Dual-function tara gum-based antiscalant with efficient antiscaling and antibacterial activity: Performance and molecular simulation investigation

Mineral scaling, resulting from the precipitation of supersaturated insoluble salts, is a prevalent yet significant problem, which limits the efficiency of reverse osmosis desalination and circulating cooling water systems. In this study, a series of dual-function carboxymethyl tara gum- graft -protocatechuic acid (CTG- g -PA) samples possessing both anti-scaling and antibacterial properties were synthesized by a free radical mediated grafting method. Static scale inhibition tests confirmed that the anti-scaling efficiency of branched CTG- g -PA at 15 mg/L was as high as 96.4% on calcium sulfate scaling, surpassing that of linear carboxymethyl cellulose- graft -protocatechuic acid (CMC- g -PA). Additionally, molecular simulations demonstrated a stronger interaction between branched CTG- g -PA and Ca 2+ /calcium sulfate scale, primarily owing to electrostatic interaction with negative oxygen-containing groups. It was also found that appropriate dose and grafting ratio of phenolic hydroxyl groups was necessary for achieving better anti-scaling efficiency. Conductivity tests indicated that the crystallization induction time of CaSO 4 using CTG- g -PA was shorter than that observed with CMC- g -PA, showing its weaker inhibition on crystal nucleation. Furthermore, CTG- g -PA exhibited inhibitory effects against both E. coli and S. aureus . This work developed a dual-function branched antiscalant with additional antibacterial activity, and elucidated the impact of chain structure on the anti-scaling performance and mechanisms, offering valuable perspectives for the molecular design of multifunctional antiscalants. • Bio-derived carboxymethyl tara gum- graft -protocatechuic acid (CTG- g -PA) was prepared. • Branched CTG- g -PA exhibited better anti-scaling efficiency than that of linear one. • Molecular simulations testified a stronger interaction between CTG- g -PA and Ca 2+ /CaSO 4 scale. • CTG- g -PA was endowed with effective antibacterial activity by grafting PA.