Application of the Schulze–Hardy rule to haematite and haematite/humate colloid stability

Contrasting Roles Of Natural Organic Matter On Colloidal Stabilization And Flocculation In Freshwaters

“…At pH 3 and 4, the CCC values of 80 and 100 mM were in reasonable agreement with literature values ranging from 62-72 mM (Zhang and Buffle 1995;Amal and Bushell 1997;Verrall et al 1999), with the small difference in observed values being explained by differences in particle sizes and shapes. As mentioned above, it is more difficult to speak of a CCC value in the presence of fulvic acids due to the less distinct transition between the RLA and DLA regimes.…”

“…As mentioned above, it is more difficult to speak of a CCC value in the presence of fulvic acids due to the less distinct transition between the RLA and DLA regimes. Nonetheless, a critical coagulation concentration of 100 mM KCl at pH 3 and ≈130 mM KCl at pH 4 are in reasonable agreement with the value of 157 mM found for a system containing 10 mg L -1 of hematite and 10 mg L -1 of humic substances at pH 4 (Verrall et al 1999).…”

Stability and transportability of biosolid colloids through undisturbed soil monoliths

“…Furthermore, the adsorption of organic components on colloid surfaces may increase their negative surface charge characteristics and stability by neutralizing positive edge charges on phyllosilicate minerals, thereby inhibiting edge-to-face particle aggregation (Kaplan et al, 1993). Organic coatings on mineral materials have been shown to enhance colloid stability by producing a sterically stabilizing adsorbed layer on colloid surfaces, which acts as a spacer that prohibits van der Waals flocculating forces from coming into play (Verrall et al, 1999). Therefore, it is highly likely that biosolid colloids, being dominantly organic in nature, may show increased stability and mobility throughout the soil profile, and may add to the stability and mobility of indigenous soil colloids as well.…”

“…Research by Kaplan et al (1997) indicated that mineral colloids fractionated from an Ultisol profile consisting primarily of quartz, HIV, Fe oxides, kaolinite and gibbsite had unusually high negative surface charge, which was attributed to organic coatings. Mineral colloids have also been found to be less stable than similar colloids coated with organic material, which, in turn, are less stable than organic colloids alone in the presence of mono-, di-and trivalent ions (Verrall et al, 1999). Furthermore, mineral colloids not completely coated with organic material tend to destabilize and flocculate more readily than completely coated colloids in which electrostatic and steric repulsion overcomes this destabilizing effect (Walker and Bob, 2001).…”

Direct coagulation casting of yttria-stabilized zirconia using magnesium citrate and glycerol diacetate

“…CCC=constant/ z 6 , where z is the charge on the counter ion. For z=1,2 and 3 the ratio of the CCCs are 1/1 6 (1), 1/2 6 (0.016) and 1/3 6 (0.0014), respectively [18][19][20][21][22]. Based on this concept, we proposed a novel ceramic forming method called direct coagulation casting via controlled release of high valence counter ions (DCC-HVCI) with a combination of the DLVO theory and the Schulze-Hardy rule.…”