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

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.

Core-shell Fenton catalyst CuFe2O4@PDA-Cu: Preparation,characterization and property in dye degradation by activated H2O2.

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 Cu²⁺ 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, CO₂, 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 H₂O₂ 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.