菜籽粕对水溶液中Pb(Ⅱ)的吸附性能

以菜籽粕为吸附剂去除水溶液中Pb2+,考察了pH值、吸附剂投放量、反应时间对吸附性能的影响,研究了不同温度下菜籽粕对溶液中Pb2+吸附热力学和动力学。当Pb2+溶液浓度为100 mg/L时,吸附剂投放量为4 g/L,pH值3~5.5,吸附时间120 min,Pb2+去除率达到95%以上。铅吸附等温线很好地符合Langmuir等温方程,293 K时饱和吸附量达31.9 mg/g。对吸附热力学参数ΔGθ,ΔHθ,ΔSθ的计算表明,吸附过程属于熵驱动型的吸热自发过程。Pb2+在菜籽粕上动力学吸附符合准二级速率方程,表观吸附活化能Ea=49.6 kJ/mol。结合吸附前后红外光谱(FTIR)分析,Pb2+在菜籽粕上吸附主要发生在蛋白质的酰胺结构、-NH2、-C-S-上,具有化学吸附的显著特征。菜籽粕作为一种廉价的生物质吸附剂,对低浓度Pb2+溶液吸附量大,吸附速度快,具有良好的开发应用前景。

Removing Pb2+ from Aqueous Solution Using Rapeseed Meal as Absorbent

With the purpose of using rapeseed meal as a low-cost adsorbent to tentatively remove Pb(Ⅱ) from water,experiments were conducted to probe the adsorption of Pb(Ⅱ) onto rapeseed meal in terms of kinetics and equilibrium adsorption.The experimental result showed the removal of Pb(Ⅱ) was above 95% under the condition of initial lead concentration of 100 mg/g,rapeseed meal dosage of 4 g/L,pH range of solution 3~5.5 and the reaction duration of 120 min.Besides,the kinetic data obtained were fit well to the pseudo-second-order kinetic model;the data regarding equilibrium adsorption could be well described by the Langmuir adsorption isothermal model over the whole range of temperatures at the laboratory.Considering the overall experimental results including the characterization of FTIR,it was suggested that the adsorption controlled mainly by chemical adsorption took place through the interactions of Pb(Ⅱ) with functional groups such as amide,-NH2,-C-S-,which were contained in rapeseed meal.