Precision Engineering of Functional Polymers for High Performance Silica Scale Inhibitors in Reverse Osmosis Desalination

Desalination of unconventional water sources, such as brackish groundwater and industrial wastewaters, offers a promising solution to combat water scarcity by supplementing limited fresh water supplies. Despite the energy-efficient nature of reverse osmosis (RO), a widely used desalination technology, its application to inland brackish water and industrial wastewater faces challenges such as low water recoveries and the disposal of generated brines. The accumulation of scale-forming species on the feed side of the membrane module further complicates increasing RO water recovery, especially in unconventional water sources rich in calcium, magnesium, sulfate ions, and silicic acid. Silica, a prevalent and troublesome inorganic scale in desalination, poses a significant challenge in RO desalination of inland brackish water and industrial wastewaters. When the concentration of silicic acid exceeds its solubility limit during the desalination process, insoluble silica forms on membrane surfaces, leading to irreversible scaling exacerbated by divalent cations. Mitigating inorganic scaling often involves chemical scale inhibitors or antiscalants, typically polymers. However, commercial inhibitors are less effective against silica due to its amorphous nature and complex scaling mechanisms. The proposed research aims to achieve a molecular-level understanding of silica scaling and inhibition processes under operational RO desalination conditions. Using a high-throughput methodology, the study will synthesize polymeric inhibitors with precisely tuned structural parameters, evaluating their impact on antiscaling function. Methods based on precision synthesis, spectroscopic studies, molecular dynamics simulations, and advanced surface characterization will be employed to investigate the thermodynamic properties and interaction behavior of polymeric inhibitors with silicic acids, extending the study to consider membrane surfaces and RO-relevant environments. The ultimate goal is to design an optimized silica scale inhibitor, rigorously tested under operando RO conditions. This comprehensive approach seeks to deepen our understanding of silica scaling mechanisms and contribute to the development of effective antiscaling solutions for practical applications.