Simultaneous pentachlorophenol decomposition and granular activated carbon regeneration assisted by microwave irradiation

• Published in: Carbon (New York) Vol. 42; no. 2; pp. 415 - 422
• Main Authors: Liu, Xitao, Quan, Xie, Bo, Longli, Chen, Shuo, Zhao, Yazhi
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2004; Elsevier Science
• Subjects: A. Activated carbon; B. Pyrolysis; C. Adsorption; Chemistry; D. Dielectric properties; Exact sciences and technology; General and physical chemistry; Solid-liquid interface; Surface physical chemistry; A. Activated carbon; B. Pyrolysis; D. Dielectric properties; C. Adsorption; Pyrolysis; Regeneration; Liquid solid interface; Liquid solid adsorption; Activated carbon; Dielectric properties; Adsorption capacity; Microwave irradiation; Phenols; Chemical decomposition; Waste water purification
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2003.12.032

This paper describes an integrated granular activated carbon (GAC) adsorption/microwave (MW) irradiation process used for the treatment of high concentration pentachlorophenol (PCP) wastewater. Firstly, PCP in water was adsorbed onto GAC, then the PCP was decomposed and GAC regenerated by MW irradiation. The liquid and gas produced during irradiation were collected through condensing, and absorbed by a 0.1 mol l −1 NaOH solution, respectively. The determination of the PCP concentrations in the distillate, absorption solution and GAC was accomplished by a HPLC. The results suggested that when irradiated with 850 W MW for 10 min, most of the PCP adsorbed by GAC and whatever fragments formed were decomposed to CO 2, H 2O and HCl or tightly bound to GAC, and less than 2% of PCP was transformed into intermediates in the distillate. Some dechlorination and dehydroxylation products were identified by the GC/MS analysis, and the degradation mechanism was proposed. It was also confirmed that GAC could be reused after several adsorption/MW regeneration cycles and its adsorption capacity could maintain a relatively high level, even higher than that of virgin GAC, as indicated by BET results, iodine values and PCP adsorption isotherms.