Synergy between activated carbon and ZnO: a powerful combination for selective adsorption and photocatalytic degradation

Abstract

Doping activated carbon with ZnO offers a compelling water treatment solution. Chemically synthesized using H₃PO₄ as an activating agent, the resulting composite material (AC/ZnO) showcases intriguing characteristics in terms of structure, specific surface, and ZnO localization on the carbon surface compared to pure activated carbon. These factors are crucial for the dual functionality of AC/ZnO in adsorption and photo-degradation of organic pollutants, such as phenol and formic acid. Empirical results reveal a significant enhancement in phenol adsorption by the AC/ZnO composite, achieving exceptional performance with 100% adsorption efficiency in just 2 hours. However, a noticeable performance drop occurs during formic acid adsorption, indicating the remarkable selectivity of AC/ZnO toward aromatic molecules, a novel finding. Evaluation of photocatalytic activity under UV irradiation demonstrates the synthetic AC/ZnO composite's high efficacy. ZnO incorporation significantly boosts the composite's ability to degrade formic acid compared to pure AC, achieving complete degradation within 240 minutes. This grants the material the advantage of auto-regeneration and reuse over four consecutive cycles, affirming its stability and lack of noticeable deactivation. The successful implementation of dual adsorption/photo-degradation functionality in the AC/ZnO composite underscores its efficacy. Consequently, even if a molecule lacks affinity for the activated carbon surface, it undergoes inevitable degradation in the presence of light.