甜菜粕对Fe(Ⅲ)的吸附平衡和动力学研究

Adsorption Equilibrium and Kinetics of Fe3+ by Sugar Beet Pulp

摘要:

甜菜粕是一种富含膳食纤维的糖厂主要副产物，因其阳离子结合能力强常用于废水中重金属及色素的污染治理。本文研究了甜菜粕粒径和用量、反应时间、溶液中Fe3+初始浓度等因素对甜菜粕静态吸附人体必需宏量元素铁的影响，以及吸附反应平衡和动力学。结果表明，甜菜粕对铁的吸附量随着甜菜粕粒径减小、铁初始浓度的增加而增加；吸附平衡时间是80~100 min；在铁初始浓度0.001 mol/L，反应时间100 min和温度25 ℃的条件下，含水分93%、粒径75 μm~150 μm的废粕5 g/L可吸附除去溶液中65%铁；吸附过程可用准二级动力学模型描述（R2≥0.99）；吸附平衡数据与Freundlich型吸附等温线模型拟合性好，，说明甜菜粕对Fe（Ⅲ）的吸附不是理想的单分子层吸附. 甜菜粕因其廉价和高选择性，是制备高生物学效价有机铁剂的潜在底物。

Abstract:

Sugar beet pulp (SBP) is rich in dietary fiber and is the major by-product in sugar industry, which is often used to treat the pollution of heavy metals and pigments in wastewater because of its strong combining capacity of cations. The effects of sorbent dosage, sorbent particle size, contact time, and initial concentration of Fe3+ on adsorption of the necessary macro element Fe in body by SBPwere studied andthe adsorption equilibrium and kinetics models were also conducted. Results showed that the uptake of Fe3+ increased with decreasing particle size and increasing initial concentration of Fe3+; the sorption process reached equilibrium after 80~100 min of contact; 65% of Fe3+ was removed by using 5g/L of SBP (particle size 75 μm~150 μm) with 93% water and 0.001 mol/L Fe3+ at 25 ℃ for contacting 100 min; the pseudo second-order kinetic model could be described by the adsorption process(R2≥0.99); and the adsorption equilibrium data fitted well with the Freundlich adsorption isotherm equation, showing the adsorption of Fe3+ by SBP was not in monomolecular layer type. SBP, which is cheap and highly selective, seems to be a promising substrate to develop organic iron agent with high bioactivity.