Natural coal gangue as a stable catalyst to activate persulfate: tetracycline hydrochloride degradation and its explored mechanism

Abstract

The surface-bonded hydroxyl groups on CG play the dominant role in PS activation and TC removal.

Anchoring defective metal-free catalysts on montmorillonite nanosheets for tetracycline removal: synergetic adsorption-catalysis and mechanism insights

“…S4f †), which includes cationic species (pH < 3.3), zwitterionic species (3.3 < pH < 7.7), and anionic species (pH > 7.7). 33,34 The increase in adsorption efficiency at a pH lower than 3.3 was attributed to electrostatic adsorption between the negatively charged catalyst surface and the TC cationic species. When the pH value was above 7.7, the adsorption competition between OH − and TC anionic species and the electrostatic repulsion between the negatively charged catalyst surface and the anionic TC appeared, which resulted in poor adsorption efficiency.…”