Assisted Photodegradation of Polychlorobiphenyls for Ecologically Rational Elimination of Persistent Organics Pollutants

Polychlorinated biphenyls (PCBs) are synthetic organic chlorinated compounds classified in persistent organic pollutants. They are very harmful for environment and human beings. Thus, international community (UNEP) has planned the complete elimination of PCBs for 2028 while there are no expansive, simple and friendly techniques for their elimination. The aim of this work is to investigate the easy and ecologically rational techniques for elimination of PCBs. So, the photodegradation of PCBs contained in Askarel formulation were conducted for this remediation. For an ecological optimization of this process, the photolysis of PCBs congeners takes place in aqueous solution (ethanol-water 1:10). The photonic effect related to the type and intensity luminous source (halogens lamps (1000 and 500W) and one LED lamp of 50W) and distance from the lamp to the reaction point (40cm /20cm) were first investigated. Also, the influence of solvent, pH and initial concentrations on PCBs photolysis were studied to choose the optimum condition of PCBs degradation. The addition of H2O2 as source of OH• radicals has boosted the chemical decomposition of PCBs. The degradation% under the optimum conditions (Lamp of 1000 W from 20 cm to reaction point, pH = 6.8, Ci = 10 ppm) after 3hours is 60% with direct photolysis and goes to 75% after addition of 5 mM of H2O2. The pseudo first order model describes well the kinetic of PCBs photodegradation under optimum conditions (R2 = 0.9628). Finally, the performance of the UV-Visible/H2O2 process which has established the photoreactivity of PCBs via OH• radicals suggest the possible use of solar energy as luminous source, a guarantee of an ecologically rational elimination of POPs.