Simultaneous adsorption and oxidative degradation of Bisphenol A by zero-valent iron/iron carbide nanoparticles encapsulated in N-doped carbon matrix

Highlights: • The materials with graphitized shell and dispersed active kernel were fabricated. • The N-doped Fe⁰/Fe₃C@C microcubes have high sorption ability for Bisphenol A (BPA). • The SO₄^- and OH radicals were responsible for the superior degradation of BPA. • This work affords a feasibly perspective to eliminate organic pollutants. The increased release and accumulation of Bisphenol A (BPA) in contaminated wastewater has resulted in the world wide concerns because of its potential negative effects on human health and aquatic ecosystems. Starting with metal-organic frameworks, we present a simple method to synthesize magnetic porous microcubes (N-doped Fe⁰/Fe₃C@C) with graphitized shell and highly dispersed active kernel via the pyrolysis process under N₂ atmosphere. Batch adsorption experimental results showed that N-doped Fe⁰/Fe₃C@C had high adsorption capacity for BPA (∼138 mg g⁻¹ at pH = 7 and 298 K). Degradation of BPA adsorbed on N-doped Fe⁰/Fe₃C@C was further investigated as a function of BPA concentration, persulfate amount, temperature and solution pH. It was found that potassium peroxodisulfate could be activated by N-doped Fe⁰/Fe₃C@C, and a large number of free radicals were generated which was crucial for the degradation of BPA. The concentration of BPA was barely changed in the individual persulfate system. BPA (10 mg L⁻¹) was almost completely degraded within 60 min in the presence of N-doped Fe⁰/Fe₃C@C (∼0.2 g L⁻¹). When the BPA content increased to 25 mg L⁻¹, the removal efficiency of BPA achieved to 98.4% after 150 min. From the XRD, Raman, and XPS analysis, the main adsorption mechanism of BPA was π-π interactions between the π orbital on the carbon basal planes and the electronic density in the BPA aromatic rings. While the superior degradation was attributed to the radical generation and evolution in phenol oxidation. This work not only proved the potential application of N-doped Fe⁰/Fe₃C@C in the adsorption and degradation of BPA, but also opened the new possibilities to eliminate organic pollutants using this kind of magnetic materials in organic pollutants' cleanup.