Efficient removal of Congo red by BiOCl/TiO2/montmorillonite photocatalytic material

Abstract

A series of BiOCl/TiO2/montmorillonite photocatalytic material (BTM) were prepared by sol-gel method combined with calcination process, and were used for the degradation of Congo red. The phase composition, morphology, and optical properties of the as-prepared materials were characterized by XRD, SEM, BET and UV–vis DRS. Compared with BiOCl and TiO2, BTM has a better removal effect on Congo red, in which BTM-20 has the highest photocatalytic activity. After 120 min of illumination, the degradation rate of Congo red by BTM-20 reached 94.04 %. The photocatalytic degradation process of Congo red by BTM-20 conformed to the pseudo-first-order kinetic model with a reaction constant of 0.00803 min−1. The type-Ⅱ heterojunction between BiOCl and TiO2 promotes the separation of photogenerated electron-hole pairs of BTM-20 and enhances the absorption for visible light. The experiment of the free radical capture indicated that superoxide radical played a leading role in photocatalytic degradation of Congo red, followed by hydroxyl radical. This study provides a new treatment ideas for environmental remediation, and provides an efficient photocatalytic material for the degradation of pollutant.