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

Abstract

Macroporous H5PMo10V2O40(n)/biochar (abbreviated as HPMoV(n)/biochar, where n is the loading amount of HPMo: 12 wt.%, 28 wt.%, 44 wt.%, 53 wt.%, and 63 wt.%) were fabricated from popcorn biocarbon and H5PMo10V2O40. The materials exhibited a pore size of 8–50 μm and high specific surface areas, allowing them to efficiently catalyze the degradation of phthalic acid esters (PAEs) in water. HPMoV(n)/biochar contained double-functional sites with strong Brønsted acidity and redox properties; additionally, biochar promoted electron transfer between the polyanions and PAEs and confined the generation of reactive oxygen species inside the pores. At the same time, macropores and high porosity endowed the materials with high adsorption capacities toward PAEs, even long carbon-chain esters such as diallyl phthalate and diethylhexyl phthalate. These characteristics allowed HPMoV(44)/biochar to degrade 80%–88% of PAEs within 90 min through tandem hydrolysis–oxidation. The mineralization of diethyl phthalate was confirmed by the 72.5% and 64.4% reductions in chemical oxygen demand and total organic carbon, respectively, at atmospheric pressure. HPMoV(44)/biochar exhibited heterogeneity and high stability in the degradation of diethyl phthalate. Furthermore, the material could be reused at least eight times with only 1.9% and 3.0% loss of mass and activity, respectively.

Keywords

• polyoxometalates (poms)
• macroporous poms/biochar
• aerobic degradation
• phthalic acid esters (paes)
• popcorn