Clinoptilolite mediated activation of peroxymonosulfate through spherical dispersion and oriented array of NiFe2O4: upgrading synergy and performance

Abstract Inspired by the features of both transition metal oxide and natural clinoptilolite (flaky structure with suitable pore diameter and open skeleton structure), we adopted a robust strategy by immobilization of nickel ferrite nanoparticles (NiFe2O4) on the clinoptilolite surface via typical citric acid combustion method. The hybrid catalyst exhibited enhanced peroxymonosulfate (PMS) activation efficiency and bisphenol A (BPA) degradation performance. Calculated by effective equivalent of NiFe2O4, it is found that the reaction rate constant (k) of NiFe2O4/clinoptilolite/PMS system (0.1859 min-1) was 11.9 times higher than that of bare NiFe2O4/PMS system (0.0156 min-1), which demonstrated that catalyst would be conjugated to PMS or contaminant efficiently and renders the rapid degradation and mineralization in the presence of clinoptilolite. After comprehensive characterization analysis and DFT simulations, natural mineral carrier effect (i.e. decreased crystalline size, increased oxygen vacancy content, etc.), abundant surface-bonded and structural hydroxyl groups as well as effective bonding with iron or nickel ions charged for the potential activation mechanism of PMS by NiFe2O4/clinoptilolite composite. And it is indicated that not only •OH and SO4•−, but also 1O2 was involved into series reactions. Overall, this study put forward a green and promising technology for high-toxic wastewater treatment.