Abstract: The adsorption behaviors of Mo⁶⁺ on collagen fiber immobilized bayberry tannin(IBT), a new kind of adsorbent, were investigated. It was found that the influence of temperature on adsorption capacity of Mo⁶⁺ is insignificant, but the effect of pH value on the adsorption was remarkable. The adsorption capacity of Mo⁶⁺ was increased with the decrease of pH value. These facts implies that adsorption is based on electrostatic association between adsorbent and polymeric anions of Mo⁶⁺. At pH value 2.0 and 303K, the adsorption capacity of Mo⁶⁺on 0.100g adsorbent was 82.4mg/g in 100 mL of 100.0mg/L Mo⁶⁺ solution. The adsorption isotherms can be well described by Freundlich equation. The adsorption rate of the adsorbent to Mo⁶⁺ was very fast at the beginning, and reached adsorption equilibrium around 600min. The adsorption kinetics can be well described by the pseudo-second-order-rate model and the adsorption capacities calculated by this model are very close to those experimentally determined. The adsorbent can be regenerated by using 0.02mol/L sodium ethylenediamine-tetraacetate(EDTA-Na₄) as desorption agent after adsorption of Mo⁶⁺. The adsorbent also showed satisfactory adsorption selectivity to Mo⁶⁺ in Mo⁶⁺-Ni²⁺ and Mo⁶⁺-Cu²⁺ mixture solutions at pH value 2.0, because these metal ions have different adsorption mechanisms on IBT and therefore, to be adsorbed at different pH value ranges.

Key words: bayberry tannin, immobilized tannin, Mo⁶⁺, collagen fibe, adsorption mechanism