Evaluation of a novel non-ionic graft starch-based antiscalant in reduction of CaSO4 scaling by static and reverse osmosis test

A novel nonionic starch-based antiscalant (St- g -GMA) was designed and obtained by graft copolymerization of starch and glycidyl methacrylate (GMA). St- g -GMA not only achieved an obvious reduction of CaSO 4 scaling in static test, but also effectively mitigated the flux decrease in dynamic reverse osmosis (RO) system. This improvement is ascribed to the grafted poly(GMA) chains on St- g -GMA. A suitable grafting ratio of this starch-based antiscalant achieve a high performance cost in control of CaSO 4 scaling. Combination of the apparent antiscaling performance, observation under scanning electron microscopy, energy dispersive x-ray spectroscopy unit, x-ray diffraction pattern, conductivity measurement, and dispersion experiment, the scale-inhibition mechanism of St- g -GMA was investigated and mainly attributed to chelation, dispersion and lattice distortion effects. The oxygen-containing groups on poly(GMA) chains such as epoxy groups can chelate with Ca 2+ , causing the induction time of crystallization prolonged; St- g -GMA with the distinct branched chain configuration can well disperse the formed microcrystal of CaSO 4 . Moreover, molecular dynamics simulations confirmed that the grafted poly(GMA) chains well bind to the crystal surfaces and the oxygen-containing groups could even enter the crystal lattice to inhibit the crystal growth and change the morphologies. St- g -GMA still mitigated the flux decrease notably in treatment of a synthetic seawater during a 24-h RO measurement. This study provided an efficient, environmentally-friendly and low-cost antiscalant with high application potentials.