核壳Fenton催化剂CuFe_2O_4@PDA-Cu的制备、表征及其活化H_2O_2降解染料的性能

Core-shell Fenton catalyst CuFe_2O_4@PDA-Cu:Preparation,characterization and property in dye degradation by activated H_2O_2

为得到新型高效多相催化剂,有效去除废水中的染料,以Cu(Ac)_2与CuFe_2O_4@PDA为原料制备了催化剂CuFe_2O_4@PDA-Cu.通过IR、XRD、XPS、UV-Vis、DRS技术对催化剂的性能进行了表征,考察了温度、H_2O_2用量、催化剂用量、pH值、盐等对催化活性的影响.利用HPLC测定降解产物,采用自由基捕获和抑制实验进行机理验证,发现催化剂是核壳结构.温度升高、pH值升高、H_2O_2和催化剂用量的增加均有利于提高催化活性;氯化物、硫酸盐、硝酸盐和磷酸盐不影响催化效果,溴化物和亚硝酸盐降低了催化效果.得到的最优降解条件为:T=30℃,催化剂用量10mg·L^(-1),pH=9,过氧化氢用量10mmol·L^(-1),染料浓度30mg·L^(-1).最优条件下催化剂可循环使用4次以上;甲基橙、茜素红和罗丹明B的去除率为100%;染料R0213、O0118和B0115的去除率大于60%.降解产物有草酸、马来酸和CO_2.甲基橙、茜素红和罗丹明B降解后COD_(Mn)=2~4mg·L^(-1).水杨酸捕获·OH生成2.5-二羟基苯甲酸,叔丁醇抑制染料降解.结果表明,催化剂可活化H_2O_2产生·OH,·OH攻击染料分子开环降解直至矿化.该研究为开发高效多相催化剂,有效去除废水中的染料提供了科学依据.

Novel and high-efficiency heterogeneous catalysts are in demand to remove the dye from the wastewater effectively.This paper proposes a catalyst,CuFe2O4@PDA-Cu,which was prepared from Cu(Ac)2 and CuFe2O4@PDA.It was characterized by IR spectra,X-ray diffraction,UV-Vis DRS and XPS and its catalytic activity was investigated with different temperature,catalyst dosage,H2O2 dosage,pH value and salts while the mechanisms were validated by free radical inhibition and free radical captured experiments.It is found that(1)CuFe2O4@PDA-Cu is of core-shell structure,on which the Cu 2+is immobilized with coordination bond.(2)Higher temperature,higher H2O2 dosage,higher catalyst dosage are favorable for catalytic activity.The higher pH is favorable for catalytic activity under pH=2~10.The catalytic effect is not affected in presence of chloride,sulfate,phosphate and nitrate,but reduced in presence of bromide and nitrite.The optimal experimental condition was T=30℃,the catalyst dosage 10 mg·L-1,pH=9,10 mmol·L-1 H2O2 and 30 mg·L-1 dye.The catalyst could be reused four times with methyl orange degradation of 95%.(3)Methyl orange,alizarin red and rhodamine B were removed with 100%degradation.And dyes containing bromine or nitro group,RO213,O0118,B0115 were removed with above 60%degradation in 24 h.The degradation products were found to have oxalic acid,maleic acid,CO 2,COD Mn=2~4 mg·L-1.(4)2.5-dihydroxybenzoic acid was formed from salicylic acid and hydroxyl radicals,and the dye degradation was inhibited in the presence of tert-butanol.All these indicated that the catalyst with core-shell structure could activate H 2 O 2 with the product hydroxyl radical effectively.And the dye molecular should be oxidized and degraded,even mineralized by hydroxyl radical in presence of salts,acid or base with pH<10.This study provides scientific supports to design and prepare highly efficient heterogeneous Fenton catalysts for the effective removal of dyes.