Pico–nano bubble column flotation using static mixer-venturi tube for Pittsburgh No.8 coal seam

The flotation process is a particle-hydrophobic surface-based separation technique. To improve the essential flotation steps of collision and attachment probabilities, and reduce the step of detachment probabilities between air bubbles and hydrophobic particles, a selectively designed cavitation venturi tube combined with a static mixer can be used to generate very high numbers of pico and nano bubbles in a flotation column. Fully embraced by those high numbers of tiny bubbles, hydrophobic particles readily attract the tiny bubbles to their surfaces. The results of column flotation of Pittsburgh No. 8 seam coal are obtained in a 5.08 cm ID and 162 cm height flotation column equipped with a static mixer and cavitation venturi tube, using kerosene as collector and MIBC as frother. Design of the experimental procedure is combined with a statistical two-stepwise analysis to determine the optimal operating conditions for maximum recovery at a specified grade. The effect of independent variables on the responses has been explained. Combustible material recovery of 85–90% at clean coal product of 10–11% ash is obtained from feed of 29.6% ash, with a much-reduced amount of frother and collector than that used in conventional column flotation. The column flotation process utilizing pico and nano bubbles can also be extended to the lower limit and upper limit of particle size ranges, minus 75 lm and 300–600 lm, respectively, for better recovery.

Analytical, Spectral, Thermal and Molecular Modeling Studies of Hg2+-2,3-Butanedionemonoxime Girard’s T Hydrazone Complex and Its Application

The coordination behavior of 2,3-butanedionemonoxime Girard’s T hydrazone (L1) towards Hg2+ ion has been investigated. The structure of Hg2+ complex, [Hg(L1)Cl]Cl·5H2O, is elucidated using elemental analyses, spectral (IR, UV-visible, 1H-NMR and mass) and TGA measurements. IR spectrum suggests that L1 behaves in a bidentate manner through the azomethine groups. The molecular modeling of L1 and its Hg2+ complex has been investigated. The bond lengths, bond angles, HOMO and LUMO have been calculated. The thermal behavior and kinetic parameters are determined using Coats-Redfern method. The use of L1 for preconcentration and separation via flotation of Hg2+ complex and determination using cold vapor atomic spectrometry (CVAAS) is described. The effects on the percentage of recovered Hg2+ by pH of sample solutions, oleic acid (HOL) concentration, Hg2+ and L1 concentrations are studied in details. The method is applied for the determination of the total Hg2+ (mg·mL-1) in natural water samples.