Engineering MOF-on-MOF heterostructure for enhanced adsorption-assisted photocatalytic decontamination of carbamazepine: Kinetics, thermodynamic and pathway study

A Cu-MOF@In-MOF heterojunction was synthesized via in-situ solvothermal growth. • Cu-MOF@In-MOF attained 99% carbamazepine removal under Vis-light irradiation. • Synergistic adsorption-photocatalysis improved CBZ removal from water. • Cu-MOF@In-MOF exhibited exceptional stability during five successive cycles. The fabrication of metal−organic frameworks (MOFs) into MOF-on-MOF heterostructures is a promising method to improve their performance across diverse applications. This study presents an organized fabrication of Cu-MOF (BUT-206-Cu) on In-MOF (BUT-205) for the elimination of carbamazepine (CBZ) by the combined effect of adsorption and photocatalytic degradation. BUT-205 was prepared by a solvothermal technique and acted as a host for the in-situ progression of BUT-206-Cu, resulting in a heterostructure BUT-206-Cu@BUT-205. The BUT-206-Cu@BUT-205 exhibited a remarkable efficiency in CBZ removal, achieving a total elimination rate of 99% and adsorption capacity of 86 mg/g, surpassing the performance of pristine MOFs. The pH impact and initial carbamazepine concentration on removal efficacy was systematically investigated. Radical scavenging and EPR investigations revealed that h + and OH • radicals are the key species involved in the degradation process. The degradation mechanism of CBZ confirmed ring cleavage, hydroxylation and carboxylation as the primary pathways. Kinetic analyses indicated that adsorption and degradation processess confirmed pseudo-second-order and pseudo-first-order models, respectively. The values of the thermodynamic variables (ΔG ads , ΔH ads , ΔS ads ) indicated that adsorption is physical, spontaneous, and exothermic in nature, resulting in increased randomness within the system. Furthermore, the BUT-206-Cu@BUT-205 demonstrate exceptional stability and reusability across five reusing cycles. Download: Download high-res image (111KB) Download: Download full-size image