CuBTC metal organic framework incorporation for enhancing separation and antifouling properties of nanofiltration membrane

CuBTC metal organic framework-based dispersive solid phase extraction of cyclosporine and tacrolimus from plasma samples prior to determination by high performance liquid chromatography-tandem mass spectrometry

Immunosuppressive drugs are prescribed to reduce the immune system of persons who are undergoing organ transplants. The concentration of these drugs in blood and plasma samples must be accurately and precisely determined during immunosuppressive therapy due to their significant side effects. In this study, a metal organic framework-based dispersive solid phase extraction method was developed for the extraction of tacrolimus and cyclosporine from plasma samples before their determination by high performance liquid chromatography-tandem mass spectrometry. For this purpose, CuBTC metal organic framework nanoparticles were prepared by a hydrothermal approach and they were used as the sorbent in the extraction procedure. The adsorbed analytes were eluted by a suitable organic solvent and then more concentrated by evaporation of the eluate. All of the effective parameters of the method including sorbent amount, adsorption time, eluent type, desorption time, eluent volume, and sample solution pH were studied and optimized. They were obtained 5 mg, 5 min, acetone, 5 min, 300 μL, and 5, respectively. Under optimal conditions, the developed method was validated and the data showed that the linear range, the limit of detection, the limit of quantification, the coefficient of determination, the enrichment factor, and relative standard deviation values were 1-1000 ng mL^-1, 0.30 ng mL^-1, 0.5 ng mL^-1, 0.99, 15.6, and 5.8 % for tacrolimus and 0.8-500 ng mL^-1, 0.25 ng mL^-1, 0.4 ng mL^-1, 0.99, 17, and 5.6 % for cyclosporine, respectively. Finally, the method was successfully used in the determination of the studied drugs in plasma samples.

An Overview of the Modification Strategies in Developing Antifouling Nanofiltration Membranes

Freshwater deficiency has become a significant issue affecting many nations' social and economic development because of the fast-growing demand for water resources. Nanofiltration (NF) is one of the promising technologies for water reclamation application, particularly in desalination, water, and wastewater treatment fields. Nevertheless, membrane fouling remains a significant concern since it can reduce the NF membrane performance and increase operating expenses. Consequently, numerous studies have focused on improving the NF membrane's resistance to fouling. This review highlights the recent progress in NF modification strategies using three types of antifouling modifiers, i.e., nanoparticles, polymers, and composite polymer/nanoparticles. The correlation between antifouling performance and membrane properties such as hydrophilicity, surface chemistry, surface charge, and morphology are discussed. The challenges and perspectives regarding antifouling modifiers and modification strategies conclude this review.

High Flux and Antifouling Nanofiltration Membrane Modified by Ag@UiO-66-NH2 and Its Application for Biphenol A Removal

Owing to the specific porous structure which could provide additional passage channel for some molecules, metal organic frameworks are attractive candidates for enhancing permeability and selectivity of membranes in pervaporation, reverse osmosis, and gas separation. In this experiment, Ag@UiO-66-NH2 was introduced into polyamide separation layer by interfacial polymerization of triethylenetetramine and 1,3,5-benzenetricarboxylic acid chloride for nanofiltration. The results indicated that Ag@UiO-66-NH2 nanoparticles did endow the membranes with rapid diffusion pathways for water molecules. When the content of Ag@UiO-66-NH2 was 0.03 g, the prepared membrane (NF-Ag-3) showed high flux about 47.3 L·m-2·h-1 at 0.6 MPa, which is about 2-fold higher than that of polyamide membrane without Ag@UiO-66-NH2, while the MgSO4 rejection rate remained about 87.4%. The membrane also showed excellent antifouling properties, and the water flux recovery ratio was 95.6% after filtration BSA solution. When it was applied for 50 mg/L bisphenol A removal, the rejection rate reached 94.6%, and the flux is about 49.1 L·m-2·h-1. Moreover, Ag particles on UiO-66-NH2 rendered the membrane with good inhibition for Escherichia coli. The antibacterial rate of the membranes is above 95% when the loading of Ag@UiO-66-NH2 is more than 0.03 g.

Thin-Film Nanocomposite Membrane Incorporated with Porous Zn-Based Metal-Organic Frameworks: Toward Enhancement of Desalination Performance and Chlorine Resistance

Metal-organic framework (MOF) materials have received extensive attention for the design of advanced thin-film nanocomposite (TFN) membranes with excellent permselectivity. However, the relationship between the unique physicochemical properties and performance of engineered MOF-based membranes has yet to be extensively investigated. In this work, we investigate the incorporation of porous zinc-based MOFs (Zn-MOFs) into a polyamide active layer for the fabrication of TFN membranes on porous poly(phenylsulfone) (PPSU) support layers through an interfacial polymerization approach. The actual effects of varying the amount of Zn-MOF added as a nanofiller on the physicochemical properties and desalination performance of TFN membranes are studied. The presence and layout of Zn-MOFs on the top layer of the membranes were confirmed by X-ray photoelectron spectroscopy, scanning electron microscopy, and ζ potential analysis. The characterization results revealed that Zn-MOFs strongly bind with polyamide and significantly change the membrane chemistry and morphology. The results indicate that all four studied TFN membranes with incorporated Zn-MOFs enhanced the water permeability while retaining high salt rejection compared to a thin-film composite membrane. Moreover, the highest-performing membrane (50 mg/L Zn-MOF added nanofiller) not only exhibited a water permeability of 2.46 ± 0.12 LMH/bar but also maintained selectivity to reject NaCl (>90%) and Na₂SO₄ (>95%), similar to benchmark values. Furthermore, the membranes showed outstanding water stability throughout 72 h filtration and chlorine resistance after a 264 h chlorine-soaking test because of the better compatibility between the polyamide and Zn-MOF nanofiller. Therefore, the developed TFN membrane has potential to solve trade-off difficulties between permeability and selectivity. Our findings indicate that porous Zn-MOFs play a significant role in the development of a TFN membrane with high desalination performance and chlorine resistance.

Adsorptive removal of aflatoxin B1 from vegetable oils via novel adsorbents derived from a metal-organic framework

Vegetable oils are essential daily diet, but they are simply contaminated with aflatoxin B₁ (AFB₁), a serious toxic compound to human health. Adsorption method due to the easy operation, high efficiency and low costing is set to become a main detoxification technique for AFB₁. Unfortunately, previous reported adsorbents were rarely used for detoxification in food industry since they cannot meet the criteria of large-scale production of edible oils. Metal-organic frameworks (MOFs) with unique textural properties could be favorable precursors for synthesis of advanced materials. In this research, three kinds of Cu-BTC MOF-derived porous materials were prepared by different carbonization temperature and characterized by XRD, SEM, FT-IR, and nitrogen adsorption-desorption techniques. Isotherm and kinetic studies on the adsorption behaviour of AFB₁ onto the three porous carbonaceous materials have been systematically conducted. The results revealed that the porous carbonaceous materials could act as the excellent adsorbents that were of enough adsorption sites for AFB₁, mainly due to the hierarchical porous structure and large surface areas for the enhancement of adsorption capacity. Notably, the porous carbonaceous materials could not only remove more than 90% of AFB₁ from real vegetable oils within 30 min, but also remain the treated oils at low cytotoxicity. Meanwhile, the detoxification process could little affect the quality of oils. Thus, the Cu-BTC MOF-derived porous carbonaceous materials with high efficiency, safe, practical and economic characteristics could be novel potential adsorbents used in the application of AFB₁ removal from contaminated vegetable oils.

Frontiers of Membrane Desalination Processes for Brackish Water Treatment: A Review

Climate change, population growth, and increased industrial activities are exacerbating freshwater scarcity and leading to increased interest in desalination of saline water. Brackish water is an attractive alternative to freshwater due to its low salinity and widespread availability in many water-scarce areas. However, partial or total desalination of brackish water is essential to reach the water quality requirements for a variety of applications. Selection of appropriate technology requires knowledge and understanding of the operational principles, capabilities, and limitations of the available desalination processes. Proper combination of feedwater technology improves the energy efficiency of desalination. In this article, we focus on pressure-driven and electro-driven membrane desalination processes. We review the principles, as well as challenges and recent improvements for reverse osmosis (RO), nanofiltration (NF), electrodialysis (ED), and membrane capacitive deionization (MCDI). RO is the dominant membrane process for large-scale desalination of brackish water with higher salinity, while ED and MCDI are energy-efficient for lower salinity ranges. Selective removal of multivalent components makes NF an excellent option for water softening. Brackish water desalination with membrane processes faces a series of challenges. Membrane fouling and scaling are the common issues associated with these processes, resulting in a reduction in their water recovery and energy efficiency. To overcome such adverse effects, many efforts have been dedicated toward development of pre-treatment steps, surface modification of membranes, use of anti-scalant, and modification of operational conditions. However, the effectiveness of these approaches depends on the fouling propensity of the feed water. In addition to the fouling and scaling, each process may face other challenges depending on their state of development and maturity. This review provides recent advances in the material, architecture, and operation of these processes that can assist in the selection and design of technologies for particular applications. The active research directions to improve the performance of these processes are also identified. The review shows that technologies that are tunable and particularly efficient for partial desalination such as ED and MCDI are increasingly competitive with traditional RO processes. Development of cost-effective ion exchange membranes with high chemical and mechanical stability can further improve the economy of desalination with electro-membrane processes and advance their future applications.

Copper-Modified Polymeric Membranes for Water Treatment: A Comprehensive Review

In the last decades, the incorporation of copper in polymeric membranes for water treatment has received greater attention, as an innovative potential solution against biofouling formation on membranes, as well as, by its ability to improve other relevant membrane properties. Copper has attractive characteristics: excellent antimicrobial activity, high natural abundance, low cost and the existence of multiple cost-effective synthesis routes for obtaining copper-based materials with tunable characteristics, which favor their incorporation into polymeric membranes. This study presents a comprehensive analysis of the progress made in the area regarding modified membranes for water treatment when incorporating copper. The notable use of copper materials (metallic and oxide nanoparticles, salts, composites, metal-polymer complexes, coordination polymers) for modifying microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), forward osmosis (FO) and reverse osmosis (RO) membranes have been identified. Antibacterial and anti-fouling effect, hydrophilicity increase, improvements of the water flux, the rejection of compounds capacity and structural membrane parameters and the reduction of concentration polarization phenomena are some outstanding properties that improved. Moreover, the study acknowledges different membrane modification approaches to incorporate copper, such as, the incorporation during the membrane synthesis process (immobilization in polymer and phase inversion) or its surface modification using physical (coating, layer by layer assembly and electrospinning) and chemical (grafting, one-pot chelating, co-deposition and mussel-inspired PDA) surface modification techniques. Thus, the advantages and limitations of these modifications and their methods with insights towards a possible industrial applicability are presented. Furthermore, when copper was incorporated into membrane matrices, the study identified relevant detrimental consequences with potential to be solved, such as formation of defects, pore block, and nanoparticles agglomeration during their fabrication. Among others, the low modification stability, the uncontrolled copper ion releasing or leaching of incorporated copper material are also identified concerns. Thus, this article offers modification strategies that allow an effective copper incorporation on these polymeric membranes and solve these hinders. The article finishes with some claims about scaling up the implementation process, including long-term performance under real conditions, feasibility of production at large scale, and assessment of environmental impact.

Progress of Interfacial Polymerization Techniques for Polyamide Thin Film (Nano)Composite Membrane Fabrication: A Comprehensive Review

In this paper, we review various novel/modified interfacial polymerization (IP) techniques for the fabrication of polyamide (PA) thin film composite (TFC)/thin film nanocomposite (TFN) membranes in both pressure-driven and osmotically driven separation processes. Although conventional IP technique is the dominant technology for the fabrication of commercial nanofiltration (NF) and reverse osmosis (RO) membranes, it is plagued with issues of low membrane permeability, relatively thick PA layer and susceptibility to fouling, which limit the performance. Over the past decade, we have seen a significant growth in scientific publications related to the novel/modified IP techniques used in fabricating advanced PA-TFC/TFN membranes for various water applications. Novel/modified IP lab-scale studies have consistently, so far, yielded promising results compared to membranes made by conventional IP technique, in terms of better filtration efficiency (increased permeability without compensating solute rejection), improved chemical properties (crosslinking degree), reduced surface roughness and the perfect embedment of nanomaterials within selective layers. Furthermore, several new IP techniques can precisely control the thickness of the PA layer at sub-10 nm and significantly reduce the usage of chemicals. Despite the substantial improvements, these novel IP approaches have downsides that hinder their extensive implementation both at the lab-scale and in manufacturing environments. Herein, this review offers valuable insights into the development of effective IP techniques in the fabrication of TFC/TFN membrane for enhanced water separation.