A novel chitosan based adsorbent for boron separation

A new type of absorbent was synthesized by grafting N-methyl-D-glucamine (MG) onto the surface of chitosan beads to separate boron element. The physicochemical properties of modified chitosan beads (CTS-MG) were examined by FT-IR and SEM analyses. The results indicated that MG had grafted on chitosan beads (CTS) successfully. Compared to surface of pure CTS, CTS-MG had a rougher surface. While the pH value ranged 3-8, CTS-MG would have a high efficiency of adsorption to boron. The characteristics of the adsorption process were evaluated by Langmuir and Freundlich adsorption isotherms, and the maximum adsorption capacity of CTS-MG was 20.36 mg·g−1. When mass of absorbent was not lower than 0.1 g, the concentration of 10 ml boron solution would decrease from 50 to 0.5 mg/L. This absorption process fit to the pseudo-second-order kinetic model. CTS-MG had a comparatively high selectivity because general competing ions had little influence on the absorptive ability of CTS-MG. After 5 times adsorption-desorption cycles, absorptive capacity of CTS-MS did not decrease obviously. CTS-MG was hopefully used in the process of boron desorption in salt lake brine.