Dechlorination pathways of ortho-substituted PCBs by UV irradiation in n-hexane and their correlation to the charge distribution on carbon atom

The Effect of Solvent, Hydrogen Peroxide and Dioxide Titanium on Degradation of PCBs, Using Microwave Radiation in Order to Reduce Occupational Exposure

“…This indicated that the reactor was highly effi cient in dechlorinating the congeners tested, and optimizing the time for degradation reduced the reaction time and therefore the main cost of the treatment, i.e. energy cost of producing MW radiation can be minimized [2,6,7,15].…”

“…Figure 1 shows the effect of changing MW intensity on the degradation effi ciency of PCB congeners. In general, the degradation effi ciency increased with increasing MW intensity and decreasing the microwave intensity decreasing the dechlorination rate, and also the degradation effi ciency tended to plateau from 540 W to 900 W [2,6,7,15].…”

“…For several decades, PCBs have been used in a wide range of industrial applications because of their excellent physical and chemical properties, such as: oil in transformers, dielectrics in capacitors, hydraulic fl uids in hydraulic tools and equipment and heat exchange liquids [3,4]. PCBs also found widespread use as lubricants for turbines and pumps, in the formulation of cutting oils for metal treatment, and to a lesser extent, in applications such as adhesives, carbonless copy paper, dyes, pesticides, surface coatings, plasticizers and waxes [2][3][4][5][6][7][8][9][10][11][12][13]. Polychlorinated biphenyls are toxic, persistent, bio-accumulative and pose a risk of causing adverse effects to human health and the environment.…”

“…Polychlorinated biphenyls are toxic, persistent, bio-accumulative and pose a risk of causing adverse effects to human health and the environment. For various social, technical and economic reasons, signifi cant quantities of PCBs contaminated transformer oil are still in use or in storage [4,7,8,13,14]. Most of the dechlorinating processes for wastes containing PCBs were carried out in various organic solvents [2-4, 6-9, 15].…”

“…Incineration is the most commonly used technology to treat wastes with high concentrations of PCBs, particularly dielectric oils, and this achieves an elimination of almost 100%. But in spite of this, incineration also presents environmental risks (dioxins and benzofurans) and is limited by the high costs of handling, transport and elimination of the fi nal contaminated material [3][4][5][6][7]15]. Alternative treatments under development for this type of residue are: chemical reaction with an alkaline hydroxide in polyethylene glycol; supercritical and wet oxidation; adsorption onto activated carbon-regeneration; and Fenton oxidation [3, 4, 6-9, 15, 16].…”