Building of a ternary AgI/ZIF-8/g-C3N4 heterojunction for efficient photodecomposition of organic pollutants in batch and split-plate airlift reactors

Abstract

Herein, we synthesized AgI/ZIF-8/g-C3N4 ternary composites as a highly efficient heterojunction photocatalyst. Various techniques such as XRD, N2 adsorption-desorption isotherm, DRS, PL, TEM, and FE-SEM were examined to analyse several properties of the synthesized g-C3N4, ZIF-8, AgI, ZIF-8/g-C3N4, and AgI/ZIF-8/g-C3N4 photocatalysts. The photodecomposition of Rh.B dye was investigated under visible-light exposure over fabricated materials in a simple batch and split-plate airlift photocatalytic reactors. The findings showed that the photodegradation efficiency of the AgI/ZIF-8/g-C3N4 heterojunction was excellent, due to the synergistic effect between g-C3N4, AgI, and ZIF-8, simplifying the fast charge transfer. Notably, the degradation efficiency of AgI/ZIF-8/g-C3N4 heterojunction in the airlift photoreactor was higher and more rapid (98.8 %) compared to the batch reactor (92 %). The photocatalytic activity is significantly enhanced by the high self-mixing under air flow and dissolved O2, and thus further O2− radicle generation. Various factors affecting the efficiency of the efficiency of the AgI/ZIF-8/g-C3N4 photocatalyst were studied including the pH, Rh.B concentration, and the AgI/ZIF-8/g-C3N4 amount. The AgI/ZIF-8/g-C3N4 cocomposite exhibited outstanding steadiness and recyclability even after five cycles, so it is probable to be very beneficial in treatment of contaminated water.

Keywords

• AgI/ZIF-8/g-C3N4 nanocomposite
• Photocatalytic heterojunction
• Batch reactor
• Airlift reactor
• Organic dyes degradation