Recovery and investigation of Cu(II) ions by tannin immobilized porous membrane adsorbent from aqueous solution

A novel porous membrane adsorbent (Tan-ESM) was prepared by grafting of amino groups onto the eggshell membrane surface and then immobilized with tannins. The prepared Tan-ESM adsorbent combined the advantage of the high metal affinity of tannins with high specific surface, high density of surface functional groups as well as water-insoluble of the eggshell membrane. Adsorption property of Tan-ESM was investigated by removing Cu(II) ions from aqueous solution. The physico-chemical properties of Tan-ESM were characterized using infrared spectrometer and scanning electronic microscope. Adsorption experiments were carried out to investigate the effects of several important parameters including solution pH, adsorbent dosage, temperature, contact time and ionic strength of solution on the adsorption behavior. Adsorption capacity of Tan-ESM for Cu(II) ions was five times as much as untreated eggshell membrane. The equilibrium adsorption could be obtained within 30 min. Kinetics experiments indicated that the pseudo-first-order model displayed the best correlation with adsorption kinetics data. Besides, the Crank model showed that the intraparticle solute diffusion is the rate-controlling step. Finally, adsorption data could be better described by the Langmuir isotherm model. Continuous adsorption tests indicated that exhaustion time decreased with increasing initial Cu(II) ions concentration. The high adsorption capacity, effective adsorption-desorption results indicate the prepared Tan-ESM can be an effective adsorbent for removing Cu(II) ions from an aqueous solution.