NANOSIZED CO-OXIDE SYSTEM AS EFFICIENT HETEROGENEOUS CATALYST FOR LOW-TEMPERATURE COMPLETE OXIDATION OF FORMALDEHYDE IN AQUEOUS SOLUTIONS

Formaldehyde is considered a carcinogen compound because causes DNA damage, mutations in microorganisms and mammalian cells. Therefore, treatment of effluents containing HCHO prior disposal into waterways is an important target from the environmental point of view. In the present study liquid-phase catalytic oxidation of 50 mg dm-3 HCHO with NaOCl at mild conditions was studied using nanosized Co-oxide system as catalyst. CoOx was synthesized by non-conventional ultrasound assisted precipitation-oxidation method with reverse order of precipitation. The synthesis’ conditions favour the formation of catalytic systems with desired structure, morphology and surface properties typical of environmental catalysts. The catalyst was characterized by XRD, FT-IR spectroscopy, thermal and chemical analyses. The catalytic activity of CoOx was evaluated through both the rate constant (k, min-1) and the overall degree of HCHO conversion (, %). The effect of main operational parameters influencing HCHO degradation efficiency such as catalyst loading, temperature, and oxidant concentration was investigated. The method of the planned experiment has been applied for determination of the optimal technological parameters of the process. Results obtained show that the optimal conditions for achieving complete conversion of HCHO are temperature 30oC, catalyst loading 1.5 g dm-3, and NaOCl concentration 15 ml dm-3.