Dynamic Column Adsorption Studies of Toxic Cr(VI) Ions onto Iron Oxide Loaded Gelatin Nanoparticles

The present study investigates the utility of iron oxide loaded nanoparticles of biopolymer gelatin (FeO-gelatin) for removing hexavalent Cr(VI) ions in aqueous solutions by continuous (fixed bed) column adsorption analysis. In column experiments the influence of pH, Cr(VI) concentration, and flow rate were studied on the adsorption profiles of the metal ions. The maximum adsorption of Cr(VI) on FeO-gelatin was observed at pH 2 due to the electrostatic attraction of acid chromate ion (HCrO4-) with protonated amine (NH3+) and surface (FeOH2+) groups on adsorbent surface. At a bed height of 3 cm and flow rate of 0.5 mLmin(-1) the metal removal capacity of FeO-gel for Cr(VI) was found to be 71.4%. The bed depth service time (BDST) model was used to analyze the experimental data. The sorption capacity per unit bed volume (N-0) and rate constant (Ka) were calculated to be 2.1 mgL(-1) and 0.657 Lmg(-1) min(-1), respectively. In the flow rate experiments, the results confirmed that the metal uptake capacity and the metal removal efficiency decreased with increasing flow rate. The characterization of the prepared nanoparticles has been accomplished by FTIR, TEM, XRD, and zeta-potential measurements. The results obtained in this study illustrated that the prepared nanoparticles of gelatin and iron oxide were effective and economically viable adsorbents for Cr(VI) removal at low concentration level from aqueous environment.