Quinoline adsorption onto combusted Rundle spent shale in dilute aqueous solution at the natural pH 8

The adsorption of quinoline from aqueous solutions onto combusted Rundle spent shale shows that the adsorption isotherm is of Langmuir type (L-4). Cations which are leached from the spent shale or which are in retort water (Ca2+, Mg2+, Na+, K+, NH+4) have a marked effect on the adsorption. The sulphate anions have a small effect, while chloride anions have almost no effect on the adsorption. The adsorption of the base is mainly attributed to the formation of quinoline-metal ion complexes that result from coordination/protonation mechanisms rather than simply to cation exchange of the quinolinium ion. It is noted that this study did not attempt to delineate the relative importance of coordination and protonation mechanisms. Thus the two mechanisms are lumped together and regarded as an important property of the system. The ionic potential is used to scale the importance of coordination/protonation in the adsorption process. The mechanism of proton transfer to the quinoline molecule could be important for the adsorption of quinoline in ammonium solutions.