Development of a Polymeric Antiscalant Having Chelating Motifs of Aspartic and Maleic Acid for Inhibiting Scale Formation on Reverse Osmosis Membranes

This research focuses on synthesizing a novel antiscalant and exploring the inhibition of CaSO₄ and CaCO₃ scaling in reverse osmosis desalination technology. The antiscalant bearing residues of aspartic and maleic acid (MA) has been synthesized via alternate cyclopolymerization of N,N-diallylaspartic acid [(H₂C═CH–CH₂)₂NH⁺CH(CO₂^–)CH₂CO₂H] and MA. The performance of the antiscalant and several commercial ones was evaluated against supersaturated CaSO₄ and CaCO₃ solutions. At a 2.5 ppm concentration, the antiscalant imparted percent scale inhibition (PSI) of ≈100% for CaSO₄ until 820 min [i.e., induction time (IT) after which scaling starts]. The superior performance of the antiscalant was ascertained at 0.5 and 1 ppm concentrations at 40 °C, where it showed ITs of 40 and 60 min, respectively, which are sufficient to mitigate scaling during the 15 min residence time of the reject brine in the osmosis chamber. The antiscalant was also examined for the mitigation of CaCO₃ scaling.