Fabrication of macroporous POMs/biochar materials for fast degradation of phthalic acid esters through adsorption coupled with aerobic oxidation

Macroporous H₅PMo₁₀V₂O₄₀(n)/biochar (abbreviated as HPMoV(n)/biochar, n = loading amount of HPMo as 12, 28, 44, 53 and 63 wt%) had been fabricated from popcorn biocarbon and polyoxometalates (POMs) as precursors with macroporous size at 8–50 mm and high specific surface area, which allowed them to catalyze O₂ to rapidly degrade phthalic acid esters (PAEs) in water. HPMoV(n)/biochar featured a double-functional sites of strong Brønsted acidity and redox property, biochar promoting electron transfer between polyanion and PAEs, generation of reactive oxygen species (ROS) confined inside the pores. Meanwhile, a macropore and high porosity permitted its own higher adsorption capacity for PAEs even for long carbon-chain esters of diallyl phthalate (DAP) and diethylhexyl phthalate (DEHP). These allowed PAEs to be degraded with almost 80 ~ 88% of degradation efficiencies at 90 min upon HPMoV(44)/biochar through hydrolysis and oxidation in tandem way. The mineralization of diethyl phthalate (DEP) was about 72.5% and 64.4% corresponding to Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) removal efficiencies at atmospheric pressure of O₂. HPMoV(44)/biochar exhibited heterogeneity, high stability and long duration in DEP degradation, which could be reused at least eight times with only 1.9 and 3.0% losses of weight and activity.