S-nZVI 复合材料修复 Cr(Ⅵ)和 TCE 复合污染地下水的效能

Using carboxymethyl chitosan (CMCS) and carboxymethyl cellulose (CMC) as stabilizers, two sulfidated nano zero-valent iron (S-nZVI) composite materials were synthesized in one-step. The apparent morphology, functional group composition, and surface chemical properties of the materials were characterized using SEM-EDS, FTIR, and XPS. Static adsorption experiments were conducted to analyze the removal performance and mechanisms of Cr(VI) and trichloroethylene (TCE) by the two S-nZVI materials. Furthermore, the resistance of the optimal material to interference from groundwater pH and coexisting anions was evaluated. The results showed that CMCS and CMC surfaces contained various functional groups that could form covalent bonds with S-nZVI, improving the dispersion of the sulfidated nano zerovalent iron particles. The adsorption kinetics of Cr(VI) and the degradation kinetics of TCE by the two S-nZVI composite materials were described by pseudo-second-order kinetic models and pseudo-first-order kinetic models, respectively. The isothermal adsorption process of Cr(Ⅵ) removal by the two S-nZVI composite materials was capable of being simulated by the Langmuir model. Moreover, the S-nZVI composite material stabilized with CMCS (CMCS-S-nZVI) presented the highest maximum adsorption capacity for Cr(Ⅵ), which was recorded as 79.46mg/g. The removal efficiency of Cr(VI) and TCE by CMCS-S-nZVI was not significantly affected by pH in the range of 6~9 or by the presence of NO₃^- and SO₄^2-. During engineering applications, the possible negative effects of Cl^- should be paid special attention to. These findings provide theoretical guidance for the effective implementation of permeable reactive barrier (PRB) technology to remediate groundwater contaminated by chlorinated hydrocarbons and heavy metals.