Use of advanced oxidation process in the degradation of trans-chlordane in water

• Main Authors: Moradas, Gerly, Auresenia, Joseph L., Gallardo, Susan M., Guieysse, Benoit
• Format: text
• Published: Animo Repository 2005
• Subjects: Organochlorine compounds; Pesticide residues; Chlordan; Surface active agents; Chemical Engineering
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/11973
• Institution: De La Salle University

This study was conducted to study the efficiency of advanced oxidation processes (AOP) for transforming chlordane into smaller, more soluble and biodegradable products that could then be biologically treated. Such physicochemical-biological methods are needed in the cases of hardly biodegradable pollutants such as chlordane because they provide the same versatility, efficiency and stability as physicochemical processes but remain less energy demanding. Hence, the degradation of 10 mg chlordane/l by UV/H2O2 and UV/H2O2/Fe2+ was assayed in aqueous phase with or without the presence of surfactant to enhance chlordane aqueous solubility. UV irradiation was carried out using a 15W-shortware ultraviolet lamp. H2O2 and FeSO4 were added at 50mM and 3mM, respectively. Triton X-114 was added at 250mg/l as surfactant. For the UV/H2O2 test, the aqueous chlordane solution was irradiated at initially neutral pH. For the phot-fenton process, the pH was initially adjusted to 2.8. Photodegradation tests without surfactant showed no significant removal of trans-chlordane or dechlorination as compared to the non-irradiated controls. Surfactant addition was crucial to the process as in the presence of Triton X-114, UV/H2O2 and UV/H2O2/Fe2+ treatments reduced trans-chlordane concentration by 96% and 61% respectively, after 48 hours of irradiation. This was confirmed by the results from the chloride initially present as chlordane was released as free chloride ion after UV/H2O2 treatment, compared to 48% after UV/H2O2/Fe2+ (based on the amount of chlordane actually removed in each experiment). The presence of low-chlorinated and non-chlorinated intermediates of lower molecular weight was confirmed by GC-MS analysis. This results shows that, under the experimental conditions tested here, UV/H2O2 was more efficient than UV/H2O2/Fe2+ for transforming chlordane in smaller, less chlorinated metabolites that should therefore also be more biodegradable.