Polyaniline Membranes Research Articles

Synergetic Combination of Bio‐Electrolytes and Bio‐Fluidic Channels as a Novel Resource of Sustainable Energy

AbstractExploration for sustainable energy resources is essential to minimize the dependence on fossil fuels and to improve environmental parameters. Here, the possibility of utilizing bio‐waste‐derived electrolytes as an electrical energy resource by placing them across semipermeable membranes prepared through parallel stacking of coir fibers is examined. The nanofluidic membrane (d‐CF‐V) prepared by modifying the inner walls of the bio‐fluidic channels with atomically thin layers of vanadium pentoxide (VO) shows excellent perm‐selectivity (t+ = 0.87, with 1000‐fold concentration difference) and electricity conversion efficiency (≈ 28.2%). With simulated sea and river water, the d‐CF‐V yields output energy up to 2.4 W m−2, similarly with mineral acid bases (0.5 m HCl and 0.01 m NaOH), the d‐CF‐V shows an energy output of 11.8 W m−2. The sun‐dried Garcinia morella (Kuji thekera), and charred peels of Musa balbisiana (banana) are used as sustainable sources of bio‐electrolytes, which in combination with permselective d‐CF‐V yielded a power density of ≈1.4 W m−2. By replacing standard Ag/AgCl electrodes with nanomaterials exhibiting contrasting charge transfer activities, oxidized carbon nanotube membrane (o‐CNT) and polyaniline (PANI) membrane the output voltage is enhanced from –127 to –568 mV and current output is increased from 10.2 to 51.5 µA.

Thin-Film Nanofiltration membrane of polyaniline Decorated graphene oxide via In-Situ polymerization for ion separation

Ion separation membranes composed of graphene oxide (GO) and polyaniline (PANI) have been successfully synthesized using the in-situ polymerization method. Various PANI species, including emeraldine base (EB PANI), emeraldine salt (ES PANI), and pernigraniline base (PB PANI), were incorporated into the GO matrix and subsequently evaluated. The integration of PANI species into the GO matrix resulted in an increased interlayer distance, enhanced surface positive charge, and greater membrane hydrophobicity. Additionally, incorporating PANI improved the membrane’s mechanical stability and resilience across a range of environmental pH levels. The membrane’s ion separation performance was assessed using feed ions such as Na+, Li+, Mg2+, and Al3+. The PANI GO-ES membrane exhibited the highest separation efficiency for Na+/Al3+ ions, achieving an ideal selectivity value of 76.23 ± 1.25. Conversely, ions with similar sizes and charges demonstrated lower selectivity. The GO-ES PANI membrane also showed superior performance stability compared to other membranes, maintaining a consistent ideal selectivity value for up to 20 h. Overall, the results indicate that the GO-ES PANI membrane offers the best ion separation performance and is recommended for practical applications.

Electrochemical modification of glassy carbon electrode (GCE) with cobalt ferrite/ reduced graphene oxide composite material comprising polyaniline for dissolved oxygen analysis in water

The study focuses on the enhancement of glassy carbon electrode (GCE) performance through electrochemical modification with a composite material comprising polyaniline (PANi) conducting polymer and CoFe2O4/reduced graphene oxide (CF/rGO) for the analysis of dissolved oxygen in water. Characterization methods, including Fourier-transform infrared spectroscopy (FT-IR) and Scanning Electron Microscope (SEM), were employed to elucidate the chemical bonding of functional groups within the PANi membrane and modified PANi on the surface of the GCE electrodes as well as examine the surface morphology. Electrochemical studies were conducted to evaluate the electrochemical activity of the modified electrodes, GCE/PANi and GCE/PANi/CF/rGO. Electrochemical studies were conducted to evaluate the electrochemical activity of the modified electrodes, GCE/PANi and GCE/PANi/CF/rGO. Notably, the electrochemically active surface area of the modified electrodes significantly increased, from 0,0756 cm2 (GCE), 0,1106 cm2 (GCE/PANi) to 0,1774 cm2 (GCE/PANi/CF/rGO), in addition the peak current intensity (Ip) on the modified electrodes GCE/PANi and GCE/PANi/CF/rGO also increased compared to the unmodified electrode (GCE), Ip increased from 0,0767.10-3 (A) to 0,18 x 10-3 (A), resulting in an increased ability to sense dissolved oxygen in water.

Preparation of polyaniline conductive membranes through immersion of dopant solution for dye/salt separation

The preparation of conductive loose nanofiltration (NF) membranes for effective separation of dye/salt wastewater mixtures remains a great challenge. In the current study, a novel method of immersing the polyaniline (PANI) membrane in some organic salt solutions to dope PANI membrane was employed to prepare conductive PANI loose NF membranes. Three dopants with different molecular weight, poly (sodium 4-styrene sulfonate) (PSS), sodium dodecyl sulfate (SDS), and sodium dodecylbenzene sulfonate (SDBS), were chosen to prepare the doping solutions under neutral and acidic (pH = 0.5 in HCl) conditions. The neutrally doped PANI membranes all had lower pore size distribution, lower Zeta potential, and higher conductivity compared with the undoped PANI membrane; and these properties were further enhanced for the membranes doped under acidic condition. The PANI membrane doped by acidic PSS solution (PANI-PSS-HCl membrane) had a pore size of 1.7 nm and a pure water flux of 44.7 L·m−2·h−1, and exhibited a rejection of over 99.9 % for eriochrome black T, acid fuchsin, congo red, and sunset yellow in the dye solutions, whereas less than 5 % for NaCl solution, which was suitable for dye/salt separation due to the large molecular size of PSS. When PANI-PSS-HCl membrane was used as the cathode, the membrane exhibited excellent anti-fouling performance with increased external voltage due to enhancement of electrostatic repulsion force between the anionic dyes and the surface of the conductive membrane. This work provides a simple and reliable method to prepare conductive loose NF membranes for effective separation of dye/salt wastewater with excellent anti-fouling performance under external voltage.

TiO2‐WO3 nanocube‐polyaniline hierarchical membrane for efficient removal of chromium in a photocatalytic membrane reactor

AbstractIn this article, the rational design of a physically coated TiO2‐WO3 nanocube‐polyaniline photocatalytic membrane (hierarchical) reactor for the efficient reduction of chromium (VI) under visible light is discussed. The incorporation of TiO2‐WO3 in the polyaniline (PANI) membrane provides excellent hydrophilicity and high photo‐corrosion resistance and facilitates the rapid permeation of water with a flux rate of 12 L/m2 h and higher Cr (VI) reduction. The exposure of bare PANI membranes in Cr (VI) solution leads to over‐oxidation of PANI membrane and eventually leads to the destruction of the membrane. The hierarchical photocatalytic coating improves the lifetime of the membrane by blocking it from deprotonation. The photocatalytic membrane could offer 79.30% Cr (VI) reduction under visible light irradiation in a photocatalytic membrane reactor. After several reduction cycles, the membrane showed good self‐cleaning ability. The present work suggests that TiO2‐WO3 nanocube‐coated PANI hierarchical membrane is a promising approach for the reduction and removal of Cr (VI) from wastewater.

Proton implantation into living cells under nonvacuum atmosphere

We report direct proton implantation into living cells by using a palm-sized ion emission gun under a nonvacuum atmosphere at room temperature (25 °C). An injection needle was coated with Nafion® to prepare the proton emission gun, and a polyaniline membrane was used as the target for the proton emission test. After the test, the polyaniline showed structural changes associated with protonation, suggesting successful proton emission from the gun. The device was then used to perform proton implantation into fibroblast-like cells. The viability and metabolic activity of the cells implanted with protons decreased with increasing proton dose within the picomole range. These are the first reported results to show that proton implantation can be effective in supplying direct, localized stimuli to living cells.

Fabrication and Characterization of Free-Standing and Flexible Polyaniline Membranes: Role of Graphene Nanoscrolls

Wearable technologies can contribute to the early and accurate detection of chronic diseases which can be achieved by the integration of biosensors into wearable technologies. However, the challenges associated with the performance of current electrode materials—i.e., flexibility, conductivity, and mechanical stability, made from conducting polymers are preventing their widespread usage. Herein, we report a freestanding and flexible electrode synthesized from polyaniline (PANI) and graphene nanoscrolls (GNS). The PANI-GNS nanohybrid membranes were synthesized via chemical oxidative polymerization and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), nanoindentation (NI), and four-point probe techniques. FTIR results showed an increase in conjugation length of the PANI after the addition of GNS into the mixture which can be indicative of an enhancement of electrical properties. Nanoindentation studies showed an elastic modulus and hardness of 2.6 GPa and 0.17 GPa, respectively, for PANI-GNS-5 nanocomposite, compared to 1.9 GPa and 0.08 GPa, for pure PANI. This was later confirmed by the four-point probe technique as the addition of GNS increased the conductivity of electrodes up to 9 S/cm at a 5% weight ratio. Moreover, SEM results of the PANI-GNS showed an open porous morphology of the polymer matrix in comparison with pure PANI samples which would readily translate into higher amounts of enzyme immobilization on the surface.

Hydrogen Production from Methanol-Water Solution and Pure Water Electrolysis Using Nanocomposite Perfluorinated Sulfocationic Membranes Modified by Polyaniline.

In this work, we report the preparation of Nafion membranes containing two different nanocomposite MF-4SC membranes, modified with polyaniline (PANI) by the casting method through two different polyaniline infiltration procedures. These membranes were evaluated as a polymer electrolyte membrane for water electrolysis. Operating conditions were optimized in terms of current density, stability, and methanol concentration. A study was made on the effects on the cell performance of various parameters, such as methanol concentration, water, and cell voltage. The energy required for pure water electrolysis was analyzed at different temperatures for the different membranes. Our experiments showed that PEM electrolyzers provide hydrogen production of 30 mL/min, working at 160 mA/cm2. Our composite PANI membranes showed an improved behavior over pristine perfluorinated sulfocationic membranes (around 20% reduction in specific energy). Methanol-water electrolysis required considerably less (around 65%) electrical power than water electrolysis. The results provided the main characteristics of aqueous methanol electrolysis, in which the power consumption is 2.34 kW h/kg of hydrogen at current densities higher than 0.5 A/cm2. This value is ~20-fold times lower than the electrical energy required to produce 1 kg of hydrogen by water electrolysis.

(Digital Presentation) Development of a Novel pH Sensor Based Polyaniline Supported on Nickel Modified Nickel Foam Electrode

pH is an essential parameter that has to be regularly monitored in biological and environmental applications [1]. Typically, handling fragile electrodes and a number of calibration steps make the measuring process time-consuming. Polyaniline-modified electrodes have several advantages in terms of dependability, miniaturization, and cost-effectiveness, all of which are important features for in vivo applications.In this work, a hybrid material made of polyaniline, nickel, and nickel foam (PANI/Ni/NF) was combined together to detect H+ ions. First, using cathodic electrodeposition, nickel (Ni) was electrodeposited onto the surface of nickel foam (NF) [2]. Then, the surface of Ni/NF was modified by a self-assembled polyaniline (PANI) membrane to improve the ability of Ni to transform charges. SEM, EDX, Raman spectroscopy and XPS were used to characterize the morphology of PANI/Ni/NF. Fig. 1 shows SEM image of PANI on the surface of nickel oxide modified nickel foam electrode. Cyclic voltammetry (CV) and Open circuit potential (OCP) were used to monitor the potential shift based on different pH in the buffer solutions. The pH sensor displays the sensitivity of −46.00 mV/pH (R2=0.99) with stable performance in the physiological pH range from 3–11. This prototype has been tested along with a commercial pH meter on real samples (orange, baking powder solution). The durability and repeatability tests also show promising results. This porous and tiny pH sensor opens up new horizons for monitoring H+ in biological, environmental or wet laboratory based samples.AcknowledgmentsUniversity of Grants Commission of Bangladesh (2021-22) for funding this research.References F. Song et al., ACS Appl. Energy Mater., 2018, 1, 1, 3–8.M. Jamal et al., J. Electrochem. Soc., 2022, 169, 057517M. Jamal et al., Microsys t. Technol . , 2018, 24, 4217–4223. Fig. 1. SEM image of PANI modified Ni/NF Figure 1

Research Trends in the Use of Polyaniline Membrane for Water Treatment Applications: A Scientometric Analysis.

Polyaniline (PANI), which is a member of the family of electrically conducting polymers, has been widely discussed as a potential membrane for wastewater treatment. Although a steady growth in PANI literature was observed, analyzing PANI literature quantitatively is still a novelty. The main aim of this study is to unearth the current research status, global trends, and evolution of PANI membranes literature and their use in water treatment applications over time. For this purpose, a scientometric study was performed consisting of bibliometric and bibliographic analysis. A total of 613 entities were extracted from Web of Science published during the last 50 years and were analyzed to map trends based on leading peer-reviewed journals, publication records, leading research disciplines, countries, and organizations. The study shows that the number of annual publications increased exponentially from 2005 to 2020 and is expected to keep increasing in the current decade. The Journal of Membrane Science published the highest number of articles and was identified as the most-cited journal in the field. China, India, and the USA were observed as the top three research hubs. The top-ranked authors in the field were Wang, Jixiao, and Wang, Zhi. To find research trends, four different clusters of keywords were generated and analyzed. The top five most frequent keywords turn out to be polyaniline, water, performance, membranes, and nanoparticles. The analysis suggests that the application of nanotechnology for modifying PANI membranes (using nanoparticles, nanotubes, and graphene specifically) is the future of this field. This study elucidates the research streamline of the field that may serve as a quick reference for early career researchers and industries exploring this field.

γ-Zirconium Titanium-Phosphates – Fibrous Cerium Phosphate / Polyaniline, Polyindole, Polycarbazole and Polyimidazole Nanocomposite Membranes

Layered nanosized mixed γ-zirconium titanium phosphates and fibrous cerium phosphate, γ-ZrxTi(1-x)..PO4.H2PO4.2H2O (γ-ZTP), Ce(HPO4)2.2.9H2O(nCePf), respectively, (x= 0.95, 0.89), and their [γ-ZrxTi(1-x).PO4. H2PO4]0.3 [Ce(HPO4)2]0.70. 2H2O nanocomposite membranes were prepared and characterized by chemical, x-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transform spectroscopy (FT-IR). Novel [γ-ZrxTi(1-x).PO4.H2PO4]0.3[Ce(HPO4)2]0.70 /polyaniline, polyindole, polycarbazole, and polyimidazole nanocomposite membranes were prepared via in-situ chemical oxidation of the monomers aniline, indole, carbazole and imidazole, respectively, that was promoted by the reduction of Ce(IV) ions present on the surface of the inorganic matrix composite. A possible explanation is nCePf occurs at the surface of the composite was attacked by the monomers, respectively, converted to cerium (III) orthophosphate (CePO4). The resultant novel composites were characterized by elemental (C,H,N) analysis and FT-IR. From elemental (C,H,N) analysis the % in weight of the resultant conducting polymers present in [γ-Zr0.95Ti0.05.PO4.H2PO4]0.3 [Ce(HPO4)2]0.70 composite were [ Pani 19.35, PIn 5,72. PCz 5.8, PIm 23.7]%. The % in weight of the conducting polymers in the composite [γ-Zr0.9Ti0.11.PO4.H2PO4]0.3[[Ce(HPO4)2]0.70 were [Pani 8.54, PIn 8.02, PCz 7.72, PIm 22.27]%. The conductivity of the resultant conducting polymers found to be in the range of semiconductors.

Superhydrophobic Functionalized Ti3C2Tx MXene-Based Skin-Attachable and Wearable Electrochemical pH Sensor for Real-Time Sweat Detection.

Sweat pH is a critical indicator for evaluating human health. With the extensive attention on the wearable and flexible biosensing devices, the technology for the monitoring of human sweat can be realized. In this study, a sensitive, miniaturized, and flexible electrochemical sweat pH sensor was developed for the continuous and real-time monitoring of the hydrogen-ion concentration in human sweat. A flexible electrode was fabricated on the poly(ethylene terephthalate) (PET) substrate by a simple and low-cost screen-printing technology, which was based on the integration of fluoroalkyl silane-functionalized Ti3C2Tx (F-Ti3C2Tx) and the polyaniline (PANI) membrane technology instead of the traditional ion-sensitive membrane. The surface functionalization strategy for Ti3C2Tx with perfluorodecyltrichlorosilane can provide environmental stability. Functionalized Ti3C2Tx (F-Ti3C2Tx) was doped with PANI to obtain improved responsiveness, sensitivity, and reversibility. The constructed microsize, portable, and wearable F-Ti3C2Tx/PANI pH sensor aimed to real-time monitor the pH value of human sweat during exercise. On-body sweat pH monitoring for females and males, respectively, exhibited high accuracy and continuous stability compared with ex situ analyses. This study thus offers a facile and practical solution for developing a highly reliable MXene-based mini-type pH sensor to realize the online monitoring of human sweat pH.

High performance in-situ tuned self-doped polyaniline (PANI) membranes for organic solvent (nano)filtration

Cross-linked polyaniline (PANI) membranes are attractive for organic solvent nanofiltration (OSN). However, inadequate tuneability to cover the full nanofiltration (NF) separation range, prolonged post-treatment cross-linking using hazardous organic chemicals and poor permeance limit their widespread application. This work introduces a new strategy to tune the transport properties of PANI membranes to suit the rejection spectrum of NF membranes without compromising permeance. Incorporating different molecular weight organic acids, metanilic acid (MA) and poly (2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA), facilitated cross-linking during polymer precipitation at different aqueous coagulation bath acidic strength using non-solvent induced phase separation (NIPS). Static ageing tests for PANI membranes immersed in tetrahydrofuran (THF) for 30 days showed no physical or chemical deterioration. All membranes were stable during long-term dynamic crossflow filtration tests over 250 h with sequential feed of methanol, acetonitrile and THF. THF permeance was 2.1–16.4 L m−2 h−1 bar−1 with apparent molecular weight cut off (MWCO) between 250 and 1000 g mol−1. PAMPSA doped membranes were successfully cross-linked but required wet annealing post-treatment to obtain membranes in NF range. The MA doped membranes surpassed the performance of cross-linked PANI membranes with glutaraldehyde (organic cross-linker) showing a 2.5 times higher permeance with better rejection. In comparison to commercial polyimide membranes, PANI membranes prepared in coagulation bath ≥0.5 M HCl(aq) were stable in N,N-dimethylformamide (DMF) whereas the former suffered complete damage. This work represents a simplified technique to in-situ optimise permselective properties of OSN self-doped PANI membranes for various applications in food, pharmaceutical and petrochemical industries.

Fabrication of visible-light assisted TiO2-WO3-PANI membrane for effective reduction of chromium (VI) in photocatalytic membrane reactor

In this work, TiO 2-WO3(40:1) nanoparticles were hydrothermally prepared and, embedded in Polyaniline (PANI) membrane with varying concentrations (3–7 wt%) and, used in photocatalytic membrane reactor for the removal of Cr(VI) from the aqueous solutions. 4-methyl piperidine (4-MP) was used as a gel inhibiting agent in N-methyl-2-pyrrolidone (NMP) solvent to prepare PANI-based flat-sheet membranes by phase inversion method. Through different characterization technique, it has been found that TiO 2-WO3 incorporated PANI membranes showed enhanced membrane properties like better hydrophilicity, better antifouling properties, higher water uptake, lower contact angle, higher porosity, and better heavy metal removal efficiency compared to bare PANI membranes. PANI membrane with 5 wt% TiO 2-WO3 exhibited a percentage rejection of 98.50% within 60 min at 0.5 MPa transmembrane pressure. Cr(VI) reduction under light and dark conditions was performed in a dead-end filtration cell with a quartz window at the top and the 5 wt% TiO 2-WO3– PANI membrane showed 67.32% reduction under visible light. TiO 2-WO3 incorporated PANI nanofiltration membranes can act as an integrated system consists of a short-circuited photo-anode and cathode under visible light irradiation. Overall, TiO 2-PANI membranes promote Cr(VI) reduction to Cr(III) in the photocatalytic membrane reactor and exhibits a better self-cleaning property.

In‐situ polymerization of polyaniline in PDADMAC/PSS complex membranes: Effect of the polyelectrolyte stoichiometry

AbstractThe direct polymerization of a polymer in a polyelectrolyte complex membrane is a quick and simple method to enhance the properties and add functionality to a pre‐formed membrane. Here, polyelectrolyte complex membrane (PECs) of poly (diallyl dimethyl ammonium chloride) (PDADMAC) [P+] and poly (styrene sulfonate) [P−] were modified by the in‐situ polymerization of aniline monomer into polyaniline (PANI). The initial PECs were prepared by the co‐precipitation of polyelectrolytes with various [P+]: [P−] molar ratio and were formed into 100 micron thin membranes by compression molding. The in‐situ polymerization of PANI was achieved by sequential dipping of the PECs in ammonium peroxydisulfate solution to load the oxidant and in the aniline monomer solution to initiate the polymerization. Both the polyelectrolyte stoichiometry and the NaCl concentration used during the formation of the complex were found to have a profound effect on the polymerization reaction. UV–visible spectroscopy, X‐ray diffraction, and infrared spectroscopy were used to characterize the changes in color of the PANI membranes and to confirm the synthesis of PANI. Scanning electron microscopy revealed the presence of a dense coating of PANI at the surface of the PEC.

Electrochemical manufacture of graphene oxide/polyaniline conductive membrane for antibacterial application and electrically enhanced water permeability

Electrofiltration, an effective approach for membrane fouling mitigation, is significantly limited by membrane properties. A facile electrochemical method was proposed to fabricate the graphene oxide/sulfuric acid-doped polyaniline (GO/S-PANI) membrane. For which, charging the graphite in H2SO4 (98 wt%) to obtain graphite intercalation compound (GIC), then in a mixed electrolyte (H2SO4, CuSO4, (NH4)2SO4), GO was exfoliated and assembled concurrently on the PANI membrane, which was doped by H2SO4 simultaneously. The introduction of Cu2+ made the GO layers on the membrane stable. Also, the GO/S-PANI membrane showed higher conductivity (55.6 S m−1) than the PANI membrane (0.019 S m−1). Moreover, GO/S-PANI membrane possessed a more applicable pore structure and improved hydrophilicity. As a result, membrane rejection increased, and the resistance to the negatively charged pollutants was enhanced. For 1 V electrofiltration of yeast suspension, water permeation was sustainably raised by using GO/S-PANI membrane than PANI membrane. The GO/S-PANI membrane was more stable with 1 V than without electric fields. The antibacterial rate can reach 92.1% for the GO/S-PANI membrane against Escherichia coli. Overall, our strategy provides a facile preparation method for the GO/S-PANI conductive membrane with application potential in electrofiltration and antibacterial fields.

Single-sided and integrated polyaniline/ poly(vinylidene fluoride) flexible membrane with micro/nanostructures as breathable, nontoxic and fast response wearable humidity sensor

Harmless and breathable flexible humidity sensor has important applications in continuous and real-time detection of human physiological activities. In this work, with hydrophobic poly (vinylidene fluoride) (PVDF) membrane as both the template and substrate and cetyltrimethylammonium bromide as a structure regulator, polyaniline (PANI) was unilaterally deposited on a PVDF microporous membrane to facilely fabricate a single-sided integrated flexible humidity sensor (IFHS). Such IFHS is featured with unique micro/nano structure and good air permeability. Moreover, it exhibits good humidity sensing properties at room temperature including fast response, small hysteresis and stable response even under bending deformation. The flexible sensor could realize non-contact monitoring of human respiration and speaking activities. Unilateral deposition of PANI and good breathability of IFHS avoids direct contact between PANI and human skin, thus averting harms to human and minimizing the deterioration of humidity sensing properties of PANI layer. The simple method is universal to the preparation of single-sided, integrated, breathable, nontoxic and fast response wearable humidity sensors based on PANI and hydrophobic microporous polymer membranes, offering useful references for the construction of advanced flexible sensors.

Simplified in-situ tailoring of cross-linked self-doped sulfonated polyaniline (S-PANI) membranes for nanofiltration applications

Sulfonated polyaniline (S-PANI) membranes could have wide-ranging applications due to their electrical tunability, antifouling behaviour and chlorine resistance. However, S-PANI membranes below the ultrafiltration (UF) separation range have not been successfully established. This study presents a scalable approach to produce the first in-situ cross-linked S-PANI membranes at nanofiltration (NF) range. S-PANI membranes were produced by non-solvent induced phase separation (NIPS). The presence of sulfonic groups as polymer cross-linking anchors and controlling the coagulation bath's acidic strength resulted in instant stabilisation of the selective layer, which hindered the solvent/non-solvent exchange rate. This enabled the production of a tailored membrane morphology with a dense skin layer, suppressed macro-voids, reduced porosity, enhanced tensile strength, increased hydrophilicity and solvent stability. S-PANI membranes cast in 3 M HCl(aq) with MWCO≈680 g mol−1 (sucrose octa-acetate) showed a rejection of 99 % for PEG 1000 g mol−1 and 91–100 % for dye solution (MW range of 320–1017 g mol−1) compared to 34 % and 74–85 % rejection for a commercial fluoropolymer membrane (nominal MWCO 1000 g mol−1), respectively. The reported approach is simple and can be applied to design new classes of cross-linked solvent stable S-PANI NF membranes.

Polyvinylidene fluoride nanocomposite super hydrophilic membrane integrated with Polyaniline-Graphene oxide nano fillers for treatment of textile effluents

Water pollution from the fashion industries containing dyes has become a major source of water pollution. These anthropogenic contaminated waters directly enter irrigation and drinking water systems, causing irreversible environmental damage to human health. Nanomembrane technology has attracted extensive attention to remove these toxic chemicals but new approaches are still required for improving removal efficiency and control the channel size. The work deals with the fabrication of a novel hybrid polyvinylidene fluoride (PVDF)-polyaniline (PANI) membrane with graphene oxide (GO). Incorporation of PANI-GO as a nanofiller has significantly improved antifouling properties and a solvent content of the fabricated membrane. Besides, pure water flux also increases from 112 to 454 L m−2 h−1 indicating the hydrophilic nature of the nanocomposite membrane. Among various compositions, the nanocomposites membrane with 0.1 %w/v GO demonstrated a maximum of 98 % dye rejection at 0.1 MPa operating pressure. After multiple testing of the membrane, the flux recovery ratio reached about 94 % and dyes rejection improved with the addition of PANI-GO. The removal efficiency of the composite membrane for Allura red is 98 % and for methyl orange is 95 %. Based on the above results the PVDF/PANI/GO membranes are recommended for practical use in wastewater treatment, particularly for anionic dyes removal from textile effluents.

Membrane Filtration of Methyl Orange

In this work, the filtration of methyl orange by polyacrylonitrile-co-poly(2-ethylhexylacrylate) copolymer and polyacrylonitrile-co-poly(2-ethylhexylacrylate)/polyaniline membranes were utilized. It was observed that the filtration performance was improved as acrylonitrile amount in the copolymer increased. Also, functionalizing membrane with polyaniline further enhanced the dye rejection rates. Moreover, this enhancement was proportional to polyaniline amount. Furthermore, the performance of polyaniline containing membranes was pH dependent. They showed higher filtration performances at acidic mediums and they further increased as pH decreased. PAN(92)-co-P2EHA(8)- PANI(10%) membrane provided 99.3% dye rejection value for 25 ppm dye concentration at pH 2. Also, this membrane demonstrated good resistance to permeate concentration. It had 97.6% and 90.1% dye rejection rates for 50 and 100 ppm, respectively.