废白土榴莲壳黏土生物炭的制备及其对Cr(Ⅵ)的吸附

Preparation of clay biochar from spent bleaching earth and durian shell and its adsorption for Cr(Ⅵ)

以废白土与榴莲壳为原料制备了黏土生物炭吸附剂(SBEC),以废白土为原料制备了黏土炭基吸附剂(SBE),并用于去除废水中的Cr(Ⅵ)。用SEM、XRD、FTIR、BET对吸附剂进行了表征。考察了溶液初始pH、初始Cr(Ⅵ)质量浓度、吸附剂投加量、吸附时间和吸附温度对Cr(Ⅵ)吸附效果的影响。在Cr(Ⅵ)初始质量浓度为100 mg/L、吸附剂投加量为0.5g/L、吸附时间120min、25℃条件下,SBEC对溶液pH为3的Cr(Ⅵ)去除率最高为86.1%,SBE则在pH为2时去除率最高为52.5%。SBEC、SBE对Cr(Ⅵ)的吸附过程符合准二级动力学模型,SBEC吸附过程符合Freundlich模型,SBE则与Langmuir吸附等温线模型较符合;吸附行为是自发吸热过程。经过5次吸附-脱附循环后,SBEC对Cr(Ⅵ)的去除率达58.8%。

Clay-biochar adsorbent(SBEC) and clay carbon-based adsorbent(SBE) were prepared using spent bleaching earth and durian shell and then used to remove Cr(Ⅵ) from wastewater. These adsorbents were characterized by SEM, XRD, FTIR and BET. The effects of initial pH of solution, initial mass concentration of Cr(Ⅵ), adsorbent dosage, adsorption time and temperature on the adsorption efficiency of Cr(Ⅵ) were studied. Under the conditions of initial mass concentration of Cr(Ⅵ) of 100 mg/L, adsorbent dosage of 0.5 g/L, adsorption time of 120 min and 25 ℃, the highest removal efficiency of SBEC for Cr(Ⅵ)at pH =3 was 86.1%, and that of SBE at pH =2 was 52.5%. The adsorption process of Cr(Ⅵ) by SBEC and SBE conformed to the quasi-second-order kinetic model. The adsorption process of SBEC and SBE accorded with Freundlich model and Langmuir isotherm model, respectively. The adsorption behavior of SBEC and SBE for Cr(Ⅵ) in the simulated wastewater was a spontaneous and endothermic interaction. The adsorption efficiency of SBEC was 58.8% after five adsorption-desorption tests.