Synthesis, characterization, and performance evaluation of AA/AMPS copolymers with different molecular weights and explanation of the inhibition mechanism of calcium carbonate and calcium sulfate

Polymeric scale inhibitors are widely acknowledged for their eco-friendliness, strong compatibility, and versatile nature. However, the impact of molecular weight variation on their inhibitory efficacy remains a relatively understudied aspect. In this investigation, AA/AMPS copolymers with distinct molecular weights (1000, 2000, 3000, 4000, 5000, 6000) were synthesized and probed for their influence on mineral scale inhibition across diverse water quality parameters (e.g., calcium ion concentration, pH) and process conditions (e.g., temperature, duration). Concurrently, the crystalline and morphological alterations of AA/AMPS during mineral scale inhibition were delved. By integrating molecular dynamics simulations and quantum chemical calculations, the effects of varying molecular weights of AA/AMPS on mineral scale inhibition were scrutinized. Moreover, the inhibition mechanism was thoroughly explored. Our findings revealed that AA/AMPS with molecular weights of 2000 and 3000 exhibited superior inhibition efficacy against calcium carbonate and calcium sulfate. This phenomenon was attributed to the movement velocity and binding energy of AA/AMPS with corresponding molecular weights towards the primary crystal growth surface. Additionally, the carboxyl oxygen atoms on the polymers facilitated chelation with calcium ions, thereby impeding further crystal formation and growth. Consequently, achieving heightened efficiency in scale inhibition.