Presenter
Dr. Zhuofan Gao1
Co-author(s)
Prof. Chen Gang2, Dr. Xia Chen1, Dr. Zeyu Fan1, Dr. Xian Zhou1, Dr. Shanshan Deng1, Ms. Ziling Peng1, Miss. Qi Lu1, Dr. Xiaohu Yan1, Mr. Ze Fang1, Dr. Wei Han1
Organisation(s)
1. Changjiang River Scientific Research Institute, Research Center of Water Engineering Safety and Disaster Prevention of Ministry of Water Resources
2. Donghua University
Sub-theme
2. Promoting Water Efficiency, Productivity and Services
Topic
2-4. Wastewater treatment and reuse
Body
Conventional water resources in many districts are globally deficient in fulfilling the water demands of the rising population and growing industrial production. To overcome the increasing water scarcity, developing reliable technologies that can convert unconventional water resources (i.e., seawater, wastewater, brackish water, etc.) to our daily water supply standards is urgently needed. Membrane-based water purification technologies (e.g., reverse osmosis) have been intensively investigated in recent years owing to their environmental-friendly, energy-saving and cost-effective features. Among various membranes, thin-film nanocomposite (TFN) membranes have outperformance in desalination from wastewater, seawater and brackish water. However, the conventional blending perpetration for TFN membranes is to synthesize nanomaterials in advance which is usually material-consuming and to disperse porous nanomaterials in aqueous/organic phases before interfacial polymerization and aggregation of fliers which may lead to a severe drop in desalination performance. In this work, ZIF-8, a type of metal-organic frameworks (MOFs), were induced into the polyamide-based TFN reverse osmosis membranes. The inherent porous structure, suitable triangular aperture size, and high chemical and water stability of ZIF-8 offer the TFN membranes with lower cross-linking and extra passageways for water molecules across the polyamide skin layers. A new methodology to produce TFN membranes is displayed by layer-by-layer (LBL) in-situ growth of ZIF-8 nanoparticles at room temperature and atmospheric pressure onto an ultrafiltration support, followed by a thin film polyamide layer coating via interface polymerization. By tuning the ZIF-8 in-situ growing procedure times, a water flux of 56.6 LMH with a salt removal rate of 99.1 % is gained for the optimal TFN membrane. Compared to the pristine membrane, the water permeance is enhanced by 78 % without scarifying the salt rejection in brackish water desalination tests. Meanwhile, in high-concentrated seawater desalination tests, the newly developed TFN membranes still present a better water flux and salt rejection than the pristine membrane for 7 days. This simple and mild method promotes a new effective strategy to fabricate TFN membranes for unconventional water treatment and reuse.