颗粒状污泥生物炭对锌铜共污染水体的吸附效应分析

Enhanced adsorption of zinc and copper co-pollution in water using modified granular sludge biochar

以城市脱水污泥为原料,经不同温度热解制备颗粒状污泥生物炭(BC),并采用硝酸酸化处理得到改性污泥基生物炭(NBC),用于单一和复合重金属溶液体系中锌铜的吸附去除.结果表明:硝酸改性剂导致了生物炭pH和灰分的降低,而生物炭的比表面积和孔体积却有所提升,含氮官能团类型也更加丰富.热解温度为500℃的改性污泥基生物炭(NBC500)对重金属的吸附性能最佳;且在溶液初始pH=7时吸附效果最好,对初始浓度分别为200和150 mg·L^(-1)的锌铜去除率达75.51%和87.12%.单一金属体系中,NBC500对Zn^(2+)和Cu^(2+)的最优施加量分别为10和12.5 g·L^(-1);而在复合污染体系下,生物炭最佳投加量为25 g·L^(-1).NBC500对重金属的单位吸附量在两种体系中均呈现出Cu^(2+)>Zn^(2+)的规律,且不存在协同或拮抗作用.NBC500的吸附过程均更符合Elvoich动力学(R^(2)>0.96)和Langmuir吸附等温线模型(R2>0.98),这表明重金属在非均匀固体表面被吸附,且固定方式较为多元.此外,机理分析表明颗粒状污泥生物炭对2种重金属的吸附机制主要是官能团络合(胺基、硝基等)、孔隙填充和静电相互作用.实验所制备的NBC500吸附提升效果显著,兼具便于从水体分离的优势,有利于实现“以废治废”的环保目标.

In this study,granular sludge biochar(BC)was prepared from municipal dewatered sludge by pyrolysis at different temperatures,and the modified sludge-based biochar(NBC)was obtained by nitric acid acidification to remove zinc and copper from single or combined heavy metal solution systems.The results showed that nitric acidification reduced pH and ash content of the biochar,while enhancing the specific surface area,pore volume,and nitrogen-containing functional groups in the biochar.The modified sludge-based biochar(NBC500)with a pyrolysis temperature of 500℃showed superior havy metal adsorption performance.NBC500 removed 75.51%and 87.12%of Zn and Cu,respectively,from initial concentrations of 200 and 150 mg∙L^(-1)in single or combined metal solution,at initial pH 7.optimal NBC500 dosages were 10 and 12.5 g∙L^(-1)for Zn^(2+)and Cu^(2+),in single systems,and 25 g∙L^(-1)in the combined pollution system.adsorption capacity of NBC500 for Cu^(2+)was higher than that of Zn^(2+)in both systems,and there was no synergistic or antagonistic effect.adsorption of NBC500 followed Elvoich kinetics(R2>0.96)and Langmuir adsorption isotherm model(R^(2)>0.98),which indicated that the heavy metals were adsorbed on the non-homogeneous solid surface.the adsorption mechanism of granular sludge biochar involved functional group complexation(Amine,nitro,etc.),pore filling and electrostatic interaction.NBC500 had significant adsorption enhancement and easy separability from water bodies,offering approach for environmentally friendly waste treatment.