Induced morphology orientation of α-FeOOH by kaolinite for enhancing peroxymonosulfate activation.

Persulfate activation technology based on sulfate radicals is currently a hot spot in the field of environmental governance. In our work, α-FeOOH was successful in situ loaded on kaolinite surface through a simple one-step hydrothermal process. The prepared composites were systematically characterized, and the relationship between the structural properties and peroxymonosulfate activation properties was explored. Interestingly, compared to bare α-FeOOH, the introduction of kaolinite in composite induced the transformation of α-FeOOH crystal and affected the morphology, where uniformly dispersed nanoparticles rather than rod-like agglomerated crystals appeared. The received FeOOH/kaolinite composite exhibited admirable adsorption and degradation of ciprofloxacin performance with the removal efficiency of 86.1%, and the degradation rate constant was up to 5.2 times higher than that of bare α-FeOOH. In addition, the main active species in the catalytic oxidation system are surface-bound SO4•-, •OH and free 1O2. This work would give a deep insight into the role of natural minerals in composite catalytic materials and the construction of high-efficient mineral-based composite materials.