Pinoy researchers develop simple oxidation tech to degrade PCBs

Filipino researchers have discovered non-burn technologies that can be used in destroying polychlorinated biphenyls (PCBs), one of the most toxic and persistent organic pollutants.

Carmela Centeno, Leonila Abella and Susan Gallardo, of the De La Salle University, developed a simple yet effective oxidation technology for degrading PCBs using a familiar reagent — hydrogen peroxide (H2O2).

The research entitled “Catalyzed Photo-oxidation: Alternative Technology Option for the Destruction of Polychlorinated Biphenyls” promotes a technology which would help in cleaning the environment, Gallardo said.

Reports said production of PCBs was banned in the 1970s due to their high toxicity.

“The danger that PCBs pose is (their) habit to accumulate in the environment, making them hard to manage and treat. But with the catalyzed photo-oxidation, PCBs can now be disposed of in an environment-friendly manner,” the researchers said.

Experiments involved the use of selected catalyzed photo-oxidation processes — ultraviolet irradiation, UV/H2O2 (hydrogen peroxide) and UV/TiO2 (titanium dioxide).

Results showed that catalyzed UV processes significantly degraded PCBs. According to the research, dechlorination must be the major mechanism occurring in the solution, especially during the first few minutes of the reaction where a drastic drop in pH was observed and where the highest percentage of degradation was achieved.

The UV system served as a pre-treatment process reducing the toxicity of the PCBs before undergoing degradation, they said.

The researchers said PCBs have become a global concern, as they are among the “dirty dozen” of persistent organic pollutants.

PCBs were used as coolants and insulating fluids for transformers and capacitors, stabilizing additives in flexible PVC coatings of electrical wiring and electronic components, pesticide extenders, cutting oils, flame retardants, hydraulic fluids, sealants, adhesives, wood floor finishes, paints, de-dusting agents, and in carbonless copy paper.

Reports said the most commonly observed health effects in people exposed to PCBs are skin conditions such as chloracne and rashes, but these were known to be symptoms of systemic poisoning dating back to the 1920s.

Animals that eat PCB-contaminated food even for short periods of time suffer from liver damage and may die. In 1968 in Japan, 400,000 birds died after eating PCB-contaminated poultry feed, reports said.

Reports also said that babies born to women who ate PCB-contaminated fish showed abnormal responses in tests of infant behavior. Some of these behaviors, such as problems with motor skills and a decrease in short-term memory, lasted for several years.

Other studies, meanwhile, revealed that the immune system was affected in children born to and nursed by mothers exposed to increased levels of PCBs. The most likely way infants will be exposed to PCBs is from breast milk.

The DLSU researchers’ work won second prize in the 7th Philippine Council for Industry and Energy Research and Development’s (PCIERD) science and technology fora and competitions in industry and energy research and development.

PCIERD is an agency under the Department of Science and Technology.