New highly-percolating alginate-PEI membranes for efficient recovery of chromium from aqueous solutions

Highly percolating membranes are prepared by the interaction of polyethylenimine and alginate (with glutaraldehyde crosslinking). SEM illustrates the macroporous structure of the material. The material is characterized by FTIR before and after chromate anions sorption. Batch-simulated continuous sorption experiments revealed that the maximum sorption occurred at pH 2 and the flow rate has limited effect on sorption efficiency. Uptake kinetics and sorption isotherms are well fitted by the pseudo-second-order rate and Sips equations, respectively. Maximum sorption is found close to 314 mg g^-1. Competition effects from Ca(II), Cu(II), Cl^-, NO₃^-, and SO₄^2- are investigated to evaluate sorbent selectivity. The membranes are applied to remediate a simulate of Cr(VI) contaminated electroplating wastewater. Successive cycles of sorption and desorption show that the membranes maintain sorption capacity higher than 200 mg Cr g^-1 for both Cr(VI) and total chromium for the first two cycles. These new highly percolating membranes have promising performances for Cr(VI) removal.