Overlooked role of transition metal impurities (cobalt and nickel) substitution in tuning pyrite to activate peroxymonosulfate for degradation of emerging pollutants

Abstract

Impurities play a crucial role in various catalytic systems. This study firstly investigated the effects of Ni and Co impurities in pyrite on peroxymonosulfate (PMS) activation to degrade emerging pollutants. The substitution of 6.30 % Ni and 5.64 % Co enhanced the catalytic activity of pyrite, with rate constants of 12 and 22 times greater than pure pyrite, respectively. Theoretical calculations revealed that impurities shifted PMS adsorption to a dual-site mode, leading to stronger adsorption energy and more electron transfer numbers than pure pyrite. The extension of oxygen–oxygen bond in PMS significantly promoted its cleavage to generate reactive oxygen species (particularly singlet oxygen of 74 times greater in 5.64 % Co-Py/PMS than that in the Py/PMS), which ensured the enhanced environment stability/adaptability and reduced pollutants toxicity within the 6.30 % Ni-Py and 5.64 % Co-Py systems. This study provides new insights into positively governing pyrite-based PMS advanced oxidation processes from the perspective of coexisting impurities.