Regeneration of pyridine saturated activated carbons using supercritical water oxidation

摘要

Supercritical water oxidation (SCWO) in a batch reactor system was used to decompose chemisorbed pyridine and regenerate activated carbons saturated with pyridine. Decomposition of pyridine was carried out with supercritical water at 400, 450, 525°C and 25 MPa in the presence and absence of oxygen. The properties of two commercial activated carbons, imported activated carbon (CAL) and activated carbon produced in Thailand from coconut shell (COCO), including their BET surface areas, pore volumes and pore size distributions measured by BET method were determined and their pyridine adsorption-desorption isotherms were investigated. Both activated carbons displayed the characteristics of type I isotherm associated with the micropores. Though the BET surface area of CAL was slightly higher than COCO, their pyridine adsorption capacities were reversed. The SCWO regeneration efficiency was calculated from the amount of pyridine adsorbed and desorbed in successive adsorption-regeneration cycles. Effects of SCWO on the adsorption capacity and textural characteristics of the carbon were investigated. Under supercritical water conditions, organic carbon would finally be converted to carbon dioxide, hydrogen to water and nitro-compounds to nitrates.