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Background: Due to concerns over the negative impacts of PCB compounds on environment and their persistence, their production, use, and import has been banned in some countries. More recently, the Chemical Treaty on Persistent Organic Pollutants (POPs) has listed PCBs among priority chemicals for eventual elimination by 2025. The aim of this study was to determine the effect of solvents on the photodegradation of askarel oils using photolysis for reducing their hazards. Materials and Methods: The photochemical reactor, used in this experimental trial, was based on photolysis through UV/ H2O2 with a 500 ml beaker and low-pressure mercury lamp with a wavelength of 254 nm. The lamp was immersed in the beaker. The temperature and PH of the samples were constantly monitored. The experiments were repeated three times. Askarel oils were analyzed by GC/ECD. Results: The means of degradation of total PCBs due to the use of lamp for ethanol solvent and isooctane were 88% and 77%, respectively. The mean degradation of total PCBs in terms of the applied solvent ratio to the oil transformer for 1:1, 2:1, and 3:1 values for ethanol and isooctane were 55%, 85%, and 88%, and 40%, 77%, and 78%, respectively. Conclusion: Photolysis of PCB compounds in the presence of ethanol solvents, isoocatnes with strong oxidants such as H2O2, indicated their degradation or reduction in oil transformers with lower energy, and no yield of toxic byproducts. There was a significant difference in the employment of ethanol solvent and isooctane in degradation of askarel oil.

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Background: Nowadays, international concern about the impact of antibiotic residues on the environment increased and their removal has received a lot of consideration. The aim of this study was to investigate the efficiency of Fenton’s advanced oxidation process (H2O2/Fe+2) in sulfadiazine antibiotic removal from aqueous solutions. Materials and Methods: An experimental-laboratory scale study was done on a synthetic wastewater containing sulfadiazine antibiotic with 0.079, 0.19, and 0.47 mM concentrations under Fenton’s process. Then optimal values of affecting parameters, such as initial antibiotic concentration, molar ratio of reagents, [Fe+2] and [H2O2] concentration, detention time, and pH, were determined. The discharged effluent analyzed by HPLC-UV to identify the antibiotic residues. Results: The results showed that the optimal parameters in the Fenton’s oxidation process to remove the sulfadiazine included antibiotics at pH 3.5, molar ratio of [H2O2] / [Fe +2] equal to 1.5, and contact time of 15 minutes, respectively. In these optimal conditions, the efficiency of removal of antibiotic in concentrations of 0.079, 0.19, and 0.47 mM were 99.82%, 97.97% and 78.23% and the wastewater COD removal degrees were 83.33%, 78.57%, and 78.57%, respectively. Conclusion: The experiments showed the efficient removal of sulfadiazine antibiotic in wastewater by Fenton’s oxidation process. The efficiency of this method can also be considered in eliminating other antibiotics resistant to biological treatment

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Background: Remaining of crude oil in storage tanks usually lead to accumulation of oily sludge at the bottom of the tank which should be treated and disposed of in a suitable manner. In this research the feasibility of chemical oxidation with H2O2 and Fenton's reagent for removal of total petroleum hydrocarbons (TPH) from composted storage tank sludges was investigated.

Materials and Methods: The sludge was mixed with immature compost at various sludge to compost ratios including 1:2, 1:4, 1:6, 1:8 and 1:10 and composted for 82 days. Then, hydrogen peroxide and Fenton’s reagent were added to the composted mixture in six concentrations including 2%, 5%, 10%, 15%, 20% and 30% w w-1 for a period of 24 and 48 hr.

Results: TPH removal in composting reactors with the ratios of 1:2, 1:4, 1:6, 1:8 and 1:10 were 66.59, 73.19, 74.81, 80.20 and 79.91 percent, respectively. The mean TPH removal of 1:8 composted mixtures with 2%, 5%, 10%, 15%, 20% and 30% of oxidant concentrations were 1, 5.09, 19.37, 28.16, 34.37 and 38.05 percent, respectively. The highest removal efficiency was achieved in stepwise addition to the sludge. As well, increasing oxidation time from 24 to 48 hr had a little effect on TPH removal increase and the removal efficiencies of H2O2 and Fenton were nearly similar.

Conclusion: Chemical oxidation with hydrogen peroxide and Fenton as a post-treatment step is an acceptable process in TPH removal from bottom sludge of storage tanks.

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