selectivity for the adsorption of BuX⁻. In the presence of humic acid ( Figure 12 (c) Although the adsorption amount decreased slightly, it remained at a high level, indicating limited site competition between BuX⁻ and BuX⁻. This phenomenon suggests that BuX⁻… - The adsorption on A-NiFe LDH is less affected by common electrolyte ions and humic acid. A-NiFe LDH can still effectively adsorb BuX even under conditions where multiple background components coexist. - It demonstrates strong anti-interference capabilities and practical application potential.

[0068] Example 4 To objectively evaluate the effect of A-NiFe LDH on BuX - To assess its adsorption performance, this invention compared it with various adsorbents reported in the literature to determine their saturated adsorption capacity (Q). m The comparison results are summarized in Table 3. The data show that traditional mineral adsorbents (such as chalcopyrite and bornite) have a lower effect on BuX. - Its adsorption capacity is relatively weak (Qm The adsorption capacity of some modified materials such as a-PbO, Cu-loaded PVA-SA porous aerogel, FeNi-biochar and multi-layer graphene oxide increased to 281 mg / g, 268 mg / g, 366.2 mg / g and 411.5 mg / g, respectively. It is worth noting that the saturated adsorption capacity of A-NiFe LDH prepared in this study for BuX - was as high as 1884.4 mg / g, which was significantly better than all the listed reference adsorbents. This excellent adsorption performance can be attributed to the unique amorphous layered structure of A-NiFe LDH, which provides a large number of adsorption active sites for BuX - through complexation and hydrogen bonding, etc. The above comparison results show that A-NiFe LDH has a significant advantage in BuX - adsorption, which shows its potential application value in the treatment of xanthate-containing wastewater.

[0069] Table 3 Comparison of adsorption performance of different adsorbents for butyl xanthate.

[0070]

[0071] Chalcopyrite: Han C, Wei D, Gao S, et al. Adsorption and desorption of butyl xanthate on chalcopyrite [J]. Journal of Materials Research and Technology, 2020, 9(6): 12654-12660. Bornite: Sun Q-Y, Yin W-Z, Cao S-H, et al. Adsorption kinetics and thermodynamics of sodium butyl xanthate onto bornite in flotation [J]. Journal of Central South University, 2019, 26(11): 2998-3007. α-PbO: Shen Q, Fan Y-J, Zhang W-M, et al. Two-dimensional correlation analysis of continuous online in situ ATR-FTIR on the adsorption of butyl xanthate at the surface of α-PbO [J]. Chinese Chemical Letters, 2015, 26(2): 193-196. copper-loaded PVA-SA porous aerogel: Cao Y, Shi J, Lu S, et al. Efficient adsorption behavior and mechanism of butyl xanthate from gold flotation wastewater using enhanced copper-loaded PVA-SA porous aerogel [J]. Journal of Environmental Chemical Engineering, 2025: 117230. FeNi-biochar: Feng S, Bi K, Cui T, et al. Removal of butyl xanthate and Cr (Ⅵ) using FeNi-biochar [J]. Arabian Journal of Chemistry, 2025, 18. OTAC / Mt-FA: Wang G, Yin M, Zhu G, et al. Preparation of a granular montmorillonite and fly ash composite adsorbent and application for Pb2+ and butyl xanthate adsorption [J]. Minerals Engineering, 2025, 228: 109345. multilayer graphene oxide: Li L, He M, Feng Y, et al. Adsorption of xanthate from aqueous solution by multilayer graphene oxide: an experimental and molecular dynamics simulation study[J]. Advanced Composites and Hybrid Materials, 2021, 4(3): 725-732.

Claims

1. A functionalized amorphous nickel-iron layered double hydroxide adsorbent, characterized in that, The adsorbent is obtained by amorphization and functional modification of a nickel-iron layered double hydroxide with L-cystine; the adsorbent has an amorphous structure, and its surface is modified with amino and sulfonic acid functional groups.

2. The functionalized amorphous nickel-iron layered double hydroxide adsorbent of claim 1, wherein, The Fourier transform infrared spectrum of the adsorbent shows characteristic absorption peaks at 1316 cm -1 and 1112 cm -1 corresponding to the asymmetric stretching vibration of -SO3 - group and the stretching vibration of C-N bond, respectively.

3. The functionalized amorphous nickel-iron layered double hydroxide adsorbent of claim 1, wherein, The specific surface area of the adsorbent is 150 m 2 / g to 170 m 2 / g, preferably 159.58 m 2 / g.

4. A method for the preparation of a functionalized amorphous nickel-iron layered double hydroxide according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: (a) dissolving a nickel source, an iron source and L-cystine in a solvent to form a mixed solution A; (b) mixing the mixed solution A with an alkaline solution B, adjusting the pH to 9.5-10.5, stirring to obtain a precursor slurry; (c) performing a hydrothermal reaction on the precursor slurry obtained in step (b); (d) performing solid-liquid separation, washing and drying on the product after the hydrothermal reaction to obtain the adsorbent.

5. The production method according to claim 4, characterized by, In step (a), the nickel source is nickel nitrate hexahydrate and the iron source is iron nitrate nonahydrate; the molar ratio of Ni 2+ to Fe 3+ in the nickel source to the iron source is (3-5): 1, preferably 4:

1.

6. The preparation method according to claim 4, characterized in that, In step (a), the L-cysteine ​​reacts with the Fe in the iron source. 3+ The molar ratio is (0.8~1.2):1, preferably 1:1; The temperature of the hydrothermal reaction is 180-220°C, preferably 200°C; the reaction time is 10-14 hours, preferably 12 hours.

7. Use of the functionalized amorphous nickel-iron layered double hydroxide adsorbent according to any one of claims 1-3 in adsorbing and removing xanthate pollutants in a water body.

8. Use according to claim 7, characterized in that, The xanthate pollutants are butyl xanthate, and the adsorption is performed in a water body with a pH value of 6-11.

9. A method of treating xanthate-containing wastewater, characterized by, The method comprises: adding the functionalized amorphous nickel-iron layered double hydroxide adsorbent according to any one of claims 1-3 to wastewater containing xanthate, mixing and performing adsorption.

10. The method of claim 9, wherein, The adsorption capacity of the adsorbent for butyl xanthate in wastewater is not less than 1800 mg / g, preferably 1884.4 mg / g; The wastewater contains coexisting substances including one or more of Ca 2+ , Mg 2+ , SO4 2- , H2PO4 - , HPO4 2- , and humic acid; and the presence of the coexisting substances does not significantly affect the adsorption capacity of the adsorbent for xanthate.

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