Synthesis of DHTA-Modified Poly(Epoxysuccinic Acid) and Scale Inhibition of Fluoride Scale

To alleviate CaF₂ scaling on reverse osmosis membranes, polyepoxysuccinic acid (PESA) was modified with 2,5-dihydroxyterephthalic acid (DHTA) to obtain DHTA-PESA. Its structure and thermal stability were confirmed through characterization. Scale inhibition performance was evaluated using static and dynamic experiments. Results showed that in static tests, at a dosage of 200 mg/L, DHTA-PESA achieved a CaF₂ scale inhibition rate of nearly 100%, demonstrating Ca²⁺ chelation ability and the capacity to prolong crystallization induction time. In dynamic experiments, indicating superior CaF₂ dispersion performance and effective mitigation of membrane fouling. X-ray diffraction and scanning electron microscopy analysis revealed that DHTA-PESA induces irregular growth of CaF₂ crystals, disrupting their formation and altering crystal morphology. The primary scale inhibition mechanisms include dispersion, lattice distortion, and chelation.