The influence of pH on chemical coagulant/flocculation may be considered as a balance of two competitive
forces: (1) between H+ and metal hydrolysis products for interaction with organic ligands and (2) between Aust. J. Basic & Appl. Sci., 7(8): 258-262, 2013
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hydroxide ions and organic anions for interaction with metal hydrolysis products. At low pH values, hydrogen
ions out compete metal hydrolysis products. At low pH values, hydrogen ions out compete metal hydrolysis
products for organic ligands, hence poor removal rates occur and some of the generated organic acids will not
precipitate. At higher pH values, hydroxide ions compete with organic compound for metal adsorption sites and
the precipitation of metal-hydroxides mainly occurs mainly by co-precipitation (Tasti et al., 2003).