废白土榴莲壳粘土生物炭的制备及对Cr(VI)的吸附

Preparation of clay- charcoal adsorbent from spent bleaching earth and durian shell and its removal of Cr(VI)

摘要:

以废白土与榴莲壳为原料制备了粘土生物炭吸附剂(spent bleaching earth biochar,SBEC)、以废白土为原料制备了粘土炭基吸附剂(spent bleaching earth,SBE)吸附废水中的Cr（VI）。用比表面积分析、SEM、XRD、FTIR对吸附剂进行了表征。考察了溶液初始pH、Cr(VI)溶液浓度、吸附剂投加量、吸附时间和吸附温度分别对吸附Cr(VI)的影响。25℃下pH为3时、SBEC 投加量为0.5g/L、Cr(VI)初始浓度为100mg/L、吸附时间120min,SBEC对Cr(VI)去除效率最高为86.1%,SBE则在pH为2去除效率最高为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-脱附后,SBEC对Cr(VI)的去除率达58.8%。

Abstract:

The clay-biochar adsorbent(SBEC) and the clay carbon-based adsorbent (SBE) were prepared using spent bleaching earth and durian shell for hexavalent chromium removal from wastewater. The structure of the adsorbents were characterised by SEM,FTIR, XRD and BET. The influence of variables like initial metal loading, pH, contact time, and adsorbent dose were studied. Results showed maximum removal efficiency for Cr(VI) at 120 min contact time, adsorbent dose of 0.5 g/L and pH 3 by SBEC and pH 2 by SBE. Pseudo-second-order kinetics was the most suitable model for the removal of chromium. Freundlich isotherm model showed fit to SBEC and Langmuir model fitted to SBE. The interaction of SBEC and SBE with the simulated wastewater was spontaneous and endothermic interaction. The adsorption efficiency of SBEC was 58.8% after five adsorption-desorption tests.