壳聚糖改性沸石对多金属污染土壤稳定化处理效果及影响因素研究

INFLUENTING FACTORS OF CHITOSAN-MODIFIED ZEOLITE AND ITS STABILIZATION EFFECT ON MULTI METAL CONTAMINATED SOIL

以壳聚糖改性后的沸石作为稳定化材料,对实际污染土壤中铅(Pb)、锌(Zn)、镉(Cd)进行稳定化处理,采用扫描电子显微镜等表征手段及TCLP毒性浸出实验对改性材料物质组成及多金属稳定化效果进行分析,探究改性材料投加量、土壤含水率与pH对多金属污染土壤稳定效果的影响。结果表明:改性材料表面具有清晰的纤维状结构和均匀的突触状结构,且在结合能400 eV左右处增加了N1s的特征峰,证实壳聚糖已负载到沸石表面且硅酸钙粒子起到修饰作用;最大投加量为10%时,稳定化效果最好;随着含水率的增加,浸出浓度小幅增加,不同含水率下,Zn、Cd对Pb的稳定化无明显竞争;当土壤环境为弱酸碱或中性时,Zn、Cd对Pb的稳定化无竞争优势,但在强酸或强碱环境下,Zn、Cd竞争优势较强,从而抑制Pb的稳定化。此种新型、高效的土壤稳化材料可为多金属污染场地修复提供新的技术方案。

In this study, Pb-, Zn-, and Cd-contaminated soil was stabilized by chitosan-modified zeolite. Scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and toxicity characteristic leaching procedure extraction methods were used to analyze the composition of the modified materials and their stabilizing effect on multi-metal-contaminated soil. In addition, the effect of the modified material dosages, soil water content, and pH on the stabilization of the contaminated soil were investigated. Results showed that the surface of the modified material had a clear fibrous structure and a uniform synaptic structure. The characteristic peak of N1 s was increased at a binding energy of approximately 400 eV, confirming that chitosan was loaded onto the surface of the zeolite and calcium silicate particles had a modifying effect. The stabilization effect reached its maximum when the maximum dosage was 10%. With the increase in water content, the leaching concentration increased slightly. Under different water content, the competition on Pb stabilization of Zn and Cd was not evident. When the soil environment was weakly acid-base or neutral, Zn and Cd showed no competitive advantage in Pb stabilization, but Zn and Cd had a stronger competitive advantage under strong acid or strong alkali environment, thereby inhibiting the stabilization of Pb. This study developed a novel and efficient soil stabilization material, providing a basis for the remediation of polymetallic contaminated sites.