Prateek Khare

Synthesis of phenolic precursor-based porous carbon beads in situ dispersed with copper–silver bimetal nanoparticles for antibacterial applications

Copper (Cu) and silver (Ag) bimetal-dispersed polymeric beads (~0.7 mm) were synthesized by suspension polymerization using phenol and formaldehyde monomers. The Cu:Ag bimetal nanoparticles (Nps) were incorporated into the polymeric matrix at the incipience of gel formation during polymerization using an anionic surfactant. The prepared bimetal-doped polymeric beads were carbonized, activated using steam, and reduced in a hydrogen atmosphere to produce metal Nps-doped porous carbon beads. The prepared bimetal (Cu and Ag) Nps-doped beads exhibited significantly larger anti-bacterial activities than single-(Cu or Ag) metal-doped beads for both gram-positive Staphylococcus aureus and gram-negative Escherichia coli bacteria. The prepared materials contained the total optimized amounts of Cu and Ag. These amounts were smaller (approximately half) than the amount of single metal (Cu or Ag) required for preparing single-metal-doped beads. Although Cu Nps exhibit lesser antibacterial activity than Ag Nps, it enhanced the porosity of the beads. The prepared bimetal beads remained effective for 120 h, completely inhibiting the bacterial growth, and therefore, they are potential antibacterial agents for water purification.

Preparation of novel carbon microfiber/carbon nanofiber-dispersed polyvinyl alcohol-based nanocomposite material for lithium-ion electrolyte battery separator

A novel nanocomposite polyvinyl alcohol precursor-based material dispersed with the web of carbon microfibers and carbon nanofibers is developed as lithium (Li)-ion electrolyte battery separator. The primary synthesis steps of the separator material consist of esterification of polyvinyl acetate to produce polyvinyl alcohol gel, ball-milling of the surfactant dispersed carbon micro-nanofibers, mixing of the milled micron size (~500 nm) fibers to the reactant mixture at the incipience of the polyvinyl alcohol gel formation, and the mixing of hydrophobic reagents along with polyethylene glycol as a plasticizer, to produce a thin film of ~25 μm. The produced film, uniformly dispersed with carbon micro-nanofibers, has dramatically improved performance as a battery separator, with the ion conductivity of the electrolytes (LiPF6) saturated film measured as 0.119 S-cm(-1), approximately two orders of magnitude higher than that of polyvinyl alcohol. The other primary characteristics of the produced film, such as tensile strength, contact angle, and thermal stability, are also found to be superior to the materials made of other precursors, including polypropylene and polyethylene, discussed in the literature. The method of producing the films in this study is novel, simple, environmentally benign, and economically viable.

Synthesis of iron-doped resorcinol formaldehyde-based aerogels for the removal of Cr(VI) from water

Abstract Iron-doped resorcinol formaldehyde-based aerogels (Fe-RF-AGs) were synthesized and used for the removal of hexavalent chromium [Cr(VI)] from water using adsorption. The synthesis steps of Fe-RF-AGs comprised the gelation by the polycondensation of resorcinol and formaldehyde, followed by drying using supercritical carbon dioxide. The produced mesoporous material was in situ doped with iron (Fe) before the incipience of gel formation, using ferrocene as the metal precursor. Various analytical techniques were used to characterize the prepared materials. The batch adsorption study was performed containing different amounts of Fe in the gel, different initial Cr(VI) concentrations of the solution, and at different solution pH and temperatures. The adsorption rate was found to be first order. The equilibrium data were explained using the Freundlich isotherm. The thermodynamic calculations revealed that the adsorption of Cr(VI) was spontaneous, endothermic and irreversible over the temperature range of 20–40°C. The maximum adsorption capacity of Fe-RF-AGs for Cr(VI) was found to be approximately 55 mg/g at 30°C at the aqueous phase concentration of 275 mg/l, which is larger than most of the data discussed in the literature. The results indicated that Fe-RF-AGs can be used as an effective adsorbent for the removal of Cr(VI) ions from waste water.