Browsing by Author "Wu, Jinjian"

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    NANOCOMPOSITE MEMBRANES FOR IMPROVED WATER PURIFICATION APPLICATIONS
    (2016-02-24) Wu, Jinjian; Li, Qilin
    Over the past decade, the rapid development of nanotechnology from academic exploration to practical application have fueled extensive interests in utilizing nanomaterials in membrane fabrication and modification, creating novel “nanocomposite membranes”. This new paradigm of membrane design revolutionize the traditional membrane fabrication technique allowing people to create membranes with unique mechanical, physical, chemical and/or biological properties. The present study explores the fabrication, characterization, and utilization of two types of nanocomposite membranes in two water treatment applications. Novel nanocomposite nanofiltration membranes were fabricated by modifying commercial membrane with Ag-zeolite for long term control of membrane biofouling, a serious issue plaguing almost every membrane water treatment systems. The modified membrane, through sustained release of Ag, exhibited prolonged antimicrobial activity effective in prohibiting the attachment and fouling by bacteria cells. Once depleted of silver, the membrane can be easily regenerated, thus having the potential for addressing long term biofouling problem. The interplays among solution conditions (e.g., Cl- and cysteine), chemical state of loaded Ag (Ag+ or Ag(0)), and Ag-zeolite loading on membrane were elucidated. Under low ionic strength condition (low Cl- concentration), release of Ag was solubility limited and thus Ag+-zeolite and Ag(0)-zeolite had similar longevity, and high Ag-zeolite loading could prolong the antimicrobial efficacy. High ionic strength condition (high Cl- concentration), on the other hand, leads to significantly increased Ag release, and similar release kinetics between the high and low Ag-zeolite loading samples. Ag(0)-zeolite effectively stabilized the release of Ag and leads to prolonged antimicrobial efficacy. Effect of cysteine in low ionic strength condition was also investigated. High cysteine condition could significantly increase Ag leaching and reduce antimicrobial efficacy. But with low and environmentally-relevant cysteine concentration, the modified membrane still exert sustained antimicrobial activity, with the high Ag-zeolite loading samples exhibiting over 80% surface bacteria inactivation after 15 days. Another type of photothermal nanocomposite membranes were fabricated by modification of hydrophobic polymeric PVDF membranes with photothermal nanomaterials for membrane distillation. The modified membrane can effectively transfer light energy into heat in the close proximity to the membrane surface, thus accelerating the vapor generation efficiency for water production. Results show that the employed physical/chemical binding methods (solvent drop-casting and polydopamine binding) effectively created even layer of nanoparticle coatings with varied surface loading amount. It was also revealed that coating density was crucial in achieving satisfactory photothermal efficiency. The design addresses the inefficiency in energy utilization in current membrane distillation systems, and have great potential to help provide clean water provision in areas where energy and transportation is lacking.
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    Studying the Impact of RO Membrane Surface Functionalities on Alginate Fouling in Seawater Desalination
    (2012) Wu, Jinjian; Li, Qilin
    The objective of this research was to elucidate how specific membrane surface functionalities affect fouling by alginate in seawater desalination. Alginate adsorption on self-assembled mono-layers with -COOH, -NH 2 , -CONH 2 groups under different solution conditions was studied using quartz crystal microbalance with dissipation monitoring. Cross-flow filtration experiments were performed using four commercial RO membranes to study the correlation of alginate fouling to membrane surface properties. Experimental results revealed the importance of solution condition, but surface functionality did not have significant impact on alginate adsorption equilibrium. The initial adsorption/deposition rate on the -COOH surface was the highest., while adsorption on the -NH 2 surface was most difficult to remove by surfactant cleaning. Filtration experiments showed that alginate fouling was more closely related to surface roughness than surface chemistry. The results suggest that surface chemistry is not an important factor for short term membrane fouling in seawater RO processes.
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    Use of surface modified porous membranes for fluid distillation
    (2022-05-17) Li, Qilin; Wu, Jinjian; Halas, Nancy C.; Zodrow, Katherine R.; Guo, Haoli; Xu, Jiarui; Yu, Cong; Rice University; William Marsh Rice University; United States Patent and Trademark Office
    In some embodiments, the present disclosure pertains to systems and methods for distilling a fluid by exposing the fluid to a porous membrane that includes a surface capable of generating heat. In some embodiments, the heat generated at the surface propagates the distilling of the fluid by converting the fluid to a vapor that flows through the porous membrane and condenses to a distillate. In some embodiments, the surface capable of generating heat is associated with a photo-thermal composition that generates the heat at the surface by converting light energy from a light source to thermal energy. In some embodiments, the photo-thermal composition includes, without limitation, noble metals, semiconducting materials, dielectric materials, carbon-based materials, composite materials, nanocomposite materials, nanoparticles, hydrophilic materials, polymers, fibers, meshes, fiber meshes, hydrogels, hydrogel meshes, nanomaterials, and combinations thereof. Further embodiments pertain to methods of making the porous membranes of the present disclosure.
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    Use of surface modified porous membranes for fluid distillation
    (2020-11-24) Li, Qilin; Wu, Jinjian; Halas, Nancy J.; Zodrow, Katherine R.; Guo, Haoli; Xu, Jiarui; Yu, Cong; Rice University; United States Patent and Trademark Office
    In some embodiments, the present disclosure pertains to systems and methods for distilling a fluid by exposing the fluid to a porous membrane that includes a surface capable of generating heat. In some embodiments, the heat generated at the surface propagates the distilling of the fluid by converting the fluid to a vapor that flows through the porous membrane and condenses to a distillate. In some embodiments, the surface capable of generating heat is associated with a photo-thermal composition that generates the heat at the surface by converting light energy from a light source to thermal energy. In some embodiments, the photo-thermal composition includes, without limitation, noble metals, semiconducting materials, dielectric materials, carbon-based materials, composite materials, nanocomposite materials, nanoparticles, hydrophilic materials, polymers, fibers, meshes, fiber meshes, hydrogels, hydrogel meshes, nanomaterials, and combinations thereof. Further embodiments pertain to methods of making the porous membranes of the present disclosure.