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A series of proton exchange membranes (PEMs) of sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide) (SPPO) with different sulfonated graphene oxide (SGO) (0, 0.25, 0.5, 0.75, 1.0, 1.5%) were prepared for possible application in Iron‐air/flow battery. The presence of SGO in the membrane improved the water uptake of all membranes prepared and decreased the swelling ratio. The SPPO/1% w/w SGO showed good properties with higher water uptake of 44.1%, water retention of 42.48% and swelling ratio of 21.4% at 25°C. However, the 0.75% SGO exhibited the highest proton conductivity of 0.98 S/cm and better dispersion, elemental distribution, and morphology. In addition, SGO improved the thermal stability of all composite membranes. The chemical stability of all membranes remained good after 7 days in a 1 M HCL solution. The SPPO/0.75%w/w SGO showed increased proton conductivity when degradation properties were evaluated. Compared to Nafion 117, all composites showed lower iron crossover. Nafion had a high permeability of 3.03 × 10−7 cm−2/s, which is 75% higher than the 7.6 × 10−8 cm−2/s of SPPO/SGO‐1.5% and 52% higher than the 1.46 × 10−7 cm−2/s of SPPO/SGO‐0.75%. The results indicate that SGO is a good inorganic filler for the composite proton exchange membrane and stable enough for possible application in an iron‐air/flow battery. [ABSTRACT FROM AUTHOR]

Water pollution and the unsustainable use of fossil fuel derivatives require advanced catalytic methods to clean waters and to produce fine chemicals from modern biomass. Classical homogeneous catalysts such as sulfuric, phosphoric, and hydrochloric acid are highly corrosive and non-recyclable, whereas heterogeneous catalysts appear promising for lignocellulosic waste depolymerization, pollutant degradation, and membrane antifouling. Here, we review the use of sulfonated graphene and sulfonated graphene oxide nanomaterials for improving membranes, pollutant adsorption and degradation, depolymerization of lignocellulosic waste, liquefaction of biomass, and production of fine chemicals. We also discuss the economy of oil production from biomass. Sulfonated graphene and sulfonated graphene oxide display an unusual large theoretical specific surface area of 2630 m2/g, allowing the reactants to easily enter the internal surface of graphene nanosheets and to reach active acid sites. Sulfonated graphene oxide is hydrophobic and has hydrophilic groups, such as hydroxyl, carboxyl, and epoxy, thus creating cavities on the graphene nanosheet's surface. The adsorption capacity approached 2.3–2.4 mmol per gram for naphthalene and 1-naphthol. Concerning membranes, we observe an improvement of hydrophilicity, salt rejection, water flux, antifouling properties, and pollutant removal. The nanomaterials can be reused several times without losing catalytic activity due to the high stability originating from the stable carbon–sulfur bond between graphene and the sulfonic group. [ABSTRACT FROM AUTHOR]

Despite being the most employed polymer electrolyte for proton exchange membrane fuel cells (PEMFCs), Nafion® has several limitations: expensiveness, poor performance when exposed to temperatures higher than 80 °C, and its potential as a source of environmentally persistent and toxic compounds (i.e., per- and polyfluoroalkyl substances, known as PFASs) when disposed of. This work explores the functional and environmental performances of three potential PFAS-free alternatives to Nafion® as electrolytic membranes in PEMFCs: sulfonated graphene oxide (SGO), graphene oxide-naphthalene sulfonate (GONS), and borate-reinforced sulfonated graphene oxide (BSGO). Investigated via ATR-FTIR spectroscopy, TGA, and cross-sectional SEM, the membranes show an effective functionalization of GO and good thermal stability. Functional properties are determined via Ion Exchange Capacity (IEC) evaluation, Electrochemical Impedance Spectroscopy, and tensile tests. In terms of IEC, the innovative materials outperform Nafion® 212. Proton conductivities at 80 °C of SGO (1.15 S cm−1) and GONS (1.71 S cm−1) are higher than that of the commercial electrolyte (0.56 S cm−1). At the same time, the membranes are investigated via Life Cycle Assessment (LCA) to uncover potential environmental hotspots. Results show that energy consumption during manufacture is the main environmental concern for the three membranes. A sensitivity analysis demonstrates that the impact could be significantly reduced if the production procedures were scaled up. Among the three alternatives, SGO shows the best trade-off between proton conductivity and environmental impact, even though performance results from real-life applications are needed to determine the actual environmental consequences of replacing Nafion® in PEMFCs. [ABSTRACT FROM AUTHOR]

Effective removal of heavy metals from water is critical for environmental safety and public health. This work presents a reduced graphene oxide (rGO) obtained simply by using gallic acid and sodium ascorbate, without any high thermal process or complex functionalization, for effective removal of heavy metals. FTIR and Raman analysis show the effective conversion of graphene oxide (GO) into rGO and a large presence of defects in rGO. Nitrogen adsorption isotherms show a specific surface area of 83.5 m2/g. We also measure the zeta-potential of the material showing a value of −52 mV, which is lower compared to the −32 mV of GO. We use our rGO to test adsorption of several ion metals (Ag (I), Cu (II), Fe (II), Mn (II), and Pb(II)), and two organic contaminants, methylene blue and hydroquinone. In general, our rGO shows strong adsorption capacity of metals and methylene blue, with adsorption capacity of qmax = 243.9 mg/g for Pb(II), which is higher than several previous reports on non-functionalized rGO. Our adsorption capacity is still lower compared to functionalized graphene oxide compounds, such as chitosan, but at the expense of more complex synthesis. To prove the effectiveness of our rGO, we show cleaning of waste water from a paper photography processing operation that contains large residual amounts of hydroquinone, sulfites, and AgBr. We achieve 100% contaminants removal for 20% contaminant concentration and 63% removal for 60% contaminant concentration. Our work shows that our simple synthesis of rGO can be a simple and low-cost route to clean residual waters, especially in disadvantaged communities with low economical resources and limited manufacturing infrastructure. [ABSTRACT FROM AUTHOR]

The aim of this research was to study the efficiency of polyvinyl alcohol (PVA)‐modified graphene oxide (GO) as a supporting material for catalysts that oxidize formic acid. The active metal catalysts (e.g., Pt and Pd) were electrodeposited on PVA/GO surfaces. The morphologies of the prepared catalysts were characterized by scanning electron microscopy and transmission electron microscopy, while their chemical compositions were identified by X‐ray diffraction and X‐ray photoelectron spectroscopy. The results show that compared with the other catalysts on GO, the prepared active PtPd alloy catalyst nanoparticles with 11.49–20.73 nm sizes were well dispersed on the PVA/GO surfaces. Electrochemical results indicate that the activities of the catalysts with PVA provided a higher current density than that of the catalysts without PVA. The bimetallic 3Pt3Pd/PVA/GO catalyst showed the greatest catalytic activity, stability, and CO oxidation when compared to those of other catalysts. The electronic, morphological, and structural properties promote the mass‐charge transfer through the interaction. These results indicate that the PVA‐modified GO provides a suitable site for active bimetallic catalyst surfaces, resulting in excellent formic acid oxidation and high CO elimination. The 3Pt3Pd/PVA/GO electrocatalyst is promising for enhancing formic acid oxidation. [ABSTRACT FROM AUTHOR]

As the core component of proton exchange membrane fuel cells, proton exchange membranes (PEM) have attracted much attention of researchers. To trade-off the proton conductivity, dimensional stability and anti-oxidation ability of PEM, graphene oxide (GO) and acidized multi-walled carbon nanotubes (MWCNT) using calcium ion as coordination bridge (GO-Ca2+-MWCNT) was synthesized, and then incorporated into sulfonated poly(arylene ether nitrile) (SPEN) to fabricate SPEN/GO-Ca2+-MWCNT organic–inorganic composite membranes by solution-casting method and explore the influence of varying loading on performances as PEM. It was found that the proton conductivity of the composite membranes was higher than that of SPEN, while maintaining better dimensional stability, excellent anti-oxidation ability and good mechanical properties. All of these were attributed to the formation of three-dimensional structure between GO and MWCNT bridged by Ca2+ and the interaction between the sulfonic acid group and calcium ions in SPEN/GO-Ca2+-MWCNT composites. Particularly, the SPEN/GO-Ca2+-MWCNT-1 composite membrane exhibited excellent tensile strength of 71.45 MPa, better thermal stability as well as high proton conductivity (0.054 S/cm at 30 °C, and 0.193 S/cm at 90 °C), above 10–2 S/cm, satisfying the requirement of PEM. All in all, the results indicate that the filler with three-dimensional network structure can effectively improve the performances of SPEN, and the prepared composite membranes show potential applications in many fields. [ABSTRACT FROM AUTHOR]

Polyethyleneimine‐functionalized reduced graphene oxide (PEI‐RGO)‐embedded sulfonated poly (vinylidene fluoride‐co‐hexafluoropropylene) (SPVDF‐co‐HFP) acid‐base composite membranes are fabricated by solution casting method for vanadium redox flow battery (VRFB) applications. The denser and crumbled morphology revealed by FESEM images and EDX results indicates the successful synthesis of PEI‐RGO nanosheets. The interfacial acid‐base pairs formed between PEI‐RGO and SPVDF‐co‐HFP matrix of composite membranes result in improvement of ion exchange capacity, water uptake, proton conductivity, as well as effective control in swelling ratio and vanadium‐ion permeability. In addition, the dispersing ability of PEI‐RGO in the SPVDF‐co‐HFP matrix improved the thermal and mechanical stability of the composite membranes. Homogeneous dispersion of PEI‐RGO nanosheets at the SPVDF‐co‐HFP surface is revealed by the FESEM images of the composite membranes, and their presence is confirmed by EDX results. The SPVDF‐co‐HFP membrane with 0.75 wt% PEI‐RGO exhibited the highest proton conductivity of 5.69 × 10−3 Scm−1 at 25°C, membrane selectivity of 25.52 × 10−4 Scm−3min, and lowest vanadium‐ion permeability of 2.23 × 10−8 cm2min−1. Overall results suggested that the SPVDF‐co‐HFP‐0.75 nanocomposite membranes are found to be a suitable alternative for commercially costly Nafion in VRFB applications. [ABSTRACT FROM AUTHOR]

BACKGROUND Membrane technology is highly applicable to water purification due to its simple operation process. During the treatment of organic wastewater, the organic compounds are deposited on the membrane surface, which leads to membrane fouling. To alleviate this problem, the membrane separation process could be combined with eco‐friendly photocatalytic technology. In this regard, facile synthesized nanomaterials, such as sulfonated graphene oxide (SGO), zinc oxide (ZnO), and SGO/ZnO (SGZ) are incorporated in a polyethersulfone (PES) membrane matrix used for antifouling analysis and degradation of organic pollutants in the presence of UV light irradiation. RESULTS: X‐ray diffraction (XRD) and Transmission Electron Microscopy (TEM) analysis shows that ZnO is bound strongly within the SGO‐ZnO nanocomposite. The optical property was also altered for hybrid SGO‐ZnO nanocomposite as compared to the ZnO photocatalyst. The physicochemical characterization of PES‐SGO, PES‐ZnO, and PES‐SGZ nanocomposite membranes was studied. Hydrophilicity and water flux are improved with the addition of nanomaterials. Among the membranes, PES‐SGZ nanocomposite membranes exhibit maximum water flux and lower contact angle value of 152 L m−2 h−1 and 51.9°, respectively. The photocatalytic activity of the membrane was assessed by organic pollutants under the UV light. The PES‐SGZ nanocomposite membrane revealed higher photocatalytic efficiency for crystal violet at 92.3% and ciprofloxacin at 95.1%. CONCLUSION: The modified PES membranes enhanced antifouling and hydrophilic properties. Specifically, the PES‐SGZ nanocomposite membrane proved to be a superior material for the effective photodegradation of organic pollutants and it achieved a higher water flux. To conclude, the prepared photocatalytic membrane could have vast potential in the treatment of toxic organic industrial effluents. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The present work demonstrated the removal of hexavalent chromium from aqueous solutions on synthesized graphene oxide (GO) from graphite. The prepared GO was characterized by various analytical techniques such as X-ray diffraction, scanning electron micrograph, Fourier transformed infrared and zero point change. The entire metal adsorption study was conducted through batch mode with keeping constant stirring rate (150 rpm). The operating variables such as pH (2–8), contact time (1–60 min), adsorbent dose (0.005 g–0.01 g L−1) and initial concentration (5–80 µg L−1) were considered, and optimized variables were fixed at maximum percentage of removal. The studied results ascertained that the maximum removal (92.8%) was achieved at acidic pH(4). The equilibrium of Cr(VI) adsorption data was nicely fitted with Langmuir model with maximum adsorption capacity (qm) 1.222 µg g−1. The sorption kinetics was nicely explained with pseudo-first-order and intraparticle diffusion mechanism. Thermodynamics of Cr(VI) adsorption revealed that the adsorption was spontaneous, endothermic and entropy-driven process. Therefore, it is concluded that graphene oxide could be an effective and efficient alternative toward removal of Cr(VI) from aqueous solution. [ABSTRACT FROM AUTHOR]

We report optical properties of ZnO nanorods dispersed graphene oxide (GO)—polyvinyl alcohol (PVA) free standing composite films (PVA-GO-ZnO) which are prepared by ex-situ method. It has been found that the loading of ZnO nanorods altered the influence of GO on PVA matrix. Optical absorption results show the band related to π → π* transitions of aromatic C–C bonds in GO, which is shifted to higher wavelength side when loading ZnO in GO-PVA. Raman spectral studies show that the incorporation of ZnO in GO-PVA film decreases the interaction of GO with hydroxyl groups in PVA matrix. Steady state and time resolved photoluminescence show the suppression of PVA luminescence and decay time due to interactions with GO, which is recovered after the loading of ZnO in the PVA-GO. [ABSTRACT FROM AUTHOR]

An approach towards the synthesis of aluminum modified graphene oxide (GO) has been studied in the present manuscript. Graphene oxide has been modified by the aluminum sulfate followed by alkalization to synthesized Al-GO composite. GO and Al-GO composite has been characterization by the means of different techniques i.e. XRD, FT-IR, FT-Raman, TEM, SEM, TGA and elemental mapping. Analysis confirmed the formation of GO and Al-GO composite. The prepared GO composite has been checked for the removal of fluoride from the potable water with different initial concentration of fluoride ions. Composite shows it's effectiveness for the removal of fluoride throughout the pH range. The maximum adsorption capacity and Langmuir constant determined for the adsorbent dose of 1 g L−1 are found to be 38.31 mg g−1 and 0.5252 L mg−1 respectively.GRAPHICAL ABSTRACT [ABSTRACT FROM AUTHOR]

In the present work, we report the comparative study of photocatalytic degradation of Rhodamine B (RhB) dye in aqueous solution by using ZnO-graphene nanaocomposites obtained using two different natural reducing agents namely Grape and Eichhornia crassipes. Graphene oxide (GO) was synthesized by Hummer's method followed by reduction of the graphene oxide using natural reducing agents Grape and Eichhornia crassipes. The two samples of graphene oxide (Gr-rGO and Ei-rGO) were treated with ZnO to form a rGO-ZnO nanocomposites. The dye degradation was observed by the decrease in the absorption and decolorization in the presence of visible light. The degradation efficiency was found to be dependent on the concentration of rGO-ZnO nanocomposites added to the dye solution. The Ei-rGO has a higher adsorbing capacity due to its large surface area. A degradation efficiency of 67% was achieved by ZnO alone, whereas with the rGO-ZnO nanocomposite, the photocatalytic degradation efficiency for removal of RhB dye was found to be enhanced. The degradation efficiency was 70.0% and 97.5% with Gr-rGO-ZnO and Ei-rGO-ZnO nanocomposites respectively. The enhanced photocatalytic activity of Ei-rGO-ZnO composites could be attributed to the strong interaction with the ZnO and the defect sites available in Ei-rGO. [ABSTRACT FROM AUTHOR]

This manuscript deals with graphene oxide (GO) and GO-metal oxide composite for heavy metal adsorption. Metal oxide-GO composites e.g. Fe3O4-GO and Mn3O4-GO have been prepared and explored for heavy metals e.g. lead, chromium, nickel, cadmium etc. adsorption from the water. Metal oxide-GO composites have been prepared through respective techniques. The various characterizations of the nanocomposites viz. structural and thermal have been analysed by transmission electron microscopy, thermogravimetric analyser etc. Different concentration of heavy metal has been taken to examine the efficiency of composites towards adsorption. Furthermore, effect of time on adsorption has also been evaluated. Metal oxide-GO composites illustrate better results as compared to GO showing the usability of composites for heavy metal adsorption for the production of clean water. [ABSTRACT FROM AUTHOR]

ABSTRACT: Simultaneously improving the proton conductivity and mechanical properties of a polymer electrolyte membrane is a considerable challenge in commercializing proton exchange membrane fuel cells. In response, we prepared a new series of miscible polymer blends and thus the corresponding crosslinked membranes based on highly sulfonated poly(ether ether ketone) and sulfonated polybenzimidazole. The blended membranes showed more compact structures, due to the acid‐base interactions between the two constituents, and improved mechanical and morphological properties. Further efforts by doping sulfonated graphene oxide (s‐GO) forming composite membranes led to not only significantly elevated proton conductivity and electrochemical performance, but also better mechanical properties. Notably, the composite membrane with the filler content of 15 wt % exhibited a proton conductivity of 0.217 S cm−1 at 80 °C, and its maximum power density tested by the H2/air single PEMFC cell at room temperature reached 171 mW cm−2, almost two and half folds compared with that of the native membrane. As a result, these polymeric membranes provided new options as proton exchange membranes for fuel‐cell applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46547. [ABSTRACT FROM AUTHOR]

In this study, sulfonated organosilane graphene oxide (SSiGO) was synthesized by grafting 3-mercaptopropyl trimethoxysilane (MTPS) with graphene oxide (GO) and follow-up oxidation with hydrogen peroxide. The SSiGO was introduced into sulfonated poly (phthalazinone ether ketone) (SPPEK) to obtain composite membranes (SSiGO/SPPEK), and the physicochemical and electrochemical properties were extensively investigated. The results show that this SSiGO/SPPEK composite membranes possess excellent thermal and dimensional stability and super high proton conductivity. The proton conductivity of 10% SSiGO composite membranes was improved greatly from 0.094 to 0.22 S/cm from 30 to 80 °C, in contrast with the 0.089-0.17 S/cm from 30 to 80 °C of Nafion 212, which indicates that the SSiGO/SPPEK composite membranes have tremendous promise for proton exchange membranes fuel cells. [ABSTRACT FROM AUTHOR]

Graphene oxide is well known as a advanced functional material because of its super high specific surface area, as well as excellent amphipathicity. Sulfonated graphene oxide bio nanocomposite membranes are presented as a potential proton exchange membrane for fuel cell applications. The GO nanopowder was produced from graphite powder by the modified Hummer’s method and then sulfonated by chlorosulfonic acid as a sulfonic reagent. The s-GO-based s-CS/PEO composite membranes were prepared by solution casting technique. The synthesized electrolytes are studied by different characterization to check the electrical and thermal properties of the membrane. FTIR and Raman showed the formation of GO, s-GO and prepared electrolytes interaction between the functional groups respectively. The maximum ionic conductivity of s-Chitosan (s-CS)/PEO/s-GO nanocomposite membranes at 6 wt% of s-GO in the order of 10−2 S/cm. Moreover, the existence of the intermolecular interactions between sulfonated-CS/PEO and s-GO can improve the thermal stability and interfacial compatibility between nanofiller and polymer matrixes. [ABSTRACT FROM AUTHOR]

Sulfonated poly(ether ether ketone) and graphene oxide nanocomposite-based polymer electrolyte membranes were prepared by facile solution casting method, and their applications for single cell were investigated. The degree of sulfonation played an important role in the proton conductivity of polymer electrolytes. Thus, we studied both the low and high degree of sulfonated poly ether ether ketones (SPEEKs) as composite with amphiphilic graphene oxide nanosheets (GNSs). The obtained results on water uptake and swelling profile showed that the physical and chemical properties of polymer electrolytes significantly improved after insertion of GNS. Morphological properties of the fabricated membranes were investigated with field emission scanning electron microscopy (FE-SEM), and the equal dispersion of GNS sheets throughout the cross section of polymer matrix was observed. The temperature-dependent conductivity reveals that SPEEK-GNS composite showed improved proton conductivity compared to pure SPEEK, because of the high degree of dispersion of GNS thus facilitated the extension of proton transport channels. Best enhancement in conductivity is observed for composite membrane containing 1.0 wt% of GNS, i.e., 149 mS cm. [ABSTRACT FROM AUTHOR]

Sulfonated polyether sulfone-based cation-exchange membranes are prepared by incorporating different amounts of graphene oxide and sulfonated graphene oxide nanosheets. The graphene oxide nanosheets are synthesized according to Staudenmaier and Hummer methods and functionalized using 3-mercaptopropyl trimethoxysilane. Transport properties of nanocomposite membranes including ion-exchange capacity, transport number, and conductivity as well as their thermal stabilities are enhanced by incorporating sulfonated graphene oxide rather than graphene oxide. Also, the enhancement is more significant for the nanocomposites having functionalized graphene oxide synthesized by Staudenmaier method than those by Hummers method due to higher density of active sites in the Staudenmier graphene oxides for functionalization. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) was served as mechanical strengthening to prepare GO/Polyvinyl Alcohol(PVA) composite film. This was accomplished in order to explore the influence of contents of GO on the tensile strength and failure strain of GO/PVA composite film. The results showed that as the GO content increased, the tensile strength of the composite film became greater rapidly at first, and then decreased gradually. When the GO content was 20%, the film had its maximum tensile strength (59.6 MPa). This is over 500% of the tensile strength of pure PVA film. The failure strain of GO/PVA composite film decreased rapidly as the GO content increased. The enhancement mechanism of the composite can be explained by the existence of multi-hydrogen bonds between the hydroxyl (-OH) groups of PVA and oxygen-containing functional groups of GO. [ABSTRACT FROM AUTHOR]

Energy efficient membranes of SGO (Sulfonated Graphene Oxide) into SPES (Sulfonated Polyethersulfone) matrix have been prepared containing different weight content of SGO. Proton conductivity and water retention capacity of membranes increases by increasing SGO while degree of swelling decreases. TEM micrograph shows the uniform distribution of SGO throughout the membrane. SGO-5 membrane shows the maximum proton conductivity (5.8 x 10−2S/cm), which is almost double to the SPES with higher stability. SGO-5 membrane shows 4.73 mole.m−2h−1ionic flux, 0.98 kWhkg−1power consumption and 93.1% current-efficiency for salt removal, which are 62% and 15.2% higher, respectively, while 16% lower power consumption is observed as compared to SPES. [ABSTRACT FROM PUBLISHER]

Hydroxide exchange membrane fuel cells (AEMFC) are clean energy conversion devices that are an attractive alternative to the more common proton exchange membrane fuel cells (PEMFCs), because they present, among others, the advantage of not using noble metals like platinum as catalysts for the oxygen reduction reaction. The interest in this technology has increased exponentially over the recent years. Unfortunately, the low durability of anion exchange membranes (AEM) in basic conditions limits their use on a large scale. We present in this review composite AEM with one-dimensional, two-dimensional and three-dimensional fillers, an approach commonly used to enhance the fuel cell performance and stability. The most important filler types, which are discussed in this review, are carbon and titanate nanotubes, graphene and graphene oxide, layered double hydroxides, silica and zirconia nanoparticles. The functionalization of the fillers is the most important key to successful property improvement. The recent progress of mechanical properties, ionic conductivity and FC performances of composite AEM is critically reviewed. [ABSTRACT FROM AUTHOR]

Pollution due to acidic and metal-enriched waters affects the quality of surface and groundwater resources, limiting their uses for various purposes. Particularly, manganese pollution has attracted attention due to its impact on human health and its negative effects on ecosystems. Applications of nanomaterials such as graphene oxide (GO) have emerged as potential candidates for removing complex contaminants. In this study, we present the preliminary results of the removal of Mn(II) ions from acidic waters by using GO functionalized with zinc oxide nanoparticles (ZnO). Batch adsorption experiments were performed under two different acidity conditions (pH1 = 5.0 and pH2 = 4.0), in order to evaluate the impact of acid pH on the adsorption capacity. We observed that the adsorption of Mn(II) was independent of the pHPZC value of the nanoadsorbents. The qmax with GO/ZnO nanocomposites was 5.6 mg/g (34.1% removal) at pH = 5.0, while with more acidic conditions (pH = 4.0) it reached 12.6 mg/g (61.2% removal). In turn, the results show that GO/ZnO nanocomposites were more efficient to remove Mn(II) compared with non-functionalized GO under the pH2 condition (pH2 = 4.0). Both Langmuir and Freundlich models fit well with the adsorption process, suggesting that both mechanisms are involved in the removal of Mn(II) with GO and GO/ZnO nanocomposites. Furthermore, adsorption isotherms were efficiently modeled with the pseudo-second-order kinetic model. These results indicate that the removal of Mn(II) by GO/ZnO is strongly influenced by the pH of the solution, and the decoration with ZnO significantly increases the adsorption capacity of Mn(II) ions. These findings can provide valuable information for optimizing the design and configuration of wastewater treatment technologies based on GO nanomaterials for the removal of Mn(II) from natural and industrial waters. [ABSTRACT FROM AUTHOR]

A membrane electrolyte that restricts the methanol cross-over while retaining proton conductivity is essential for better electrochemical selectivity in direct methanol fuel cells (DMFCs). Extensive research carried out to explore numerous blends and composites for application as polymer electrolyte membranes (PEMs) revealed promising electrochemical selectivity in DMFCs of carbon nanomaterial-based polymer composites. The present review covers important literature on different carbon nanomaterial-based PEMs reported during the last decade. The review emphasises the proton conductivity and methanol permeability of nanocomposite membranes with carbon nanotubes, graphene oxide and fullerene as additives, assessing critically the impact of each type of filler on those properties. [ABSTRACT FROM AUTHOR]

As a clean energy utilization device, full cell is gaining more and more attention. Proton exchange membrane (PEM) is a key component of the full cell. The commercial-sulfonated, tetrafluoroethylene-based fluoropolymer-copolymer (Nafion) membrane exhibits excellent proton conductivity under a fully humidified environment. However, it also has some disadvantages in practice, such as high fuel permeability, a complex synthesis process, and high cost. To overcome these disadvantages, a low-cost and novel membrane was developed. The sulfonated poly (ether ether ketone) (SPEEK) was selected as the base material of the proton exchange membrane. Sulfonated graphene (SG) was cross-linked with SPEEK through the elimination reaction of hydrogen bonds. It was found that the sulfonic acid groups and hydrophilic oxygen groups increased obviously in the resultant membrane. Compared with the pure SPEEK membrane, the SG-reinforced membrane exhibited better proton conductivity and methanol permeability prevention. The results indicate that the SG/SPEEK could be applied as a new proton exchange membrane in fuel cells. [ABSTRACT FROM AUTHOR]