A META analysis on the efficacy of functional materials for soil chromium remediation

Metallic chromium pollution in soil is widespread, which aroused intensive research in recent decades. In mainstream research, most studies use materials with a reducing ability to adsorb and reduce hexavalent chromium. However, comprehensive analyses and systematic verifications of these different materials are scarce. Therefore, this study conducted a meta-analysis of relevant papers published from 2013 to October 2024 to compare and analyze the performance and usage conditions of some common materials, such as iron-based materials, mineral inorganic materials, organic materials, and layered double hydroxide materials. We synthesized 31 papers for 186 pairwise comparisons and selected the Standardized Mean Difference (SMD) as the appropriate effect size for mean-to-mean comparisons. Fe-based materials had the most stable performance based on its numerous data support, while organic materials had the worst performance. The difference in performance between inorganic mineral materials was the greatest, which was closely related to the selection of components. The difference in the effectiveness of inorganic materials was the greatest, which was closely related to the selection of components and there was room for further improvement. Through further analysis of the impact of environmental factors on material performance, it can be concluded that the effect of the material was better under alkaline, non-sandy, low organic matter, and high CEC soil conditions.