Waste-Derived Nitrogen-Doped Biochar for Persulfate Activation and Bisphenol A Degradation

Abstract

Plastic waste constitutes a major environmental concern within municipal solid waste management systems. Its progressive degradation and weathering facilitate the leaching of hazardous additives, notably bisphenol A (BPA), a well-documented endocrine-disrupting compound with significant toxicological effects for aquatic ecosystems and human health. The aim of this study was to use municipal solid waste (MSW) compost residue biomass, including coconut shell, coconut husk, and wood fractions, to prepare nitrogen- doped biochar (N-MSW-BC) for persulfate (PS)- mediated catalytic degradation of BPA. The biomass was pyrolyzed in the presence of urea and sodium bicarbonate. The physicochemical properties of N-MSW-BC were assessed using proximate analysis, point of zero charge (pHpzc), and Fourier transform infrared (FTIR) spectroscopy. The potential of BPA degradation by N-MSW-BC was evaluated through adsorption experiments, pre-adsorption kinetics, and synchronous degradation studies. FTIR verified the integration of nitrogen-containing heterocycles into the carbon matrix, which showed distinctive bands near 3660–3280 cm−1 (O-H/N-H stretching) and at 1594 cm−1, attributed to overlapping aromatic C=C and C=N stretching and N-H bending vibrations. A stable carbon content of 41.83% was determined by proximate analysis, suggesting a graphitic-rich carbon matrix ideal for PS activation. BPA removal remained consistently high (~99.7%) across a pH range of 2-9 in a pH-edge experiment with the N- MSW-BC persulfate (10 mM) system. At 180 min, pre-adsorption followed by PS activation achieved 99.5% BPA elimination; whereas, the synchronous system only achieved 90.5% within the same exposure period. The electrostatic forces with BPA and biochar were influenced by their pHpzc (~ 8.2). These findings suggest an interfacial, adsorption- mediated catalytic process, establishing N-MSW- BC generated from compost residues as a sustainable material for BPA remediation by persulfate activation.