Dechlorination of Environmental Contaminants Using a Hybrid Nanocatalyst: Palladium Nanoparticles Supported on Hierarchical Carbon Nanostructures

Abstract

This paper demonstrates the effectiveness of a new type of hybrid nanocatalyst material that combines the high surface area of nanoparticles and nanotubes with the structural robustness and ease of handling larger supports. The hybrid material is made by fabricating palladium nanoparticles on two types of carbon supports: as-received microcellular foam (Foam) and foam with carbon nanotubes anchored on the pore walls (CNT/Foam). Catalytic reductive dechlorination of carbon tetrachloride with these materials has been investigated using gas chromatography. It is seen that while both palladium-functionalized carbon supports are highly effective in the degradation of carbon tetrachloride, the rate of degradation is significantly increased with palladium on CNT/Foam. However, there is scope to increase this rate further if the wettability of these structures can be enhanced in the future. Microstructural and spectroscopic analyses of the fresh and used catalysts have been compared which indicates that there is no change in density or surface chemical states of the catalyst after prolonged use in dechlorination test. This implies that these materials can be used repeatedly and hence provide a simple, powerful, and cost-effective approach for dechlorination of water.

Silver nanoparticles supported on carbon nanotube carpets: influence of surface functionalization

“…O 7 , MP bio; 99%). The overall process is discussed in an earlier publication [10] and involves two steps: AgNO 3 deposition from an aqueous solution followed by a reduction in the presence of a sodium citrate-DMSO solution [27]. The only change made in this study compared to earlier ones [10] is that here, the molarity AgNO 3 precursor solution was increased to 0.72 M compared to about 0.24 M in most reported studies.…”

“…For the synthesis of AgNPs, silver nitrate was used as the metal precursor [AgNO 3 (Sigma Aldrich; 99.99%)], dimethyl sulfoxide was the selected reducing agent [26] [DMSO (Sigma Aldrich; 99.5%)], and trisodium citrate was used as the stabilizing agent [26] (Na 3 C 6 H 5 O 7 , MP bio; 99%). The overall process is discussed in an earlier publication [10] and involves two steps: AgNO 3 deposition from an aqueous solution followed by a reduction in the presence of a sodium citrate-DMSO solution [27]. The only change made in this study compared to earlier ones [10] is that here, the molarity AgNO 3 precursor solution was increased to 0.72 M compared to about 0.24 M in most reported studies.…”

“…CNTs offer several advantages as NP supports and several earlier studies have discussed the influence of the physical and chemical nature of various support structures on advanced applications [4]. The CNT-enhanced substrates reported by our group have proved to be useful for several applications such as nanocomposite formation [5], surface adsorption [6], cell scaffolding [7], thermal management materials [8] in addition to support for metallic NPs [9][10][11].…”

Carbon Nanotube Based Groundwater Remediation: The Case of Trichloroethylene

“…To obtain large increments in remediation, a smart hierarchical approach that increases the surface area for remediation, while also dispersing catalytic particles for highest availability, is proposed by Mukhopadhyay et al [60,61,62,63,64,65,66] (Figure 8 shows the schematic and Figure 9 shows the SEM micrographs). CNT forests are fabricated onto a porous carbon substrate, with a dispersion of nanoparticles that is controlled by surface functionalization.…”

“…SEM micrographs of two different hierarchies: ( a ) Palladium nanoparticles (Pd–NPs) supported on carbon foam, and ( b ) Pd–NPs supported on CNT-grafted carbon foam. Reprinted with permission from [65]. ©2012 Hindawi Publishing Corporation.…”