不同改性污泥生物炭对Cd^(2+)的吸附特性

Adsorption Characteristics of Cd^(2+)by Different Modified Sludge Biochar

[目的]提高污泥生物炭对Cd^(2+)的吸附容量,拓展污泥资源化再利用途径。[方法]以生活污水处理厂的剩余污泥为原料制备污泥生物炭,并利用H_(2)SO_(4)、KOH、H_(2)O_(2)、ZnCl_(2)对其进行改性制备改性生物炭(SBC-H_(2)SO_(4)、SBC-KOH、SBC-H_(2)O_(2)、SBC-ZnCl_(2)),通过动力学和等温吸附试验探讨其对Cd^(2+)的吸附性能和机制,并确定最佳改性方案。[结果]改性生物炭对Cd^(2+)的动力学吸附过程符合准二级动力学和Elovich模型,等温吸附过程可以用Sips模型和Toth模型进行描述;对Cd^(2+)的吸附过程存在物理和化学多种机制共同作用,吸附速率主要受到外扩散和颗粒内扩散步骤的控制;改性法提高了污泥生物炭对Cd^(2+)的吸附速率和容量,其中KOH改性污泥生物炭对Cd^(2+)的吸附效果最好,吸附量可达140.78 mg/g,吸附量提高了近3.7倍。[结论]SBC-KOH吸附材料在重金属废水处理方面具有广泛的应用前景。

[Objective]To improve the adsorption capacity of biochar for Cd^(2+),a new way to recycle sludge resources was sought.[Method]Modified sludge biochar(SBC-H_(2)SO_(4),SBC-KOH,SBC-H_(2)O_(2),SBC-ZnCl_(2))was prepared by activation of H_(2)SO_(4),KOH,H_(2)O_(2) and ZnCl_(2) with the residual sludge from sewage treatment plants as raw materials.Kinetic and isothermal adsorption experiments were conducted to explore the adsorption performance and mechanism of Cd^(2+).The best modification scheme was determined by comparing the adsorption effect.[Result]The kinetic adsorption process of Cd^(2+)by modified biochar conformed to the quasi-second-order kinetics and Elovich model,and the isothermal adsorption process could be described by Sips and Toth models.The adsorption process of Cd^(2+)had a variety of physical and chemical mechanisms,and the adsorption rate was mainly controlled by the steps of external diffusion and internal diffusion.The modification method improved the adsorption capacity of sludge biochar for Cd^(2+),and KOH modified sludge biochar had the best adsorption effect on Cd^(2+),with the adsorption capacity up to 140.78 mg/g,and the adsorption capacity increased nearly 3.7 times.[Conclusion]SBC-KOH as adsorbent material for wastewater treatment has a wide application prospect.