Boron removal from aqueous solutions by a polyethylenimine-epichlorohydrin resin

The use of a polyethylenimine–epichlorohydrin resin for the boron removal from aqueous solutions (boron concentration: 100–5000 mg L-1) of non-adjusted and pre-adjusted pH (pHnat, pHinit 8.0, 9.0 and 10.0) aqueous solutions was investigated using a batch technique. The boron concentration in the solutions after sorption was determined photometrically. The results indicated that the pH-dependent boron uptake was related to the protonation/deprotonation of the surface functional groups of the resin and to the boron speciation in solutions of different pH values. The maximum boron sorption capacity observed in solutions of pH 9.0 was 55 mg g-1 exceeding the majority of other commercial or alternative sorbents. Five empirical adsorption equations (Freundlich, Langmuir, Redlich–Peterson, Langmuir–Freundlich and Toth) were applied to the modelling of the boron adsorption equilibrium. The modelling results identified the homogenous boron sorption from acidic and heterogeneous from alkaline solutions. At alkaline pH, the system non-ideality can originate either from the different binding mechanism or from the competitive sorption of different boron species. The homogenous type boron sorption from acidic solutions was further confirmed by kinetic studie

The Treatment of Waste Waters Containing Heavy Metals by Magnetic Nanoparticles

This study presents the synthesis and the characterization of the structural and sorption properties of magnetic nanoscale particles, which play a significant role in wastewater treatment technologies.Aqueous suspensions of magnetic particles were prepared by co-precipitation of Fe(III) and Fe(II) in the presence of NH4OH. Adsorption of heavy metal ions adsorption from single metal aqueous solutions was investigated in batch adsorptionequilibrium experiments. Magnetic particles were used in the adsorption of selected bivalent heavy metal ions, i.e. Cd(II), Cu(II) and Pb(II) from aqueous media containing different amounts of these ions (20400 mg.l-1) and at different pH values of 2.0-8.0 at the sorbent concentration of 2 g.l-1. The model solutions of Cu(NO3) 2, Cd(NO3) 2, Pb(NO3)2 were used to realize the adsorption tests. The pH of the solutions was adjusted with a suitable concentration of NaOH and HNO3.Based on the experimental results it was observed that heavy metal ions could be adsorbed by nanoscale magnetic particles with the significant adsorption capacity

Chromium (VI) removal from aqueous solutions using a polyethylenimine - epichlorohydrin resin

The ability of a synthesized polyethylenimine - epichlorohydrin resin to remove Cr(VI) from aqueous solutions was investigated in absence (initial pH 2 to 7) and presence of background electrolytes (NaNO3 and Na2SO4 solutions of initial pH 3 and 6). The determined Cr-uptake was significantly higher than the one reported for the majority of other sorbents. The photo-metrically determined uptake data were modeled by the Langmuir, Redlich-Peterson, Langmuir-Freundlich, and Toth equations. The modeling results did not point out any preference to one specific model in terms of the goodness-of-fit and the prediction of maximum sorption capacity. The Cr-sorption kinetics was investigated at 15, 25, 35 and 45 oC using 51Cr-labeled solutions and γ-ray spectroscopy. The Cr-sorption was very fast at all studied temperatures and well reproduced by the pseudo-second order kinetics equation. Rate constant and activation energy values were calculated using the experimental data. The Cr-loaded resin was also examined by XRD, XPS, XAFS and SEM/EDS. The XPS and XAFS investigations indicated a partial reduction of Cr(VI) to Cr(III). The environmental compatibility of the Cr-loaded resin was examined using the EPA-TCLP method. The Cr-binding by the resin was very stable and regeneration attempts by HCl solutions of pH 3 were rather unsuccessful