Preparation of polyvinyl alcohol/chitosan hydrogel compounded with graphene oxide to enhance the adsorption properties for Cu(II) in aqueous solution

Abstract

A novel bio-adsorbent, composite hydrogel beads, composed of polyvinyl alcohol (PVA), chitosan (CS) and graphene oxide (GO) was prepared by an instantaneous gelation method. The micromorphology and thermal stability of the PVA/CS/GO hydrogel beads were characterized by scanning electronic microscope (SEM) and thermo gravimetric analysis (TGA) respectively. Adsorption of Cu(II) onto PVA/CS/GO hydrogel beads was investigated with respect to pH, initial concentration, temperature and adsorption time. Adsorption data were well matched by Langmuir isotherm and pseudo-second-order kinetic model at the optimum pH 5.5. The maximum adsorption capacities of PVA/CS/GO hydrogel beads were found to be 162 mg g −1 for Cu(II) at 30°C, which was much higher than that of PVA/CS hydrogel. Thermodynamic studies indicated that the adsorption was spontaneous and endothermic process in nature. Besides, desorption efficiency and reusability of the adsorbents were assessed on basis of six consecutive adsorption-desorption cycles. Based on these studies, it can be seen that PVA/CS/ GO hydrogel beads will be a potential recyclable adsorbent for removal of hazardous metal ions in waste water.

Optimization of synthesis condition for carboxymethyl cellulose‐based hydrogel from rice straw by microwave‐assisted method and its application in heavy metal ions removal

“…It was observed that the equilibrium adsorption capacity slightly decreases after each regeneration cycle. This result is due to some active sites on CMC‐g‐AMPS hydrogel being occupied by heavy metal ions, which could not be completely recovered by desorption . Figure shows desorption ratios of 97.23 ± 0.46%, 95.69 ± 0.32% and 96.54 ± 0.19% for the first adsorption–desorption cycle of Cu 2+ , Pb 2+ and Fe 3+ ions, respectively.…”

Carbon nanotubes, graphene, and their derivatives for heavy metal removal

“…Graphene as the nanoadsorbent mainly includes three forms: pristine graphene, graphene oxide (GO), and reduced graphene oxide (rGO) [58]. GO is an oxidized form of graphene, containing various oxygen-containing groups, such as epoxide, carbonyl, carboxyl, and hydroxyl groups [59][60][61][62][63]. Since the oxygen groups break the double bonds holding the carbon atoms together, GO loses its electrical conductivity.…”

Recent Progress of Graphene‐Containing Polymer Hydrogels: Preparations, Properties, and Applications

“…For example, Rodrigues and co‐workers fabricated PAA–CS–GO hydrogels by first dissolving PAA and CS solution and then mixing GO dispersions. Chen and co‐workers also fabricated PVA–CS–GO hydrogels by utilizing a similar method.…”

“…Another kind of polymer–GO hydrogels have the ability to absorb heavy metal ions. For example, Chen and co‐workers prepared PVA–CS–GO hydrogel, which can absorb Cu 2+ . Wang and co‐workers prepared a series of cross‐linked sodium acrylate and acrylamide copolymer/graphene oxide hydrogels, which can be used as the adsorbent for systematic adsorption of Pb 2+ and Cd 2+ from aqueous solutions.…”