Study On Degradation Of Chlorophenols Substances Using Composite Gel Supported Nano-Fe/Ni

Chlorophenol organic compounds(CPs)are widely used in medicine,rubber and other industries.They have a typical "three-effect"(carcinogenesis,teratogenicity,mutagenicity)and have great harm to human and aquatic organisms.According to the number of chloro-substituted groups,CPs can be divided into three groups:monochlorophenol(CP),dichlorophenol(DCP)and trichlorophenol(TCP),with a total of 19 similar substances.In order to better solve the harm of CPs in the water and make the water body in the natural environment reach a relatively safe state,6isomers of CP,DCP and 2,3,6-TCP were selected as the research objects in this study,and the degradation of them was studied using synthetic PNIPAm/PHEMA-nZVFe/Ni composites.The specific contents of the study are as follows:(1)A linear poly(2-hydroxyethyl methacrylate)(PHEMA)having a viscosity of692 cp was prepared.Using it as the second network,five kinds of PNIPAm/PHEMA gels with different structures and properties were prepared by adjusting the porogen size and dosage.Using a gel as a carrier load,a zero-valent nano-iron-nickel bimetal(PNIPAm/PHEMA-nZVFe/Ni)composite was successfully loaded by chemical reduction.The synthesized materials were characterized by SEM,SEM-EDS,SEM-Mappig,XRD and FTIR.The results showed that through-hole structure with a pore size of 5 ?m-30 ?m,and the particle size of nano-metal particles was mostly in the range of 50-90 nm.The nano-bimetallic particles were uniformly dispersed on the pore wall and inside the pores without obvious agglomeration.(2)Through the control variable method,single factor experimental analysis was designed to investigate the effect of PNIPAm/PHEMA-nZVFe/Ni composites on the degradation of 4-CP for six different influencing factors,such as Ni/Fe ratio,amount of gel carrier,initial pH of solution,reaction temperature,porogen and the ratio of PHEMA/NIPAm.The optimum conditions are as follows: the ratio of Ni/Fe ratio is3.5%;the dosage of gel carrier is 0.3 g;the initial pH of the solution is set to 3.0-5.0;the reaction temperature is set to 20 ?;and the pore-forming agent is 0.1 g PEG1500.(3)The mechanism of degradation and dechlorination of 4-CP was analyzed.The volatilization loss of 4-CP can be ignored.The adsorption rate of 4-CP on the gel carrier is about 30%;It is speculated that the carrier has a synergistic effect on the dechlorination degradation of 4-CP.The zero-valent nano-Fe releases electrons,which are then dechlorinated by electron transfer and catalysis of Ni.Degradation and reduction of 4-CP by HPLC analysis revealed that only one product of phenol was produced.The degradation kinetics model of 4-CP degradation process under different conditions was studied and analyzed.The fitting results show that the process of degradation of 4-CP by PNIPAm/PHEMA-nZVFe/Ni composite conforms to the first-order reaction kinetics model.The study investigated the recyclability of the carrier and the storage stability of the PNIPAm/PHEMA-nZVFe/Ni composite.The results showed that the carrier recycling performance and the storage stability of the composite were good.(4)In this paper,the degradation and dechlorination of monochlorophenol,6isomers of dichlorophenol and 2,3,6-trichlorophenol were studied under optimal conditions.The experimental results show that the degree of dechlorination of monochlorophenol is from easy to difficult: 4-CP > 2-CP > 3-CP;the degree of dechlorination of dichlorophenol is from easy to difficult: 2,4-DCP > 3,5-DCP >2,3-DCP > 2,5-DCP > 2,6-DCP > 3,4-DCP;The degradation reactions of chlorophenols are consistent with the first-order reaction kinetics model.