Study of the Histamine Electrochemical Oxidation Catalyzed by Nickel Sulfate

Thin layer technique was applied to the indirect anodic oxidation of histamine, catalyzed by NiSO4. Coulometric determination of the electron number demonstrates that histamine complexes Ni(II) and resulting adducts can be electrochemically oxidized in a single‐electron reaction, to lead Ni(III)‐histamine. The system Ni(III)/Ni(II) acts as ‘redox mediator’ for histamine oxidation. The equilibrium constant of the Ni(II)‐histamine complex formation was 106 , value showing the strong affinity between species. High content of histamine (>0.1 M), detected in fresh fish (previously exposed to the sun) extracts, showing potentialities for future design of a sensor for direct measurement in fish

Processes for working-up an aqueous fluosilicic acid solution

Aqueous fluosilicic acid solutions were once considered to be only adverse by-products of phosphoric acid production, which required treatment to prevent ecosystem destruction when discharged into the sea. However, a range of chemicals can be generated by the transformation of this industrial waste product. Through experiments undertaken in the laboratory, we have shown the possibility of caustic soda production. Volumetric analysis showed caustic soda to be present as a 6% - 7% solution with yields of about 70% - 80% by weight. Two processes were investigated for the caustification of sodium fluoride, using different precipitates: sodium chloride and ethanol and are described by modelling caustification curves. The activation energies of precipitation determined by semi-empirical correlations showed that precipitation by ethanol (EA = 933.536 J/mol) was more successful than precipitation by sodium chloride(EA = 7452.405 J/mol). Analyses performed on the precipitates highlighted compositions that are essential and useful constituents in the cement industry

Processes for working-up an aqueous fluosilicic acid solution

Aqueous fluosilicic acid solutions were once considered to be only adverse by-products of phosphoric acid production, which required treatment to prevent ecosystem destruction when discharged into the sea. However, a range of chemicals can be generated by the transformation of this industrial waste product. Through experiments undertaken in the laboratory, we have shown the possibility of caustic soda production. Volumetric analysis showed caustic soda to be present as a 6%– 7%solution with yields of about 70% – 80%by weight. Two processes were investigated for the caustification of sodium fluoride, using different precipitates: sodium chloride and ethanol and are described by modelling caustification curves. The activation energies of precipitation determined by semi-empirical correlations showed that precipitation by ethanol (EA = 933.536 J/mol) was more successful than precipitation by sodium chloride (EA = 7452.405 J/mol). Analyses performed on the precipitates highlighted compositions that are essential and useful constituents in the cement industry