Preparation and characterization of polysulfone/graphene oxide nanocomposite membranes for the separation of methylene blue from water

PSf Membrane-Impregnated Jute-Copper Nanocomposite as Highly Efficient Dye Removal Material

Water pollution, driven by the discharge of dyes from industrial processes, poses a significant environmental and health hazard worldwide. Methylene blue, a common dye, constitutes particular concern due to its persistence and toxicity. Conventional wastewater treatment methods often struggle to effectively remove such contaminants. In this study, we introduce a novel approach utilizing a polysulfone-based composite membrane incorporating pretreated jute fibers and copper nanoparticles for the removal of methylene blue from aqueous solutions. The pretreated jute fibers undergo alkali and hydrogen peroxide treatments to enhance their adsorption capabilities, while copper nanoparticles are incorporated into the membrane to bolster its antimicrobial properties. Through comprehensive characterization techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), and scanning electron microscopy (SEM), we confirm the structural and chemical properties of the composite membranes. Batch adsorption studies reveal the superior performance of the composite membrane compared with individual components. Specifically, at lower methylene blue concentrations (∼20 ppm), the composite membrane demonstrates a remarkable percent removal value of about 97%, while at higher concentrations (∼100 ppm), the percent removal remains substantial at 85%. Additionally, desorption studies elucidate the retention capacity of the adsorbed dye, indicating the feasibility of the composite membrane for practical applications in wastewater treatment. These findings underscore the potential of nanocomposite-fiber membranes as sustainable and cost-effective solutions for mitigating water pollution. By harnessing advancements in nanotechnology and materials science, the presented innovative composite membranes could offer promising avenues for addressing water pollution challenges and promoting environmental sustainability.

Risk mitigation to healthcare workers against viral and bacterial bioaerosol load in laparoscopic surgical exhaust with a new flow mode in hollow fiber membranes-based filter

Laparoscopy of COVID-19-infected/suspected patients needs to be performed with the utmost care due to the chances of virus carryover through the pneumoperitoneum gas. In this study, polysulfone/polyvinyl-pyrrolidone hollow fiber membranes (HFMs) were fabricated by phase inversion process, and these HFMs were bundled into a module consisting of tortuous, circular-helical arrangement. Further, copper (Cu) and zinc (Zn) nanoparticles (NPs), known to have antimicrobial and antiviral properties, were flow-coated on the lumen side of the HFMs. To test functional efficiency, the modules were challenged with wet aerosol and bioaerosols. Wet aerosol removal efficiency was ∼98%. Bioaerosol-containing bacteria E. coli strain K-12, showed 2.6 log (∼99.8%), and 2.1 log (∼99.3%) removal efficiency for Cu NPs and Zn NPs coated HFMs modules, respectively, and 1.6 log (∼97%) removal for plain (uncoated) HFMs. Bioaerosols containing SARS-CoV-2 surrogate virus (MS2 bacteriophage) showed ∼5-7 log reduction of bacteriophage for plain HFMs, 3.9 log, and 2.3 log reduction for Cu and Zn coated HFMs, respectively. The flow of aerosols entirely through the HFM lumen helps in attaining a low ΔP of < 1 mm Hg, thus rendering its usefulness, particularly for exhausting pneumoperitoneum gases where high upstream pressures could lead to barotrauma. STATEMENT OF ENVIRONMENTAL IMPLICATION: Surgical smoke is generated during minimally invasive surgical (MIS) procedure such as laparoscopy when electrosurgical devices are used to cut any tissues. This smoke is a hazard as it contains toxic volatile compounds, mutagens, carcinogens, bacteria, and virus-laden aerosols. Infection to healthcare professionals through the bioaerosols containing smoke is well reported in literature. The limitation of using hypochlorite and pleated/HEPA filter, led us to design a low pressure drop bioaerosol filter, which can remove smoke, tissue fragments, and COVID-19 virus. It provides a much safer operation theatre environment during MIS procedures as well as in general for bioaerosol removal.

Investigation on Nanocomposites of Polysulfone and Different Ratios of Graphene Oxide with Structural Defects Repaired by Cellulose Nanocrystals

In this manuscript, nanofillers of graphene oxide (GO) and cellulose nanocrystal (CNC) with different weight ratios (G/C ratios), named GC 2:1, GC 4:1, GC 8:1, GC 16:1, and GC 32:1, were successfully prepared. Characterization methods such as Raman spectroscopy, X-ray photoelectron spectrometry (XPS), and thermogravimetric analysis (TGA) were performed. Additionally, the effects of these samples on the thermal stability, mechanical properties, and gas barrier properties of polysulfone (PSF) nanocomposites were investigated. A hydrophilic interaction took place between CNC and GO; as a consequence, CNCs were modified on the surface of GO, thus repairing the structural defects of GO. With the increase in G/C ratios, the repair effect of insufficient CNCs on the defects of GO decreased. The G/C ratio had a great influence on the improvement of mechanical properties, thermal stability, and gas barrier properties of nanocomposites. Compared with PSF/GC 2:1 and PSF/GC 32:1, the differences in the growth rates of tensile strength, elongation at break, and Young's modulus were 30.0%, 39.4%, and 15.9%, respectively; the difference in Td 3% was 7 °C; the difference in decline rate of O2 permeability was 40.0%.

Impact of Silver-Decorated Graphene Oxide (Ag-GO) towards Improving the Characteristics of Nanohybrid Polysulfone Membranes

The utilization of membranes has been extensively employed in the treatment of water and wastewater. Membrane fouling, attributed to the hydrophobic nature of membranes, constitutes a noteworthy concern in the realm of membrane separation. The mitigation of fouling can be achieved through the modification of membrane characteristics, including but not limited to hydrophilicity, morphology, and selectivity. In this study, a nanohybrid polysulfone (PSf) membrane embedded with silver-graphene oxide (Ag-GO) was fabricated to overcome problems related to biofouling. The embedment of Ag-GO nanoparticles (NPs) is the aim towards producing membranes with antimicrobial properties. The fabricated membranes at different compositions of NPs (0 wt%, 0.3 wt%, 0.5 wt%, and 0.8 wt%) are denoted as M0, M1, M2, and M3, respectively. These PSf/Ag-GO membranes were characterized using FTIR, water contact angle (WCA) goniometer, FESEM, and salt rejection. The additions of GO significantly improved the hydrophilicity of PSf membranes. An additional OH peak at 3380.84 cm^-1 of the nanohybrid membrane from FTIR spectra may be related to hydroxyl (-OH) groups of GO. The WCA of the fabricated membranes decreased from 69.92° to 54.71°, which confirmed the improvement in its hydrophilicity. In comparison to the pure PSf membrane, the morphology of the finger-like structure of the fabricated nanohybrid membrane slightly bent with a larger bottom part. Among the fabricated membranes, M2 achieved the highest iron (Fe) removal, up to 93%. This finding proved that the addition of 0.5 wt% Ag-GO NPs enhanced the membrane water permeability together with its performance of ionic solute removal (Fe²⁺) from synthetic groundwater. In conclusion, embedding a small amount of Ag-GO NPs successfully improved the hydrophilicity of PSf membranes and was able to achieve high removal of Fe at 10-100 mg L^-1 towards purification of groundwater for safe drinking water.

Synthesis, characterization, DFT studies, and adsorption properties of sulfonated starch synthesized in deep eutectic solvent

In this study, sulfonated starch (SS) was successfully synthesized using sulfamic acid as a sulfonating agent in a deep eutectic solvent (DES). Four-factor and three-level orthogonal experiments were conducted to determine the optimal preparation conditions, which were found to be a molar ratio of starch to urea of 1:20, a reaction temperature of 90 °C, a reaction time of 5 h, and a stirring speed of 200 rpm. The sulfonation reaction mechanism was extensively studied using various techniques, including Fourier transform infrared spectroscopy, elemental analysis, X-ray diffraction, molecular weight, particle distribution, X-ray photoelectron spectroscopy, scanning electron microscopy, and DFT calculations. The results showed that the sulfonation reaction slightly damaged starch granules, occurred on the surface of starch granules, and on the O6 atoms of the glucose unit. SS exhibited a wide pH range of application (5-10), a fast adsorption rate (400 s to reach adsorption equilibrium), and a high adsorption capacity (118.3 mg/g) under optimal conditions. The adsorption process of SS for methylene blue followed the pseudo-first-order kinetic model and was consistent with the Langmuir model, which was endothermic and spontaneous. The adsorption process was attributed to hydrogen bonding and electrostatic interactions.

Porous Membranes of Polysulfone and Graphene Oxide Nanohybrids for Vanadium Redox Flow Battery

Porous nanohybrid membranes of polysulfone (PSF) with graphene oxide (GO) nanosheets (PSF/GO membrane) were developed to serve as proton exchange membranes in a vanadium redox flow battery (VRFB). Various ratios of PSF/GO and thickness were investigated to evaluate the optimal voltage efficiency (VE), coulombic efficiency (CE), and energy efficiency (EE) of the VRFB. The pore size, distribution, and hydrophilicity of PSF/GO membranes were studied using scanning electron microscopy (SEM) images and contact angles. Functional groups of GO were evaluated using Raman spectroscopy. The mechanical properties and thermal stability of PSF/GO membranes were analyzed using a tensile tester and thermogravimetric analysis (TGA), respectively. The results show that the mechanical properties of the PSF porous membrane with GO nanosheets were significantly improved, indicating that the addition of graphene oxide nanosheets consolidated the internal structure of the PSF membrane. Cyclic voltammetry revealed an obviously different curve after the addition of GO nanosheets. The CE of the VRFB in the PSF/GO membrane was significantly higher than that in the pristine PSF membrane, increasing from 80% to 95% at 0.6 wt.% GO addition. Moreover, PSF/GO membranes displayed great chemical stability during long-term operation; thus, they can evolve as potential porous membranes for application in VRFBs for green energy storage.

Synthesis of Graphene-Based Nanocomposites for Environmental Remediation Applications: A Review

The term graphene was coined using the prefix "graph" taken from graphite and the suffix "-ene" for the C=C bond, by Boehm et al. in 1986. The synthesis of graphene can be done using various methods. The synthesized graphene was further oxidized to graphene oxide (GO) using different methods, to enhance its multitude of applications. Graphene oxide (GO) is the oxidized analogy of graphene, familiar as the only intermediate or precursor for obtaining the latter at a large scale. Graphene oxide has recently obtained enormous popularity in the energy, environment, sensor, and biomedical fields and has been handsomely exploited for water purification membranes. GO is a unique class of mechanically robust, ultrathin, high flux, high-selectivity, and fouling-resistant separation membranes that provide opportunities to advance water desalination technologies. The facile synthesis of GO membranes opens the doors for ideal next-generation membranes as cost-effective and sustainable alternative to long existing thin-film composite membranes for water purification applications. Many types of GO-metal oxide nanocomposites have been used to eradicate the problem of metal ions, halomethanes, other organic pollutants, and different colors from water bodies, making water fit for further use. Furthermore, to enhance the applications of GO/metal oxide nanocomposites, they were deposited on polymeric membranes for water purification due to their relatively low-cost, clear pore-forming mechanism and higher flexibility compared to inorganic membranes. Along with other applications, using these nanocomposites in the preparation of membranes not only resulted in excellent fouling resistance but also could be a possible solution to overcome the trade-off between water permeability and solute selectivity. Hence, a GO/metal oxide nanocomposite could improve overall performance, including antibacterial properties, strength, roughness, pore size, and the surface hydrophilicity of the membrane. In this review, we highlight the structure and synthesis of graphene, as well as graphene oxide, and its decoration with a polymeric membrane for further applications.

Synthesis, physico-chemical characterization, and environmental applications of meso porous crosslinked poly (azomethine-sulfone)s

To develop innovative mesoporous crosslinked poly(azomethine- sulfone)s with environmental applications, a simple Schiff base condensation technique based on barbituric acid BA or condensed terephthaldehyde barbituric acid TBA in their structures as monomeric units are applied. Different analysis methodologies and viscosity measurements identify them as having stronger heat stability and an amorphous structure. The photophysical features of the multi stimuli response MSR phenomenon are observable, with white light emission at higher concentrations and blue light emission at lower concentrations. Their emission characteristics make them an excellent metal ions sensor through diverse charge transfer methods. They can have a better inhibition efficiency and be employed as both mixed-type and active corrosion inhibitors according to their fluorescence emission with metals, demonstrating their capacity to bind with diverse metals. The adsorption of two distinct dye molecules, Methylene blue MB cationic and sunset yellow SY anionic, on the mesoporous structures of the polymers is investigated, revealing their selectivity for MB dye adsorption. Quantum studies support these amazing discoveries, demonstrating a crab-like monomeric unit structure for the one that is heavily crosslinked.

Preparation and Characterization of Polymer Membranes Impregnated with Carbon Nanotubes for Olive Mill Wastewater

In this study, polymer membrane(s) impregnated with carbon nanotubes (CNTs) were developed, characterized and evaluated for removing phenolic compounds from olive mill wastewater; thus, protecting the environment and public health. Polyethersulfone/functionalized, multi-walled carbon nanotube (PES/fCNTs) membranes were synthesized via the phase inversion method using PES and acid-treated CNTs. The prepared membranes were then characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and contact angle. Results obtained from this study indicate a more hydrophilic surface for the prepared PES/fCNTs membranes, with a higher pure water flux compared to the polyethersulfone (PES) membranes. In addition, the amount of fCNTs in the membranes was found to be the most significant factor affecting the morphology and water flux of the membranes. The PES/fCNTs membranes at 1 bar with 0 wt.% and 1 wt.% of CNTs showed water flux of 37.8 and 69.71 kg/h.m², respectively. In addition, PES/fCNTs membranes with 0.5 wt.% fCNTs showed the highest total phenol content removal of 74%.

Construction of a highly stable g-C3N4/NH2-MIL-88B(Fe)/CD@graphene oxide self-cleaning membrane for dye wastewater separation and degradation

A g-C3N4/NH2-MIL-88B(Fe)/CD@GO membrane (M2) was prepared by a simple vacuum filtration method.

Determination of the effect of proteoliposome concentration on Aquaporin Z incorporated nanofiltration membranes

We report on the fabrication of AqpZ immobilized flat sheet membranes. The effects of interfacial polymerization conditions as well as proteoliposome concentration were evaluated. Commercial AqpZ were used as positive control for cloned AqpZ. Specific permeate flux of membranes at higher proteoliposome concentrations increased up to 25 times higher than thin film composite membranes; however; MgSO₄ rejection is lowered almost to 1.5%. FTIR and SEM confirm immobilization of proteoliposomes. Thermal analysis showed that increasing proteoliposome concentration has no positive effect on the incorporation of proteoliposomes into polyamide structures. On the contrary, at lower proteoliposome concentrations, incorporation of proteoliposomes was found better. When combined membrane performances were compared in terms of specific permeate flux; MgSO₄ and humic rejection and flux recovery after humic acid filtration, the performance of cloned AqpZ incorporated membranes (having 0.1 mg/mL proteoliposome concentration and polyamide formed with 2 min piperazine reaction time) improved 1.7 times regarding TFC membranes. According to the results, increasing proteoliposome concentration did not improve nanofiltration membrane performance. On the contrary, lower proteoliposome concentrations were found to be more effective in increasing membrane performance.

Removal of methylene blue via bioinspired catecholamine/starch superadsorbent and the efficiency prediction by response surface methodology and artificial neural network-particle swarm optimization

This paper demonstrates coupling of the artificial neural network (ANN) technique with the particle swarm optimization (PSO) method and compares the performance of ANN-PSO with response surface methodology (RSM) in prediction of the adsorption of methylene blue (MB) by a novel bio-superadsorbent. To this, a starch-based superadsorbent was synthesized using acrylic acid and acryl amid polymers and then catecholamine functional groups were combined onto the surface with oxidative polymerization of dopamine. The adsorption of MB was considered as a function of pH, dye concentration, and contact time. The best topology of the ANN was found to be 3-7-1, and prediction model of the adsorption capacity was demonstrated as a matrix of explicit equations. ANN-PSO is more accurate than RSM. The results revealed that the root-mean-square error, correlation coefficient, and normalized standard deviation for the ANN-PSO are 22.46, 0.99, and 16.83, respectively, while for RSM are 82.89, 0.98, and 65.41, respectively.

Tannic acid modified MoS2 nanosheet membranes with superior water flux and ion/dye rejection

Energy-efficient membranes are urgently needed for water desalination and separation due to ever-increasing demand for fresh water. However, it is extremely challenging to increase membrane water flux and simultaneously achieve high rejection rates of cations or organic dyes. Herein, we report a tannic acid (TA) assisted exfoliation method to fabricate TA-modified MoS₂ (TAMoS₂) nanosheets with high production yield (90 ± 5%). The TAMoS₂ nanosheets membranes show excellent non-swelling stability in water. It is found that a hybrid membrane with 1 wt% of TAMoS₂ in MoS₂ nanosheets demonstrates overall better performance than pure MoS₂ and TAMoS₂ membrane. Such a hybrid membrane with a thickness of 5 µm shows fast water flux at around 32 L m^-2 h^-1 (LMH) and >97% rejection of various cations under static diffusion mode. Under vacuum-driven filtration condition, the as-prepared hybrid membrane demonstrates ultrafast water flux of 15,000 ± 100 L/(m² h bar) and 99.87 ± 0.1% rejection of multiple model organic dyes. To the best of our knowledge, the above performances are superior to those of all MoS₂-based membranes reported previously in terms of water flux and ion/dye rejection. This work represents a leap forward towards the practical applications of 2D TAMoS₂ membranes in various engineering and environmental areas.

Preparation and Characterization of a Hydrophilic Polysulfone Membrane Using Graphene Oxide

In general, the polysulfone (PSf) membranes are popular choices for water treatment because they have high thermal stability and good chemical resistance. On the other hand, the filtration capacity of the polysulfone membrane is limited because of its low water flux and poor antifouling ability, which are caused by the low surface hydrophilicity of the membranes. In this research, blending of graphene oxide (GO) or graphene oxide-titanium dioxide (GO-TiO2) mixture into the polysulfone matrix had been carried out through the phase inversion method to enhance the hydrophilic and antifouling properties. Methods such as energy-dispersive X-ray spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and water contact angle measurement were used to examine the surface properties of the prepared membranes. Experimental results have led to a conclusion that graphene oxide can be stabilized into prepared membranes, and then, by reducing the water contact angle values, the surface of these membranes becomes hydrophilic, which increases the permeability and the water flux of methylene blue from the aqueous feed solution, improving the membrane’s antifouling resistance.

Bioinspired catecholamine/starch composites as superadsorbent for the environmental remediation

Focusing on the encouraging properties of starch-based composite materials, starch‑g‑(acrylic acid‑co‑acrylamide) superabsorbent was synthesized using solution polymerization method, and then the catecholamine functional groups were introduced on to pore surface of the absorbent via oxidative polymerization of dopamine (DA). The adsorbent was optimized in terms of the monomers' mass ratio and synthesis conditions, and characterized by different characterization techniques. The polydopamine (PDA) coating thickness was estimated using transmission electron microscopy (TEM) image and it was found to be 83 nm. The bimodal mesoporous adsorbent with 5914.66% swelling ratio bearing micropores with a specific surface area of 2.8031 m² g^-1 was used for the adsorption of methylene blue (MB) as a model water pollutant dye. The maximum adsorption capacity was obtained 2276 mg g^-1 at pH 9 and within 100 min. The adsorbent with unprecedented super high adsorption capacity can be encouraging from different environmental remediation points of view.

Progress of Nanocomposite Membranes for Water Treatment

The use of membrane-based technologies has been applied for water treatment applications; however, the limitations of conventional polymeric membranes have led to the addition of inorganic fillers to enhance their performance. In recent years, nanocomposite membranes have greatly attracted the attention of scientists for water treatment applications such as wastewater treatment, water purification, removal of microorganisms, chemical compounds, heavy metals, etc. The incorporation of different nanofillers, such as carbon nanotubes, zinc oxide, graphene oxide, silver and copper nanoparticles, titanium dioxide, 2D materials, and some other novel nano-scale materials into polymeric membranes have provided great advances, e.g., enhancing on hydrophilicity, suppressing the accumulation of pollutants and foulants, enhancing rejection efficiencies and improving mechanical properties and thermal stabilities. Thereby, the aim of this work is to provide up-to-date information related to those novel nanocomposite membranes and their contribution for water treatment applications.