NSTI Nanotech 2009

Adsorption of Pb2+ using platinum and ruthenium on carbon nanotubes

J.A. Azpeitia, A. Zepeda, L. Torres, Y. Verde
Instituto Tecnologico de Cancun, MX

Keywords: carbon nanotubes, lead, platinum, ruthenium, wastewater

Abstract:

Recently, remove Pb2+ ions from drinking water has been focused due to its high toxicity to our health, such as nausea, convulsions, coma, renal failure, cancer and subtle effects on metabolism and intelligence. Different approaches to remove Pb2+ ions from wastewater, including chemicals precipitation, ion exchange, reverse osmosis and adsorption have been used. Adsorption is the simplest and best cost-effective method. Various adsorbents such as activated carbon, iron oxides, filamentous fungal biomass and natural condensed tannin have been explored and the results are promising. Carbon nanotubes (CNTs) have attracted special attentions to many researchers since 1991 because they posses exceptionally morphologies and have showed excellent physical and chemical properties and great potential for environmental applications. CNTs are also good anion and cation adsorption materials for wastewater treatment and they exhibit large specific surface areas which are easy to decorate. For example, CNTs oxidized with nitric acid showed very good lead and cadmium (II) cation adsorption capability. Transition metals deposited on CNT had demonstrated to improve the heavy metals adsorption. In this work, a Pb2+ adsorption study using a Pt and Ru on Multiwall Carbon Nanotube (MWCNT) matrix is presented. Pt/MWCNT and Ru/MWCNT were synthesized using an aqueous deposition method follow by a H2 thermal reduction. Nanostructured materials were post-treated with nitric acid at different concentrations. Pb2+ synthetic solution and M/MWCNT (M= Ru or Pt) were placed in centrifugation process during several hours at room temperature. Samples of the synthetic solution were taken before and after centrifugation step and analyzed by atomic absorption spectroscopy (AAS) to determine lead concentration. AAS results show Pb adsorption of 41 +- 3% and 29 +- 1% from Pt/MWCNT and Ru/MWCNT respectively at 0.4 N HNO3 concentration. Scanning Electron Microscopy (SEM) shows lead adsorption on the MWCNT matrix by growing of Pb crystals (Figure 1). High Pb2+ adsorption on the synthesized M/MWCNT convert them in a good candidate to be use as wastewater treatment materials.
 
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