A study on the sorption of NO3- and F- on the carboxymethylated starch-based hydrogels with Fe2+ ions

Using the principle of geochernistry of fluoride, green and cost effective anion adsorbents were developed for the removal of F- from water systems. The scheme was further applied for the removal of NO3- also. Carboxymethylated starch functionalized through network formation with acrylamide was used as adsorbent, and the resultant hydrogels were loaded with Fe2+ ions to generate anchorage for the anions. Sorption of Fe2+ was studied as a function of different factors such as time, temperature, pH, and ion strength. The network having the highest Fe2+ uptake was loaded with the Fe2+ ions under optimum conditions and used for the sorption of F- and NO3. High efficiency has been observed for F-, as even up to 100% uptake has been observed within just 10 minutes. The support shows high selectivity for NO3-, which was used as anion reference. Thermodynamics of sorption confirms low order and low energy processes. (c) 2007 Wiley Periodicals, Inc.