ABSTRACT

Immobilisation is an effective technique in the remediation of heavy metals polluted soils. A laboratory experiment was conducted to clarify the kinetics of Zn and Cd release using citric, oxalic, acetic and tartaric acids and to evaluate the effectiveness of fish scale powder (FSP), chitin (CTN) and chitosan (CTS) in the immobilisation of these metals in a calcareous soil exposed to high levels of Zn and Cd. Characterisation of Fourier-transform infrared spectroscopy (FTIR) revealed the presence of amines, amides, alkenes and phosphate esters in fish scale and its derivatives. Citric acid released Zn and Cd much higher than tartaric, acetic and oxalic acids. Addition of fish scales derivatives drastically decreased the cumulative release of Zn and Cd in the order of CTS> CTN> FSP. Zn release data well fitted to pseudo-second-order model only in the presence of citric and tartaric acid and to Elovich model in the presence of acetic and oxalic acids. Cd release data were mostly fitted to pseudo-second-order model followed by Elovich model. Results of the present study demonstrate the high capability of citric acid in releasing metals, and high effectiveness of fish scales derivatives especially chitosan in immobilising Cd and Zn in polluted soils.

摘要

固定化是修复重金属污染土壤的有效技术。进行了一项室内实验，以阐明使用柠檬酸，草酸，乙酸和酒石酸释放锌和镉的动力学，并评估了鱼鳞粉（FSP），甲壳质（CTN）和壳聚糖（CTS）固定这些物质的有效性。钙质土壤中的金属暴露于高含量的锌和镉。傅里叶变换红外光谱（FTIR）的特征表明鱼鳞及其衍生物中存在胺，酰胺，烯烃和磷酸酯。柠檬酸释放的锌和镉比酒石酸，乙酸和草酸高得多。鱼鳞衍生物的添加以CTS> CTN> FSP的顺序显着降低了Zn和Cd的累积释放。锌释放数据仅在柠檬酸和酒石酸存在下才能很好地拟合拟二阶模型，而在乙酸和草酸存在下则非常适合Elovich模型。镉释放数据主要拟合伪二阶模型，其次是埃洛维奇模型。本研究结果表明柠檬酸具有释放金属的高能力，并且鱼鳞衍生物，尤其是壳聚糖在固定污染土壤中的Cd和Zn方面具有很高的有效性。