| dc.description.abstract | Power generating companies using and recycling cooling water usually experience deposition of
insoluble salts on pipes carrying the water, leading to scaling problems. By controlling parameters
that optimize competitive Ca complexation, the scaling potential could be reduced. This semiempirical
study determined the effect of ligands in binding, as well as the optimum parameters for Ca
complexation experimentally using simulated water solutions before modelling. Experimental results
showed that metal binding to ligands depended on the type of metal in competition, the pH and the
humic substance used. Zn and Pb voltammetric peaks decreased with the addition of humic acid,
tannic acid and catechol. Ca showed a synergistic phenomenon in the form of increased peak
heights of the trace cations. Using PHREEQC model saturation index output results, the mineral
phases likely to precipitate were successfully described. Furthermore, the effect of changing pH on
scale formation was determined. For example, we successfully described the influence of pH on
speciation and complexation through the formation of H-humate and humate2 . The models
showed that pH may be manipulated to govern the incidence of scale. Predictive models were
derived to determine what would be a useful tool in reducing the potential for scaling. | en_US |
