Collagen fiber immobilized myrica rubra tannin and its adsorption to uo(2)(2)(+)

Tannins, which are rich in ortho-hydroxyl groups, have a high affinity for UO22+. In this paper, Myrica rubra tannin was immobilized on collagen fiber by an aldehydic cross-linking reaction to prepare a novel adsorbent for uranium (UO22+) recovery from wastewater. The adsorption equilibrium, the adsorption kinetics, and the effects of temperature and pH on the adsorption equilibrium were investigated in detail. It was found that the Myrica rubra tannin immobilized on collagen fiber exhibits an excellent adsorption capacity for UO22+. The adsorption capacity at 293 K and pH 5.0 was as high as 1.19 mmol UO22+/g (283.3 mgU/g) when the initial concentration of UO22+ in solution was 7.5 mmol/L. The adsorption isotherms could be described by the Freundlich equation, and the increase of temperature promoted the adsorption to UO22+. The adsorption kinetics data were fitted very well by the pseudo-second-order rate model, and the equilibrium adsorption capacity calculated by the pseudo-second-order rate model was almost the same as that determined by the actual measurement with the error less than or equal to4%. The pH has a significant effect on the adsorption process. According to our experiments, the suitable pH scope should be 5-8.