Preparation of Persimmon Tannins Immobilized on Collagen Adsorbent and Research on its Adsorption to Cr(VI)

Persimmon tannins (PT) were immobilized on a matrix of collagen fiber by cross-linking of glutaraldehyde. The adsorption behaviours to Cr(VI) on PT were investigated including the effects of initial pH, initial concentration of Cr(VI), temperature, adsorbent dosage, adsorption kinetics and the recycling performance of PT adsorbents. The results showed that pH value had a major influence in adsorption. PT showed a strong adsorbability to Cr(VI) in the pH range of 1.0 to 3.0, whereas the effect of temperature on the adsorption was comparatively weaker. The adsorption equilibrium could be well described by Freundlich equation. PT adsorption efficiency of Cr(VI) reached 98.04% and the maximum equilibrium adsorption capacity of Cr(VI) was up to 49.01 mg/g at 303 K with a pH value of 2.0, 100 mg/L of initial concentration of Cr(VI) and 0.1g of adsorbent dosage. The adsorption data could be well fitted by pseudo-second-order rate model. PT adsorbents were characterized by FUR and EDS. The analysis indicated that the adsorption mechanism was mainly contributed by redox adsorption.