Study On Removal Of Chlortetracycline Hydrochloride By Cobalt Aluminum Bimetallic Oxide

Antibiotic wastewater is characterized by high concentration of organic matter,r efractory degradation and high biotoxicity.It is widely present in water bodies and po ses great harm to humans,plants,and animals,as well as to the entire ecosystem.The traditional biological method is difficult to deal with,and antibiotics will also cause s ome disturbance to the traditional biological treatment system.And antibiotics can als o disrupt traditional biological processing systems.At present,there are a variety of methods for antibiotic wastewater treatment,among which the synergistic removal of antibiotic contamination in water by adsorption and catalysis has become a new trend.Antibiotics in wastewater accumulate on the catalyst surface by adsorption and then degrade in situ by photocatalytic process.This method not only solves the problem of adsorption saturation in adsorption method,but also solves the problem of separation in photocatalytic degradation.In this paper,cobalt-aluminum layered double oxide（CoAl-LDO）was employed as an excellent photocatalyst.Various synthesis parameters were investigated to expl ore their effect on the structure of CoAl-LDO.Combined with X-ray diffraction（XR D）,Fourier transform infrared spectroscopy（FT-IR）,X-ray photoelectron spectroscop y（XPS）,scanning electron microscopy（SEM）and surface analyzer（BET）analysis,e tc.,the synthesis and influence control mechanism was revealed in detail.Based on th ese discussions,the optimum parameters were determined to prepare the CoAl-LDO with well structure and performance.To get insight into the catalytic performance,au reomycin hydrochloride（CTC·HCl）was selected as the representative antibiotics.Bat ch adsorption and photocatalytic experiments were conducted to explore the effects of p H,adsorbent dosage,initial concentration of CTC·HCl,reaction temperature and co ntact time on the"adsorption-catalytic"performance of CoAl-LDO.Moreover,the re moval mechanisms were revealed with the help of adsorption kinetic,adsorption isoth ermal,thermodynamic model,solid characterizations（e.g.,XRD,SEM）,as well as sc reening experiment and ESR analysis:（1）In this work,co-precipitation method was used to prepare cobalt-aluminum layered double oxide（CoAl-LDH）,one-step calcination method was used to prepare cobalt-aluminum layered double oxide（CoAl-LDO）with different calcination temperatures and different metal proportions.CoAl-LDO with chloromycin hydrochloride as the degradation target pollutant was selected,and the CoAl-LDO with better adsorption-catalytic effect was selected.For the analysis of subsequent experiments.（2）The adsorption behavior of chlortetracycline hydrochloride by 400-Co₂Al₁-LDO was studied.The removal process of chlortetracycline hydrochloride by 400-Co₂Al₁-LDO conforms to the S isothermal adsorption model and the quasi-second-order kinetic model,indicating that the adsorption process of chlortetracycline hydrochloride is mainly chemical adsorption.The adsorption mechanism mainly depends on the complexation with the metal oxygen bond in LDO.（3）The optimal conditions and influencing factors of photocatalytic degradation of aureomycin hydrochloride were investigated,including the influence of photocatalyst dosage,p H,initial concentration,and anion.The experimental results showed that the optimal photocatalyst dosage was 0.3g/L,and the optimal p H for degradation of aureomycin hydrochloride was 5.Among the anions,Cl^-and NO₃^-had almost no effect on the reaction,while PO₄^3-showed a certain degree of inhibition on the photocatalytic reaction.（4）The photocatalytic mechanism of 400-Co₂Al₁-LDO was studied.The results of free radical capture experiments and ESR showed that superoxide radicals（·O₂^-）,hydroxyl radicals（·OH）and holes（h⁺）played an important role in TC degradation.