Removal of Heavy Metals Using Nanostructured Graphite Oxide, Silica Nanoparticles and Silica/Graphite Oxide Composite

Heavy metals are known to be toxic for living organisms even if they are present at low levels. The presence of heavy metals and other pollutants in water continues to be a major concern and the removal of such contaminant is considered to be a major problem in environmental remediation. In the present study, nanostructured graphite oxide, silica/graphite oxide composites and silica nanoparticles were used for the removal of the heavy metal ions from aqueous solutions by a batch adsorption method and have been modelled using classical Langmuir and Freundlich adsorption isotherms. The results revealed that the adsorption of heavy metals by nanostructured graphite oxide was observed in the following order: nickel > zinc > lead > cadmium > chromium. Langmuir adsorption isotherm results showed that graphite oxide is an effective adsorbent for the removal of Nickel ions from aqueous solutions, while Freundlich data obtained for Cadmium, Chromium, Lead, Nickel and Zinc ions suggest monolayer type of adsorption by graphite oxide. Results showed that silica/graphite oxide composite (2: 3) is a highly effective adsorbent material for heavy metal ions and highly recommended to be used in water purification technologies. (C) 2014 Elsevier Ltd.