Performance evaluation and mechanistic insights into melanoidin adsorption and photodegradation by PMoV-X@101(Fe)

Abstract

To address the substantial presence of melanoidin (MD) in wastewater, a Z-scheme heterojunction photocatalyst, PMoV-X@101(Fe), was synthesized using a metal-organic framework (101(Fe)) and polyoxometalate (H₅PMo₁₀V₂O₄₀, PMoV) via an in situ hydrothermal method. Subsequently, a systematic study was carried out to assess the adsorption performance of PMoV-X@101(Fe)for MD, including its adsorption capacity, isotherms, kinetics, and underlying mechanisms. In addition, the degradation performance of PMoV-X@101(Fe) was also assessed by analyzing the degradation kinetics, the reactive species involved, and their interactions. The results showed that PMoV-X@101(Fe) exhibited an exceptional adsorption capacity of 450 mg/g, driven primarily by electrostatic interactions and hydrogen bonding. Furthermore, under visible light irradiation for 40 min, PMoV-0.2@101(Fe) achieved a 90.2 % degradation rate of a 500 mg/L MD solution. The dominant reactive species, O₂⋅⁻ and h⁺, synergistically interacted with ⋅OH and ¹O₂, In addition to these findings, the influence of coexisting ions on MD degradation, along with toxicity assessments, recyclability, and catalyst stability, was also explored. Compared with previously reported materials, PMoV-X@101(Fe) independently provides both high adsorption and high photocatalytic activity, while treated MD solutions exhibited reduced toxicity, demonstrating environmental safety. Overall, PMoV-X@101(Fe) demonstrated dual-function efficiency, robust stability, and practical applicability, offering a comprehensive strategy for MD removal and addressing critical gaps in wastewater treatment research.