不同添加顺序下腐殖酸-沸石复合体对镉的吸附性能

Adsorption of cadmium by humic acid-zeolite complex in different addition sequences

进行沸石与腐殖酸不同的添加顺序下复合体系对镉的等温吸附实验以及形态分析实验和解吸实验,探究了不同添加顺序下复合体系对镉的吸附能力与吸附稳定性,并通过FTIR及XRD分析了复合体系对镉的吸附机理。高镉浓度下腐殖酸均使沸石对镉的吸附量降低了3.28~3.58 mg/g,但增强了对镉的吸附稳定性,使镉的可还原态占比大幅提高,同时酸解吸pH由5降低至3。当镉浓度较低时,“先沸石后腐殖酸”的添加顺序对镉的吸附量无影响,故在修复低镉浓度土壤时推荐以此顺序进行修复。而当土壤腐殖酸含量较高时则不适用沸石进行修复。

The isothermal adsorption experiments,morphological analysis experiments and desorption experiments of Cd were carried out under different addition sequences of zeolite and humic acid.The adsorption capacity and stability of Cd were investigated under different addition sequences.The adsorption mechanism of Cd by the composite system was analyzed by FTIR and XRD.Under high Cd concentration,humic acid reduced the adsorption capacity of zeolite to Cd by 3.28~3.58 mg/g,but enhanced the adsorption stability of Cd,significantly increased the proportion of Cd reducible states,and reduced the pH of acid desorption from 5 to 3.When the cadmium concentration is low,the addition order of“zeolite first and then humic acid”has no effect on the adsorption capacity of cadmium,so it is recommended to remediation the soil with low cadmium concentration in this order.When the soil humic acid content is high,zeolite is not suitable for remediation.