Enhancement of peroxydisulfate activation by inherent nature of Fe-N-P/C biochar derived from Capsosiphon fulvescens as a green biomass material for organic pollutants degradation

This study explores the catalytic activity of biochar materials derived from seaweed biomass (Capsosiphon fulvescens) for groundwater treatment. A facile pyrolysis process was utilized to prepare C. fulvescens biochar (CFBC_X), where X represents the pyrolysis temperature. The instrumental analysis using surface characterization techniques revealed that CFBC₈₀₀ inherently contained heteroatoms (N, P) and a trace metal (Fe) in the biochar. The adsorption kinetics and isotherm experiments depicted a mixed mechanism of physical and chemical adsorption of SDZ on CFBC. Consequently, in optimal conditions with 2 mM peroxydisulfate (PDS), 200 mg L⁻¹ CFBC₈₀₀, and 6.1 initial solution pH, SDZ degradation (>97.2%) is achieved within 60 min. Chemical quenching tests indicate the involvement of radical (O₂^•– = 41.6%) and non-radical processes, including electron transfer (58.4%), in the PDS/CFBC₈₀₀ system. The electron spin resonance spectroscopy confirmed the formation of reactive oxygen species (ROS) in the PDS/CFBC₈₀₀ system, including radical (O₂^•–, SO₄^•–, and HO^•) and non-radical (¹O₂) species. Furthermore, electrochemical studies demonstrated the existence of an electron transfer pathway in the non-radical process of the PDS/CFBC₈₀₀ system. Based on chemical scavenger and ESR analyses, the PDS/CFBC₈₀₀ system exhibited both radical and non-radical mechanisms, with the electron transfer pathway being more dominant in this catalytic system. The excellent catalytic activity of the PDS/CFBC₈₀₀ system toward co-existing ions and various organic contaminant degradation is demonstrated. Moreover, the CFBC₈₀₀-activated PDS system successfully demonstrated catalyst reusability in SDZ degradation. Thus, this study establishes CFBC₈₀₀ as an ecofriendly catalyst with remarkable catalytic activity for groundwater remediation.