Modified Chitosan Hydrogels and Nano Hydrogels for Congo Red Removal from Aqueous System

In the present work, sulfonamide chitosan derivatives were prepared via the reaction of chitosan (Cs) with diphenyl ether – 4, 4`- disulfonylchloride (DPE) in absence and/or presence of glutaraldehyde (G) to form the hydrogel (DPE-I) and (DPE-II) respectively. The nanogels (DPE-III) and (DPE-IV) were prepared via ionotropic gelation method in presence of sodium tri polyphosphate (TPP) under the same reaction conditions. The hydrogels (DPE-I, DPE-II, DPE-III, and DPE- IV) were characterized by different tools as: Elemental analysis, Fourier Transform Infra-Red spectrometer (FT-IR), Proton Nuclear Magnetic Resonance (1HNMR), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The adsorption efficiency of the prepared hydrogels for removal of congo red dye (CR) from aqueous solution under different parameters such as (time, pH, and concentration) was evaluated. The adsorption capacity of CR by the prepared hydrogels increased with time, adsorbent dosage and the initial concentration of CR. The optimum adsorption capacity for CR dye by the prepared hydrogels was at pH 7. Hydrogels (DPE-III and DPE-IV) showed the highest efficiency for adsorption of (CR) dye