Synthesis of a terpolymer and a tetrapolymer using monomers of diallylamine salts and SO2 and their application as antiscalants

Abstract

An aqueous solution of diallylammonium salts (CH2 = CHCH2)2NH+(CH2)3A− having A− as: CO2 − (I), PO3H2 Cl− (II) and SO3 − (III) in 1:1:1 mol ratio underwent ammonium persulfate-initiated ter cyclopolymerization to yield pH-responsive zwitterionic polymer IV with random placements of the monomers in the same ratio. During dialysis, PO3H2Cl− of the incorporated monomer units of II upon depletion of HCl became PO3H−. Likewise, azobisisobutyronitrile-initiated cyclopolymerization of I, II, III, and SO2 in a mole ratio of 1:1:1:3 provided pH-responsive tetrapolymer V in over 90 % yield with random and alternative placements of I–III and SO2 units, respectively, in the same ratio as the feed. Polyzwitterions (PZs) IV and V were insoluble in salt-free water but soluble in the presence of salts. The critical salt concentrations required to promote water solubility of PZ IV were determined to be 0.356 M NaCl, 0.237 M NaBr and 0.128 M NaI, whereas for PZ V the corresponding values were found to be 2.25, 1.26 and 0.862 M, respectively. PZs IV and V were converted into anionic polyelectrolytes VI and VII upon basification with NaOH. The viscosity and antiscalant behaviors of VI and VII were examined. The polymers demonstrated remarkable scale inhibition efficacies; at a dose of 10 ppm, both IV (+NaOH) and V (+NaOH) delayed the precipitation of CaSO4 from its supersaturated solution up to 920 and over 4000 min, respectively. For a small concentration of 5 ppm of polymer V, a scale inhibition of 100 % over 100 min verified it to be a potential effective antiscalant additive in reverse osmosis plants.