尖晶石型双金属修饰生物炭对水中镉的去除

Removing cadmium from water with spinel bimetal modified biochar

为实现农林废弃生物质的资源化利用,以弃置水稻、大豆秸秆为基底,采用浸渍-溶胶凝胶法制备了非贵双金属协同含氧官能团修饰生物炭。通过调控热解温度、生物质原料、改性剂投加比例以及蛋清液投加量等制备参数条件,筛选对水中镉具备高效去除能力的改性生物炭。结果表明:热解温度为450℃,以铁锰双金属添加,蛋清液投加量为10 mL条件下,尖晶石型水稻基铁锰改性生物炭(MF-BCS)相较于未改性生物炭、大豆基铁锰改性生物炭对镉表现出更优的吸附性能,最大吸附容量可提升至109.2 mg·g^(-1),吸附平衡时间为100 min。研究表明,双金属与羟基、羧基官能团的协同修饰显著提高了生物炭的比表面积并增加了吸附点位。改性生物炭吸附镉的过程更符合准一级动力学方程,吸附过程以物理吸附为主,化学络合吸附为辅。

To realize resource utilization of agricultural and forestry waste biomass, non-precious bimetal biochar with oxygen-containing functional groups was prepared by the impregnation-sol-gel method with discarded rice and soybean straw as the base. The modified biochar with a high ability to remove cadmium from water was screened by controlling the pyrolysis temperature, biomass raw material, modifier proportion, and egg white liquid dosage. The results showed that when the pyrolysis temperature was 450 ℃ and the dosage of egg white was 10 mL, compared with unmodified biochar and soy-based biochar, spinel type Fe-Mn rice-based modified biochar(MF-BCS)showed better adsorption capacity for cadmium, with a maximum adsorption capacity of 109.2 mg·g^(-1) and adsorption equilibrium time of 100 min. Research has shown that the synergistic modification of bimetal with hydroxyl and carboxyl functional groups significantly increased the specific surface area and adsorption sites of biochar. Adsorption process of cadmium by modified biochar was more consistent with the quasi-firstorder kinetic equation, which indicates that the adsorption was mainly physical and supplemented by chemical complexation adsorption.