Abstract: The new adsorbent was obtained from bark of bayberry being rich in tannin, and cross-linking reaction with formaldehyde was used to immobilize tannin in situ to get the adsorbent. The adsorption property of this new adsorbent to Nd³⁺ in aqueous solution was investigated. Experiments showed that the equilibrium adsorption capacity of this adsorbent to Nd³⁺ was 342.144mg/g at 303K when initial concentration of Nd³⁺ was 432mg/L. The adsorption isotherm of Nd³⁺ on the in situ immobilized bayberry tannin(SIBT) could be described by the Freundlich equation. The equilibrium adsorption capacity of this adsorbent to Nd³⁺ was related to pH value and temperature of solution. Within the range of pH value 3.0-5.5, adsorption capacity would be rising along with the increase of pH value. When pH value is higher than 5.5, adsorption capacity began to decrease. When temperature varied from 283 to 313K, the change of adsorption capacity to Nd³⁺ was not obvious. However, over 313K, adsorption capacity started to decrease. The effect of pH value to the equilibrium adsorption capacity was more significant than that of temperature. This study also indicated that the adsorption kinetics data of this adsorbent to Nd³⁺ fitted with the pseudo-second-order rate model well and the equilibrium adsorption capacities calculated by pseudo-second-order rate model were consistent with the experimental data with deviation within 4%.

Key words: in situ immobilized bayberry tannin, Nd³⁺, adsorption