College of Environmental Science and Engineering, Taiyuan University of Technology, Yuci University Campus, Jinzhong, 030600, Shanxi Province, China.
State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), Harbin Institute of Technology, Harbin, 150090, Heilongjiang Province, China.
Environ Sci Pollut Res Int. 2018 Jul;25(21):20743-20755. doi: 10.1007/s11356-018-2026-y. Epub 2018 May 12.
Corncob activated carbon (CCAC) was prepared by a HPO activation method. The optimum conditions for the preparation of CCAC were determined by orthogonal experiments. The effects of pH, reaction time, CCAC dosage, and hexavalent chromium (Cr(VI)) concentrations on Cr(VI) removal by CCAC were studied. Corn straw activated carbon (CSAC) was also prepared using the optimum preparation conditions determined for CCAC. The properties of samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The results showed that the optimum preparation conditions for CCAC were as follows: a mass of corncob of 10 g; a mass ratio of corncob to HPO of 1:2; a 5% HBO content of 10 mL; an impregnation time of 45 min; a carbonization temperature of 500 °C. The optimum conditions for the removal of Cr(VI) were as follows: pH < 9; temperature, 308 K; rotation speed, 150 r min; reaction time, 60 min; CCAC dosage, 1 g L. The Cr(VI) removal rate was above 98%, and the maximum adsorption capacity of CCAC was 9.985 mg g. The concentration of residual Cr(VI) in water was less than 0.05 mg L. FTIR showed that the surfaces of the samples had more oxygen-containing functional groups, which promoted the adsorption. XRD showed that CCAC and CSAC had similar peaks and that these peaks promoted the adsorption of Cr(VI). BET indicated that the number of pores in the samples followed the order CCAC > CSAC > CAC. SEM showed that the CCAC surface had a more porous structure, which enhanced adsorption. EDS showed that the C contents of CCAC and CSAC were much higher than that of CAC. Cr(VI) adsorption on CCAC followed quasi-second-order kinetics and was in accordance with a Langmuir adsorption isotherm, with monolayer adsorption. The adsorption reaction was endothermic, where higher temperatures increased the degree of spontaneous reaction.
玉米芯活性炭（CCAC）采用 HPO 活化法制备。通过正交实验确定了制备 CCAC 的最佳条件。研究了 pH 值、反应时间、CCAC 用量和六价铬（Cr(VI)）浓度对 CCAC 去除 Cr(VI)的影响。还使用确定的 CCAC 最佳制备条件制备了玉米秸秆活性炭（CSAC）。通过傅里叶变换红外光谱（FTIR）、X 射线衍射（XRD）、BET 分析、扫描电子显微镜（SEM）和能谱（EDS）对样品的性质进行了表征。结果表明，CCAC 的最佳制备条件如下：玉米芯质量为 10 g；玉米芯与 HPO 的质量比为 1:2；5% HBO 的含量为 10 mL；浸渍时间为 45 min；碳化温度为 500°C。去除 Cr(VI)的最佳条件如下：pH<9；温度，308 K；转速，150 r min；反应时间，60 min；CCAC 用量，1 g L。Cr(VI)去除率高于 98%，CCAC 的最大吸附容量为 9.985 mg g。水中残留 Cr(VI)的浓度小于 0.05 mg L。FTIR 表明，样品表面具有更多的含氧官能团，促进了吸附。XRD 表明 CCAC 和 CSAC 具有相似的峰，这些峰促进了 Cr(VI)的吸附。BET 表明样品中的孔数顺序为 CCAC>CSAC>CAC。SEM 表明 CCAC 表面具有更多孔的结构，增强了吸附。EDS 表明 CCAC 和 CSAC 的 C 含量远高于 CAC。CCAC 对 Cr(VI)的吸附符合准二级动力学和 Langmuir 吸附等温线，为单层吸附。吸附反应是吸热的，较高的温度增加了自发反应的程度。
