Atomic layer deposition fabricating of ceramic nanofiltration membranes for efficient separation of dyes from water

Atomic layer deposition on flexible polymeric materials for lithium-ion batteries

Polymers have the distinctive qualities of being lightweight, flexible, and inexpensive and possessing good mechanical qualities. Consequently, these materials are employed in a wide range of applications, including lithium-ion batteries (LiBs). Interestingly, a variety of thin film materials can be deposited onto polymer substrates using the atomic layer deposition (ALD) technique. This is because the surface of many polymers has abundant reactive sites that are essential for the initial growth of ALD, such as functional hydroxyl -OH groups and -C[double bond, length as m-dash]O polar groups, aiding the smooth growth of ALD materials. Moreover, the diffusion growth mechanism, which is initiated by the nucleation and infiltration of precursors, can enable the initial growth of ALD materials even if the polymers lack these reactive polar groups. As polymers are composed of several chains, they have microporous characteristics, forming voids between the polymer chains. Because of these characteristics, polymers are considered ideal material substrates for investigating the promising future of the widely used ALD technique. The combination of polymer materials and the ALD method is becoming increasingly important in the advancements of high-performance LiBs. This review focuses on the present understanding of the role of polymer materials in the ALD technique for the fabrication of lithium-ion batteries.

A New Strategy of Chemical Photo Grafting Metal Organic Framework to Construct NH2-UiO-66/BiOBr/PVDF Photocatalytic Membrane for Synergistic Separation and Self-Cleaning Dyes

Photocatalytic membranes are typical multifunctional membranes that have emerged in recent years. The lack of active functional groups on the surface of membranes made of inert materials such as polyvinylidene fluoride(PVDF) makes it difficult to have a stable binding interaction with photocatalysts directly. Therefore, in this study, we developed a simple method to prepare NH2-UiO-66/BiOBr/PVDF(MUB) membranes for efficient dye treatment by grafting benzophenolic acid-functionalized NH2-UiO-66 onto the surface of membranes with photocatalytic properties under visible light irradiation using benzophenolic acid with photoinitiating ability as an anchor. The structural characteristics, photocatalytic properties, antifouling properties, and reusability of the composite membranes were investigated in subsequent experiments using a series of experiments and characterizations. The results showed that the benzophenone acid grafting method was stable and the nanoparticles were not easily dislodged. The MUB composite membrane achieved a higher dye degradation efficiency (99.2%) than the pristine PVDF membrane at 62.9% within a reaction time of 180 min. In addition, the composite membranes exhibited higher permeate fluxes for both pure and mixed dyes and also demonstrated outstanding water flux recovery (>96%) after the light self-cleaning cycle operation. This combination proved to improve the performance of the membranes instead of reducing them, increasing their durability and reusability, and helping to broaden the application areas of membrane filtration technology.

Membrane Fabrication and Modification by Atomic Layer Deposition: Processes and Applications in Water Treatment and Gas Separation

Membrane-based separation processes are part of most water purification plants worldwide. Industrial separation applications, primarily water purification and gas separation, can be improved with novel membranes or modification to existing ones. Atomic layer deposition (ALD) is an emerging technique that is proposed to upgrade certain kinds of membranes independent of their chemistry and morphology. ALD deposits thin, defect-free, angstrom-scale, and uniform coating layers on a substrate's surface by reacting with gaseous precursors. The surface-modifying effects of ALD are described in the present review, followed by a description of various types of inorganic and organic barrier films and how these can be used in combination with ALD. The role of ALD in membrane fabrication and modification is categorized into different membrane-based groups according to the treated medium, i.e., water or gas. In all membrane types, the ALD-based direct deposition of inorganic materials, mainly metal oxides, on the membrane surface can improve antifouling, selectivity, permeability, and hydrophilicity. Therefore, the ALD technique can broaden the applications of membranes to the treatment of emerging contaminants in water and air. Finally, the advancement, limitations, and challenges of ALD-based membrane fabrication and modification are compared to provide a comprehensive guideline for developing next-generation membranes with improved filtration and separation performance.

Surface Mineralization of the TiO2-SiO2/PES Composite Membrane with Outstanding Separation Property via Facile Vapor-Ventilated In Situ Chemical Deposition

Conventional polymeric membranes are broadly employed in water treatment processes; however, most of them suffer from relatively low water permeance and severe membrane fouling phenomena owing to their relatively hydrophobic nature. In this work, a novel class of inorganic-organic composite membranes was developed through a newly developed vapor-ventilated in situ chemical deposition method, where the Ti and Si precursors were first hydrolyzed and then conferred into metal oxides to form a continuous TiO₂-SiO₂ modification layer. Owing to the distinct physicochemical properties, the Ti and Si precursors were leveraged as quasi-molecular regulators to tune the membrane surface chemistry and pore aperture (within the nanoscale) to benefit highly efficient water purification by underpinning the rapid transport of water molecules and featuring an excellent fouling-resistant and fouling-releasing property against typical pollutants. The as-developed TiO₂-SiO₂/PES composite membrane showed a high water permeance of 187.4 L·m^-2·h^-1·bar^-1, together with a relatively small mean pore aperture of 4.2 nm, showing an outstanding permeating efficiency among state-of-the-art membranes with a similar separation accuracy. This study provides a paradigm shift in membrane materials that could open avenues for developing high-performance inorganic-organic composite membranes for complex wastewater treatment.

Recent developments in porous ceramic membranes for wastewater treatment and desalination: A review

The development of membrane technology has proved vital in providing a sustainable and affordable supply of clean water to address the ever-increasing demand. Though liquid separation applications have been still dominated by polymeric membranes, porous ceramic membranes have gained a commercial foothold in microfiltration (MF) and ultrafiltration (UF) applications due to their hydrophilic nature, lower fouling, ease of cleaning, reliable performance, robust performance with harsh feeds, relative insensitivity to temperature and pH, and stable long-term flux. The enrichment of research and development on porous ceramic membranes extends its focus into advanced membrane separation technologies. The latest emerging nanofiltration (NF) and membrane distillation (MD) applications have witnessed special interests in constructing porous membrane with hydrophilic/functional/hydrophobic properties. However, NF and MD are relatively new, and many shortcomings must be addressed to compete with their polymeric counterparts. For the last three years (2018-2020), state-of-the-art literature on porous ceramic membranes has been collected and critically reviewed. This review highlights the efficiency (permeability, selectivity, and antifouling) of hydrophilic porous ceramic membranes in a wide variety of wastewater treatment applications and hydrophobic porous ceramic membranes in membrane distillation-based desalination applications. A significant focus on pores characteristics, pore sieving phenomenon, nano functionalization, and synergic effect on fouling, the hydrophilic porous ceramic membrane has been discussed. In another part of this review, the role of surface hydrophobicity, water contact angle, liquid entry pressure (LEP), thermal properties, surface micro-roughness, etc., has been discussed for different types of hydrophobic porous ceramic membranes -(a) metal-based, (b) silica-based, (c) other ceramics. Also, this review highlights the potential benefits, drawbacks, and limitations of the porous membrane in applications. Moreover, the prospects are emphasized to overcome the challenges in the field.

In-situ coating TiO2 surface by plant-inspired tannic acid for fabrication of thin film nanocomposite nanofiltration membranes toward enhanced separation and antibacterial performance

A major issue hindering development of thin film nanocomposite (TFN) nanofiltration (NF) membrane is the interfacial defects induced by nanomaterial aggregation in top layer. Although various nanomaterials surface modification strategies have been developed to eliminate the interfacial defects, they usually involve extra modification steps and complex post-treatments. Inspired by the substrate-independent coating ability of tannic acid (TA) and the fact that the phenolic hydroxyl groups in TA can react with acyl chloride group in trimesoyl chloride, a TA coating solution containing TiO₂ nanoparticles was used as an aqueous phase of interfacial polymerization to prepare interfacial modified TFN NF membranes in this study. Surface modification of TiO₂ nanoparticles and interfacial polymerization can be carried out in a single step without any extra pre-modification step. It was found that the TA coating on TiO₂ nanoparticles surface could decrease TiO₂ aggregations and enhance interfacial compatibility between TiO₂ and polyester matrix. The TFN NF membrane prepared at a TiO₂ loading of 0.020 wt% exhibited a pure water flux of 28.8 L m^-2 h^-1 (284% higher than that of the controlled TFC membrane), and possessed enhanced NaCl and Na₂SO₄ rejections of 57.9% and 94.6%, respectively, breaking through the trade-off between permeability and selectivity.

Atomic layer deposition for membrane interface engineering

In many applications, interfaces govern the performance of membranes. Structure, chemistry, electrostatics, and other properties of interfaces can dominate the selectivity, flux, fouling resistance, and other critical aspects of membrane functionality. Control over membrane interfacial properties, therefore, is a powerful means of tailoring performance. In this Minireview, we discuss the application of atomic layer deposition (ALD) and related techniques in the design of novel membrane interfaces. We discuss recent literature in which ALD is used to (1) modify the surface chemistry and interfacial properties of membranes, (2) tailor the pore sizes and separation characteristics of membranes, and (3) enable novel advanced functional membranes.