AbstractThe behavior of polycations as flocculants for kaolinite was examined by means of turbidity measurement, with the use of the following four kinds of cationic polysulfones, with molecular weights ranging from 14,000 to 330,000; diallyldimethylammonium chloride SO2copolymer P(DADMAmClSO2), diallyldiethylammonium chloride–SO2copolymer P(DADEAmClSO2), diallylmethylamine hydrochloride–SO2copolymer P(DAMAHClSO2), diallylamine hydrochloride–SO2copolymer P(DAAHClSO2). The effect of the degree of polymerization on the flocculation was remarkable at low molecular weight range. The flocculation value, which is defined as the quantity of the polycation required to obtain 50 transparency at 660 mμ of the supernatant fluid of 2 kaolinite suspension, was inversely proportional to the degree of polymerization to the 0.734 power in the case of P(DADMAmClSO2). This can be understood as the extension of Schulze‐Hardy's law. The four different kinds of polysulfones having a similar molecular weight show almost the same capacity for flocculation in acidic or neutral solution. In alkaline solution, however, P(DAMAHClSO2) and P(DAAHClSO2) are less effective and have higher flocculation values than P(DADMAmClSO2) and P(DADEAmClSO2), which are classified as polyquaternary ammonium chlorides. Moreover the difference increases with increasing pH. This may be attributable to the difference of the dissociability of the polycation. The degree of dissociation of P(DAMAHClSO2) or P(DAAHClSO2) decreases with increasing pH and more additive is required to neutralize negative charges on kaolinite. On the other hand, P(DADMAmClSO2) and P(DADEAmClSO2) are almost completely dissociated and ar
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