Preparation of Cross-Linked Graphene Oxide on Polyethersulfone Membrane for Pharmaceuticals and Personal Care Products Removal

Removal of endocrine disruptors and pharmaceuticals by graphene oxide-based membranes in water: A review

Membrane-based water treatment has emerged as a promising solution to address global water challenges. Graphene oxide (GO) has been successfully employed in membrane filtration processes owing to its reversible properties, large-scale production potential, layer-to-layer stacking, great oxygen-based functional groups, and unique physicochemical characteristics, including the creation of nano-channels. This review evaluates the separation performance of various GO-based membranes, manufactured by coating or interfacial polymerization with different support layers such as polymer, metal, and ceramic, for endocrine-disrupting compounds (EDCs) and pharmaceutically active compounds (PhACs). In most studies, the addition of GO significantly improved the removal efficiency, flux, porosity, hydrophilicity, stability, mechanical strength, and antifouling performance compared to pristine membranes. The key mechanisms involved in contaminant removal included size exclusion, electrostatic exclusion, and adsorption. These mechanisms could be ascribed to the physicochemical properties of compounds, such as molecular size and shape, hydrophilicity, and charge state. Therefore, understanding the removal mechanisms based on compound characteristics and appropriately adjusting the operational conditions are crucial keys to membrane separation. Future research directions should explore the characteristics of the combination of GO derivatives with various support layers, by tailoring diverse operating conditions and compounds for effective removal of EDCs and PhACs. This is expected to accelerate the development of surface modification strategies for enhanced contaminant removal.

Graphene nanocomposites for real-time electrochemical sensing of nitric oxide in biological systems

Nitric oxide (NO) signaling plays many pivotal roles impacting almost every organ function in mammalian physiology, most notably in cardiovascular homeostasis, inflammation, and neurological regulation. Consequently, the ability to make real-time and continuous measurements of NO is a prerequisite research tool to understand fundamental biology in health and disease. Despite considerable success in the electrochemical sensing of NO, challenges remain to optimize rapid and highly sensitive detection, without interference from other species, in both cultured cells and in vivo. Achieving these goals depends on the choice of electrode material and the electrode surface modification, with graphene nanostructures recently reported to enhance the electrocatalytic detection of NO. Due to its single-atom thickness, high specific surface area, and highest electron mobility, graphene holds promise for electrochemical sensing of NO with unprecedented sensitivity and specificity even at sub-nanomolar concentrations. The non-covalent functionalization of graphene through supermolecular interactions, including π-π stacking and electrostatic interaction, facilitates the successful immobilization of other high electrolytic materials and heme biomolecules on graphene while maintaining the structural integrity and morphology of graphene sheets. Such nanocomposites have been optimized for the highly sensitive and specific detection of NO under physiologically relevant conditions. In this review, we examine the building blocks of these graphene-based electrochemical sensors, including the conjugation of different electrolytic materials and biomolecules on graphene, and sensing mechanisms, by reflecting on the recent developments in materials and engineering for real-time detection of NO in biological systems.

A review on hybrid membrane-adsorption systems for intensified water and wastewater treatment: Process configurations, separation targets, and materials applied

In the era of rapid and conspicuous progress of water treatment technologies, combined adsorption and membrane filtration systems have gained great attention as a novel and efficient method for contaminant removal from aqueous phase. Further development of these techniques for water/wastewater treatment applications will be promising for the recovery of water resources as well as reducing the water tension throughout the world. This review introduces the state-of-the-art on the capabilities of the combined adsorption-membrane filtration systems for water and wastewater treatment applications. Technical information including employed materials, superiorities, operational limitations, process sustainability and upgradeing strategies for two general configurations i.e. hybrid (pre-adsorption and post-adsorption) and integrated (film adsorbents, low pressure membrane-adsorption coupling and membrane-adsorption bioreactors) systems has been surveyed and presented. Having a systematic look at the fundamentals of hybridization/integration of the two well-established and efficient separation methods as well as spotlighting the current status and prospectives of the combination strategies, this work will be valuable to all the interested researchers working on design and development of cutting-edge wastewater/water treatment techniques. This review also draws a clear roadmap for either decision making and choosing the best alternative for a specific target in water treatment or making a plan for further enhancement and scale-up of an available strategy.

Insight into the adsorptive removal of ibuprofen using porous carbonaceous materials: A review

Over the last decade, the removal of pharmaceuticals from aquatic bodies has garnered substantial attention from the scientific community. Ibuprofen (IBP), a non-steroidal anti-inflammatory drug, is released into the environment in pharmaceutical waste as well as medical, hospital, and household effluents. Adsorption technology is a highly efficient approach to reduce the IBP in the aquatic environment, particularly at low IBP concentrations. Due to the exceptional surface properties of carbonaceous materials, they are considered ideal adsorbents for the IBP removal of, with high binding capacity. Given the importance of the topic, the adsorptive removal of IBP from effluent using various carbonaceous adsorbents, including activated carbon, biochar, graphene-based materials, and carbon nanostructures, has been compiled and critically reviewed. Furthermore, the adsorption behavior, binding mechanisms, the most effective parameters, thermodynamics, and regeneration methods as well as the cost analysis were comprehensively reviewed for modified and unmodified carbonaceous adsorbents. The compiled studies on the IBP adsorption shows that the IBP uptake of some carbon-based adsorbents is significantly than that of commercial activated carbons. In the future, much attention is needed for practical utilization and upscaling of the research findings to aid the management and sustainability of water resource.

Recent developments in microplastic contaminated water treatment: Progress and prospects of carbon-based two-dimensional materials for membranes separation

Micro (nano)plastics pollution is a noxious menace not only for mankind but also for marine life, as removing microplastics (MPs) is challenging due to their physiochemical properties, composition, and response toward salinity and pH. This review provides a detailed assessment of the MPs pollution in different water types, environmental implications, and corresponding treatment strategies. With the advancement in nanotechnology, mitigation strategies for aqueous pollution are seen, especially due to the fabrication of nanosheets/membranes mostly utilized as a filtration process. Two-dimensional (2D) materials are increasingly used for membranes due to their diverse structure, affinity, cost-effectiveness, and, most importantly, removal efficiency. The popular 2D materials used for membrane-based organic and inorganic pollutants from water mainly include graphene and MXenes however their effectiveness for MPs removal is still in its infancy. Albeit, the available literature asserts a 70- 99% success rate in micro/nano plastics removal achieved through membranes fabricated via graphene oxide (GO), reduced graphene oxide (rGO) and MXene membranes. This review examined existing membrane separation strategies for MPs removal, focusing on the structural properties of 2D materials, composite, and how they adsorb pollutants and underlying physicochemical mechanisms. Since MPs and other contaminants commonly coexist in the natural environment, a brief examination of the response of 2D membranes to MPs removal was also conducted. In addition, the influencing factors regulate MPs removal performance of membranes by impacting their two main operating routes (filtration and adsorption). Finally, significant limitations, research gaps, and future prospects of 2D material-based membranes for effectively removing MPs are also proposed. The conclusion is that the success of 2D material is strongly linked to the types, size of MPs, and characteristics of aqueous media. Future perspectives talk about the problems that need to be solved to get 2D material-based membranes out of the lab and onto the market.

Next-generation graphene oxide additives composite membranes for emerging organic micropollutants removal: Separation, adsorption and degradation

In the past two decades, membrane technology has attracted considerable interest as a viable and promising method for water purification. Emerging organic micropollutants (EOMPs) in wastewater have trace, persistent, highly variable quantities and types, develop hazardous intermediates and are diffusible. These primary issues affect EOMPs polluted wastewater on an industrial scale differently than in a lab, challenging membranes-based EOMP removal. Graphene oxide (GO) promises state-of-the-art membrane synthesis technologies and use in EOMPs removal systems due to its superior physicochemical, mechanical, and electrical qualities and high oxygen content. This critical review highlights the recent advancements in the synthesis of next-generation GO membranes with diverse membrane substrates such as ceramic, polyethersulfone (PES), and polyvinylidene fluoride (PVDF). The EOMPs removal efficiencies of GO membranes in filtration, adsorption (incorporated with metal, nanomaterial in biodegradable polymer and biomimetic membranes), and degradation (in catalytic, photo-Fenton, photocatalytic and electrocatalytic membranes) and corresponding removal mechanisms of different EOMPs are also depicted. GO-assisted water treatment strategies were further assessed by various influencing factors, including applied water flow mode and membrane properties (e.g., permeability, hydrophily, mechanical stability, and fouling). GO additive membranes showed better permeability, hydrophilicity, high water flux, and fouling resistance than pristine membranes. Likewise, degradation combined with filtration is two times more effective than alone, while crossflow mode improves the photocatalytic degradation performance of the system. GO integration in polymer membranes enhances their stability, facilitates photocatalytic processes, and gravity-driven GO membranes enable filtration of pollutants at low pressure, making membrane filtration more inexpensive. However, simultaneous removal of multiple contaminants with contrasting characteristics and variable efficiencies in different systems demands further optimization in GO-mediated membranes. This review concludes with identifying future critical research directions to promote research for determining the GO-assisted OMPs removal membrane technology nexus and maximizing this technique for industrial application.

Remediation of pharmaceutical pollutants using graphene-based materials - A review on operating conditions, mechanism and toxicology

Graphene is a high surface area special carbon compound with exceptional biological, electronic and mechanical properties. Graphene-based materials are potential components used in water treatment on different modes and processes. Ibuprofen and ciprofloxacin are two commonly found pharmaceutical contaminants discharged into water bodies from industrial, domestic and hospital sources. Their concentration levels in water bodies are reported in the range of 1 μg/L to 6.5 mg/L and 0.050-100 μg/L respectively. Their toxic effects pose very high risk to the inhabiting organisms. Their ability to resist biodegradation and capacity to bioaccumulate makes the conventional methods less effective in removal. In the present article, treatment of these compounds via three methods, adsorption, photocatalytic degradation and electro-fenton reactions using graphene-based materials along with the methods adopted for synthesis and treatment are reviewed. The uptakes obtained by graphene-derived adsorbents are presented along with the optimal operating conditions. Studies reported complete removal of ibuprofen from wastewater was achieved at 7 pH for 60 min using graphene membrane as adsorbent and uptake of 99% of ciprofloxacin was exhibited for graphene nanoplates/boron nitrate aerogel at a pH of 7 and 60 min. The reduced graphene oxide surface exhibits higher affinity to light adsorption which leads to the formation of photo generated electrons. The future perspectives for improved applications of graphene-based materials and the research gap currently existing are highlighted.

Ibuprofen Removal by Graphene Oxide and Reduced Graphene Oxide Coated Polysulfone Nanofiltration Membranes

The presence of pharmaceutical products, and their metabolites, in wastewater has become a focus of growing environmental concern. Among these pharmaceutical products, ibuprofen (IBU) is one of the most consumed non-steroidal anti-inflammatory drugs and it can enter the environment though both human and animal consumption, because it is not entirely absorbed by the body, and the pharmaceutical industry wastewater. Nanofiltration has been described as an attractive process for the treatment of wastewater containing pharmaceutical products. In this paper, the modification of a polysulfone nanofiltration membrane by coating with graphene oxide (GO) and reduced graphene oxide (RGO) has been carried out. The morphology and elemental composition of the active layer of unmodified and modified membranes were analyzed by scanning electronic microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), respectively. Initial characterization membranes was carried out, studying their water permeability coefficient and their permeate flux and rejection coefficients, at different applied pressures, using magnesium chloride solutions. The behavior of both pristine and coated membranes against ibuprofen solutions were analyzed by studying the permeate fluxes and the rejection coefficients at different pressures and at different contaminant concentrations. The results have shown that both GO and RGO coated membranes lead to higher values of ibuprofene rejection than that of uncoated membrane, the latter being the one that presents better results in the studies of permeability, selectivity, and fouling.

Modification of Ceramic Membranes with Carbon Compounds for Pharmaceutical Substances Removal from Water in a Filtration-Adsorption System

The aim of this work is to develop a new type of carbon-ceramic membranes for the removal of pharmaceutical substances from water. The membranes were prepared by the chemical modification method using an organosilicon precursor—octadecyltrichlorosilane (ODTS). Graphene oxide, multi-walled carbon nanotubes with carboxylic groups, and single-walled carbon nanotubes were used in the modification process. The filtration properties and adsorption properties of the developed membranes were tested. In order to characterize the membrane, the water permeability, the change of the permeate flux in time, and the adsorbed mass of the substance were determined. Additionally, the surface properties of the membranes were characterized by contact angle measurements and porosimetry. The antibiotic tetracycline was used in the adsorption tests. Based on the results, the improved adsorption properties of the modified membrane in relation to the unmodified membrane were noticed. Novel ceramic membranes modified with MWCNT are characterized by 45.4% removal of tetracycline and permeate flux of 520 L·h·m⁻²·bar⁻¹. We demonstrated the ability of modified membranes to adsorb pharmaceuticals from water streams that are in contact with the membrane. Novel membranes retain their filtration properties. Therefore, such membranes can be used in an integrated filtration–adsorption process.

A novel polyethersulfone/modified activated carbon fiber composite membrane: potential for removal micropollutants from water under the electric field

This study aimed to develop a novel composite membrane based on polyethersulfone (PES) and modified activated carbon fibers (ACFs) to remove of sulfamethoxazole (SMZ) from water. The modification of ACFs was conducted by using acid, Fe, and Mn and was confirmed by Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDS), and water contact angle measurement. Later on, the composite membranes were prepared using PES (9 wt%), N-N-dimethylacetamide (DMAc) (75 wt%), polyethylene pyrrolidone (PVP) (5 wt%), anhydrous lithium chloride (LiCl) (1 wt%), and various types of modified ACFs (0.8 wt%) as additives. It was found that the contact angle of the membrane decreased by more than 20°, and the zeta potential decreased by more than 10 mV. ACF modified by Fe was used as an admixture, membrane obtained the high comprehensive performance. Especially bovine serum albumin (BSA) rejection rate and flux recovery ratio (FRR) reached 98.8% and 98.4%, respectively. And the removal rates of SMZ increased by 24.6% under the electric field. The degradation products were detected by high-performance liquid chromatography/mass spectrometry (HPLC/MS). Based on this result, the possible degradation pathways of SMZ are proposed.