Carboxylated Graphene Oxide Research Articles

Covalently Linked 2D-Co3O4/GO Heterostructures: Catalytic and Electrochemical Properties.

Covalently cross-linked 2D heterostructures may represent a ground-breaking approach to creating materials with multifunctionalities. To date, however, this field still remains relatively unexplored. In the present work, Co3O4/GO covalently linked heterostructures (Co3O4/GO-CL) were produced using 2D-Co3O4 functionalized with (3-aminopropyl)triethoxysilane (APTES) to react with the carboxyl groups of graphene oxide (GO). The surface and interface properties of the final material were assessed through electrochemical and catalytic studies. We found that the covalent bonds lead to a self-standing and ordered final structure, not observed for the noncovalent material (Co3O4/GO-nCL), also produced for comparison. The catalytic activity of Co3O4/GO-CL over the degradation of Rhodamine 6G showed great performance and the possibility of recycling the catalyst. Electrochemical evaluation stated higher specific capacitance for the covalently bonded material (468 F g-1 against 110 F g-1). Overall, results showed that the covalent bonds may be improving charge-transfer and interfacial area features, thus leading to enhanced catalytic and electrochemical performances.

A ratiometric fluorescent biosensing platform based on CDs and AuNCs@CGO for patulin detection

BackgroundPatulin (PAT) is a mycotoxin, usually found in fruit and their products, that can potentially be harmful to human health. In order to achieve rapid detection of mycotoxins and ensure the safety of food. This study reported a novel ratiometric fluorescent aptasensor for PAT detection. In this study, we used aptamer as the recognition element, Hybrid double stranded modified with fluorescent substances as the fluorescent donor, and AuNCs@CGO as the fluorescent acceptor. After the addition of PAT, the ratiometric fluorescence “turn on” response was exhibited. ResultsThe AuNCs@CGO are obtained by amide reaction between BSA-AuNCs and carboxylated graphene oxide (CGO). The prepared AuNCs@CGO can shorten the time of FRET effect and exhibit highly efficient quenching ability by adsorption effects (π-π stacking and electrostatic gravity) on the Aptamer-modified CDs. When the target PAT bound specifically to the CDs-apt, the fluorescence of the CDs-apt would recover, while the fluorescence of ROX modified cDNA remained unchanged. This ratiometric fluorescence response improved the accuracy of PAT detection. In addition, the proposed had good linearity for PAT in the range of 0.1–50 ng/mL with a limit of detection 0.16 ng/mL. The recovery of standard addition in grapes were 95.9%–105.4 %. SignificanceAn effective fluorescent detection method for PAT was constructed based on aptamer and nanomaterials. This new fluorescent biosensor has the characteristics of simple synthesis, easy operation, high sensitivity, strong selectivity and a low LOD, which may be a promising idea and platform for the detection of food safety hazard factors.

Fluorescent aptasensor based on competitive recognition strategies and point-of-care testing system for brain natriuretic peptide detection

Brain natriuretic peptide (BNP) is the preferred biomarker for clinical analysis, widely used in early screening and prognostic monitoring of cardiovascular and neurological diseases. Due to the low concentration and short half-life of BNP in the blood, its sensitive detection remains a challenge that must be overcome. With the rapid development of molecular diagnosis and point-of-care testing (POCT), developing a BNP biosensor with high sensitivity, good stability, accuracy, speed, and low-cost is of great significance for clinical applications and emergency diagnosis. However, BNP in human blood exists in various forms, and traditional fluorescence sensors may lead to overestimation of the concentration. In this work, we constructed an “on” fluorescent aptasensor based on competitive recognition strategy for quantitative detection of BNP, and built a fluorescence sensing detection system based on smartphone to achieve rapid on-site detection. We designed a specific aptamer labeled with carboxyfluorescein (FAM) with a simple structure and high biological affinity for selective capture of BNP, and utilized the large specific surface area and excellent fluorescence quenching effect of carboxylated graphene oxide (GO-COOH) as a carrier and quencher for the aptasensor. By optimizing experimental parameters such as aptamer and GO-COOH concentrations, as well as quenching/recovery time, linear sensitive detection of BNP was achieved in the concentration range of 0.01 ng/mL–10 ng/mL, with a detection limit as low as 10 pg/mL, good specificity, and excellent application potential in artificial serum spiking experiments. Additionally, a stable and sensitive fluorescence signal collection system has been developed to meet the needs of portable detection, breaking through the usage environment of traditional fluorescence detection equipment and filling the gap of portable fluorescence biosensing. In summary, we have creatively proposed a fluorescent aptasensor that enables rapid and sensitive detection of BNP and the development of low-cost fluorescent biosensors. The combination with POCT has shown broad application prospects and also provides some ideas for the fluorescence detection of other protein biomarkers.

Nanocarrier-based drug delivery system with dual targeting and NIR/pH response for synergistic treatment of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is highly heterogeneous and aggressive, but therapies based on single-targeted nanoparticles frequently address these tumors as a single illness. To achieve more efficient drug transport, it is crucial to develop nanodrug-carrying systems that simultaneously target two or more cancer biomarkers. In addition, combining chemotherapy with near-infrared (NIR) light-mediated thermotherapy allows the thermal ablation of local malignancies via photothermal therapy (PTT), and triggers drug release to improve chemosensitivity. Thus, a novel dual-targeted nano-loading system, DOX@GO-HA-HN-1 (GHHD), was created for synergistic chemotherapy and PTT by the co-modification of carboxylated graphene oxide (GO) with hyaluronic acid (HA) and HN-1 peptide and loading with the anticancer drug doxorubicin (DOX). Targeted delivery using GHHD was shown to be superior to single-targeted nanoparticle delivery. NIR radiation will encourage the absorption of GHHD by tumor cells and cause the site-specific release of DOX in conjunction with the acidic microenvironment of the tumor. In addition, chemo-photothermal combination therapy for cancer treatment was realized by causing cell apoptosis under the irradiation of 808-nm laser. In summary, the application of GHHD to chemotherapy combined with photothermal therapy for OSCC is shown to have important potential as a means of combatting the low accumulation of single chemotherapeutic agents in tumors and drug resistance generated by single therapeutic means, enhancing therapeutic efficacy.

Lightweight and hierarchical carboxyl chitosan-derived carbon aerogel for electromagnetic wave absorber and heat insulation

In recent years, carbon aerogels derived from biomass have shown promising potential in electromagnetic wave (EMW) absorption field owing to their lightweight nature, controllable structure, environmental friendliness, and abundant pore structure. This study reports a novel type of carbon aerogels based on carboxyl chitosan (CCS) and graphene oxide (GO) with rich pores and a unique three-dimensional interconnected structure through solution mixing, freeze-drying, and pyrolysis process. The EMW absorption performances of the carboxyl chitosan/GO xerogel derived carbon aerogels (CGCAs) are adjusted by varying the content of graphene oxide (GO). The nitrogen elements inherent in chitosan can provide a large number of defects to the carbonized material, effectively capturing and attenuating EMW. Synthesized CGCAs show excellent EMW absorption performance with increasing GO content and the CGCA-6 exhibits the best performance. At a thickness of 1.7 mm, it has RLmin of −61.67 dB, and at a thickness of 1.5 mm, it has the widest effective absorption bandwidth (EAB) of 4.24 GHz (12.96–17.12 GHz). Additionally, under far-field conditions, at a thickness of 1.7 mm, the maximum radar cross-section (RCS) reduction relative to a PEC plate for the prepared CGCA-6 is 22.28 dB m2. Furthermore, the good thermal insulation capability exhibited by CGCA-6 makes it suitable for complex application scenarios. Therefore, this biomass-derived multi-functional carbon aerogel with excellent EMW absorption performance, radar stealth, infrared stealth, and thermal insulation capabilities has broad prospects for applications in EMW protection and aerospace fields.

A self-healing polyurethane/imidazole-modified carboxylated graphene oxide composite coating for antifouling and anticorrosion applications

Marine corrosion and biofouling present significant challenges to maintaining maritime vessels and oceanic infrastructure. Developing coatings that integrate anti-fouling, anti-corrosion, and self-healing properties remains a critical issue. This study introduces imidazolium-modified carboxylated graphene (FCGO) into polyurethane coatings (F-PUSS) containing disulfide bonds to address this challenge. The incorporation of FCGO significantly enhances the mechanical properties of the coating, improving tensile stress by 40 % to 20.97 MPa. The barrier properties of FCGO also provide strong corrosion resistance, with |Z|0.01Hz values an order of magnitude higher than the original samples, even after 15 days of immersion in sodium chloride (3.5 wt%). Additionally, F-PUSS retains corrosion resistance after repairs. The synergistic action of imidazole groups and graphene provides excellent antifouling performance with nearly to an alga rate of 100 % and an antimicrobial rate of 96 %. F-PUSS demonstrates remarkable self-healing capabilities, with a healing efficiency of 78 % after 48 h at 60 °C. This study provides valuable insights for designing multifunctional polymer materials with anti-fouling, anti-corrosion, and self-healing functions.

An electrochemical sensor for the rapid detection of zearalenone based on the mimic peptide screened by molecular simulation

An electrochemical sensor was developed for detecting zearalenone (ZEN) based on the mimic peptide, which was screened from the library and validated by molecular simulation and electrochemical methods. The library of the mimic peptide was constructed according to the structural analysis, molecular docking, molecular dynamics and amino acid mutation. Then, the enhanced electrical signal was attributed to gold nanoparticles (AuNPs) and reduced carboxylated graphene oxide (rGO-COOH). Under the optimal conditions, the detection limit was 0.91 pg·mL−1 (S/N = 3) with a wide linear range from 0.01 ng·mL−1 to 10 ng·mL−1. In grain samples, a good recovery rate of 84% to 105.3% was achieved, while the rate ranged from 82% to 108.8% in the commercial ELISA kits. Additionally, the electrochemical sensor exhibited the remarkable specificity, excellent stability and better reproducibility (RSD = 1.94%). This sensor has great potential for rapidly detecting ZEN in food.

Study of the microstructure, corrosion behavior, and mechanical properties of AZ91D composites containing various graphene-based nanomaterials

Incorporating two-dimensional carbon materials into magnesium alloys has notably improved both their mechanical strength and resistance to corrosion. This study specifically investigated AZ91D composites containing graphene, carboxyl graphene, and graphene oxide, which were synthesized using spark plasma sintering. Results revealed that AZ91D-0.1 GC exhibited superior mechanical properties, while AZ91D-0.1G showed exceptional resistance to corrosion. Despite being categorized similarly, their distinct structural characteristics led to varying mechanical and corrosion performance. Molecular dynamics simulations were utilized to explore the compression behavior of graphene-reinforced AZ91D alloy, while the phase-field method simulated the sintering of particles. A comprehensive understanding of these materials' behavior is critical for their further application in engineering.

Portable electrochemical sensing platform based on amidated GO-MOF and PEDOT:PSS for high-efficient detection of ponceau 4R.

Apromising electrochemical sensing platform for the detection of ponceau 4R in food has been fabricated based on the carboxylated graphene oxide (GO-COOH), metal-organic framework (MOF) UIO-66-NH2, and poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). To this endGO-COOH was covalently coupled with UIO-66-NH2 through amide reaction, endowing the material (GO-CONH-UIO-66) unique hierarchical pores and high chemical stability and as a result improving the conductivity of MOF and the dispersion of GO. After the addition of PEDOT:PSS into GO-CONH-UIO-66, the continuity and conductivity of the composite (PEDOT:PSS/GO-CONH-UIO-66) have been further enhanced, due to the high conductivity, favorable film-forming, and hydrophilic properties of PEDOT:PSS. Systematic electrochemical experiments confirm that the PEDOT:PSS/GO-CONH-UIO-66/GCE shows satisfactory electrochemical sensing properties towards the detection of ponceau 4R, with a wide linear detection range of 0.01-30μM, a low limit of detection of3.33nM, and a high sensitivity of 0.606 μA μM-1cm-2. ThePEDOT:PSS/GO-CONH-UIO-66 sensing platform was successfully used to detect ponceau 4R in beverage, and the detection results were compared with high-performance liquid chromatography. As a result, the PEDOT:PSS/GO-CONH-UIO-66 composite shows a promising application prospect for rapid detection of ponceau 4R in food and will play significant role in food safety detection and supervision.

Electrochemical sensing of cortisol by gold nanoparticle incorporated carboxylated graphene oxide based molecularly imprinted polymer

In this work, we report a simple electrochemical biosensor for cortisol (Cor) detection using a molecularly imprinted polymer (MIP). MIP was prepared by graft copolymerization method on allylated gold nanoparticle (Au) incorporated carboxylated graphene oxide (allylated Au/GO-COOH) polymerized along with the template molecule Cor. Cor is one of the important corticosteroid hormones in human physiology. Cor, the stress hormone, is a steroid hormone that comes under the class of glucocorticoid hormones and is produced as a part of our body’s stress response. This Cor imprinted polymer (Cor-MIP) was chosen to modify the working glassy carbon electrode surface. Thereby developing a highly selective and sensitive electrochemical biosensor. Electrochemical Impedance Spectroscopy and Cyclic Voltammetry explored the electrochemical properties of the developed electrochemical biosensor. The investigation reports from the electrochemical studies revealed that the current value increases proportionally with increasing concentration of Cor. This confirmed the excellent electrocatalytic activity of the prepared Cor-MIP based biosensor toward Cor. The nanomaterials as well as the electroactive sites on Cor-MIP together enhancing the electron transfer rate and lower detection. Differential Pulse Voltammetry is used to find the limit of detection and quantification, and were obtained as, 0.61 × 10−14 M and 2.02 × 10−14 M, respectively. With excellent specificity, stability, and selectivity, this newly developed electrochemical biosensor has been successfully used for Cor measurements in human blood serum samples.

A novel electrochemical aptamer biosensor for lead (Ⅱ) ion detection utilizing GO/PAMAM @Au and Au/MB as dual signal amplifiers

A competitive electrochemical aptamer biosensor for the selective detection of Pb2+ was developed in this study. The PAMAM@Au hybrid materials and the bioprobe MB-GNPs-ssDNA were synthesized with chemical methods. Modified electrode with carboxylated graphene oxide was prepared via electrodeposition. PAMAM@Au was immobilized on the modified electrode using the EDC/NHS crosslinker, and aptamer (Apt) was bound to PAMAM@Au hybrid materials using the glutaraldehyde crosslinker. The assembly of MB-GNPs-ssDNA/Apt/PAMAM@Au/GO/SPCE biosensors was achieved through immobilizing bioprobe onto electrodes, based on the theory of aptamer-complementary chain reactions. The fabricated biosensor was characterized through electrochemical experiments, SEM, AFM, TEM, XPS and FTIR. The biosensor's performance was evaluated in a series of Pb2+ aqueous solutions by differential pulse voltammetry (DPV), and the results demonstrated this biosensor had excellent repeatability, stability, and specificity. The detection range spanned from 0.5 pM/L to 500 nM/L, with a detection limit of 5 fM/L. Consequently, the proposed biosensor can serve as a reliable analytical tool for the sensitive detection of lead ions.

Sequestration of Pb(II) using channel-like porous spheres of carboxylated graphene oxide-incorporated cellulose acetate@iminodiacetic acid: optimization and mechanism study

The adsorption property of the costless green cellulose acetate (CA) was boosted by the dual modifications: inner modification by incorporating carboxylated graphene oxide (COOH-GO) into the CA spheres and outer modification by the surface modification of the COOH-GO@CA spheres by iminodiacetic acid (IDA) for removing Pb(II). The adsorption experiments of the Pb(II) proceeded in a batch mode to evaluate the adsorption property of the COOH-GO@CA@IDA spheres. The maximal Pb(II) adsorption capacity attained 613.30 mg/g within 90 min at pH = 5. The removal of Pb(II) reached its equilibrium within 20 min, and the removal % was almost 100% after 30 min at the low Pb(II) concentration. The Pb(II) adsorption mechanism was proposed according to the kinetics and isotherms studies; in addition, the zeta potential (ZP) measurements and X-ray Photoelectron Spectroscopy (XPS) analysis defined the adsorption pathways. By comparing the XPS spectra of the authentic and used COOH-GO@CA@IDA, it was deduced that the contributed chemical adsorption pathways are Lewis acid–base, precipitation, and complexation. The zeta potential (ZP) measurements demonstrated the electrostatic interaction participation in adsorbing the cationic Pb(II) species onto the negatively charged spheres (ZP = 14.2 mV at pH = 5). The unique channel-like pores of the COOH-GO@CA@IDA spheres suggested the pore-filling mechanism of Pb(II). The promising adsorption results and the superb recyclability character of COOH-GO@CA@IDA enable it to extend of the bench scale to the industrial scale.

Simultaneous Determination of Magnolol and Honokiol Using a Glassy Carbon Electrode Modified by UIO-66-NH2 and Electroreduced Carboxylated Graphene Oxide

An electrochemical sensor for the simultaneous detection of magnolol (MAG) and honokiol (HON) was constructed based on the metal-organic framework, UIO-66-NH2, and electroreduced carboxylated graphene oxide (ErGO-GOOH). The UIO-66-NH2@ErGO-COOH coating was characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. Cyclic voltammetry was applied to investigate the electrochemical behavior of MAG and HON on UIO-66-NH2@ErGO-COOH/GCE. The electroanalytical method for the simultaneous determination of MAG and HON was established using linear sweep voltammetry. Under optimal experimental conditions, a linear range of 0.05 ∼ 8 μM and limits of detection of 16 and 7.0 nm for MAG and HON, respectively, were obtained. The sensor exhibited good repeatability, reproducibility, stability and anti-interference ability. The sensor was successfully applied to the simultaneous detection of MAG and HON in urine and serum samples with good recovery.

Superior Adsorptive Removal of Anionic Azo Dyes from Aqueous Solutions Using Sulfonic Acid Group-Modified MIL-101@Graphene Oxide Composite.

It is critical to remove organic contaminants from wastewater released by the printing and dyeing industry for addressing water pollution issue. Therefore, the fabrication of new adsorbents with excellent removal efficiencies is an urgent task. A composite of MIL-101 partially functionalized with -SO3H (MIL-101-SO3H) and graphene oxide (GO) was prepared by assembling MIL-101-SO3H truncated octahedrons on the GO framework. The synthesized MIL-101-SO3H@GO has a superior adsorption efficiency for anionic azo dyes. The maximum adsorption capacities of MIL-101-SO3H@GO-1 for Congo red, methyl orange, acid orange 7, and acid orange G reached 2711.3, 818.8, 551.2, and 319.8 mg/g, respectively, which are considerably higher than those obtained using unmodified MIL-101. This is because additional interactions that promote azo dye adsorption, such as hydrogen bonding between the dye and the sulfonic acid groups of MIL-101-SO3H or the carboxyl groups of GO, were induced, and agglomerate pores that accommodated the dye were formed in the composite. The ultrahigh removal efficiency of the composite for azo dyes is mainly driven by hydrogen bonding, electrostatic interactions, π-π stacking between the MIL-101-SO3H@GO and dye molecules, synergistic interactions at the interface of GO and MIL-101-SO3H microcrystals, and the pore-filling effect. Understanding these driving forces for dye adsorption can contribute to the development of sustainable and functionally modified metal-organic framework composite adsorbents.

An energy-saving structural optimization strategy for high-performance multifunctional graphene films

Graphene has been widely studied for its excellent properties of outstanding conductivity, strength, and flexibility. However, interlayer defects formed during the macroscopic assembly of graphene nanosheets will severely degrade the performance of graphene films. Herein, a strategy combined with trace carboxyl graphene oxide (GO), mild reduction, and chemical crosslinking is employed to minimize the interlayer defects for enhancing both the conductivity and mechanical strength of graphene films. The trace carboxyl feature of GO allows nanosheets to assemble orderly into highly oriented GO films. Subsequently, the mild chemical reduction preserves the highly oriented and packed microstructure. Coupling with further crosslinking by introducing conjugated molecules with pyrene terminal groups (1-pyrene butyric acid-1,6-hexane diamine, PHD) to provide extra π-π bonds, both the mechanical strength and conductivity of graphene films are improved to 548.4 MPa and 1.7 × 105 S m−1, respectively. In addition, the graphene film with only ∼2 μm in thickness possesses an excellent electromagnetic interference shielding effectiveness (EMI SE) of ∼40 dB and a specific shielding effectiveness of up to 74 278 dB cm2 g−1 in a wide frequency range of 8.2–40.0 GHz. Thus, this study provides an energy-saving fabrication route for mechanically strong, effective thermal management and EMI shielding films.

Magnesium Ion Gated Ion Rejection through Carboxylated Graphene Oxide Nanopore: A Theoretical Study.

While nanoporous graphene oxide (GO) is recognized as one of the most promising reverse osmosis desalination membranes, limited attention has been paid to controlling desalination performance through the large GO pores, primarily due to significant ion leakage resulting in the suboptimal performance of these pores. In this study, we employed a molecular dynamics simulation approach to demonstrate that Mg2+ ions, adhered to carboxylated GO nanopores, can function as gates, regulating the transport of ions (Na+ and Cl-) through the porous GO membrane. Specifically, the presence of divalent cations near a nanopore reduces the concentration of salt ions in the vicinity of the pore and prolongs their permeation time across the pore. This subsequently leads to a notable enhancement in salt rejection rates. Additionally, the ion rejection rate increases with more adsorbed Mg2+ ions. However, the presence of the adsorbed Mg2+ ions compromises water transport. Here, we also elucidate the impact of graphene oxidation degree on desalination. Furthermore, we design an optimal combination of adsorbed Mg2+ ion quantity and oxidation degree to achieve high water flux and salt rejection rates. This work provides valuable insights for developing new nanoporous graphene oxide membranes for controlled water desalination.

Fabrication of novel 4-methyl-5-thiazoleethanol covalently-linked graphene oxide composite with adsorption selectivity for Cu2+ from aqueous solutions

BackgroundThe covalent coupling of specific organic components to graphene oxide (GO) can improve its adsorption selectivity and reduce its hydrophilicity for fast separation by acylation of the abundant carboxyl groups (-COOH) on the surface. MethodsIn this study, a novel composite material with excellent adsorption selectivity toward copper ions (Cu2+) was prepared by covalent-linking of 4-methyl-5-thiazoleethanol (MTE) to GO through a facile one-step esterification reaction. The composition and morphology of GO-MTE composites pre- and after-adsorption of Cu2+were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analyses. The adsorption conditions of GO-MTE composite for Cu2+were investigated and optimized. To further reveal the possible adsorption mechanism of GO-MTE composite toward Cu2+, the experimental data were fitted by different adsorption dynamics and isothermal models. The reusability of GO-MTE composite was evaluated by repeating the adsorption/desorption experiments in eight consecutive cycles. Significant findingsThe introduction of MTE effectively inactivates most of the carboxyl groups of GO, and the covalently-linked thiazole ring with N- and S-containing heteroatoms endows GO-MTE composite with excellent adsorption selectivity for Cu2+ in aqueous solution. The adsorption capacities of GO-MTE composite for Cu2+ are 2.39, 17.08 and 26.64 times higher than those of Pb2+, Nd3+ and Y3+, respectively, indicating that it possesses stronger binding ability for Cu2+. After eight adsorption/desorption cycles, the recycled GO-MTE composite still maintained high adsorption capacity and removal rate for Cu2+, indicating that GO-MTE composite possesses excellent stability and reusability, and it could be used for the separation and recovery of Cu2+ from aqueous solutions.

The Development of New Nanoplatforms Based on Albumin and Graphene Oxide for Aticancer Therapy

This study focuses on the covalent functionalization of the carboxylated graphene oxide layers with human serum albumin for developing new nanoplatforms capable of efficient drug loading and release for antitumor therapy. Thus, new GO-HSA conjugates have been developed and their interactions with methotrexate (MTX) molecules were evidenced through FT-IR, UV-Vis and Raman spectroscopy. The cumulative in vitro release profiles of MTX drug from GO-HSA-MTX nanoplatforms were analyzed through UV-Vis spectroscopy showing a more controlled release behavior of MTX drug under acidic conditions that simulate the tumor microenvironment demonstrating the potential use of GO-HSA-MTX as antitumoral nanocarriers.

The effects of formation and functionalization of graphene-based membranes on their gas and water vapor permeation properties

The gas and water vapor permeabilities of graphene-based membranes can be affected by the presence of different functional groups directly bound to the graphene network. In this work, one type of carboxylated graphene oxide (GO-COOH) and two types of graphene oxide synthesized i) under strong oxidative conditions directly from graphite (GO-1) and ii) under mild oxidative conditions from exfoliated graphene (GO-2) were used as precursors of self-standing membranes prepared with thicknesses in the range of 12–55 μm via slow-vacuum filtration preparation method. It was observed that the permeabilities for all tested gases decreased in order GO-2 > GO-1 > GO-COOH and depended on both the arrangement of graphene sheets and their functionalization. The GO-1 membrane with a high content of oxygen-containing groups showed the best performance for water vapor permeability. The GO-2 membrane with a thickness of 43 μm exhibited a disordered GO sheet morphology and, therefore, unique gas-separation performance towards H2/CO2 gas pair, showing high hydrogen permeability while keeping extremely high H2/CO2 ideal selectivity that exceeds the Robeson 2008 upper bound of polymer membranes.

Development of a new promising nanocomposite photocatalyst of polyaniline/carboxylated graphene oxide supported on PVA film to remove different ecological pollutants

The process of removing dye and antibiotic contaminants from wastewater is quite challenged, especially with water shortage crisis. In this study, for the first time a composite of polyaniline (PANI) and carboxylated graphene oxide (CGO) supported on polyvinyl alcohol (PVA) film (PVA/PANI/CGO) was investigated as anticipated nanocomposite film that can be used to promote wastewater treatment. The effectiveness of this nanocomposite film in wastewater treatment was optimized in a batch system for the removal of methylene blue (MB) and tetracycline antibiotic (TC). The presence of CGO proved to be significant in both adsorption and photocatalytic process and assist the photocatalytic activity of PANI. The optimized conditions for photodegradation process were assessed by using a response surface methodology model (RSM). The optimum resulting scores at 25 °C and pH equal 7 for achieving 97.8 removal % for MB were 15.3 mg L−1 initial concentration, with using 2 lamps as a maximum light intensity and weight of film equal 0.02 g. While the optimum conditions for TC removal are; 23.9 mg L−1 initial concentration of TC, with using 2 lamps and weight of film equal 0.017 g to achieve 73.1 removal %. For potential usage in wastewater treatment, the produced nanocomposite film appears to be promising.