柳絮纤维生物质炭的制备及其对染料废液中Cr(Ⅵ)的吸附性能

针对目前酸性媒染染料废水中的六价铬Cr(VI)对水体环境污染严重的问题,以柳絮纤维为原料,通过限氧裂解法制备了KOH活化生物质炭(CBK)、NaOH活化生物质炭(CBN),采用吸附批实验法研究模拟染料废液pH值、吸附剂投放量、温度效应等对柳絮纤维生物质炭吸附处理Cr(VI)的影响,利用动力学和热力学相关模型对吸附过程进行拟合,探究柳絮纤维生物质炭对Cr(VI)的吸附机制。结果表明:CBK较CBN比表面积显著增大,表面吸附位点增多;在模拟废液pH值为2时,CBK、CBN对Cr(VI)的理论最大吸附量分别为82.68、47.16 mg/g,且吸附过程符合Freundlich热力学模型和准二级动力学模型,吸附过程主要为多分子层吸附,同时还伴随着化学吸附,该吸附反应是自发进行且为吸热反应,温度升高可显著提高柳絮纤维生物质炭对Cr(VI)的吸附量。

Preparation of catkin fiber biochar and its adsorption properties for Cr(VI) in dye wastewater

In view of the serious pollution of hexavalent chromium Cr(VI) in acid mordant dye wastewater to water environment, KOH activated biochar (CBK) and NaOH activated biochar (CBN) were prepared by oxygen limiting pyrolysis with catkin fiber. The effects of pH value of a simulated dye waste liquid and dosage of adsorbent and temperature effect on the adsorption treatment of Cr(VI) by catkin fiber biochar were studied by adsorption batch experiment. The adsorption process was fitted by kinetic and thermodynamic models to explore the adsorption and fixation mechanism of Cr(VI) by catkin fiber biochar. The results show that the specific surface area of CBK is significantly larger than that of CBN, and the surface adsorption sites are increased. When the pH value of the solution is 2, the theoretical maximum adsorption capacity of Cr(VI) by CBK and CBN is 82.68 and 47.16 mg/g respectively. The adsorption process conforms to Freundlich thermodynamic model and quasi second-order kinetic model, which means that the adsorption process is mainly multi-molecular layer adsorption, accompanied by chemical adsorption. The adsorption reaction is spontaneous and endothermic, and the increase of temperature can significantly improve the adsorption capacity of catkin fiber biomass carbon for Cr(VI).