Study On The Performance Of Modified Hydrotalcite In Adsorption Of Anionic Pollutants In Water

As industry and agriculture developed at a rapid rate,the problem of high pollutant content in water bodies is becoming increasingly serious,and the need to remove and recover pollutants from wastewater to achieve sustainable use of water resources became very pressing.Adsorption methods have the advantages of simple operation,low cost of equipment,good effect,and less chance of producing toxic byproducts,making it widely used in the field of wastewater treatment.Layered double hydroxides（LDHs）,as a new type of adsorbent material with a special laminar structure,have been extensively studied in water treatment because of their ion exchange properties and memory effect.In this paper,sulfide,nitrates and phosphates in water are selected as the target pollutants and the aim is to prepare modified hydrotalcite adsorbents with strong adsorption properties using a simple modification method,a series of studies have been carried out to this end,with specific work and results as follows..The transition metal oxide modified hydrotalcite was synthesized by impregnation roasting using industrial hydrotalcite as the carrier material.XRD,BET,SEM,FT-IR,and other characterization methods were used to analyze the physicochemical properties of the modified hydrotalcite in order to explore its efficacy in desulfurization applications.The results showed that among the five transition metal oxide-loaded hydrotalcite adsorbents,Fe₂O₃,CoO,NiO,CuO and ZnO,the adsorption performance of the CuO-loaded hydrotalcite was the best,and the adsorption performance of the composite adsorbent（CuO-HT-5-300）was the best when the loading of CuO was 5%and the calcination temperature of the complex was 300℃,and the adsorption performance of the composite adsorbent（CuO-HT-5-300）on sulfide in water was the best after 80 min.Adsorption equilibrium was achieved and the rate of removal approached 100%.The adsorption process was fitted and the adsorption of sulfide by CuO-HT-5-300 was in accordance with the primary kinetics.The adsorption of CuO-HT-5-300 was regenerated four times and the removal rate remained above 90%.XPS characterisation of CuO-HT-5-300 before and after adsorption showed that the sulfide were adsorbed by interacting with CuOThe aforementioned transition metal oxide modified hydrotalcite was applied to the adsorption of nitrate in water and the results showed that the CuO-loaded hydrotalcite had the best performance in the adsorption of nitrate.When the effects of CuO loading and complex roasting temperature on the adsorption performance were investigated,it was found that the best performance of the composite adsorbent（CuO-HT-5-500）for the adsorption of nitrate in water was achieved at a CuO loading of 5%and a complex roasting temperature of 500℃.The removal rate of 25 mg of adsorbent from 100 mL of nitrate solution with a concentration of 100 mg·L^-1reached51%.After fitting the adsorption kinetics of the adsorption process,the results showed that the adsorption of nitrate by CuO-HT-5-500 was in accordance with the primary kinetics,the rate of adsorption of CuO-HT-5-500 was gradually increased as the reaction temperature was increased,and the reaction process conformed to the Langmuir model of isotherm adsorption,which indicated that the adsorption process was a monolayer adsorption process.The previously prepared transition metal oxide modified hydrotalcite was applied to the adsorption of phosphate in water,and the results showed that the Fe₂O₃-loaded hydrotalcite had the best phosphate adsorption performance.Investigated the effect of load and roasting temperature on the adsorption performance and found that the adsorption performance of the compound adsorbent was the best performance（Fe₂O₃-HT-5-400）for phosphate adsorption in water was achieved at 5%Fe₂O₃loading and 400℃complex roasting temperature,and the removal rate of phosphate solution with a concentration of 100 mg·L^-1was 97%for 25 mg of adsorbent.The results of fitting the adsorption kinetics data.,and the results showed that the adsorption of phosphate by Fe₂O₃-HT-5-400 was in accordance with the primary kinetics,With the increase of reaction temperature,the adsorption rate increases gradually,and the reaction process conforms to Longmuir isothermal adsorption model.The modified hydrotalc adsorbent still possesses strong adsorption properties after four cycles of adsorption and desorption.The results show that the loading of metal oxides and roasting oxidation can effectively enhance the adsorption performance of hydrotalcite on pollutants in wastewater,and the prepared modified hydrotalcite has a large adsorption capacity and good regeneration performance,which is a valuable wastewater adsorbent for research.Figure 41 Table 8 Reference 90...