Flocculation efficiency of blends of short and long chain polyelectrolytes

The efficiency of blends of short and long chain cationic polyelectrolytes in the flocculation of waterborne colloidal silica dispersions was investigated. The polyelectrolytes were synthesized by inverse microemulsion copolymerization of acrylamide and [2-(acryloyloxy)ethyl]-trimethylammonium chloride. It was found that short and long chains provided complementary properties in terms of clarity of the supernatant, sedimentation rate and compactness of the sediment. The optimum balance was achieved with blends containing 20–30 wt% of short chains.

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► Flocculation efficiency of blends of short and long cationic polyelectrolytes.
► Polyelectrolytes synthesized by inverse microemulsion copolymerization.
► Short chains led to clean supernatant, low settling rate and loose sediment.
► Long chains led to fast settling rate and compact sediment, but turbid supernatant.
► Blends of short (20–30 wt%) and long chains provided optimal balance of properties.