Preparation Of Biotemplate Hydrotalcite And Its Adsorption/Photocatalytic Activity For NO^-₃-N

As is well known to public that excessive NO^-₃-N in water will cause serious harm to human health,and the research and development of NO-3、-N treatment agent is currently a research hotspot.In this paper,Biological tem,plate hydrotalcite（C-LDO）was synthesized by coprecipitation-calcination method and characterized by FT-IR,SEM,XRD,BET,XPS and UV-Vis DRS.Taking C-LDO as an adsorbent,the optimal preparation conditions of the adsorbent were investigated.The effects of adsorption time,initial concentration,pH,dosage,temperature,coexisting ions and other factors on NO^-₃-N adsorption effect were investigated.The adsorption kinetics,adsorption isotherm,adsorption thermodynamics,desorption kinetics were discussed.C-LDO as catalyst,the effects of dosage,pH,initial concentration and other factors on the photocatalytic treatment of NO^-₃-N were investigated,and the photocatalytic kinetics,active groups and degradation pathways were discussed.The main conclusions are as follows:（1）C-LDO is synthesized by coprecipitation-calcination method.The optimal preparation process is as follows:the molar ratio of Zn-Ti-Fe is 2:1:1,the calcination temperature is 450 ℃,and the dosage of cotton is 2 g.C-LDO keeps the fiber shape and structure of cotton,avoids the block agglomeration of hydrotalcite,increases the specific surface area to 74.8m2 g-1,and increases the num,ber of macropores;The introduction of element C into the chemical composition has a structural memory effect and can improve the adsorption performance of the adsorbent.（2）Under the temperature of 25℃,NO^-₃-Nconcentration is 50mg/L,adsorbent dosage is 0.67g/L,pH=7,C-LDO has the best adsorption effect on NO^-₃-N,which can reach equilibrium within 120min,equilibrium adsorption quantity is 66.57mg/g,and NO^-₃-N removal rate is 88.76%.The adsorption process can be described by a quasi-second-order kinetic model and Langmuir adsorption isotherm,and it is a spontaneous endothermic reaction.Theresults of competitive adsorption tests show that the higher the valence of coexisting anions,the greater the influence on the adsorption of NO^-₃-N by C-LDO.NO^-₃-N is adsorbed onto the surface of C-LDO through anion intercalation,and the adsorbed saturated C-LDO can be desorbed under ultraviolet light,with the desorption rate at desorption equilibrium being 92.50%,and the process follows a pseudo-second-order desorption kinetic model.（3）The dosage is 0.25g/L,pH=7,the initial concentration of NO^-₃-N is 50mg/L,and the degradation rate of NO^-₃-N by C-LDO is 70.58%after 8h reaction.the photocatalytic degradation of NO^-₃-N by C-LDO reached the quasi-first-level kinetic standard under 20W ultraviolet light.Photogenerated electrons are the active groups in the process of photocatalytic treatment of NO^-₃-N by C-LDO.To sum up,C-LDO is a potential NO^-₃-N treatment agent,which can effectively remove NO^-₃-N from water...