ENVIRONMENTAL-FRIENDLY ION EXCHANGE RESIN FROM WATER HYACINTH

Abstract

The objective of this research was to prepare ion exchange resin using environmentally friendly processes and materials. Ion exchange resin was synthesized by the non-strong acid catalytic esterification of cellulose in water hyacinth and citric acid at optimal operating conditions. The highest total ion exchange capacity, in terms of free carboxylic content, was obtained when the reaction was performed at 60^oC for 1 hour, then increased to 140^oC for 1.5 hours after pre-treatment of water hyacinth with 0.4 mol/l of sodium hydroxide. The average carboxylic content of synthetic resin was 4.49 ± 0.11 meq/g. The morphology and functional groups of synthetic resin were characterized by SEM and FTIR, respectively. Adsorption study of the chromium (III) ion in aqueous solution by batch and column methods showed that the synthetic resin had good adsorption efficiency. The sorption capacities were 21.96–23.02 mg/g. In a three-cycle regeneration test with 0.25mol/l nitric acid, adsorption efficiencies by batch and column methods decreased progressively by less than 45% in the second cycle. Therefore, it is not suitable for reuse more than two times. However, the synthetic resin offered stable adsorption efficiency throughout the storage period of 18 months. The ion exchange resin prepared in this research is biodegradable and low-toxic, so it is friendly to animals, humans, and the environment. In addition, it has a low cost, reusability, and long storage time, so it has a high probability of application in many fields, such as environment (metal adsorbent in waste water), water hardness treatment and chemical analysis (preconcentration and separation).