DECOMPOSITION OF THE CONGO RED DYE IN THE PRESENCE OF THE MOF/AC COMPOSITES

Abstract

Synthetic dyes, which are used in various industries such as textiles, paper, and plastics, are particularly of great concern due to their characteristics and often excessive discharge into natural water bodies. The negative impact on the environment is significant, as these dyes can be highly toxic, persistent, and non-biodegradable, disrupting photosynthetic processes and harming aquatic ecosystems. Additionally, some dyes, such as azo dyes, are known to be carcinogenic and mutagenic, posing serious health risks to humans and wildlife. Congo Red (CR) is used in this work to study the influence of the metal-organic framework/activated carbon (MOF/AC) composite catalysts on the decomposition of the Congo Red in aqueous solutions. Removal efficiency of the CR was evaluated by using UV-Vis spectroscopy and material characterization was performed by XRD. Results showed that both pure MOF and AC, as well as their composite powder mixtures, improve i.e. catalyze the decomposition of the CR in both dark and sun conditions. All MOF-containing samples (100%, 75%, 50% and 25% of MOF) showed greater activities than pure AC. Sample made from 75% UiO-66 MOF and 25% AC showed the greatest removal efficiencies in both dark (38.3%) and sun (74%) conditions, which greatly exceeds the activities of individual components, thus indicating the existence of a synergetic effect due to the MOF-AC interaction. Clear evidence that a strong photocatalytic effect exists, lies in the fact that all samples showed greater activity under the solar light irradiation than in the dark condition.