title: Preparation of functionalized graphene oxide and its application as a nanoadsorbent for Hg(2+) removal from aqueous solution.
abstract: A poly(allyl acetoacetate)-grafted graphene oxide (GO-GAA) was successfully synthesized using Hummer's method by divinyl sulfone modification and allyl acetoacetate polymerizaton. This novel functionalized graphene oxide was characterized thoroughly by FTIR, XRD, FE-SEM, TEM, and TG-DT analyses. GO-GAA was then employed as an adsorbent for Hg(2+) removal from aqueous solutions. It exhibited higher adsorption capacity with regard to the pristine graphene oxide because of its effective functionalities, especially the dicarbonyl groups which are significant chelating agents. The effects of pH, temperature, and contact time on Hg(2+) adsorption were also investigated. The optimum Hg(2+) adsorption was obtained at pH 4 and T = 20-30 °C. The adsorption isotherm and kinetics were found to follow the Langmuir and pseudo-second-order models, respectively, with a correlation coefficient of 0.99 for both. The calculated maximum adsorption capacity of the adsorbent was 282.7 mg Hg(2+) per unit mass of GO-GAA, which is much more than 56 mg/g of that obtained for GO. The results showed that adsorption reaches up to 95 % of its maximum in less than 2 min. The synthesized GO-GAA as a novel and efficient adsorbent has been regenerated by HNO3 and reused. It retained its performance for Hg(2+) removal for several times and a less than 5 % decrease in removal efficiency was observed after four cycles of adsorption-desorption.
authors.affiliation: Environmental Pollution Group, Department of Environment and Energy, Sciences and Research Branch, Islamic Azad University, Tehran, Iran. Aghdam_khaledeh@yahoo.com.
authors.forename: Khaledeh
authors.initials: K
authors.lastname: Aghdam
authors.affiliation: Department of Chemistry, Central Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Homayon Ahmad
authors.initials: HA
authors.lastname: Panahi
authors.affiliation: Research Institute of Petroleum Industry (RIPI), Tehran, Iran.
authors.forename: Ebrahim
authors.initials: E
authors.lastname: Alaei
authors.affiliation: Environmental Pollution Group, Department of Environment and Energy, Sciences and Research Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Amir Hesam
authors.initials: AH
authors.lastname: Hasani
authors.affiliation: Department of Chemistry, Varamin (Pishva) Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Elham
authors.initials: E
authors.lastname: Moniri
mesh_terms: D000327:Adsorption; D004784:Environmental Monitoring; D006108:Graphite / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008628:Mercury / Q000032:analysis / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D010087:Oxides; D014874:Water Pollutants, Chemical; D006108:Graphite; D008628:Mercury
keywords: GO-GAA; Graphene oxide; Hg2+; Nanoadsorbent; Polymer grafting; Removal