In the present study, nanocrystalline tungsten oxide powders were prepared by a modified plasma arc gas condensation technique where a gas nozzle was introduced to provide blowing gas. With the aid of the blowing gases, nanocrystalline tungsten oxide powders can be prepared under various chamber pressures ranged from 4.9 to 101.3 kPa. The mean grain size and powder production rate of the as-prepared nanocrystalline WO 3 powders increased with increasing chamber pressure. For an increasing chamber pressure from 4.9 to 101.3 kPa, asignificant increase in powder production rate from 0.374 to 13.658 g/h can be noticed, while the mean grain size only enlarged acceptably from 5.9 to 15.7 nm. Meanwhile, by controlling the partial oxygen pressure of the mixed gas, nanocrystalline blue tungsten oxide powders can be prepared successfully. The blowing mixed gas from the nozzle not only suppressed the nucleation and growth for powders from the gas phase, but can be used to prepare stoichiometric or nonstoichiometric tungsten oxide powders.

A new type of poly(vinyl alcohol)(PVA)/peat/clay composite bead was prepared and shown to be suitable for use as an adsorbent. The mass transport process for the adsorption of metal ions onto the composite beads in an aqueous system was investigated. In the external mass transport process, the rate of ion diffusion decreased and increased with increasing initial metal ion concentrations for Pb+2and Zn+2 ions, respectively. In the intraparticle diffusion process, the diffusion coefficient decreased with increasing initial metal ion concentrations in the range of 1×10-3 to 4×10-3 M, and the diffusion coefficient maintained an almost constant value in the range of 6×10-3 to 22×10-3 M. The rate of ion diffusion within the adsorbent for the Pb+2 ions was faster than that for the Zn+2 ions. The adsorption mechanism was controlled by the intraparticle diffusion process. The maximum amount of adsorbed metal ions at adsorption equilibrium for Pb+2 and Zn+2 ions in this study was 134.57 and 13.28 mg/g composite bead, respectively.