Preparation and Visible-light Photocatalytic Degradation on Metronidazole of Zn₂SiO₄-ZnO-biochar Composites

Abstract

1.河北师范大学化学与材料科学学院，石家庄 050024；2.河北省无机纳米材料重点实验室，石家庄 050024) 摘 要: 以松木碱解液代替 NaOH 溶液作为锌盐沉淀剂，采用水热法制备了 Zn2SiO4-ZnO-生物炭三元复合材料 (SOB-x-y，x 代表松木粉的用量，y 代表 NaOH 浓度)，通过不同手段对样品进行了表征，研究了光催化 H2O2 降 解甲硝唑的性能。结果表明，制备的催化剂由枣核状硅锌矿型 Zn2SiO4 介晶、多边形六方晶相 ZnO 和松木生物炭 构成；与纯六方晶相 ZnO 相比，它具有更大的比表面积与孔容、更小的带隙能和更弱的荧光发射，因而具有更好 的光催化活性。 Zn2SiO4-ZnO-生物炭对甲硝唑的光催化 H2O2 降解过程符合准一级动力学方程， 其催化活性随 NaOHAbstract: Using pine alkali hydrolysate to replace NaOH solution as zinc salt precipitator, the Zn2SiO4-ZnO-Biochar (SOB-x-y, x is the dosage of pine powder, y is the concentration of NaOH) ternary composites were prepared by hydrothermal method. The photocatalysts were characterized through different methods. The degradation of metronidazole over the H2O2 photocatalysis was studied. The results showed that the as-prepared photocatalysts were composed of jujube-type willemite Zn2SiO4 mesocrystals, hexagonal ZnO and pine biochar. Compared with pure hexagonal ZnO, the SOB-x-y photocatalysts has better H2O2 photocatalytic activity due to the higher surface area and pore volume, lower band gap energy, lower PL emission peak intensity. The metronidazole degradation using the H2O2 photocatalysis was well-fitted to a pseudo-first-order kinetic model by SOB-x-y. Its catalytic activity increased with the increase of NaOH concentration, and increased at first and then decreased with the increase of pine flour content. The SOB-3-4 has best photocatalytic acitivity. The rate constant (k) and degradation rate (η) of SOB-3-4 increase with the decrease of pH, increase with the increase of H2O2 concentration, increase first and then decrease with the increase of catalyst dosage. The degradation rate of metronidazole gradually decreases with the increase of its initial concentration. Under the optimal condition (pH=3, catalyst dosage of 0.4 g/L , H2O2 dosage of 80 mmol/L, initial metronidazole concentra-

Novel synthesis method of oxygen vacancy WO3 and its photocatalytic performance for degradation of rhodamine B

“…This colored wastewater is discharged into the natural ecosystem, seriously polluting scarce water resources, which has been a broad concern. Conventional methods for organic pollution include physical adsorption methods, 3,4 biodegradation methods, 5 and chemical methods, 6‐14 among which semiconductor photocatalysis has been widely studied as a ‘green’ technology to deal with environmental pollution 9‐15 . For example, titanium dioxide, a cheap and readily available semiconductor material, has shown degradation properties against many organic pollutants, such as surfactants, pesticides, colorants, and other organic pollutants, under ultraviolet (UV) light 16 .…”

“…Conventional methods for organic pollution include physical adsorption methods, 3,4 biodegradation methods, 5 and chemical methods, [6][7][8][9][10][11][12][13][14] among which semiconductor photocatalysis has been widely studied as a 'green' technology to deal with environmental pollution. [9][10][11][12][13][14][15] For example, titanium dioxide, a cheap and readily available semiconductor material, has shown degradation properties against many organic pollutants, such as surfactants, pesticides, colorants, and other organic pollutants, under ultraviolet (UV) light. 16 Modified bismuth tungstate, such as MIL-101(Fe) octahedron-modified Bi 2 WO 6 microspheres, carbon dots (CDs) and Cd, Zn, and S (CZS) loaded onto the surface of bismuth tungstate (BWO) (CZS/CDs/ BWO heterojunction), significantly improved the photodegradation effect for organic pollutants.…”