Work

Fast degradation of chlorinated volatile organic compounds using soluble cobalt complexes

Year: 2025

Type: article

Abstract: Chlorinated volatile organic compounds (Cl-VOCs), used in dry cleaning and textiles are stable and resistant to degradation, posing significant environmental challenges. This has led to a growing focus on developing effective treatment technologies for wastewater and groundwater contamination. This study demonstrates the efficacy of cationic analogues of vitamin B 12 (VB 12 ) as swift electron transfer mediators for the reduction of perchloroethylene (PCE), trichloroethene (TCE), and dichloromethane (DCM) in a homogeneous aqueous solution using Ti III citrate as the primary electron donor. By utilizing cobalt tetratrimethylammonium phthalocyanine (CoTTMeAPc) for the first time in dechlorination process, notable degradation efficiencies were achieved. Within 5 minutes, CoTTMeAPc achieved high degradation efficiencies (94.6% for PCE, 91.6% for TCE, and 55.4% for DCM), outperforming VB 12 (21.6%, 15.4%, and 6.7%, respectively) within the same period, as well as insoluble CoPc, which degraded only 27.4%, 46.7%, and 21.9% within 20 minutes. This result highlights a novel application of CoTTMeAPc in dechlorination, demonstrating its potential for rapid and effective pollutant removal. The effects of various concentrations of the initial chlorinated compound, catalyst, and reductant concentrations, as well as pH, were investigated in the dechlorination reaction. The reaction was monitored through UV/VIS spectroscopy to unravel the reason behind the substantial degradation of chlorinated compounds using reduced CoTTMeAPc. The plausible mechanism is proposed by the analysis of intermediate products generated at different time intervals during this study, UV-Vis spectral analysis and supported by the previously published reports. This study provides new insights into the degradation of halogenated compounds utilizing water-soluble cationic cobalt phthalocyanine complexes. While this research focuses on chemical degradation, the findings are expected to create opportunities for future exploration in bioremediation, potentially involving microorganisms.

Source: Process Safety and Environmental Protection

DOI: 10.1016/j.psep.2025.107356