Reductive Dechlorination of PCBs Using Photocatalyzed UV Light

Abstract

Feasibility of photocatalytic dechlorination of PCB‐138 and Aroclor‐1254 using platinum loaded TiO2 (P25) in an alkaline 2‐propanol medium has been investigated. Experiments were conducted in batch mode using a Rayonet photo‐reactor under aerated and deaerated conditions with black lamps emitting around 350 nm as light source. Two forms of platinum deposition were investigated: Photochemically loaded P25 as well as addition of potassium hexachloroplatinate into the reaction medium. Partial dechlorination of PCBs was observed after 7 h of irradiation with pure TiO2 as catalyst when the reaction vessel was kept open to air. Complete dechlorination was observed after 5 h of irradiation in a deaerated environment. Enhanced photocatalytic efficiency was observed when platinum deposited P25 was used as catalyst, with the best result being obtained when aqueous potassium hexachloroplatinate was added into the reaction medium. Lower potassium hexachloroplatinate concentration (0.1 mM) yielded better performance.

Heterogeneous Photocatalysis Remediation of Wastewater Polluted by Indigoid Dyes

“…Fujishima and Honda [17] studied the heterogeneous photocatalysis of water extensively by TiO 2 . As a consequence, several studies have reported the use of titanium dioxide as process able to degrade all persistent pollutants [18][19][20][21][22][23] and wastewater textile dyes from industries [24,25]. The TiO 2 has low cost and toxicity, high photochemical reactivity, and non-specific oxidative attack.…”

Potential Environmental Risk Characteristics of PCB Transformation Products in the Environmental Medium

“…The metabolism of PCBs by organisms can produce polychlorinated biphenyl methane sulfonate (MeSO 2 -PCB) through reactions such as oxidative substitution [7]. Under natural light radiation conditions, PCBs in the environment can absorb ultraviolet light and undergo Toxics 2021, 9, 213 2 of 20 direct photodegradation, and optically active chlorine atoms can break bonds in order to produce dechlorination products [8].…”

Photocatalytic degradation of 2,4,4′-trichlorobiphenyl into long-chain alkanes using Ag nanoparticle decorated flower-like ZnO microspheres

“…[11][12][13][14][15][16][17][18][19] In these reports, pure TiO 2 particles with nano or micro dimensions were used as the photocatalysts to degrade PCBs, and the degradation mechanism of dechlorination reactions was revealed. [11][12][13][14][15][16][17][18][19] In these reports, pure TiO 2 particles with nano or micro dimensions were used as the photocatalysts to degrade PCBs, and the degradation mechanism of dechlorination reactions was revealed.…”

“…For example, Lin et al reported that the final products of photocatalytic degradation of 2,2 0 ,3,4,4 0 ,5 0 -hexachlorobiphenyl (PCB138) were PCB congeners 99, 87, 66, 49, 28, 17, 9, and 7. 12 Obviously, the degradation products were also toxic PCBs with less chlorine, suggesting that the photocatalytic activity of the TiO 2 might be not high enough to completely degrade the PCBs, which had high physical and chemical stability. 19 Ghosh et al also reported the dechlorination of PCB-138 and Aroclor-1254 after 5-7 h of irradiation using platinum loaded TiO 2 .…”

“…In the past few decades, there have been only a few reports that focused on the TiO 2 -based photocatalytic degradation of PCBs. [11][12][13][14][15][16][17][18][19] In these reports, pure TiO 2 particles with nano or micro dimensions were used as the photocatalysts to degrade PCBs, and the degradation mechanism of dechlorination reactions was revealed. For example, Lin et al reported that the final products of photocatalytic degradation of 2,2 0 ,3,4,4 0 ,5 0 -hexachlorobiphenyl (PCB138) were PCB congeners 99, 87, 66, 49, 28, 17, 9, and 7.…”