ADSORPTION OF TANNIC ACID BY HYPER-CROSSLINKED RESIN MODIFIED BY AMINO FUNCTION GROUPS

Abstract

Tannic acid(TA) as a typical natural organic acid of high solubility and medium molecular weight,was used to study the adsorption act and mechanism on a new hyper-crosslinked resin modified by amino function groups WJN-08.The adsorption isotherm data indicates that the equllibrium adsorption capacity of WJN-08 for TA is 15% higher than that of other commercial adsorbents.Moreover,the static adsorption assay indicates that the adsorption capacity for TA is related to the pore structure and the amounts of amino function groups of resin.The FTIR spectra of WJN-08 before and after adsorption of TA indicate that both "π-π" conjugation and electric attraction are the adsorption force during the adsorption process.The adsorption enthalpy changes ΔH of TA by WJN-08 is in a range from 20 to 22 kJ mol~(-1),which exhibit the adsorption is a chemical and endothermic process.Batch kinetic studies indicate that the adsorption of TA on WJN-08 can be fitted by the membrane and intra-particle diffusion model.In particular,excellent adsorption and de-sorption performance of WJN-08 for TA is shown in dynamic column assay.The break though adsorption capacity is 19.56 mg g~(-1) and saturation adsorption capacity is 22.43 mg g~(-1),respectivey,and the desorption rate of TA on WJN-08 is more than 98%.