Adsorption of image on tannins immobilized collagen fiber membrane

A novel adsorption membrane was prepared by immobilizing condensed vegetable tannins onto collagen fiber membrane. The tannins immobilized onto the membrane keep their ability of chelating metal ions and can withstand the exposure to water and organic agents. The adsorption capacities of bayberry tannin and black wattle tannin immobilized membranes to image were 56.8 mg U/g and 53.0 mg U/g, respectively, at 303 K when the initial concentration of image was 263 mg U/L.The adsorption isotherm of tannins immobilized membrane to image can be described by the Freundlich model. The adsorption kinetics of the membrane to image can be well described by the pseudo-second-order rate model. The adsorption capacity calculated by the pseudo-second-order rate model was closed to that determined by actually measurement. The continuous adsorption–desorption studies indicated that this kind of adsorption membrane has excellent adsorption–desorption properties. For monolayer membrane, more than 90% image was adsorbed when 500 mL image solution (conc. 263 mg U/L) passed through it. When three layers of membrane were employed, no image was detected until 1000 mL the effluent was collected. The membrane can be easily regenerated by a small quantity of 0.1 M HNO3 after adsorption, and therefore image can be greatly concentrated. The repeated adsorption–desorption experiments confirmed that the tannins immobilized membrane could be used for at least 10 times without considerable decrease of adsorption capacity.