摘要
Novel CMCS sacrificial layer enhances silica scaling resistance in MD. • CMCS coatings can be removed and re-coated in situ. • Synergy of CMCS layer and smooth PVA substrate boosts silica scaling resistance. • CMCS-PVA membrane showed sustainable anti-silica performance in long-term tests. Membrane distillation (MD) is a promising technology for hypersaline wastewater treatment, yet it is often limited by severe silica scaling. This study proposes a carboxymethyl chitosan (CMCS) sacrificial layer strategy to achieve in situ silica scale removal and restore membrane reusability for MD. The influence of substrate properties on anti-scaling performance was systematically evaluated by depositing the CMCS layer onto Thin Film Composite (TFC) and Polyvinyl Alcohol (PVA) Janus membranes. Characterization results indicated that the CMCS coating significantly improved surface smoothness and introduced silica-resistant functional groups, reducing the average roughness (Ra) of the TFC and PVA membranes from 74.2 to 2.79 nm and from 8.26 to 1.19 nm, respectively. After a single-cycle silica scaling test, the CMCS-TFC and CMCS-PVA membranes retained 92.7% and 97.2% of their initial specific flux, respectively, 26.2 and 2.1 percentage points higher than their pristine counterparts. Notably, the CMCS-modified PVA membrane exhibited superior anti-scaling stability, maintaining a specific flux above 90% for the first 4 cycles and achieving a flux recovery ratio (FRR) exceeding 99% across all cleaning cycles. This synergistic effect between the CMCS sacrificial layer and the smooth PVA substrate effectively inhibited silica penetration, while enabling interfacial renewal and foulant removal via in situ exfoliation and re-deposition of the CMCS layer. This work provides a facile and robust approach for treating silica-rich hypersaline streams. Download: Download high-res image (137KB) Download: Download full-size image
危险品化学品经营许可证（带存储）