Optimization of hybrid polymer preparation by ex situ embedding of waste Fe/Mn oxides into chitosan matrix as an effective As(III) and As(V) sorbent.

A hybrid polymer for deep removal of arsenic from aqueous solutions was obtained by loading of waste Fe/Mn oxides into a chitosan matrix. The process was optimized by studying the influence of selected individual factors and their reciprocal combinations on the adsorptive and physical properties of the product. The influence of chitosan solution concentration, inorganic load amount, the ratio of Fe/Mn oxides to chitosan, and polymer cross-linking degree on kinetics of As(III) and As(V) adsorption was examined. The optimal values of the parameters were chitosan polymer concentration 1.5% w/w, inorganic load to chitosan ratio 1.67, and glutaraldehyde to chitosan amine groups molar ratio 3:1. The selected products were evaluated in terms of their morphology (scanning electron microscopy (SEM) with EDS analysis), porosity (N and CO adsorption isotherms), surface properties (Fourier-transform infrared spectroscopy (FTIR), isoelectric point determination) and durability in an acidic environment. The proposed process makes it possible to obtain a product combining beneficial adsorptive properties toward arsenic with the physical form and durability essential in fixed-bed adsorption systems.