Coagulation experiments

The nature of the phase formed in the slow coagulation experiment can be deduced on the basis of its thermal transitions, and from its X-ray diffraction pattern. In the DSC trace of the slowly coagulated PBT-MSA-water system shown in Figure 6, three endothermic transitions are observed between 90 °C and 240 °C. Corresponding transitions were observed by optical microscopy using a hot stage. Solid PBT fibers or films do not exhibit thermal transitions below about 650°C (1). 

The DLVO theoiy thus enabled theoretical significance to be given to the valence sequence in coagulation experiments that bad been observed many years earher by Schulze (1882) and Hardy (1900). Although expre ions of this type are useful in a qualitative predictive sense, the implication that there is a simple rule applicable to alt systems must be treated with considerable caution. It must be borne in mind that coagulation is a complicated phenomenon involving quite a range of kinetic and specific ion effects. 

So for, the assumption has been made that the ions used in the coagulation experiments do not interact with water. In a number of cases, however, the ions do react with water under certain pH conditions to form hydrolyzed species. For example, in the case of aluminum, the ion exists at pH values below about 3.3 as the hexaaquo ion, with six water molecules in the octahedral coordinate positions. As the pH is sloviy increased, reaction occurs with water to form a sequence of species. The chemistry involved in these reactions is somewhat complex and has not... 

For the electro coagulation experiment an overnight TSB culture (10 mL) of E. coli was added to 1 L of RO water in a conical flask. RO water when tested with the oxidation electrode gave a very high resistance and, on the advice of the supplier of the equipment under test, tap water was added (500 mL E. coli in RO -i- 300 mL tap water in a 1 L beaker). Two beakers of E. coli suspension (500 mL E. coli in RO + 300 mL tap water) were prepared, one for each type of treatment. Treatment of the water was performed using equipment for bench-top trials from Axonics. 

The mobility data and stability ratias from coagulation experiments both show systematic change with variations in concentration and in the carbon number of the molecules. In general, the adsorption of fatty acid is repre.sented by Equation (4), where K [ is proportional to the adsorption density and inversely proportional to the aqueous anion concentration. If — A T/Lt (A is a constant), and it is assumed that each -CH2 group contributes an energy hydrophobic interaction energy, then AGhyd = where n is the number of... 

Locust bean gum, like other hydrocolloids, may be precipitated from aqueous solutions by electrolyte (, IS), Table I shows the results of quantitative coagulation experiments with water-soluble polysaccharides and other high polymers (12). 

The distinction between inert counterions and surface-coordinating (specifically adsorbable) ions is readily seen in coagulation experiments the critical coagulation concentration of the specifically sorbable ion depends on the surface area concentration of the dispersed colloid (Figure 14). 

Lipps et al. (10,11) assumed a system mix of three types of aggregates (linear, planar, and close-packed three dimensional) in deriving form factors for singlet multiplicities up to 13. In coagulation experiments on polystyrene latex, Lips et al. (10) concluded that aggregates consisting of more than 13 singlets accounted for less than 0.5% of the... 

Two sets of equipment were used for coagulation experiments - a conventional jar testing apparatus with six 500 mL cylindrical beakers with an overhead stirrer each, and a Heidoloph RZ R2021 overhead stirrer. The paddle was identical for both stirrer types (1 cm by 4 cm rectangular plate). The jar tests were used for screening tests and MF experiments. In that case the FeCl r was added from a 20 mM (5.4 gL FcCls 6H2O) stock solution, the soludon was then rapidly mixed at 100 rpm for 2 minutes and then at 25 rpm for 20 minutes. The method was adapted from Dennett et al. (1996). 

In a recent study Roche et al performed coagulation experiments with films prepared from a 20% (w/w) solution of PpPTA in sulfuric acid. " ... 

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