Engineered mesoporous hollow carbon spheres for pollutant degradation: Disclosing catalytic activity, matrix effect, transport, and aquatic ecotoxicity

Remediation of organic contaminants through advanced oxidation process hold great promise for both ground and surface water environments. Despite the fact, the treatment efficiency depends on multiple factors, i.e., catalyst dosage, persulfate/peroxymonosulfate activation capability, and catalyst toxicity to aquatic creatures. Herein, we aimed to demonstrate the potential of the mesoporous carbon hollow sphere (MCHS) catalyst in persulfate activation for advanced oxidation in pure and groundwater matrix by choosing tetracycline as a model compound. Surface properties of MCHS were examined using multiple characterization techniques and the data revealed that MCHS is benefited by high specific surface area, numerous mesopores, and an excellent degree of particle dispersion. The results of this study indicate that pH, catalyst dosage, and persulfate and tetracycline concentrations influence tetracycline's degradation rate. Features like colloidal nature, high specific surface area (>1200 m²/g), and porosity of MCHS allow for very low catalyst dosage (10 mg L⁻¹). Electron spin resonance (ESR) and scavenger studies showed that the TC degradation in persulfate/MCHS system is dominated by ¹O₂ rather than ^[rad]OH, and SO₄^[rad]– radical species. Electrochemical study confirmed that electrons are transferred from tetracycline to the persulfate/MCHS complex during oxidation reaction. Additionally, the tetracycline degradation performance in natural groundwater matrices outperforms the persulfate/MCHS pure water system. Ecotoxicity study revealed the survival rate of Daphnia magna neonates is >95% if MCHS is <12 mg L⁻¹.