响应曲面法强化生物炭吸附含Cd^(2+)废水的研究

Optimization of Adsorption of Biochar for Cd^(2+)-containing Wastewater by Response Surface Method

针对含Cd^(2+)废水污染问题,开展生物炭对含Cd^(2+)实验模拟废水的吸附实验研究。通过单因素确定了反应时间、吸附剂用量和pH的中心值分别为180 min、2.0 g/L和6.0。利用Box-Behnken-Design(BBD)探究了反应时间、吸附剂用量和pH值对生物炭吸附Cd^(2+)的影响以及各因素之间的交互作用,并通过构建响应曲面模型,预测出最优实验条件组合。结果显示:各因素对Cd^(2+)去除率的影响顺序从大到小依次为吸附剂用量、pH值、反应时间,但各因素间的交互作用不显著;在最优条件(吸附时间为171 min、吸附剂用量为3.0 g/L、pH=6.5)下,模型预测去除率为93.85%,实际去除率为97.72%,误差为4.12%。对生物炭进行了SEM、EDS和XRD表征,初步探讨了生物炭对Cd^(2+)的吸附机理,主要有生物炭孔隙位点的物理吸附、羧基等官能团的化学吸附,以及与K、Ca和Mg元素的离子交换。本研究可为含Cd^(2+)废水污染强化修复技术提供参考。

In order to solve the pollution problem of Cd^(2+)-containing wastewater,the adsorption of simulated Cd^(2+)-containing wastewater by biochar was studied.The central values of reaction time(A),adsorbent dosage(B)and pH were determined to 180min,2.0g/L and 6.0,respectively.The Box-Behnken-Design(BBD)experiment was designed to explore the interaction of A,B and pH on the adsorption of Cd^(2+)by biochar,and to optimize the combination of the optimal adsorption conditions.The results showed that the order of the influence of various factors on the adsorption effect was B>pH>A,and the interaction of A and various factors on the removal rate of Cd^(2+)was not significant.Under the optimal conditions(A=171 min,B=3.0 g/L,pH=6.5),the predicted removal rate was 93.85%,the actual removal rate was 97.72%,and the error was 4.12%.Combined with the performance characterization of biochar,the adsorption mechanism of biochar for Cd^(2+)was preliminarily discussed.The SEM results showed that there were more pores in biochar,which could provide more adsorption sites for Cd^(2+).And the FTIR show that the adsorption of Cd^(2+)by biochar is mainly the chemical adsorption of the carboxyl and carbonyl groups in the material and Cd^(2+).EDS and XRD showed the presence of K,Ca and Mg elements in the biochar,and the ion exchange reaction between Cd^(2+).The above research results provides reference for enhanced remediation technology of wastewater containing Cd^(2+).