Frother structure-property relationship: Aliphatic alcohols and bubble rise velocity

Abstract

This study is part of our investigation into the frother structure-property relationship, here focusing on aliphatic alcohols. The structure variation is the length of the alkyl chain (C4 to C7), and position of the methyl branch (CH3) and hydroxyl (OH) group in five- and six-carbon alcohols. The property was bubble rise velocity. Single bubble velocity profiles were determined in a 350cm water column. Velocity at 300cm as a function of concentration is determined and the concentration to reach minimum velocity at 300cm (CMV) estimated. The most significant effect is the chain length which decreases CMV by about one order of magnitude for each additional carbon. The next strongest effect is the methyl branch position which decreases CMV as it is moved away from the hydroxyl group. The least effect is the position of OH which nevertheless systematically decreases CMV as it is moved from position C-3 to C-1 (i.e., from the center to the terminus of the molecule). An argument based on surfactant molecule packing on the bubble surface is proposed to account for the effect on CMV. From the results the structure of the most effective aliphatic alcohol frother is suggested.