The properties and efficacy of S-nZVI as a remediation agent in response to its preparation process and reaction conditions: a truth from meta-analysis

Abstract

The influence of the preparation process (including the sulfurization method, sulfur reagents, and S/Fe molar ratio) and the reaction conditions of decontamination (pH value of the initial solution, reaction temperature, etc.) on the decontamination effect was quantitatively evaluated through meta-analysis. The results showed that compared with nZVI, S-nZVI increased the removal efficiency of heavy metals by 56.83% [95% CI: 32.31%, 85.89%] and the degradation efficiency of organic contaminants by 118.15% [95% CI: 85.89%, 156.00%]. Specifically, the analysis of key factors regarding the preparation process revealed that S-nZVI with Na₂S₂O₄ and Na₂S as sulfur reagents significantly improved the removal effect on heavy metals and the degradation effect on organic contaminants, respectively. In the range of S/Fe molar ratios of 0.3–0.5, the decontamination ability of S-nZVI was significantly improved compared with nZVI. The analysis results of decontamination reaction conditions showed that the removal of heavy metals by S-nZVI was significantly improved in acidic and neutral solutions compared to nZVI, while the improved degradation performance of organic pollutants was more pronounced in alkaline solutions. Overall, this study provided a comprehensive examination of the factors affecting the remediation performance of S-nZVI and provided the optimal preparation process and decontamination conditions.