Effective Activation of Peroxymonosulfate by Oxygen Vacancy Induced Musa Basjoo Biochar to Degrade Sulfamethoxazole: Efficiency and Mechanism

Abstract

Biochar materials have garnered attention as potential catalysts for peroxymonosulfate (PMS) activation due to their cost-effectiveness, notable specific surface area, and advantageous structural properties. In this study, a suite of plantain-derived biochar (MBB-400, MBB-600, and MBB-800), possessing a well-defined pore structure and a substantial number of uniformly distributed active sites (oxygen vacancy, OVs), was synthesized through a facile calcination process at varying temperatures (400, 600, and 800 °C). These materials were designed for the activation of PMS in the degradation of sulfamethoxazole (SMX). Experimental investigations revealed that OVs not only functioned as enriched sites for pollutants, enhancing the opportunities for free radicals (^•OH/SO₄^•-) and surface-bound radicals (SBRs) to attack pollutants, but also served as channels for intramolecular charge transfer leaps. This role contributed to a reduction in interfacial charge transfer resistance, expediting electron transfer rates with PMS, thereby accelerating the decomposition of pollutants. Capitalizing on these merits, the MBB-800/PMS system displayed a 61-fold enhancement in the conversion rate for SMX degradation compared to inactivated MBB/PMS system. Furthermore, the MBB-800 exhibited less cytotoxicity towards rat pheochromocytoma (PC12) cells. Hence, the straightforward calcination synthesis of MBB-800 emerges as a promising biochar catalyst with vast potential for sustainable and efficient wastewater treatment and environmental remediation.

Keywords: Musa basjoo biochar; defect/oxygen vacancy; peroxymonosulfate activation; sulfamethoxazole degradation; water treatment.

Figure 1

(a,b) The TEM images and (c) elemental mapping of MBB-800. (d) Raman spectra, and (e) EPR spectra of different samples.

Figure 2

(a) Degradation rate of SMX in different systems. (b) Relationship of TOF values between different metal-based catalysts and MBB-800 in PMS activation. (c) SMX degradation in MBB-800/PMS system under different inorganic anions. (d) Degradation of organic pollutants in MBB-800/PMS system. Reaction conditions: [MBB-800] = 0.1 g L⁻¹; [oxidants] = 0.33 mM; [organic pollutants] = 1 mg L⁻¹; [dyes] = 1 mg L⁻¹; pH = 6.8.

Figure 3

(a) The effect of quenching agents of SMX degradation in MBB-800/PMS system. Spin-trapping EPR spectra for (b) DMPOX, (c) DMPO-O₂^•−, and (d) TEMP-¹O₂ in various systems at different times. Reaction conditions: [MBB-800] = 0.1 g L⁻¹; [oxidants] = 0.33 mM; [SMX] = 1 mg L⁻¹; pH = 6.8.

Figure 4

(a) Chronoamperometry curve of MBB and MBB-800, (b) LSV curves of MBB and MBB-800 in different systems, and (c) EIS curves of different samples.

Figure 5

(a) EPR spectra, (b) FTIR spectra, and (c) C 1s XPS spectrum of fresh and used MBB-800.

Figure 6

(a) TOC removal and (b) possible degradation pathways of SMX in MBB-800/PMS system. (c) Corresponding cell viability percentage of PC21 cells at the selected concentrations of MBB-800. Data are presented as mean ± SD, ** p < 0.01, no significance.