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

New sustainable chemically modified chitosan derivatives for different applications: Synthesis and characterization

The functionalization of chitosan (CS) by terephthaloyl chloride (TPC), glutaraldehyde (GA), and 4(4-(ethyl carbamoyl) benzoyl chloride) benzene sulfonamide was performed under different reaction conditions to yield the new hydrogels (I, II, III) respectively. However, hydrogel (I-NPs) was prepared from reaction of chitosan with (TPC) via ionic gelation technique using sodium tripolyphosphate (TPP) as a cross-linker. Moreover, hydrogel (I) was loaded (Au, Ag and ZnO) nanoparticles to give the nanoformulations (I-Au NPs, I-Ag NPs and I-ZnO NPs) respectively. Structural and morphological analysis of the new chitosan derivatives hydrogels and NPs formulations were characterized by FTIR, elemental analysis, TGA, DSC, XRD, SEM and TEM. From swelling study, chitosan derivatives hydrogels revealed higher swelling degree compared to (CS) with increasing time, temperature and pH values which reached maximum at pH 7 then decreased at pH 10. In addition, the maximum sorption capacities of Congo Red (CR) in aqueous solution were in the range 81–88%. Moreover, adsorption equilibrium isotherm results displayed favorable Langmuir model than Freundlich model. Furthermore, chitosan derivatives hydrogels showed broad spectrum antimicrobial activities against Gram-negative bacteria, Gram-positive bacteria and fungi with the inhibition zone diameter ranged from 13 to 25 mm compared to (CS) hydrogel which revealed inhibition zone diameter ranged from 11 to 16 mm, especially the nano formulation hydrogel (I-Ag NPs) showed the highest antimicrobial activity. The results were promising suggesting that the new modified chitosan derivatives could be potential for dye removal and as antimicrobial agents