Synthesis characterization and dye adsorption of amphoteric hydrogels

Inthisthesis, synthesis of amphoteric hydrogels and removal of dyes from aqueous solutions by adsorption method using hydrogels were investigated. The synthesised hydrogels were characterised. In adsorbent synthesis studies, hydrogels were synthesised using sodium 4-vinylbenzene sulfonate (4VBS) and [2- (Methacryloyloxyloxy)ethyl]trimethylammoniumchloride (MOEAMCl) monomers, N,N'- methylenebisacrylamide (MBAAm) crosslinker and ammonium persulfate (APS) radicalinitiator. The hydrogels were characterised using FTIR, SEM, TGA techniques. Swelling studies of the synthesised hydrogels were carried out in differentenvironments (pH=3,5, 8 and 10 buffer solutions with ure and NaCl). According to the swelling results, it was determined that the hydrogels showed the highest swelling behaviour at pH 3 and the swelling behaviour decreased as the pH increased. A significant decrease in swelling ratios was determined with increasing 4VBS monomer ratio at pH 3. Since theneutralcharge of the adsorbent (pHpzc) is an important criterion in adsorption studies, the neutral charge point of the synthesised amphoteric hydrogel was determined as 4,5. Tartrazine (TART) as acidic dye and Methylene Blue (MM) as basic dye and SYB-5 [4VBS-MOEAMCl (50:50)] hydrogel as adsorbent were selected for adsorption studies. The effects of ambient pH, adsorbent amount, time, dye initialconcent ration, synthetic sea water (SDS) effect and temperature on the adsorption of TART and MM on SYB-5 hydrogel were investigated. Under optimum conditions (m=0.15 g; pH=10 and V=50 mL), the adsorption capacity for MM adsorption on SYB-5 hydrogel was 137 mg/g and for TART adsorption (m=0.5 g; pH=1.5 and V=50 mL) was 16 mg/g. Indyemixtures (50:25 ppm MM:TART mixture), MM adsorption occurre defficiently while TART adsorption was weak.