Balsamo M., Di Natale F., Erto A., Montagnaro F., 2013, On the Effect of the Coal Ash Pre-treatment as a Mean to Improve their Sorptive Behaviour toward Heavy Metals in Wastewaters, Chemical Engineering Transactions, 32, 325-330.
The use of raw coal combustion ash (CCA) and of suitable pre-treatments to enhance its adsorption capacity towards specific pollutants (namely cadmium and arsenic) were considered in this work. Pre- treatments included mechanical sieving, acidification, demineralization and gasification (either with steam or CO2 as gasifying agents). After each pre-treatment, ash characteristics were determined and both equilibrium and kinetic adsorption experiments were carried out under fixed operating conditions. Results were expressed in terms of adsorption isotherms and kinetic curves, which confirmed that specific pre-treatments allow achieving substantial improvements of CCA adsorption capacity towards heavy metals. Post-processing of experimental data allowed the estimation of relevant parameters such as the equilibrium and the kinetic constants, the separation factor, the initial adsorption rate and the characteristic adsorption time. Besides, a correlation between the properties of raw or pre-treated CCA samples and the magnitude of heavy metals adsorption was carried out to assess the optimal pre-treatment for each of the investigated pollutant.
