油菜(Brassica campestris L.)秸秆生物炭对Cr(Ⅵ)的吸附研究

Adsorption of Cr(Ⅵ)onto Biochar Derived from Brassica Campestris L.Straw

研究了油菜秸秆生物炭对Cr(Ⅵ)的吸附性能、影响因素及吸附动力学和吸附热力学.实验结果表明:该生物炭对Cr(Ⅵ)的吸附受pH、时间、Cr(Ⅵ)初始浓度等因素的影响.其中:pH是影响其吸附性能的重要因子.溶液中Cr(VI)的去除率随溶液pH值降低而升高,在pH值为2.0时达到最大98.87%.油菜秸秆生物炭对Cr(Ⅵ)的吸附符合准二级吸附速率方程,吸附等温线与Langmuir等温方程拟合较好,20℃、25℃、30℃和35℃下的最大吸附量分别为5.96、6.62、7.49和8.59mg/g.吸附量随温度的升高而增加,说明油菜秸秆生物炭对Cr(Ⅵ)的吸附机理主要是吸热的化学吸附.

Adsorption performance,kinetic and thermodynamics of Cr （Ⅵ）onto biochar derived from Brassica Straw were studied.The results showed that the adsorption capacity depended on pH,time,initial Cr（VI）concentration.pH was the most active factor among them.The removal rate of Cr（VI）increased with the decrease of solution pH value,and the maximum removal rate was up to 98.87% at pH 2.0.It was also showed that the adsorption kinetics followed the mechanism of the pseudo-second-order equation.The isotherm adsorption followed the isothermal model of Langmuir.The maximum capacity was 5.96mg/g,6.62 mg/g,7.49 mg/g and 8.59 mg/g at the temperature of 20℃,25℃,30℃ and 35℃,respectively.The capacity increased with increase of temperature,which indicated that this adsorption mechanism was mostly an endothermic chemical adsorption.