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Graphene oxide-based nanofiltration membranes for separation of heavy metals

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Abstract

Membrane separation is the most promising water treatment technology that combines high separation efficiency, modest operation, concise of space, low footprints, and low operating cost. However, the current membrane technology has limitations in permeability and solute rejection which are highly influenced by membrane material and operating conditions. Recent studies show that the graphene oxide (GO) incorporation on membrane promotes the permeation and metal ions rejection rates efficiently. Many efforts have been made to improve the waste removal performance of GO using a variety of techniques. This chapter mainly focuses on the applications of GO-based nanofiltration membranes (GO-NFMs) for heavy metals (HMs) removal from polluted water. It also covers membrane types, fabrication methods, unique properties of GO, and characterization techniques. Parameters required for best-performing GO-NFMS along with rejection mechanisms and factors affecting the performance of membranes for the removal of HM ions from wastewater have also been discussed. A good comparison of GO-NFMs with conventional membranes and efficiency of GO-modified polymeric membranes have also reviewed in the chapter. Perspectives, recommendations, and challenges for future development of GO-NFMs technologies for metal ions removal are given as complement at the end of the chapter.

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... The adsorption process of HMIs onto the GO decorated PES membrane is intricately governed by a complex interplay of diverse interactions, ultimately leading to highly efficient metal ion removal (Ayub and Othman, 2023). GO, renowned for its extensive specific surface area and the presence of diverse functional groups, such as epoxy, carboxy, and keto moieties, exhibits remarkable versatility in its interactions with metal ions (Goyat et al., 2022b;Marcano et al., 2010). ...
... These interactions encompass electrostatic attraction, complexation, and chemical bonding, collectively orchestrating the multifaceted adsorption phenomenon. The unique surface properties of the PES membrane further contribute to the stability and dispersion of GO particles, thereby synergistically optimizing the uptake of HMIs from water sources (Ayub and Othman, 2023;Giwa and Hasan, 2020). The remarkable properties of GO play a pivotal role in the adsorption mechanism. ...
... The vast surface area inherent to GO nanosheets provides an abundance of binding sites for metal ions. The functional groups present on GO, particularly the epoxy, carboxy, and keto moieties, actively participate in intricate interactions with metal ions (Ayub and Othman, 2023;Giwa and Hasan, 2020;Khan et al., 2021;Moradi et al., 2020). Electrostatic forces come into play as metal ions are drawn toward the charged functional groups residing on the surface of GO (Moradi et al., 2020). ...
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The WO3 nanostructures were modified by doping with iron and then the polyethersulfone (PES) ultrafiltration (UF) membrane was developed using prepared Fe⁰-doped WO3 photocatalytic nanoparticles via layer by layer technology. According to UV–vis diffuse reflectance spectroscopy (UV–vis/DRS) characterization, the photocatalytic activity of WO3 nanoparticles could be improved by doping with Fe impurity. The prepared membranes were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and contact angle analyzer. The novel photocatalytic membranes were used in removal of hexavalent chromium (Cr(VI)) ions in batch mode as well as filtration system. The novel photocatalytic membranes have shown significant Cr(VI) ions removal under visible-light illumination. By depositing the (CHI-ALG)3.5 bilayers on the PES/UF membrane surface, the Cr(VI) rejection for 5, 25 and 50 mg/l feed concentration were enhanced from 21%, 17% and 9% for neat PES to 56.3%, 41.6% and 30.1% for PES/ (CHI-ALG)3.5 membrane and 99.2%, 92.1% and 78.1% for PES/ (CHI-ALG)3.5/ Fe⁰@WO3 membrane, respectively.
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The advanced synthesis and development of raw graphene based on various significant functionalization has been outstanding in the wastewater treatment compared to the other alternatives such as carbon nanotubes and other carbon nanomaterials. Nano size graphene is known to possess large surface area and some promising properties in terms of mechanical, electrical, chemical and magnetism. Besides, the graphene can be generated via both Top-down and Bottom-up methods such as chemical exfoliation, chemical vapour deposition and other techniques so that it can be further functionalized to form graphene oxide-based nanomaterials. Hence, graphene oxide-based nanomaterials are discovered to be useful in the application of heavy metal removal from wastewater. In short, this paper critically reviewed on the synthesis method of graphene and application of graphene oxide-based nanomaterials in the term of heavy metal removal. The advantages, drawbacks, comparison of the data efficiencies, and research requirements are further highlighted, elaborated and discussed detailly. Lastly, the future challenges of graphene are elaborated. Therefore, it can be guaranteed that the wastewater discharged should be detected with the minimum or none of the heavy metals so that minimum effects on the ecosystem is discovered. © 2018 The Korean Society of Industrial and Engineering Chemistry
Article
A novel adsorbent for divalent metal cations was prepared as nanocomposite of Fe–Mg (hydr)oxide with graphene oxide by one-step coprecipitation. This material showed adsorption selectivity of Pb²⁺ > Cu²⁺ > Ag⁺ > Zn²⁺ ≫ Co²⁺, Ni²⁺, Cd²⁺ with high adsorption capacity of 100–600 mg/g for Pb²⁺, Cu²⁺, Ag⁺, and Zn²⁺. Distribution coefficient (Kd) was as high as ∼10⁷ mL/g for Pb²⁺ and Cu²⁺. The adsorption isotherms for Pb²⁺, Cu²⁺, Ag⁺, and Zn²⁺ followed the Langmuir model, indicating monolayer adsorption. The adsorption kinetics for Pb²⁺, Cu²⁺, Ag⁺, and Zn²⁺ followed pseudo-second-order model, suggesting chemisorption. Removal of 50 ppm Pb²⁺ or Cu²⁺ from 100 mL solution by 0.1 g of the nanocomposite was over 99.7%. The thermodynamics studies implied that the adsorption process toward heavy metals was spontaneous and endothermic. Together with recyclability through magnetic separation, this adsorbent would be useful in polluted water processing.
Article
To date, according to the latest literature inputs, membranes-based technologies (microfiltration, ultrafiltration and nanofiltration) have demonstrated to meet the recovery of biologically active compounds, mainly phenolic compounds and their derivatives, from agro-food products and by-products. The goal of this paper is to provide a critical overview of the on ongoing development works aimed at improving the separation, fractionation and concentration of phenolic compounds and their derivatives from their original sources. The literature data are analyzed and discussed in relation to separation processes, molecule properties, membrane characteristics and key factors affecting the performance of such technologies. Technological advances and improvements over conventional technologies, as well as critical aspects to be further investigated are highlighted and discussed. Finally, a critical outlook about the current status for a large-scale application and the role of these processes from an environmental viewpoint is provided.
Article
In this work, a novel sodium alginate (SA)/polyvinyl alcohol (PVA)/graphene oxide (GO) hydrogel microspheres were prepared by a simple method. Sodium alginate was physically crosslinked by Ca2+; GO was encapsulated into the composite to strengthen the hydrogels; PVA played a significant role in well dispersing of GO in SA. The SA/PVA/GO (SPG) hydrogels were employed as an efficient adsorbent for removal of Cu (II) and U (VI) from aqueous solution. Batch experiments with the subject of the pH, initial metal ion concentration, competing ions and contact time were investigated. Structure characterization was successfully conducted by FTIR, SEM, EDX, BET and XPS. Furthermore, the sorption kinetics of Cu2+ and UO22+ followed pseudo-second order model and exhibited 3-stage intraparticle diffusion model. Equilibrium data were best described by Langmuir model and the obtained maximum adsorption capacities of SPG hydrogel microspheres for Cu2+ and UO22+ were 247.16 and 403.78 mg/g, respectively. The difference in adsorption capacity can be confirmed by the percentage of elements in EDX spectra and the intension of peak of elements in XPS spectra. The SPG sorbent exhibited excellent reusability after 5 adsorption-desorption cycles. All results suggested that the prepared adsorbents could be considered as effective and promising materials for removal of Cu (II) and U (VI) in wastewater.
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The efficient removal of heavy metals (HMs) from the environment has become an important issue from both biological and environmental perspectives. Recently, porous metal-organic frameworks (MOFs), combining central metals and organic ligands, have been proposed as promising materials in the capture of various toxic substances, including HMs, due to their unique characteristics. Here we review recent progress in the field of water remediation from the perspective of primary HMs (including divalent metals and variable-valent metals) in water pollution and the corresponding MOFs (including virgin and modified MOFs, magnetic MOFs composites and so on) that can remove these metals from water. The reported values of various MOFs for adsorption of heavy metal ions were 8.40-313 mg Pb(II) g-1, 0.65-2173 mg Hg(II) g-1, 3.63-145 mg Cd(II) g-1, 14.0-127 mg Cr(III) g-1, 15.4-145 mg Cr(VI) g-1, 49.5-123 mg As(III) g-1, and 12.3-303 mg As(V) g-1. The main adsorption mechanisms associated with these processes are chemical (including coordination interaction, chemical bonding and acid-base interactions) and physical (including electrostatic interaction, diffusion and van der Waals force) adsorption, which were discussed in detailed. Further efforts should be made towards expanding the repertoire of MOFs that effectively remove multiple targeted HMs, as well as exploring possible applications of MOFs in the removal of HMs from non-aqueous environments.
Article
A novel hydrous iron-nickel-manganese (HINM) trimetal oxide was successfully fabricated using oxidation and coprecipitation method for metalloid arsenite removal. The atomic ratio of Fe:Ni:Mn for this adsorbent is 3:2:1. HINM adsorbent was identified as an amorphous nanosized adsorbent with particle size ranged from 30 nm to 60 nm meanwhile the total active surface area and pore diameter of HINM area of 195.78 m2/g and 2.43 nm, respectively. Experimental data of arsenite adsorption is best fitted into pseudo-second order and Freundlich isotherm model. The maximum adsorption capacity of arsenite onto HINM was 81.9 mg/g. Thermodynamic study showed that the adsorption of arsenite was a spontaneous and endothermic reaction with enthalpy change of 14.04 kJ/mol and Gibbs energy of -12 to -14 kJ/mol. Zeta potential, thermal gravimetric (TGA) and Fourier transform infrared (FTIR) analysis were applied to elucidate the mechanism of arsenite adsorption by HINM. Mechanism of arsenite adsorption by HINM involved both chemisorption and physisorption based on the electrostatic attraction between arsenite ions and surface charge of HINM. It also involved the hydroxyl substitution by arsenite ions through the formation of inner-sphere complex. Reusability of HINM trimetal oxide was up to 89% after three cycles of testing implied that HINM trimetal oxide is a promising and practical adsorbent for arsenite.
Article
The magnetic graphene oxide and MgAl-layered double hydroxide nanocomposite (MGL) was synthesized via a simple one-pot solvothermal method, and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrum (EDS), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM) and N2 adsorption-desorption. The results proved that the MGL nanocomposite had typical features of graphene oxide and MgAl-layered double hydroxide. Moreover, the MGL had magnetism which related to the fabrication of Fe3O4 during the solvothermal reaction, and could be easily separated from mixture with easy magnetic separation assistance. Subsequently, the MGL was used to evaluate the adsorption efficiency for lead, copper and cadmium in aqueous solutions by batch equilibrium experiments. The MGL showed excellent adsorption ability for Pb²⁺, Cu²⁺, and Cd²⁺. The pseudo-second-order kinetic equation and Langmuir model well fit the adsorption kinetic data and isotherm data, respectively. Furthermore, the adsorption mechanisms of Pb²⁺, Cu²⁺ and Cd²⁺ by MGL were detailed conducted by XRD and XPS analysis, and could be ascribed to the surface complexation, precipitation and isomorphic replacement.
Article
We investigate the removal of heavy metal ions from synthetic contaminated water on a laboratory scale using a carboxylated-graphene oxide (GO)-incorporated polyphenylsulfone (PPSU) nanofiltration membrane (the so called PPSU/carboxylated-GO nanocomposite membrane). The prepared membranes were characterized with respect to the rheology of the doping solutions and based on the morphology, topography, and charge density of the membranes. Spectroscopic analysis of the membranes was also performed. The nanofiltration performance was demonstrated by the removal of five heavy metal ions (arsenic, chromium, cadmium, lead, and zinc). The effects of carboxylated-GO on the membrane molecular weight cut-off, hydraulic permeability, and heavy metal ion removal performance were investigated with respect to different factors, including feed concentration from single ions, transmembrane pressure (TMP) with mixed ions, and permeate flux. The addition of carboxylated-GO produced a membrane with enhanced properties that exhibited superior performance. Increasing the feed concentration and TMP did not affect the removal of anions; however, the removal of cations slightly decreased with the resulting membrane. The maximum removal rates of heavy metal ions were >98% and ∼80% for the anions and cations, respectively, and an enhanced volumetric flux of 27 ± 3 L m⁻² h⁻¹ was observed. This result is based on the Donnan exclusion principle, which is attributable to the surface charge of −70 mV and the order of the hydrated metal radii. The prepared PPSU/carboxylated-GO nanocomposite membrane provided impressive heavy metal ion removal and showed an acceptable volumetric flux under the applied parameters; this work demonstrates very economically advantageous conditions for heavy metal ion removal.
Article
Poly 3-aminopropyltriethoxysilane is highly reactive high-molecular polymer because of the existence of abundant amino groups, which presents a strong affinity towards different metal cations. In view of this, the novel poly amino siloxane oligomer-modifed graphene oxide composite (PAS-GO) was fabricated by a facile cross-linking reaction and applied to capture U(VI)/Eu(III) ions from aqueous solution. The interaction mechanisms between the PAS-GO and U(VI)/Eu(III) were elaborated. The modification by -NH2 increased the sorption sites and improved the sorption capacities because of the synergistic effect of chelation with U(VI)/Eu(III). X-ray photoelectron spectroscopy revealed that nitrogen groups involved in the removal of U(VI)/Eu(III) since nitrogen atoms of amine groups provided the lone pair of electron with U(VI)/Eu(III) species. The maximum sorption capacity of U(VI) and Eu(III) on the PAS-GO at 298 K calculated by the Langmuir isotherm model was 310.63 and 243.90 mg/g, respectively. The PAS-GO could be repeatedly used for more than five cycles with slight degradation of sorption. High sorption efficiency and excellent reusability make PAS-GO composite an ideal candidate for the capture of U(VI)/Eu(III) from aqueous solution.
Article
Over the last decades, different polymers have been employed as continuous phase for preparing selective membranes for gas separation. Today, some of these materials have been consolidated commercially; however, the necessity to improve the performance (in terms of permeability/selectivity) of polymeric membranes above Robeson’s upper bound has been conducted by blending polymers, use of additives, implementation new methods, development of new materials, coating films, development of mixed matrix membranes, and so on. One of the most recent approaches is the use of polymers such as polyimides, i.e., Matrimid® 5218, which has demonstrated, to provide remarkable gas separation performance using the attempts aforementioned. The aim of this work is to present the current state-of-the-art of the use of Matrimid® 5218 in preparation of membrane for gas separation. The progress in this field is summarized and discussed chronologically in two periods, decade (from 1998 to 2008) and current (from 2009 up to now) frameworks. This contribution leads to take a complete and compelling overview of the state-of-the-art based on Matrimid. Furthermore, the main approaches, aim of study, gas separation evaluated, main techniques used for membrane characterization, main supplier of the polymer, main secondary materials for blending, fillers incorporated into the matrix, and remark of the study are summarized in detail. Finally, it denotes the prospects and future trends on use of Matrimid® 5218 for membrane applications.
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Organic solvent nanofiltration (OSN) is an emerging technology for molecular separation and purification in organic media. The separation performances are mainly depended on the material and structure of the membrane. In this study, Zeolitic Imidazolate Framework (ZIF-8) nanoparticles were in situ growth onto the surface of graphene oxide (GO) sheets to form [email protected] composites, which were co-deposited with polyethyleneimine (PEI) matrix on tubular ceramic substrate through a vacuum-assisted assembly method. The dispersion of ZIF-8 nanoparticles in PEI matrix as well as the compactness and uniformity of the composite membranes were readily improved due to the templating effect of lamellar GO sheets and the transmembrane pressure. Membrane performance in OSN was evaluated on the basis of methanol permeance and retention of dye molecules. Methanol permeance increased when [email protected] laminates were embedded into the PEI layer, whereas the retention remained higher than 99%. The improvement of separation performance may be due to the well dispersion of ZIF-8 nanoparticles in PEI matrix, which offers more well-defined pathways for solvent molecules. Building on these findings, we demonstrate a simple scalable method to obtain robust [email protected] based membranes with enhanced OSN performance.
Article
A graphene oxide-Polydopamine-(β-cyclodextrin) (GPC) ultrafiltration membrane was fabricated by using the method of drop-coating combined with vacuum filtration. The prepared GPC membrane was characterized with FTIR and XPS spectrophotometry and evaluated for its performances for the rejection of organic molecules (methylene blue) and adsorption of trace heavy metals (Pb(2+)) from aqueous solutions. The membrane exhibited an excellent rejection coefficient of 99.2% for methylene blue and the permeation flux was 12 L m(-2) h(-1) at 0.1 bar. The membrane also exhibited fast adsorption kinetics for Pb(2+) and the adsorption capacity was 101.6 mg g(-1) at a solution pH of 6. The performance of membrane could almost be completely recovered after a simple clean and regeneration process. These results indicate that the GPC membrane has potential applications in treatment of complex industrial wastewater streams.
Article
Elemental mercury (Hg0) is a widespread concern due to its high toxicity and long residence time in the environment. Various methods to remove mercury from the waste stream are available which includes the membrane based separation which becomes more preferable in waste water treatment area due to its ease of operation, mild operating condition and insensitivity to toxic pollutants. The membrane process in mercury removal from waste stream is continuously being improved by using various approaches, including material design. Graphene is a novel material which has unique properties due to its ultrathin layer and nanometer-sized pores. Moreover, graphene based membrane was used as a barrier for mercury vapor, which exhibit excellent performance for mercury vapor emission. Its application on membrane separation technique, especially nanofiltration is currently being explored. The purpose of the present study is to investigate the mercury removal using functionalized graphene nanofiltration. The main focus is the effectiveness of the separation process which also considers the operating conditions and the drawbacks during the process.
Article
In this paper, an in-L polymerization technique was employed to functionalize GO nanoparticles using polyaniline (PANI). In this regard, nanocomposite membranes were prepared by embedding [email protected] nanoparticles into matrix of PES membrane, and characterized by measuring permeability, porosity, mean pore size and water contact angle as well as by the use of scanning using SEM and AFM. Moreover, response surface method, based on central composite design (CCD) experimental plan, was utilized to analyze, to model and to optimize the efficacy of membranes in removal of Pb²⁺ from water. In general, addition of nanoparticles into the membrane matrix decreased its permeability, porosity and hydrophilicity; however, lead removal increased noticeably. To add to that, it should be noted that decreasing the feed concentration and increasing the solution pH caused an increment in lead removal from water, and nanocomposite membrane fabricated by 0.25 wt.% of nanoparticles successfully removed almost all Pb²⁺ from water. In order to investigate the adsorption mechanism, the isotherm model and the kinetic of adsorption were experimented, and based on the outcomes, the Langmuir isotherm and pseudo-first order kinetic offered the most appropriate models for fitting the adsorption of Pb²⁺ ions onto the membrane. As a further point, results of reusability tests indicated the ability of membrane in removal of lead ions from water after several sequential adsorption-desorption tests.
Article
The decontamination of selenium (Se) and arsenic (As) from aqueous environments has been an emerging area for membrane technology. They are difficult to be removed because of various oxidation states, range of toxicity and solubility. In this work, three water stable zirconium metal-organic framework (MOF) UiO-66 nanoparticles with different diameters, i.e., 30, 100 and 500 nm, have been synthesized and incorporated into the selective layer to form thin-film nanocomposite (TFN) membranes. These membranes were tailored to remove the Se and As concurrently. Comparing to the thin-film composite (TFC) membranes, the TFN membranes exhibit higher pure water permeability (PWP) and rejections for both pollutants due to their smaller pore size and higher hydrophilicity. In addition, the TFN membrane comprising 30 nm UiO-66 has the best performance among the three TFN membranes. The effects of particle loading have also been investigated for the 30 nm UiO-66 TFN membranes. The TFN membrane containing 0.15 wt% UiO-66 has the highest PWP of 11.5 LMH/bar and remarkable rejections of 96.5%, 97.4% and 98.6% toward SeO3²⁻, SeO4²⁻ and HAsO4²⁻, respectively. Higher rejections are also achieved in the concurrent removal of Se and As. Additionally, the TFN membrane exhibits robust long term stability. To our best knowledge, this is the first work to study the particle size and loading effects of UiO-66 particles in the selective layer of TFN membranes for Se and As removal. The results achieved in this work may provide promising insights for the development of next generation NF membranes with superior performance.
Article
Graphene-based materials have been extensively employed for removal of heavy metals and radionuclides from water and wastewater. This work critically reviews the current status of researches on the use of graphene as well as its modified materials, and their efficacy for the adsorption of heavy metals and radionuclides. It focuses on the examination of different factors influencing the adsorption capacity, including the properties of graphene-based materials, solution pH, contact time, initial concentration of metal ions, initial dosage of graphene-based materials, temperature, organic acid ligands, co-existing ions and competitive adsorption. Adsorption dynamics, isotherms and thermodynamics are addressed in some detail. The proposed adsorption mechanisms deduced by various characterization methods and analytical techniques involve in one or combination of electrostatic interaction, surface complexation, ion exchange, reduction and precipitation. Many of the graphene-based materials have proved to be stable and regenerable over a number of adsorption-desorption cycles. Further research trends on practical application of graphene-based materials are also given.
Article
Graphene oxide (GO) has recently emerged as a new membrane material for high performance separation processes. The separation mechanisms, together with the manipulations of microstructures and surface properties of GO membranes have been well studied for the nanofiltration (NF) process. In this review, current achievements of GO membranes for NF applications are highlighted. Furthermore, the challenges and future research directions toward the stability enhancement and scale-up production of GO membranes are discussed.