Porous Spherical Cellulose Carrier Modified with Polyethyleneimine and Its Adsorption for Cr（Ⅲ） and Fe（Ⅲ） from Aqueous Solutions

An efficient porous spherical polyethyleneimine-cellulose （PEI-cell） absorbent was synthesized and char- acterized. The main influencing factors and adsorption mechanism for two typical metal ions, Cr3＋ and Fe3＋, were investigated. The adsorption performance primarily depends on the initial concentration of metal ions, pH value and temperature, and the chelation action between N atoms of PEl-cell and metal ions plays an important role. Under dynamic adsorption conditions, the saturation adsorption of polyethyleneimine-cellulose is 83.98 mg.g-1 for Cr（Ⅲ） and 377.19 mg-g-1 for Fe（Ⅲ）, higher than report- ed data and that of unmodified cellulose. The adsorption can be well described with second-order kinetic equation and Freundlich adsorption model, and AH, AG and 5 of the adsorption are all negative. With 5% HCI as eluent, the elution ratio of Cr（Ill） and Fe（llI） achieved 99.88% and 97.74% at 313 K, respectively. After the porous PEI-cell was reused 6 times, it still presented satisfactory adsorption performance. Above results show the advantages such as easily-acquired raw material, high efficiency, stable recycling oerformance and biodegradability.