Simultaneous determination of intraparticle diffusivities from ternary component uptake curves using the shallow bed technique.

In order to design and operate a fixed-bed reactor, accurate modeling is important. For a single component system, the determination of intraparticle diffusivity is rather easy. However, the calculations of multi-component systems are normally complicated and very time-consuming. Therefore, an alternative simple determination procedure using the shallow bed technique is proposed in this research to determine the intraparticle diffusivities for multi-component systems. Ternary component systems of phenol (PH), benzoic acid (BA), and p-nitro-phenol (PNP) were investigated as model components. This study illustrated that adsorption uptake curves of different components in ternary systems can be converted into one typical characteristic curve (theoretical uptake curve, TUC) by using a set of dimensionless groups. By matching the dimensionless experimental uptake curve (DEUC) with TUC, diffusivities of PH, BA and PNP were determined as 8.00 x 10(-8), 5.92 x 10(-8) and 5.05 x 10(-8)cm2 s(-1), respectively. These values are in good agreement with simulated experimental values. This study demonstrated that the shallow bed technique can be used to simultaneous determination of intraparticle diffusivities from multi-component systems.

Decolorization of acid black 24 by the FeGAC/H2O2 process.

FeGAC/H2O2 process was developed and employed in this research for the treatment of acid back 24. The removal efficiencies of five treatment processes (GAC, FeGAC, H2O2, GAC/H2O2, and FeGAC/H2O2) were studied in this research. The adsorption capacity of granular activated carbon (GAC) was greatly improved by the coating of iron oxide on GAC surface (FeGAC). The presence of H2O2 significantly improved the removal abilities of FeGAC and GAC. For instance, at solution pH 2, the removal efficiency of FeGAC/H2O2, GAC/H2O2, H2O2, FeGAC, and GAC were 76, 74, 59, 11, and 7%, respectively. The possible removal mechanisms of FeGAC/H2O2 process were proposed in this research. When treating the actual dye contaminated wastewater, the removal efficiencies of FeGAC/H2O2 and GAC/H2O2 were approximately six times greater than that of H2O2 process.

Amination of n-hexanol in supercritical water.

The amination of 1-n-hexanol followed by amidation was carried out in supercritical water at 380, 400, and 420 degrees C and water densities of 0.1, 0.3, and 0.5 g/cm3. The replacement of the hydroxyl group with the amino group was found to occur in 1-n-hexanol using ammonium acetate in supercritical water without the addition of a metal or an acid catalyst. The yield of the final product, N-n-hexylacetamide, increased by increasing the reaction temperature, water density, and the amount of ammonium acetate. The yield and the selectivity of N-n-hexylacetamide were 78.5% and 87.5%, respectively, in supercritical water at 400 degrees C, 0.5 g/cm3, for 10 min.