Removal of As(V) from aqueous solutions using calcium-alginate microspheres with encapsulated iron nanoparticles

This work investigated As(V) removal from aqueous solutions using calcium alginate microspheres with encapsulated iron nanoparticles (FeNPs) in batch systems. The kinetic, equilibrium, and thermodynamic parameters of the adsorption process were evaluated. Adsorbents were characterized using Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, and Zeta Potential techniques. The FeNPs were obtained by a simple and low-cost method and they were successfully encapsulated and uniformly dispersed over the microspheres' surface. Significantly fast adsorption kinetic rates were observed due to microspheres' particle size and FeNPs encapsulation. The chemisorption mechanism was recognized in both adsorbate-adsorbent systems. The As(V) isotherms data suggested that the process is associated with heterogeneous adsorption. Available sorption sites with different adsorption energies were related to the functional groups involved in removing As(V), such as hydroxyl and carboxyl groups. Significantly high adsorption capacities were obtained for both materials, suggesting they can be competitive compared to conventional adsorbents, even at low FeNPs concentrations. Besides FeNPs encapsulation enhancing arsenate removal, higher adsorption was obtained at slightly acidic pH values and, together with their small particle size, suggests that the microspheres have a great potential to be used as arsenate adsorbents in the water treatment for human consumption.

Sorption Capacity of Toxic Heavy Metal Cr (VI) Ion on bentonite clay from Aqueous Solution by Kinetic and Thermodynamic Studies

The present study removal of toxic heavy metal Cr (VI) ion on bentonite clay from aqueous solution under different experimental conditions and also study sorption capacity are effect different pH, concentration, temperature and contact time of shaking.My study focused on use of bentonite clay as a best adsorbent for the removal of toxic heavy metal Cr (VI) ions from aqueous solution. Initial metal ions concentration increases 50 to 250mgL-1 the % removal Cr (VI) ion decreases from 66.64 % to 53.94 % but amount of sorption increases from 0.833 to 3.371mgg-1, The particle size of bentonite clay increase from 45 to 150μ by amount of adsorption of Cr (VI) decreasing from1.589 mgg-1 to 1.153mgg-1 , pH increasing from 2.0 to 10.0 the amount of sorption decrease from 2.018 to 1.161 mgg-1, temperature increasing from 303K to 313K adsorption is also increases from 1.589 to 1.822mgg-1. Kinetic study for value of rate constant k1 and k2 is favour concentration increases the amounts of the metals sorbent qcal also increases. Q and kf sorption capacity related to Langmuir and Freundlich adsorption isotherm constant. Value of both is favour sorption is temperature dependent. Thermodynamic study the value of ΔG0 increase -1.402 to -2.655it is best evidence temperature increases from 303K to 323K the adsorption of Cr (VI) ion increases because value of ΔG0 is negative favour the adsorption. My investigation best evidence the value of kinetic, equilibrium and thermodynamic parameter also favours the Sorption of Cr (VI) ion on bentonite clay from aqueous solution.