CO2 mediated optical investigation of pyridine transformation into 2,2′-bipyridine for nitrogen pollutant removal

Nitrogen containing organic compounds such as pyridine are major industrial water pollutants that pose serious environmental and health risks. This study presents a sustainable, CO₂ mediated process for removing dissolved pyridine from water through its conversion into 2,2'-bipyridine, an insoluble and recoverable compound of industrial value. The highly exothermic transformation was monitored by UV-visible spectroscopy to elucidate its kinetics and underlying mechanism. Characteristic bands at 255 nm and 282 nm were used to track the consumption of pyridine and the formation of bipyridine, respectively. The results show that CO₂ acts as an electron transfer mediator, promoting dehydrogenative coupling of pyridine and accelerating its conversion into bipyridine. This process simultaneously enables the purification of pyridine contaminated water and the production of a valuable heterocyclic compound. Overall, these findings highlight a promising CO₂ assisted pathway for the treatment of nitrogenous organic pollutants and demonstrate the utility of optical spectroscopy for monitoring green water purification reactions.