Markedly Boosted Peroxymonosulfate Activities of Ni-Fe Ldh Via Sulfur Dopant: The Acceleration of Metal Redox Cycle and New Production of Fe(Iv)

In this study, peroxymonosulfate (PMS) activation of Ni-Fe layered double hydroxide (Ni-Fe-LDH) toward to Tetracycline hydrochloride (TC) degradation was enhanced by sulfur doping. The characterization and catalytic process of S-Ni-Fe-LDH were investigated. When compared to the catalytic performance of Ni-Fe-LDH, the kinetic rate constant of the S-Ni-Fe-LDH/PMS system was 3.3 times higher than that of the Ni-Fe-LDH/PMS system. The boosted performance was lie in: (i) the superior electrical conductivity; (ii) the low redox potential of S2- that facilitate Metal redox to produce more radical species; (iii) the production of 1O2 has been found to be increased in S-Ni-Fe-LDH compared to Ni-Fe-LDH, due to the higher energy desorption exhibited by S-Ni-Fe-LDH towards radical species; (iv) the new generation in high-valent metal-oxo species in S-Ni-Fe-LDH/PMS system. Consequently, the S-Ni-Fe-LDH/PMS system displayed satisfactory degradation efficiency in a broad pH range of 3-11 and even under the presence of inorganic ions and humic acid, as well as continuous-flow catalytic process. This work introduces new opportunities for designing highly efficient LDH-based catalysts for the decomposition of organic pollutants in water solutions.