Quantitative Analysis of Inorganic Photocatalysts for PAH Degradation in Petroleum-Contaminated Soils: Kinetic Performance and Implications for Microbial Bioremediation

Polycyclic aromatic hydrocarbons (PAHs) are among the most persistent and toxic fractions of petroleum-contaminated soils, and their strong sorption to soil organic matter often limits remediation efficiency. This study quantitatively evaluates inorganic photocatalysts used for PAH degradation in direct-soil, soil-suspension, and soil-washing-derived systems, emphasizing TiO2, iron oxides/oxyhydroxides, doped TiO₂, ZnO-based materials, while also examining their reported consequences for soil microbial communities and bioremediation. A PRISMA-informed framework was adopted, and quantitative evidence was standardized as parent-compound removal, rate constants, half-lives, and kinetic enhancement ratios when calculable. The quantitative analysis showed that 0.5% TiO₂ reduced the reported half-lives of phenanthrene, pyrene, and benzo[a]pyrene from 533.15, 630.09, and 363.22 h to 130.77, 192.53, and 103.26 h, corresponding to kinetic enhancements of 4.08-, 3.27-, and 3.52-fold. Recent TiO₂/α-FeOOH, MIL-88A(Fe), and other visible-light systems improve solar utilization, but cross-study comparison remains constrained by heterogeneity in matrix type, catalyst dosage, irradiation conditions, and uncertainty reporting. None of the primary studies measured soil microbial abundance, diversity, or community structure, leaving the biological consequences for the native microbiome and downstream bioremediation as a gap. Overall, the quantitative findings support inorganic photocatalysis as a promising hybrid remediation strategy, but future studies must standardize reporting, verify mineralization, assess post-treatment microbial recovery, and support field-scale validation.