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Study On Liquid Phase Removal Of Bromate Over Carbon-nanotubes

Posted on:2013-06-25Degree:MasterType:Thesis
Country:ChinaCandidate:Y M ZhaoFull Text:PDF
GTID:2231330371488004Subject:Environmental Engineering
Abstract/Summary:PDF Full Text Request
Nano-materials has got a lot of development in physics, chemistry, biology, materials, medicine and other disciplines, for its unique physical and chemical properties and will bring new opportunities for the study of these disciplines. Carbon nanotubes (CNTs) as a new nano-material is attracting the increasingly widespread concern due to its advantages of light density, good mechanical properties, large surface area, good adsorption properties, unique electrical properties and so on. Recently, the attention is foucused on the nature of the carbon nanotubes and its applications. Some significant progresses have been achieved.In this study single-walled carbon nanotubes (SWNT) and multi-walled carbon nanotubes (MWNT) after treatment were used as reductant to remove the aqueous bromate. The carbon nanotubes were pre-treated by pickling, ultrasonic oscillation and calcining at high temperature under a nitrogen atmosphere to purify. Then the reduction properties of bromate over the CNTs were investigated. To explore the reduction mechanism, the treated SWNT and MWNT before and after bromate reduction reaction were characterized by the transmission electron microscopy (TEM), zeta potential, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), laser Raman spectroscopy (Raman) and Boehm titration.The reduction reaction results indicated that both SWNT and MWNT showed activities for the remove of bromate, and the SWNT showed more activity compared to MWNT. For example, as the initial concentration of bromate is5mg·L-1, after48h, the time period was sufficient to reach adsorb and reduction equilibrium, the removal rate of bromate over SWNT and MWNT are approximately83%and16%respectively. Additionally, the reaction conditions also affected the remove of bromate. The results showed the removal rate of bromate increasing with the reaction temperature and decrease with the solution pH.The characterization results indicated that a significant difference between SWNT and MWNT observed on the surface acid-basic properties. In addition, the calcined temperature for the CNTs also affected the amount of the basic group on the CNTs surface. And the removal rate of bromate depended on the amount of the surface basic group.And lastly, a recycling experiment of the CNTs were tested, the results indicated that after four times reuse, a stable and highly activity was maintained over the CNTs, such as the initial removal rate of bromate over SWNT was65%while it was only decreased to61%after four times reused. It further confirmed the SWNT is a good reductant for the removal of bromate.
Keywords/Search Tags:carbon nanotubes, single-walled carbon nanotubes, multi-walledcarbon nanotubes, adsorb-reduced activity, bromate
PDF Full Text Request
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