Engineered ball-milled colloidal activated carbon material for advanced oxidation process of ibuprofen: Influencing factors and insights into the mechanism

Abstract

This study explores a simple and efficient, physically modified ball-milled activated carbon (AC_BM) preparation from granular activated carbon (GAC), which can be demonstrated for groundwater application. The colloidal stability of the AC_BM plays a vital role in the activation of peroxymonosulfate (PMS) and the degradation of pollutants. Adsorption kinetics and isotherm studies explain that the AC_BM has more active sites and maximum adsorption capacity (q_max = 509 mg g^-1) on the surface of the materials than GAC. The 92% of ibuprofen degradation was achieved at 240 min along with 0.1 g L^-1 of AC_BM, 5 mM of PMS, and 6.3 of initial solution pH. A chemical scavenger and electron spin resonance spectra also confirmed the formation of reactive oxygen species such as radicals (O₂^•-, HO^•, SO₄^•-) and non-radical (¹O₂) in the AC_BM/PMS system. Three major degradation pathways, hydroxylation, demethylation, and decarboxylation involved in ibuprofen degradation. Nearly 13 degradation by-products were detected during the AC_BM/PMS oxidation of ibuprofen. The toxicity analysis of oxidation by-products of ibuprofen was also discussed by computational simulation employing the ecological structure-activity relationships software. The AC_BM/PMS system was successfully applied to the natural groundwater system for ibuprofen degradation. Hence, the AC_BM/PMS system is an excellent catalyst for real groundwater applications.

Keywords: Ball-milled activated carbon; Degradation mechanism; Ibuprofen; Peroxymonosulfate; Singlet oxygen.