Colloidal surfaces and oligomeric species generated by water treatment chemicals

Abstract

Properties of water treatment chemicals were investigated by a novel combination of analytical methods. Oligomer distribution, total surface charge, zeta potential and conductivity were evaluated in simulated systems containing highly and moderately basic polyaluminium chlorides, aluminium sulfate (alum), ferric chloride and ferric sulfate. Species were quantified on the basis of mass spectrometric results. Polyaluminium chemicals gave rise to an intensive and completely cationic distribution of mainly Al 13 -based oligomers and high surface charges. Both cationic distribution and charge decreased with increase of pH and increased with concentration of the chemical. The other chemicals produced a wider oligomeric distribution of smaller species, including anions. The dimeric form was typical for iron. In the case of the sulfate-containing chemicals, sulfate was present in the majority of oligomers and zeta potentials were stable. For the chemicals without sulfate, pH values needed to be high enough to provide high zeta values. The results can be utilized in the improvement of coagulation and flocculation mechanisms aimed at the removal of bacteria, viruses and other micro organisms, as well as at humic and mineral particles. In addition, semi quantitative information about oligomeric species may be helpful in breaking down cell membranes to support disinfection.

Role of Aluminum Speciation in the Removal of Disinfection Byproduct Precursors by a Coagulation Process

“…This is consistent with the results of Rämö et al (21). As shown in Figure 3b According to a previous study (22), the presence of TMA adducts also was observed in the samples due to pH adjustment by TMA.…”

Preparation and coagulation performance of solid aluminium formate

“…The highest observed charge quantities are in the same range as the charge quantities reported for both commercial and laboratory made polyaluminium chlorides [12,13]. In addition, the sharp decrease in the charge quantity after the optimum when the pH is increased has been observed with polyaluminium chlorides.…”

“…In addition, the sharp decrease in the charge quantity after the optimum when the pH is increased has been observed with polyaluminium chlorides. Aluminium sulphate has been reported to have very low charge quantities in similar conditions [12]. In this study too, the charge quantities of aluminium sulphate solution containing 1 mM Al were below the detection limit of the analyser.…”

Effect of pH on the aluminum salts hydrolysis during coagulation process: Formation and decomposition of polymeric aluminum species

“…The abundance of polymeric aluminum species was evaluated semi-quantitatively by the signal intensities of relative to aluminum species [12,16]. Five aluminum species were classified as follows: Al 1 -Al 2 species (monomeric and dimeric aluminum complexes), Al 3 -Al 5 species (small polymeric aluminum species), Al 6 -Al 10 species (median polymeric species), Al 11 -Al 21 species (large polymeric species) and undetected part (Al u , i.e., solid-phase Al(OH) 3 and/or Al(OH) − 4 ).…”

“…Furthermore, aluminum salts in the presence of sulfate were emphasized investigated [15]. In contrast to AlCl 3 , Rämö et al [16] demonstrated that aluminum speciation variation of highly 80% and moderately 42% basic polyaluminum chloride (PACl) at different pH values using ESI-MS. Therefore, based on detecting mass to charge ratio (m/z) of complexes, the ESI-MS measurement has been proved as a good method for aluminum speciation.…”