Abstract
FLOCCULATION AND DEFLOCCULATION BEHAVIOURS OF FINES IN THE COFACTOR-POLYETHYLENE OXIDE RETENTION AID SYSTEM: EFFECTS OF COFACTOR CONCENTRATION
*Mohammad Raji Abdallah Qasaimeh
ABSTRACT
Flocculation and deflocculation of fines obtained from paper pulp were studied in the presence of polyethylene oxide (PEO) as a retention aid and different concentrations of a phenol-containing cofactor (CF). Depending on the CF concentration, significant enhancements of flocculation and deflocculation were observed. The relative floc size increased with CF addition at low concentrations, reached the maximum in the optimum zone, and then decreased to produce small flocs at high CF concentrations. The flocculation rate constant increased at first with CF concentration, plateaued in the optimum zone, and then significantly increased at higher CF concentrations. Deflocculation occurred in all experimental runs, and the reverse equilibrium constant (i.e., the ratio of deflocculation rate constant to flocculation rate constant) was about 0.408 when using PEO alone, decreased to 0.11 in the optimum zone of CF concentration, and then increased to 0.56 at high CF concentrations. These measured data on floc size and flocculation and deflocculation rate constants at different CF concentrations are useful for mills to produce paper with the desired characteristics.
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