Preparation and Characterization of Anion‐Exchange Starches

Treatment of poly (glycidyl methacrylate (GMA))‐starch graft copolymer containing 270 m.eq.epoxy groups/100 g sample with ethylenediamine was carried out under different conditions. Results indicated that three reactions are likely to occur during this treatment, namely amination, crosslinking and hydrolysis. The highest amine content could be achieved upon using amine/epoxy molar ration of 2.5 and material to liquor ratio 1:3, at 90°C for 180 min. The dependence of the amination percent on the type and nature of the amine was also studied. The values of amination percent for the different types of amine follows the order: O‐phenylene‐diamine > m‐phenylenediamine > p‐phenylenediamine > ethylenediamine; whereas studying the nature of the amine brings about the order: diethylamine derivative > ethylamine derivative > ethanolamine derivative > triethylamine derivative. Evaluation of the different reaction products (aminated copolymers) for their anion exchange properties was made. The capacity of the anion exchangers relied on the inital epoxy content of the copolymer and type and nature of the amine used. On the other hand, heavy metal anions and dye removal efficiency followed the order: diethylamine derivative > ethylenediamine derivative > triethylamine derivative > p‐phenylenediamine > derivative > ethylamine derivative. The pH‐metric titration curves revealed that triethylamine derivative behaves as a strong base while the other exchangers as weak bases. Other properties such as pKb value, durability, solubility, etc. indicated that the synthesized products can be regarded as anion exchangers with acceptable properties.