DEVELOPMENT OF METAL-ORGANIC FRAMEWORK-BASED CATALYSTS FOR ENHANCED AQUEOUS NITRATE REMOVAL

Abstract

This thesis focuses on the development of a catalyst supported by the metal-organic framework (MOF)-derived Co-doped material for the reduction of nitrate (NO3-) in aqueous systems. Nitrate pollution poses severe risks to human health and the environment, and efficient technologies are required for its control. The catalytic reduction of aqueous nitrate is a desirable choice since it can be tailored to the necessary reactivity and selectivity and requires no excessive energy inputs. The study aims to synthesize and characterize zeolitic imidazole framework ZIF-67-based catalysts and evaluate the catalytic activity for nitrate removal in batch kinetic tests. The study also aims to investigate different parameters affecting the reactivity and selectivity of the process to achieve the optimum conditions, identify the reaction mechanism by analytical investigation of the catalyst surface before and after reaction, and evaluate the catalyst stability and durability in consecutive reaction cycles with analysis of metal leaching. Compared to other catalysts reported in the literature, Pt-Co@NC showed competitiveness, demonstrating one of the highest rate constants for the reaction at similar conditions. Carbonization of ZIF-67 resulted in the improved stability of the structure, exposing Co to the surface of carbon material. Impregnation of Pt on the surface of Co@NC was beneficial for nitrate reduction compared to other metals and resulted in enhanced reactivity with the full reduction of 60 mg/L NO3- -N in 30 min. Moreover, an increase in catalyst loading and Pt content positively affected the reactivity of the system as well as the reduction in contaminant concentration. Overall, the study's findings suggest that Pt-Co@NC can effectively reduce nitrate pollution in aqueous systems with high selectivity towards ammonium (NH4+). The catalyst is durable and stable, making it a promising candidate for nitrate removal from water sources. The study provides valuable insights into the synthesis and characterization of ZIF-based catalysts and their catalytic activity for nitrate removal.