Abstract
Hydrogels are 3D interconnected network polymer chains that are hydrophilic, swell in water and imbibe a significant amount of water. When hydrogel absorb water, dye molecules transfer to their surface, aiding adsorption. Adsorption is efficient, cheap, and versatile technique to remove dye from aqueous media. In this study, high-performance adsorbents from chitosan/polyethylene glycol (CS/PEG) hydrogel cross-linked with intermolecular H-bonds and chitosan/polyethylene glycol/ZnO (CS/PEG/ZnO) composite hydrogel cross-linked with Zn2+ were developed by an instantaneous gelation method. The prepared composite hydrogels were characterized by Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), transmission electron microscopy (TEM) and Zeta-sizer. The developed composite hydrogels effectively adsorbed Congo red (CR) dye from aqueous media. CR adsorption efficiency using adsorbent dosage, contact time, pH and temperature factors were conducted by batch adsorption experiments. The obtained results for CR adsorption equilibrium were compatible with the Langmuir model with maximum adsorption capacity (qmax) of 212.76 mg/g for CS/PEG and 256.41 mg/g for CS/PEG/ZnO composite hydrogel. The qmax was measured at pH 3 and 25 min and kinetic study confirmed that pseudo 2nd order kinetic model was best followed. Thermodynamic study indicated that the nature of the adsorption phenomena was physical, endothermic and spontaneous. The high adsorption efficiency is mainly ascribed to the protonation of –NH2 groups present in CS/PEG and CS/PEG/ZnO composite hydrogels which enhanced its electropositivity. Hydrogen bond formation and electrostatic attraction among adsorbent and dye govern the adsorption mechanism. It can be concluded that CS/PEG hydrogel and CS/PEG/ZnO composite hydrogels could be considered as efficient, beneficial and potential adsorbents for environmental remediation.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
