Flocculants solids content measurement

Percent solid settled In tests where adsorption and flocculation were determined simultaneously, the 200 ml sample was allowed to settle for 30 seconds and then 100 ml of the supernatant was removed using a suction device and after centrifugation analyzed for residual polymer concentration. The minimum level of detection was at 0.5 to 1 ppm and the reproducibility of the adsorption measurements was 2-3%. The settled 100 ml portion was analyzed for solid content. Flocculation due to polymer addition is measured by noting % solid settled as a function of polymer concentration. 

The solids content of the flocculant solution would be a useful parameter in any integrated control system. However, the solids are dissolved, and the concentrations involved are a fraction of 1%, with an accuracy requirement probably down to 0.001"/ . Moreover viscosity of solutions covers a wide range, and is dependent upon a number of other factors, not the least of which is temperature. Therefore, it is not practicable to measure polymer concentration directly. However, there is no reason why the powder feeder could not be calibrated for the powder in use, and its on-time measured. With liquid polymer make-up, the on-time of a calibrated raw liquid polymer pump would be measured. 

Finally, rheological measurements are also found in many contexts. They can certainly provide a rapid estimate of the state of the reactor contents. If only from a safety standpoint, this is useful in itself. Also, with an appropriate relationship between the viscosity and a property of interesL it can be used to furnish reliable information about the order of magnitude of the molar mass, the solid content in the reactor, and eventually to detect problems such as flocculation in an emulsion polymerization reaction. 

The direct determination of the polymer content adsorbed onto the solid surface avoids the systematic measuring error arising from particle-initiated PVFA-co-PVAm flocculation which can be important by the determination of the PVFA-co-PVAm amount in the supernatant solution after the adsorption [23], Figure 1 shows a wide-scan XPS spectrum of PVFA-co-PVAm (degree of hydrolysis > 90%, pH = 8) adsorbed onto copper. 

The adsorption and electrophoretic measurements were supplemented by the qualitative observation of the flocculation of solid particles in the surfactant solutions. The turbidity of the content of each adsorption tube after adsorption, recorded at various time intervals, was compared with that of a control tube containing the same solid concentration but in pure solvent. This suspension of reference was always prepared under the same conditions as the others. A marked increase in the turbidity was taken as evidence of flocculation. 

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