title: Lactose electroisomerization into lactulose: effect of the electrode material, active membrane surface area-to-electrode surface area ratio, and interelectrode-membrane distance.
abstract: The aim of the present work was to study and develop an innovative, clean, and environmentally friendly process for lactulose synthesis by electroactivation of lactose. In this work, the electrode material (type 304 stainless steel, titanium, and copper), dimensionless interelectrode-membrane distance at the cathodic compartment (0.36, 0.68, and 1), and the membrane:electrode surface area ratio (0.23, 0.06, and 0.015) were considered to be the factors that could affect the kinetic conversion of lactose into lactulose. The reactions were conducted under an initial lactose concentration of 0.15mol/L at 10°C, Froude number (mixing speed) of 2.05×10(-2), and electric current intensity of 300mA for 30min. The highest lactulose formation yield of 32.50% (0.05mol/L) was obtained by using a copper electrode, interelectrode-membrane distance of 0.36, and membrane:electrode surface area ratio of 0.23. The 2-parameter Langmuir, Freundlich, and Temkin isotherm models were used for the prediction of the lactose isomerization kinetics as well as the 3-parameter Langmuir-Freundlich isotherm model. It was shown that the lactose isomerization kinetics into lactulose followed the Temkin and Langmuir-Freundlich models with coefficients of determination of 0.99 and 0.90 and a relative error of 1.42 to 1.56% and 4.27 to 4.37%, respectively.
authors.affiliation: Department of Soil Sciences and Agro-Food Engineering, Université Laval, Quebec, QC G1V 0A6, Canada; Institute of Nutrition and Functional Foods (INAF), Université Laval, Quebec, QC G1V 0A6, Canada.
authors.forename: Amara
authors.initials: A
authors.lastname: Aït-Aissa
authors.affiliation: Department of Soil Sciences and Agro-Food Engineering, Université Laval, Quebec, QC G1V 0A6, Canada; Institute of Nutrition and Functional Foods (INAF), Université Laval, Quebec, QC G1V 0A6, Canada. Electronic address: mohammed.aider@fsaa.ulaval.ca.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Aïder
mesh_terms: D002241:Carbohydrates / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D003300:Copper / Q000737:chemistry; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D007536:Isomerism; D007785:Lactose / Q000737:chemistry*; D007792:Lactulose / Q000737:chemistry*; D008962:Models, Theoretical; D013193:Stainless Steel / Q000737:chemistry; D014025:Titanium / Q000737:chemistry
chemical_list: D002241:Carbohydrates; D013193:Stainless Steel; D007792:Lactulose; D003300:Copper; D014025:Titanium; D007785:Lactose
keywords: adsorption isotherm; electrochemical cell; electrode material; lactose/lactulose; membrane