Electrocatalytic Reduction of 2, 2, 2–Trichloro-1, 1-Bis (4-Chlorophenyl) Ethanol (Dicofol) in Acetonitrile-Aqueous Solution Using Cyanocobalamin as a Catalyst
Wanjau Tabitha Wangui,
Geoffrey Njuguna Kamau,
Mwaniki Silas Ngari,
Muya Catherine Njambi
Issue:
Volume 3, Issue 1, February 2015
Pages:
1-10
Received:
5 December 2014
Accepted:
23 December 2014
Published:
20 January 2015
Abstract: This paper reports on the catalytic behaviour of cyanocobalamin (VB12) towards the reduction of polyhalogenated organic pollutant 2, 2, 2–trichloro-1,1-bis (4-chlorophenyl) ethanol (dicofol) in acetonitrile-aqueous solution containing 0.1M KNO3 supporting electrolyte. Dicofol is a persistent, toxic organochlorine acaricide used in agriculture and horticulture to control spider mites and soft-bodied mites. Due to the chronic toxicity, bioaccumulation and carcinogenity, determination of persistent organochlorine pesticides like dicofol has become very important. The available methods are disfavored as they lack necessary simplicity, inexpensiveness and environmentally friendliness for routine analysis, and consequently, electrochemical methods have shown to be possible alternatives. Cyanocobalamin being one of the most nucleophilic species known in aqueous solution can undergo nucleophilic reactions which are efficient for dehalogenation of various organic halides. Direct reduction of cyanocobalamin exhibited a quasi-reversible two-electron reduction with the oxidation state of the central cobalt species going from +3 to +1 and E½ of 0.696 ± 0.009 V. Dicofol exhibited a single two-electron reduction peak at -1.182±0.029 V vs SCE. The E½ was -1.074 V and the diffusion coefficient was 2.21x10-5 cm2s-1. Addition of dicofol to solution of cyanocobalamin resulted in a large reduction peak at around the reduction peak potential of cyanocobalamin (-0.732±0.018V versus SCE for six scan rates). This makes it clear that when cyanocobalamin is adsorbed on pyrolytic graphite electrode, it causes the lowering of overpotential for the reductive decomposition of dicofol by approximately 0.45 V and therefore ΔG was about 1½ times lowered. The decrease in ΔG implies that electrocatalysis is more kinetically favourable compared to direct electrochemical activation of carbon–halogen bonds.
Abstract: This paper reports on the catalytic behaviour of cyanocobalamin (VB12) towards the reduction of polyhalogenated organic pollutant 2, 2, 2–trichloro-1,1-bis (4-chlorophenyl) ethanol (dicofol) in acetonitrile-aqueous solution containing 0.1M KNO3 supporting electrolyte. Dicofol is a persistent, toxic organochlorine acaricide used in agriculture and h...
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Improvement of Dyeing and Weighting Properties of Silk Via Grafting with Acrylic (AA) and Glycidyl Methacrylate (GMA)
S. H. Abdel Fattah,
A. M. Ramadan,
S. M. Abo El-Ola,
M. Abdelkreem
Issue:
Volume 3, Issue 1, February 2015
Pages:
11-17
Received:
30 December 2014
Accepted:
15 February 2015
Published:
2 March 2015
Abstract: Copolymerization of acrylic acid (AA) and /or glycidyl methacrylate (GMA) with silk was carried out using H2O2/Cu2+reduced system. The results revealed that increasing H2O2 concentrations enhance polymerization up to 0.078 meq/l and also decreased the (TC) and (GY). Presences of Cu+2 ions up to 5 mmol/l accelerate the polymerization of (GY), (GE) and (TC). Increasing GMA and AA concentrations within the range studied were accompanied by enhancing (GY) in contrast with the (HP), (GY), (TC), and (GE) while the (HP) decrease. Crease recovery angle increased from 233o to 324o in the dry state. Dyeability as well as weighting and moisture regain properties were also improved.
Abstract: Copolymerization of acrylic acid (AA) and /or glycidyl methacrylate (GMA) with silk was carried out using H2O2/Cu2+reduced system. The results revealed that increasing H2O2 concentrations enhance polymerization up to 0.078 meq/l and also decreased the (TC) and (GY). Presences of Cu+2 ions up to 5 mmol/l accelerate the polymerization of (GY), (GE) a...
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