Photodegradation of 2,2',4,4',5,5' hexachlorobiphenyl in aqueous solution using UV/H2O2: Effect of light intensity

• Main Author: Macawile, Maria Cristina Arboleda
• Format: text
• Language: English
• Published: Animo Repository 2006
• Subjects: Polychlorinated biphenyls—Oxidation; Environmental Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/6768
• Institution: De La Salle University

The photodegradation of 2,2’,4,4’, 5,5’ Hexachlorobiphenyl (PCB 153) , a di-ortho substituted and non-coplanar PCB congener, was studied under ultraviolet radiation and ultraviolet in combination with hydrogen peroxide using a tubular circulating photoreactor with 17 and 24W UV-C lamps emitting at 254 nm. Using ferrioxalate chemical actinometry, light intensities emitted by the 17 W and 24 W lamps were measured at 3.714 x 10-6 Einstein/min and 1.284 x 10-5 Einstein/min, respectively. Under ultraviolet radiation, the increase of light intensity from 17 W to 24W increased the degradation from 90.430% to 94.712% of an 80 ppb aqueous PCB 153 solution at t=120 minutes. The addition of 50µL (0.441 mM) of a 30% wt. hydrogen peroxide resulted into a drastic decrease of the same concentration of PCB 153. The 17W lamp exhibited a 95.953% after t=30 minutes while complete degradation was attained with the 24W UV lamp during the same period. Effects of different process parameters, such as initial PCB 153 concentration and H2O2 concentrations have been investigated. Effects of various parameters such as initial H2O2 concentration and initial PCB concentration have been investigated. Experimental results showed that addition of hydrogen peroxide led to a higher degradation of PCB 153 however excess peroxide resulted into a lower degradation of PCB 153 due to •OH scavenging. Likewise, increasing the concentration from 50 to 100 ppb resulted to a decrease of percentage PCB degradation from 91.946 % to 87.664% and 97.8% to 93.923% for 17W and 24W respectively at time = 120 minutes.