Elaboration and characterization of new conductive porous graphite membranes for electrochemical advanced oxidation processes (original) (raw)
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The Journal of Physical Chemistry C, 2017
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A novel composite electrode was constructed by pressing together Co 3 O 4 and graphite and it was used as the cathode in an electro-Fenton-like (EFL) system. The poor electron transport characteristic of Co 3 O 4 was overcome by incorporating graphite. In situ electro-catalytic generation of hydroxyl radicals (·OH) occurred at high current efficiencies from pH 2-10, extending the traditional Fenton reaction pH range. Cyclic voltammetry and AC impedance spectrometry were used to characterize the composite electrode. The ability of the EFL system to degrade organic compounds was investigated using sulforhodamine B (SRB) and 2,4-dichlorophenol (2,4-DCP) as probes. Decoloration of SRB (1.0×10 5 mol/L) was complete (100%) in 150 min and SRB was effectively degraded from pH 2-10. The decomposition of SRB was studied using Fourier transform infrared spectroscopy (FT-IR) and total organic carbon (TOC) analysis and results indicated that the final degradation products were carbon dioxide, carboxylic acids and amines. The EFL system also decomposed 2,4-DCP and the degradation was 98.6% in 240 min. Electro-catalytic degradation of SRB occurs by a ·OH mechanism. After 5 times reused, the degradation rate of SRB did not significantly slow down. The electrode shows excellent potential for use in advanced oxidation processes (AOPs) used to treat persistent organic pollutants (POPs) in wastewater.
Application and prospects of carbon nanostructured materials in water treatment: A review
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The search for novel and cost-effective material for water treatment is one of the ongoing challenges. Among the various new materials, carbon-based nanostructured materials (CNMs) are considered to be the most robust and versatile candidate for the effective treatment of water. Carbon nanotubes (CNTs), graphene oxide (GO) and reduced graphene oxide (rGO) have enticed wide attention, and these materials can be used in a variety of applications due to its superior physio-chemical properties. The CNMs and their composites have been employed to develop unique adsorbents, novel catalytic materials and high-performance membranes with superior permeation properties for the removal of unwanted species from (waste)water. This review article presents a critical assessment of the existing literature on CNTs, GO and rGO in the field of adsorption, catalytic degradation, and membrane technology for water treatment. In addition, structural properties, challenges, and prospects of carbon nanostructured materials for decontamination of water are discussed.
Chemical Engineering Journal, 2021
This work presents a ceramic tubular membrane coated with a continuous graphene-TiO 2 nanocomposite thinfilm for contaminants of emerging concern (CECs) removal from synthetic and real matrices in single-pass flow-through operation. Microfiltration ceramic membranes were coated in situ with graphene (G)-TiO 2-P25 nano-composite using two different methods: Membrane type A-TiO 2-P25 incorporated in the G preparation stage (1% [MA-1], 2% [MA-2] and 3% [MA-3] [w/v]), and Membrane type B-TiO 2-P25 thin-film uniformly coated over the G film surface (coating layers: 3 [MB-1], 6 [MB-2], and 9 [MB-3]). After the catalyst deposition and before the pyrolysis step, air was forced to pass through the membranes pores (inside-outside mode), providing a porous film. The CECs solution (diclofenac-DCF, 17β-estradiol-E2, 17α-ethinylestradiol-EE2 and amoxicillin-AMX) was prepared using Ultrapure water (UPW) or an urban wastewater after secondary treatment (UWW) fortified with 500 µg L − 1 of each CEC. Membranes were characterized by the following techniques: Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Fourier-Transform Infrared spectroscopy (FTIR), Diffuse Reflectance UV-Visible spectroscopy (DR UV-Vis) and Raman spectroscopy. The membranes coated with MA-3 and MB-2 catalyst films, irradiated by UVA light, showed the highest ability for CECs removal. Furthermore, the Relative flux reduction ratio (RFR) decreased around 45% in the absence of UVA light, owing to membrane fouling. The combination of filtration and oxidation (G-TiO 2-UVA) provided a permeate with higher quality and minimized membrane fouling. Although membrane type B allowed for a permeate with higher quality, membrane type A provided a higher permeate flux.
Reduced graphene oxide filtration membranes for dye removal – production and characterization
Proceedings of 2nd International Online-Conference on Nanomaterials, 2020
Dye removal from manufacturing and textile industry wastewater is one of biggest challenges in plants. The improper disposal of water with residual dyes can contaminate effluents and fresh water sources. In this work, filtration membranes based on reduced graphene oxide (rGO) were fabricated by spray coating method, and its capability to remove dyes from water was evaluated. Graphene oxide was prepared by modified Hummers method and posteriorly reduced with ascorbic acid; a simple and fast spray coating fabrication method was employed to produce stable membranes, which were analyzed in a home-made permeation cell. Raman spectroscopy and scanning electron microscopy (SEM) were able to prove that rGO dispersion was formed by graphene flakes with about 45.9 μm of lateral dimension; X-ray diffraction, SEM and Raman analyses indicate that spray method was efficient in producing stable and uniform filtration membranes; UV-vis absorption spectra of feed and permeation solution indicate that rGO membranes were capable in removing dye from water. By the main results, it is possible to affirm that rGO filtration membranes are an efficient, low-cost, scalable and fast way to remove dyes from wastewater.
Current State of Porous Carbon for Wastewater Treatment
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Porous materials constitute an attractive research field due to their high specific surfaces; high chemical stabilities; abundant pores; special electrical, optical, thermal, and mechanical properties; and their often higher reactivities. These materials are currently generating a great deal of enthusiasm, and they have been used in large and diverse applications, such as those relating to sensors and biosensors, catalysis and biocatalysis, separation and purification techniques, acoustic and electrical insulation, transport gas or charged species, drug delivery, and electrochemistry. Porous carbons are an important class of porous materials that have grown rapidly in recent years. They have the advantages of a tunable pore structure, good physical and chemical stability, a variable specific surface, and the possibility of easy functionalization. This gives them new properties and allows them to improve their performance for a given application. This review paper intends to understa...
Electrochemically oxidised graphite
Carbon, 2000
An evaluation of some of the properties of electrochemically oxidised graphite has been carried out. These studies include textural characterisation, magic angle spinning NMR, ESR and ion exchange properties. A study of the surface morphology has also been carried out using high-resolution transmission electron microscopy and identification of surface groups confirmed by FTIR spectroscopy. The electrochemical method of preparation is shown to confer, to the porous graphite oxide obtained, different surface chemical groups that can be used for ion exchange purposes. ESR shows that Cu(II) is coordinated to the oxidised graphite.
Journal of Materials Science, 2016
Graphene has a great potential to substitute other amorphous carbon materials and has been widely used in many water and wastewater treatments such as purification or photocatalytic processes. Graphene powder with different degrees of oxidation was synthesised and subsequently used to prepare supported membranes. Ceramic porous materials were chosen as membrane support due to the robustness and long life required in a likely application. Ultrathin membranes (7-9 lm) were successfully prepared through vacuum filtration of highly oxidised graphene or reduced graphene oxide solutions (1 mg ml-1). The influence of depositing different amounts of membrane precursor was extensively studied (0.003-0.037 mg cm-2); above 0.037 mg cm-2 , drying-related shrinkage problems are detected. Moreover, the ceramic support pore size (SPS) (0.008-0.08 lm) shows little impact in terms of the overall membrane flux resistance, and the deposited graphene layer usually governs the membrane permeation. Finally, long-term filtration experiments were also performed for weeks without substantial variation of the membrane structure or permeation (B2 %), which is demanded in most conventional water treatments. Overall, the addition of partially oxidised graphene to conventional ceramic membranes greatly decreases their electrical resistivity (*2.8 9 10-5 X m), opening up the possibility of being employed for many environmental purposes.
Journal of Membrane Science, 2009
This work (designated Part 2 of this study) aims to further discuss the present authors' research findings relevant to that of reported earlier (designated Part 1 of this study). In Parts 1 and 2 of this study, carbon fibers/carbon/alumina tubular composite membranes (CCA-TCMs) were first prepared through substrate formation, polyvinylidene chloride (PVDC) film wrapping, PVDC carbonization, catalyst precursor coating, and the chemical vapor deposition (CVD) process. The finished CCA-TCMs, with a pore size distribution ranging from 2 to 20 nm and a nominal pore size of ca. 3.5 nm, were further characterized by environmental scanning electron microscopy (ESEM), high-resolution transmission electron microscopy (HR-TEM), and permporometry. The so prepared CCA-TCMs were incorporated into a crossflow simultaneous electrocoagulation and electrocoagulation (EC/EF) treatment module to evaluate their capabilities in treating Cu-CMP (chemical mechanical polishing of the copper layer) wastewater obtained from a wafer fab. Crossflow EC/EF performance tests were carried out based on the Taguchi experimental design using the electric field strength, crossflow velocity, transmembrane pressure, and filtration area as the experimental factors. Under the optimal operating conditions, the EC/EF treatment module coupled with CCA-TCMs are capable of treating Cu-CMP wastewater to yield permeate with a turbidity of below 0.3 NTU. In the meantime, the removal efficiencies ranging from 82 to 91% for total solids (TS), total organic carbon (TOC), Cu, and Si could be obtained. By comparing the results of Part 1 and Part 2 of this study, the optimal operating conditions determined from the experimental designs based on the fractional factorial and Taguchi method yielded similar good qualities of permeate. A further evaluation of the technical significance of this study shows promising fundamental and practical results.
An activated carbon fiber-supported graphite carbon nitride for effective electro-Fenton process
Electrochimica Acta, 2018
Advanced oxidation processes based on the electro-Fenton process are alternative technologies for water and wastewater remediation. In the present work, an activated carbon fiber-supported graphite carbon nitride (g-C 3 N 4 /ACF) was prepared by a wet impregnation method, followed by calcination. The results from scanning electron microscopy and X-ray photoelectron spectroscopy demonstrated that the g-C 3 N 4 was successfully supported on the surface of the ACF, leading to a slight decrease in the Brunauer-Emmett-Teller surface area. In the presence of externally added Fe 2+ to the electrolyte, the g-C 3 N 4 /ACF used as a cathode exhibited a relatively higher activity in the electrochemical degradation of aqueous rhodamine B (RhB) compared to the ACF cathode. The effect of several experimental conditions, such as initial pH, current density, the quantity of Fe 2+ added, and the loading amounts of g-C 3 N 4 , on the removal of total organic carbon was explored. In the range investigated, the mineralization of RhB had the most rapid progression, with an initial pH of 3.0, current density of 3.0 mA cm-2 , initial Fe 2+ concentration of 0.25 mM and g-C 3 N 4 load of 0.03 g. The removal efficiency of total organic carbon was ~91% after 240 min of electrolysis. In addition, the g-C 3 N 4 /ACF electrode was stable as evidenced by five successive cyclic tests. On the basis of quantitative measurements of iron (zero-valent iron, ferrous ion, and ferric ion) and qualitative determination of hydroxyl radicals, and with the help of electrochemical characterization in the form of linear sweep voltammetry, cyclic voltammetry and chronoamperometry, it could be concluded that