Sorption of boron calcium alginate gel beads

In this work, the removal of boron by a biopolymer of alginate was studied in an aqueous solution. The effects of pH, initial boron concentration, alginate concentration in the beads and stirring time were evaluated. The ratio of mannuronic acid to guluronic acid (M/G) in the alginic acid used in this study was determined by NMR. FTIR spectroscopy was used to characterize the alginate and to observe the interactions produced by the boron adsorbed onto the beads. The maximum boron removal observed was 94 mg/g; this rate was obtained with a high initial boron concentration in an alkaline medium. A study of the isotherms established that the experimental data conform better to the Langmuir than the Freundlich isotherm model. The results obtained in the kinetic studies showed that the pseudo-second-order adsorption model is predominant and that the overall rate of boron adsorption appears to be controlled by chemisorptions. (C) 2013 Elsevier Ltd. All rights reserved.