Novel approach for the synthesis of Mg(OH) 2 nanosheets and lamellar MgO nanostructures and their ultra-high adsorption
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Chunge Niu and Xinping Zhen Petrochemical Research Institute, Karamay Petrochemical Company, Karamay, Xinjiang 83400, China
Jide Wang and Xintai Sua) Ministry Key Laboratory of Oil and Gas Fine Chemicals, College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046, China (Received 5 February 2015; accepted 6 April 2015)
A phase transfer method was developed to prepare Mg(OH)2 nanosheets and a subsequent adsorption–calcination process was followed to obtain lamellar MgO nanostructures. The as-prepared MgO nanosheets also showed a superior adsorption property of Congo red. Transmission electron microscopy and x-ray diffractometer results indicated that the as-obtained Mg(OH)2 was plate-shaped with a hexagonal crystal structure where MgO possessed a lamellar structure with a cubic phase. The maximum adsorption capacities of Mg(OH)2 and MgO were reached up to 1820 and 2650 mg g1, respectively. The high adsorption capacity might be related to the particle geometry and large surface area (87.97 m2 g1 for Mg(OH)2 and 132.31 m2 g1 for MgO). The adsorbents can be easily regenerated for five times without any significant loss in their adsorption property. The adsorption behaviors of the Mg(OH)2 and MgO adsorbents showed that the adsorption kinetics and isotherms were in good agreement with pseudo-second-order rate equation and Freundlich adsorption model.
I. INTRODUCTION
Dyes discharged by the textile, paper, and tannery industries are primary pollutants of water source.1,2 The major limitation in treating textile wastewater is their resistance to conventional biological treatment processes.3 Several methods have been developed to remove the synthetic dyes from the wastewaters, including coagulation and flotation,4 ozonation,5 membrane separation,6 photocatalysis,7 and adsorption.8 Among them, the adsorption method is a simple and effective method due to its advantages in terms of energy savings and ease of operation. Up to now, nanomaterials used for the adsorption of dye have gained considerable interest because of their large surface areas, numerous active sites, and unusual adsorptive properties.9,10 Among the nanomaterials that are currently being developed, Mg(OH)2 and MgO nanoparticles are extensively exploited in wastewater treatment due to their nontoxic, abundance, economy, and environmentally friendly nature.11,12 Different methods Contributing Editor: Edson Roberto Leite a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2015.113 J. Mater. Res., Vol. 30, No. 10, May 28, 2015
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have been utilized to prepare Mg(OH)2 and MgO nanostructures, such as the electrodeposition,3 sol–gel,13 precipitation,14 hydrothermal,15 and solvothermal process.16 However, the as-obtained samples usually have larger size, inhomogeneous morphology, and relatively poor adsorption performance. Recently, a general two-phase strategy for the synthesis of monodisperse nanoparticles has been developed by our group.17 In this
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