The sedimentation speed is proportional to the intrinsic viscosity of the polymer in the range of 4 to 23 dl/g. The flocculation effects were evaluated from sedimentation speed of kaolin suspension and transparency of the separated water. The crosslinking of polymer or the formation of water-insoluble polymer could be avoided by the addition of K/sub 2/CO/sub 3/ or NaOH to raise the pH of the reaction mixture above 6.5. The water-soluble polymer with the largest molecular weight of 6.7 x 10/sup 6/ is produced in the polymerization with monomer concentration of more » 2.91 moles/l at 0/sup 0/C at a dose rate of 6.2 x 10/sup 2/ rad/hr in acetone-water mixture containing 60 vol. For polymerization in acetone-water mixtures, the molecular weight of polymer increases with monomer concentration but at the high concentration intermolecular imidation of amide groups tends to take place during the polymerization to form crosslinked and water-insoluble polymer. Among various solvents, mixtures of water-tert-butyl alcohol and water-acetone were found to be suitable for the synthesis of the high molecular weight polyacrylamide. The radiation-induced polymerization of acrylamide was studied to prepare a high molecular weight and highly effective polyacrylamide flocculant. The crude oil/water Pickering emulsions could be broken using alkali as a trigger, which suggests the potential utility for the recovery of crude = ,

Compared to the crude oil, the corresponding Pickering emulsions showed excellent flowability at various shear rates. Interestingly, the string-like structures of nanogel aggregations were found in the aromatic hydrocarbons/water Pickering emulsions, which significantly enhanced the emulsion stability. In addition, the average diameter of oil drops was independent of sonication period in the range of 15–240 s. The average diameter of oil droplets was no longer decreasing with nanogel concentration increment above 1000 mg/L. A small amount of nanogels were sufficient for the formation of Pickering emulsions. The PAM nanogel-stabilized o/w Pickering emulsions were quickly demulsified in alkaline solutions whereas they showed markedly stability in brines and under acidic conditions. Nanogels with different crosslinking and charge degree were synthesized through suspension polymerization and characterized at various salinities and pH using dynamic light scattering (DLS) and scanning electron microscopy (SEM). Oil-in-water (o/w) Pickering emulsions stabilized by polyacrylamide (PAM) and poly(acrylamide-co-acrylic acid) nano-sized crosslinked polymeric particles (nanogels) under various conditions are described herein.

Pickering emulsion salt water