Performance of aquatic weed - Waste Myriophyllum spicatum immobilized in alginate beads for the removal of Pb(II).

A new biosorbent - alginate encapsulated with Myriophyllum spicatum - MsA was investigated for lead ions removal. This biosorbent was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), zeta potential, X ray Diffraction (XRD) and size distribution analysis. FT-IR analysis demonstrated that the lead ions sequestration mechanism included ion exchange and lead complexation with the carboxyl, carbonyl and hydroxyl groups in MsA. In order to better understand the mechanisms of the binding of Pb(II) on immobilized M. spicatum beads, 3 reaction and one diffusion based kinetic models were applied on kinetic data removal lead ions on three materials: M. spicatum, Ca-alginate and MsA. Myriophyllum spicatum encapsulated with alginate - MsA have higher adsorption capacity than M. spicatum. Among examined six isotherms Redlich-Peterson and the Langmuir isotherm model exhibited the best fit to the experimental data, with capacities ranging from 230 to 268.7 mg/g. Among the various tested desorption agents, nitric acid has proven to be the best. The obtained results suggest that the immobilized M. spicatum biosorbent holds great potential for lead wastewater treatment applications.

Influence of natural zeolitic tuff and organozeolites surface charge on sorption of ionizable fumonisin B(1).

Natural zeolitic tuff was modified with 2, 5 and 10mmol M(+)/100g of octadecyldimethylbenzyl ammonium (ODMBA) ions and the products were denoted as OZ-2, OZ-5 and OZ-10. The starting material and organozeolites were characterized by determination of the point of zero charge (pH(pzc)) and by thermal analysis. In vitro sorption of fumonisin B(1) (FB(1)) was studied for all sorbents at pH 3, 7 and 9. The pH(pzc) for the zeolitic tuff was 6.8+/-0.1, while the pH(pzc) for OZ-2, OZ-5 and OZ-10 pH(pzc) was 7.0+/-0.1. The curves pH(final)=f(pH(initial)) suggest that the surfaces of all sorbents are positively charged at pH 3 and uncharged at pH 7 and 9. High sorption of FB(1) by the zeolitic tuff in acidic solution suggests electrostatic interactions between the anionic FB(1) and the positively charged surface. At pH 7 and 9, adsorption of FB(1) is prevented because anionic FB(1) cannot be adsorbed at the uncharged surface. From the pH(pzc) for the organozeolites, it is possible that with lower amounts of ODMBA (OZ-2 and OZ-5), at pH 3, beside interactions between head groups of ODMBA and its alkyl chains and anionic FB(1), electrostatic interactions between positive uncovered surface and anionic FB(1) contribute to the sorption, while at pH 7 and 9 there is only the possibility for interactions between FB(1) and ODMBA. When the zeolitic surface was completely covered with ODMBA (OZ-10), FB(1) sorption was independent of the form of FB(1) suggesting only interactions between ODMBA and FB(1).