Synergistic effects of adsorption and photocatalysis in MIL-88A(Fe) catalyst for remediation of phenanthrene-contaminated saline-alkaline soils

In arid and semi-arid areas, the remediation of saline-alkaline soils polluted by organic contaminants is challenging. In this study, the adsorption–photocatalysis synergistic removal of organic contaminants was realised using the MIL-88A(Fe) catalyst, and the saline-alkaline soils were remediated simultaneously. The adsorption isotherm of catalyst conformed to Langmuir model, and the photocatalytic degradation of PHE in an optimal visible light system achieved a PHE degradation efficiency of up to 86.2 % within 30 min. Based on the identification of active oxygen species, the PHE photocatalytic degradation was primarily driven by holes (h + ) and superoxide radicals (·O 2 - ), followed by hydroxyl radicals (·OH) and singlet oxygen ( 1 O 2 ). Furthermore, the determined physical and chemical properties of the saline-alkaline soils indicated that the soil pH value decreased to 6.82, effectively increasing the absorbable nitrogen content and improving soil fertility. This study offers a new strategy for the removal of organic contaminants under special soil medium conditions.