铝污泥基复合凝胶球对Cr(Ⅵ)的吸附性能与机理

Adsorption performance and mechanism of Cr(Ⅵ)by aluminum sludge composite gel spheres

以铝污泥、聚乙烯醇、海藻酸钠为原料,采用溶胶-凝胶、冷冻干燥技术制备铝污泥基复合凝胶球(AS-GEL),用于吸附溶液中Cr(Ⅵ)。通过静态吸附实验探究pH、AS-GEL投加量、初始质量浓度、温度、吸附时间、共存阴离子浓度对AS-GEL吸附Cr(Ⅵ)的影响。采用SEM、FTIR、XPS对AS-GEL吸附Cr(Ⅵ)的机理进行分析。结果表明,在p H=4、AS-GEL投加量为1.2 g/L、Cr(Ⅵ)初始质量浓度200 mg/L、温度为35℃、吸附时间为120 min、无其他阴离子共存的条件下,AS-GEL对Cr(Ⅵ)的最大吸附量为73.364mg/g。共存阴离子影响顺序为PO_(4)^(3-)>NO_(3)^(-)>Cl^(-)。吸附过程符合Langmuir等温吸附模型和准一级、准二级动力学方程。其主要吸附机理包括质子化基团对Cr(Ⅵ)的静电吸附及还原作用。5次吸附-解吸实验后,其吸附量保持初次吸附量的89.71%。同时,AS-GEL具有成本低、固液易分离的特性,有望应用在工程上。

Aluminum sludge composite gel spheres(AS-GEL)for the adsorption of Cr(Ⅵ)in the solution was prepared by sol-gel,freeze-drying technology using aluminum sludge,polyvinyl alcohol and sodium alginate as raw materials.The effects of solution pH,dosage of AS-GEL,initial mass concentration of Cr(Ⅵ)solution,temperature,adsorption time,and coexisting anion concentration on the adsorption of Cr(Ⅵ)were explored by static adsorption experiments.The mechanism was analyzed by SEM,FTIR and XPS.The results showed that under the conditions of pH=4,AS-GEL dosage of 1.2 g/L,Cr(Ⅵ)initial mass concentration of 200 mg/L,temperature of 35℃,adsorption time of 120 min and no coexistence of other anions,the maximum adsorption capacity of Cr(Ⅵ)by AS-GEL was 73.364 mg/g.The effect order of coexisting anions was PO_(4)^(3-)>NO_(3)^(-)>Cl^(-).The adsorption of Cr(Ⅵ)by AS-GEL conformed to Langmuir isotherm adsorption models,pseudo-first-order and pseudo-second-order kinetic equations.The main adsorption mechanism included the electrostatic adsorption and reduction of Cr(Ⅵ)by the protonated group.The adsorption capacity remained 89.71% of the initial adsorption capacity after 5 adsorption-desorption experiments.AS-GEL has the characteristics of low cost and easy solid-liquid separation,which has the prospect of engineering application.