Humic substance charge determination by titration with a flexible cationic polyelectrolyte

Predictive model of cationic surfactant binding to humic substances

“…For PAHA the data of Saito et al [45] can be used. When no reliable proton titration data are available X H,0 can be estimated from titrations of the HS with the cationic polyelectrolyte, polyDADMAC, till the iso-electric point (IEP) of the complex is reached [12,13]. For DHA, IHA, SFA and LFA these data are available [22].…”

“…Also complex formation of HS with cationic polyelectrolytes is well studied. Polyelectrolyte binding to HS can be used to obtain insight in the charge density of the humics [12,13]. The main emphasis of these studies is however on the optimization of the complexation conditions for the removal of HS from aqueous solution by selective flocculation [14].…”

Characterization of pH-fractionated humic acids with respect to their dissociation behaviour

“…Carboxylic acidity was determined using standard acetate method (Klucakova andPekar 2005, 2008;Schnitzer and Khan 1972;Stevenson 1994).…”

“…Since the humic substance is not a single well-defined molecule but a mixture of various heterogeneous particles or aggregates containing a variety of functional groups resulting in polyelectrolyte and polyfunctional properties, it cannot be treated as an ordinary complex-forming ligand in the Responsible editor: Philippe Garrigues * Martina Klučáková klucakova@fch.vutbr.cz interaction with ions. They have a colloidal character whose size and negative charge are strictly dependent on surface functional groups (Angelico et al 2014;Fernandes et al 2009;Kirishima et al 2010;Koopal et al 2001;Tan et al 2011). The acid-base chemistry of humic acids is an important component of metal speciation models in natural systems.…”

“…However, the understanding of physical-chemical processes associated with chelation reactions still remains a challenge, fundamentally due to the dynamic nature and complexity of organic matter (Fernandes et al 2009). Since the anionic charge of humic substances plays a major role in their interactions with other components, pH and ionic strength are the most important variables controlling metal complexation (Liu and Gonzalez 2000;Michalowski and Asuero 2012;Tan et al 2011;Yonebayashi and Hattori 1990), many authors hope that fractionation of humic matter by extractions at different pH values would be useful in reducing their complexity and detail understanding of the interactions of natural organic matter with other components. Baalousha et al (2006) studied the influence of pH on size, molecular weight, conformation and aggregation of humic acids as important aspects to control their physicochemical reactions in aquatic systems.…”