Synthesis and characterization of silica-copper oxide composite derived from microemulsion processing

Silica-copper composite powders with high surface areas of about 200-400 m( 2)/g have been successfully synthesized by the controlled hydrolysis/polyme rization of sodium metasilicate (Na2SiO3) and copper nitrate [Cu(NO3)(2). 3 H(2)O] via partial-microemulsion and double-microemulsion processes at 28 d egrees C. Each microemulsion system consists of sodium 1,4-bis(2-ethylhexyl ) sulfosuccinate and sodium dodecyl sulfate, cyclohexane, and an aqueous so lution of sodium metasilicate or copper nitrate. The partial-microemulsion method can produce silica-copper oxide composites consisting of nanoparticl es ranging from 20 to 50 nm with an uniform elemental distribution. The com posites also exhibit a narrow distribution of mesopores (3-6 nm) having spe cific surface areas ranging from 320 to 370 m(2)/g. This partial-microemuls ion process is very attractive because ultrafine powders of silica-copper o xide composites can be produced from inexpensive Na2SiO3 using relatively l ow amounts of organic solvent and surfactants. However, the role of mixed a nionic surfactants in the microemulsions affecting the formation of these n anocomposites is yet to be clarified.