Coconut Shell Biochar Catalyst Activates Sodium Percarbonate for Rapid Rhodamine B Removal: Efficiency, Influencing Factors, and Mechanisms

The efficient activation of sodium percarbonate (SPC) is essential for degrading organic contaminants.Converting biomass into biochar as a multifunctional biocatalyst to accelerate oxidizer activation for water remediation has attracted much attention.In this study, we explored the performance of coconut shell biochar (CSBC) as a catalyst to activate SPC for degrading a model pollutant, rhodamine B (RhB).Optimal CSBC was synthesized via pyrolysis at 700°C for 4 h.In the CSBC/SPC system, the removal efficiency of RhB reached 96.11% within 4 h, which was much higher than that of the SPC system (7.76%).Quenching and electron paramagnetic resonance (EPR) spectroscopy results showed that hydroxyl radicals are crucial reactive oxygen species for RhB removal.Graphitization structures of the material, oxygen-containing functional groups, and persistent free radicals were the dominant factors controlling the activation of SPC by CSBC.Moreover, higher pH (11.72) enhanced the removal of RhB in the CSBC/SPC system; a 30% increase in removal rate was observed.However, anions Cl -, SO 4 2-, and PO 4 3-in water slightly inhibited the removal of RhB.This work provided a new method to activate SPC for the degradation of contaminants in water.