大蒜废弃物吸附柠檬酸淋洗液中镉离子的研究

Removal of Cadmium Ions from the Citric Acid Solution Using Garlic Waste

摘要: 柠檬酸试剂对复合重金属污染土壤具有良好的洗脱效果，兼之对环境友好等优点而在土壤修复领域备受关注。如何高效经济地脱除淋洗液中的重金属离子，实现柠檬酸淋洗液的循环使用，是土壤淋洗技术实用化过程中非常关键的问题。本文提出生物吸附的方法，来实现对柠檬酸溶液介质中镉离子的脱除。具体采用了大蒜皮生物吸附剂，对人工配制的柠檬酸溶液中镉离子的吸附脱除进行了实验考察，包括溶液pH、吸附时间、吸附剂用量、柠檬酸浓度、共存离子、搅拌速度、反应温度等实验参数对脱除效果的影响。实验结果表明60分钟内吸附可达平衡；pH为4时吸附效率最佳；吸附剂用量增加，吸附效率迅速升高；反应温度、搅拌速度和共存干扰离子对吸附效果的影响不显著。吸附剂经过多次的吸附/解吸操作后，还可以对镉离子具有良好的吸附效果。

Abstract: Citric acid, as an ecofriendly reagent, can be used to wash the soil polluted by heavy metal ions effectively, and it is also concerned in the field of soil remediation. But how to remove heavy metal ions effectively in the leacheate and make the citric acid solution be recycled and reused for soil washing, is rather critical in the soil washing process. The present study proposed a method of biosorption, which is used to remove Cd²⁺ in the soil washed wastewater. It uses saponified garlic peel (GP) gel as the adsorbent to remove Cd²⁺ in the artificial citric solution. The parameters were evaluated systematically including pH, reaction time, adsorbent dosage, citric concentration, coexisting ions, temperature and shaking speed, etc. Results show that adsorption reaches equilibrium within 60 minutes, and when pH is 4, adsorption efficiency is highest. With the increase of adsorpbent dosage, adsorption efficiency was improved significantly, and the parameters including coexisting ions temperature and shaking speed have no significant effect. In addition, after several operations of adsorption and desorption, garlic peel gel still can remove Cd²⁺ effectively.