Graphite Waste Research Articles

Investigation of the mechanism for simulated graphite waste treatment via microwave sintering technology

With the decommissioning of nuclear facilities, an increasing amount of radioactive graphite needs to be treated safely and effectively. In this work, microwave sintering technology was initially applied to treat simulated graphite waste. The effects of microwaves on the phase composition and microstructure of graphite were investigated. Combined with the mass loss results and fitting results of the phase, the mechanism for simulated graphite waste treatment via microwave sintering was obtained. According to the results, there are three stages regarding the effect of microwave sintering on the microstructure of graphite waste. This work reveals the potential application of microwave sintering technology in the treatment of graphite waste and its treatment mechanism.

Graphene oxide synthesized from zinc-carbon battery waste using a new oxidation process assisted sonication: Electrochemical properties

The purpose of this paper is to fabricate graphene oxide (GO) from carbon rods of spent (ZnC) batteries using a new optimized approach in electrochemical applications. The proposed method-based sonication for the recycling of carbon rods was adopted as a fast and economical process via a less aggressive pathway. The energy reaction time and explosion problems were avoided by the proposed protocol. The waste graphite powder (carbon rods) and the powder produced by the developed method-based sonication (SGO) were characterized by UV–Visible, XRD, FTIR and SEM. The electrochemical performance of the prepared SGO was evaluated by cyclic voltammetry (CV) and current-voltage (I–V) techniques. The results revealed that SGO has a higher electrocatalytic property compared to the graphene oxide by the standard Hummers method (HGO).

Preparation and properties of situ-sintered SiC ceramics aided by ZnO-Al2O3-CaO

The safe treatment and disposal of radioactive graphite waste is becoming an important issue worldwide. The objective of this paper is to prepare the SiC-ZAC (ZAC: ZnO-Al2O3-CaO) composite ceramic for immobilizing radioactive graphite, where ZAC is as sintering additives. The effects of the sintering system and ZAC content on the phase compositions, microstructure, and properties of SiC-ZAC composite ceramic are studied by XRD, SEM-EDS, TEM-EDS, linear shrinkage, Vickers hardness, and thermal conductivity. By vacuum hot pressing sintering at 1600 °C for 1 h, the results show that the S-35-1600 (65 wt% SiC, 10.5 wt% ZnO, 15.72 wt% Al2O3, 8.78 wt% CaO) sample is the potentially applicable formula composition due to its better performance, in which the Vickers hardness and the thermal conductivity are 165.2 HV10, 14.6 W m−1 k−1 respectively, and the normalized elemental mass loss of Si, Al and Ca are 0.0064–0.0108 g/m2, 21.4784–24.7837 g/m2, 56.9108–67.5637 g/m2 after 42 days at pH = 5/7/9 solution, respectively. Importantly, ZAC sintering additives can form the bond phases of CaAl4O7, CaAl2O4, Ca3Al2(OH)12, and Ca2Al2SiO7 under relatively low temperatures to reduce the sintering temperature for SiC ceramics. Meanwhile, the existing form of the Zn element is revealed: one part of the Zn forms glass phase, and the other part volatilized by carbothermic reduction.

Comparative impact of gamma radiation on reinforced nitrile rubber with graphite and agro waste activated carbons

Abstract In this article, graphite fine powder and two types of activated carbon (AC) namely based-on waste corn and sugarcane bagasse were implemented as reinforcers for the nitrile rubber (NBR). Both types of AC were prepared through a low-temperature chemical carbonization treatment. Each type of these fillers, at 5, 10, and 15 wt%, was mixed with NBR on a rubber mill and pressed under heat to develop sheets to be gamma irradiated at 100 kGy. Filler characterization using Fourier Transform Infrared spectrophotometer (FTIR) spectroscopy and scanning electron microscopy (SEM) were discussed. X-ray diffraction (XRD) proved that graphite has a crystalline structure but corn and bagasse ACs have amorphous nature. Furthermore, dynamic light scattering (DLS) analysis was used to determine the particle size of the studied fillers. In addition, mechanical properties, XRD, thermal stability, and SEM of the prepared unirradiated or irradiated NBR‒composites were investigated. The physicomechanical features of the NBR matrix could be enhanced by the presence of reinforcing fillers, even at relatively low filler loading. The composites filled with graphite showed superior mechanical parameters and also have the highest thermal stability as indicated by their high-temperature mass loss (Tm). Generally, irradiated samples expressed grander properties than unirradiated ones as a result of the radiation-induced crosslinking structures.

Structural and radiological characterization of irradiated RBMK-1500 reactor graphite

This study aims to characterize the irradiated RBMK-1500 nuclear graphite in terms of both structural and radiological properties. The experimental results of morphological and structural analysis of the irradiated graphite samples by using SEM, Raman spectroscopy as well as the theoretical evaluation of primary displacement damage are presented. Moreover, the experimental and theoretical evaluation of the neutron flux is provided and the presence of several γ emitters in the analyzed graphite samples is assessed. Furthermore, the improved version of rapid analysis method for 14C activity determination is applied and the experimentally obtained results are compared with calculated ones. Results indicate that structural changes are uniform enough in all the analyzed samples. However, the distribution of radionuclides is non-homogeneous in the irradiated RBMK-1500 reactor graphite matrix. The comprehensive understanding of both structural and radiological characteristics of nuclear graphite is very important when dealing with decision about irradiated graphite waste management strategy or treatment options prior to its final disposal.

Graphite Foil Waste to Graphene: New Carbon Precursors for Synthesis of Graphene and its Oxides

In this paper, graphene oxide (GO) was obtained by oxidation of powdered graphite foil wastes (pGFW) at 0 - 40°C. Oxidizing reagents can easily penetrate the layers of graphite foil and thus, the intercalation or functionalization-oxidation processes may occur resulting in graphite oxide formation. The methods of synthesis of GO and its separation from the reaction mixture were partially corrected. GO was reduced, also, to the reduced graphene oxide (rGO) by using hydroiodic acid, ascorbic acid, zinc powder, hydrazine, and Alnus extract. Thermal treatment of GO powders and GO films, obtained from pGFW was implemented at 20-300° C in air and at 20-1000° C under argon flow and in a vacuum. At high-temperature treatment (1000°C) of GO graphene was obtained with a defective structure.

Electrochemical preparation of graphene from waste battery-electrodes directed to organic dyes removal in aqueous solution

In this research, we present a new method for preparation of graphene from waste zinc carbon battery (ZCB) electrodes using electrochemically exfoliation via a intercalating of sulfate ions into the graphitic layers at different D.C. voltages and optimized conditions (i.e., electrolyte medium and applied voltage). The synthesized graphene was characterized by X-ray diffraction (XRD), Raman spectroscopy and Scanning/Transmission electron microcopy (SEM/TEM). The synthesized graphene has been used as the adsorbents for efficient removal of methylene blue (MB) as a cationic dye from aqueous solutions to test their qualities. Results shown that the equilibrium adsorption capacity (qe) of prepared graphene samples are from 92.32 mg.g-1 to 99.73 mg.g-1 which are extremly higher than that of the pristine waste graphite electrode (5.03 mg.g-1) or powdered waste electrode graphite (40.05 mg.g-1). These obtaned results indicated that the graphene can be produced from waste graphite electrodes by electrochemical method, which can be considered as an eco-friendly method not only for production of quality graphene but also for reuse of waste graphite electrodes.

Eco-safe chemicothermal conversion of industrial graphite waste to exfoliated graphene and evaluation as engineered adsorbent to remove toxic textile dyes

Industrial graphite becomes waste after its use and dumping of such graphite waste leads to environmental damage and health risks, thus needs alternative measures. This study is the first of its kind to convert industrial graphite to exfoliated graphene(EG) and using EG as an adsorbent. The used conversion method is chemicothermal which is greener and competent. The resultant EG was micro-analyzed for its application as an engineered adsorbent. The adsorption capacity of EG is tested for the removal of five toxic dyes from aqueous solution, namely royal blue (RB), turquoise blue (TB), black supra (BS), navy blue (NB), and deep red (DR) for various environmental conditions. The order of adsorption at equilibrium was found to follow, DR > TB > BS > NB > RB at circum-neutral pH in the range of 5 - 25 mg/L of dye, having 0.2 gm of EG. The notable adsorption capacity of dye onto EG can be credited to the various interface mechanisms which were studied using kinetic and thermodynamic models. The reusability studies recommend EG as the alternate adsorbent against commercial activated carbon which holds a huge carbon and water footprint. These results suggest that the applicability of potential EG adsorbent can be extended to the removal of organic pollutants in water and wastewater treatment. The success of converting graphite waste to an engineered dye adsorbent couples the advantages of converting industrial waste to a beneficial product and removal of toxic dyes thus achieving the circular economy and sustainable development in industrial practices.

Decrease in the activity of irradiated graphite and liquid radioactive waste

Nowadays, the problem of nuclear waste deactivation is very urgent. The method proposed consists of exposing the aqueous solution of radionuclide to powerful nanosecond electromagnetic pulses by placing the treated solution between two electrodes connected to the outlets of the generator. Single-pole current pulses with a length of 1 ns, an amplitude of more than 5 kV, and a repetition frequency of 1 kHz are used. Such pulses can be obtained from the generator units with an amplitude of 5 kV to 15 kV. They have a pulse capacity of 1 to 4 MW, and the mains capacity is below 50 W. The pulse action leads to radiolysis of water and accelerated decay of radionuclides. As a result of radiolysis, hydrated electrons, hydrogen atoms, and various radicals are formed that causes precipitation of radionuclides, such as 137Cs and 90Sr. The description of several experiments and results of experimental investigations of the influence of powerful nanosecond electromagnetic pulses on the properties of water solutions with radioactive nuclides 137Cs and 90Sr and on items of irradiated graphite is presented. Under the influence of pulses on real liquid waste and aqueous solutions, radioactive nuclides in water are reduced by 5 to 50 times during 15 minutes. The effect described is preserved for 20 days. The reduction of beta activity twice during 25 min is observed in big blocks of the irradiated graphite. Flow-through unit for processing of liquid waste is developed, tested, and patented (RU 2726145. MPK G21F 9/28, July 7, 2020). This technology can be used to treat emergency solutions with tritium at Fukushima NPP. of the irradiated graphite.

Co-Solvent Free Electrochemical Synthesis of Biodiesel Using Graphite Electrode and Waste Concrete Heterogeneous Catalyst: Optimization of Biodiesel Yield

This study optimized a co-solvent free electrochemical method for biodiesel synthesis using graphite electrode and waste concrete heterogeneous catalyst. Various parameters were evaluated, including: applied voltage (9.6, 14.4, 19.2 V), catalyst particle size uniformity (unfiltered and filtered with 150 mesh), and reaction time (15, 30, 120, 240 min). The results obtained 100% FAME content and 78.51% of biodiesel yield that were achieved at 14.4 V within 30 min using filtered catalyst and cooking oil feedstock. However, a slight decline was observed with the use of waste cooking oil. This optimized method offers a reliable and simple condition for mass biodiesel production. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Enhancement of bioelectric parameters of multi-electrode plant–microbial fuel cells by combining of serial and parallel connection

Innovative electro-biotechnology of plant–microbial fuel cell involves the use of electrodes for the collection of bioelectricity produced by soil rhizosphere microorganisms, utilizing products of photosynthesis and plant residues compounds. The performance of plant–microbial electro-biosystem is highly dependent on the electrode materials and their configurations. Various materials as electrodes for electro-biosystems were analyzed, conducting experiments in laboratory with indoor plants and in situ with forest and garden plants. Graphite wastes of electric transport as cathodes and perforated zinc-galvanized steel plates as anodes were selected as electrodes for plant–microbial fuel cell due to their electro-efficiency, low cost and sustainability in environment. To design multi-electrode system, electrodes were connected each other by copper wires into cathode and anode system. The use of graphite wastes and polyvinyl chloride-insulated copper wires promoted reduction of the cost of electro-biotechnology. Multi-electrode plant–microbial fuel cells with 12 anodes and 11 cathodes with Caltha palustris plants at 10 Ω produced current of 40.98 mA that is 10.1 times more than mono-electrode plant–microbial fuel cells. The parallel connection of two multi-electrode electro-biosystems was resulted in 2.1-fold increase in current compared to the current generated by the one multi-electrode electro-biosystem. The serial connection of three multi-electrode plant–microbial fuel cells was led to an increase in the bioelectric potential in 2.9 times; at the same time, their parallel connection did not increase voltage. Variations of parallel–serial connections of several multi-electrode plant–microbial fuel cells as energy subunits into one complex multi-electro-biosystem were appeared the way to maximize the receiving of plant–microbial bioelectricity.

Utilization of waste graphite crucible for the fabrication of ex-situ AA1100/Graphite composite via stir casting route

This study presents the fabrication of aluminium alloy based ex-situ composite, where waste graphite crucible in the form of powder has been utilized as a reinforcement. X-ray diffractometer (XRD) has been employed for phase analysis and confirmed the presence of the carbon phase in the composite. Optical microscopy (OM), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) have been employed for microstructural analysis and confirmation of Gr particles. OM reveals the existence of second phase graphite (Gr) particles which attribute the grain refinement of the matrix. SEM and EDX confirm the presence and distribution of Graphite particles. To illustrate the effect of graphite content on mechanical properties of composite, tensile strength, hardness, and percentage elongation have been evaluated. Three compositions with 0, 3, and 6 wt% (wt %) of graphite were prepared. Analysis of mechanical characteristics reveals that as Gr content increases till 3 wt% leads to improvement in the tensile strength as well as in hardness of composites but further enhancement in Gr content till 6 wt% shows a decrease in the tensile strength, while a very minor change in hardness of the composite.

N,N′-Bis-(2-aminoethyl)piperazine functionalized graphene oxide (NAEP-GO) as an effective green corrosion inhibitor for simulated acidizing environment

In this work we evaluated the corrosion inhibition efficacy of N,N′-Bis-(2-aminoethyl)piperazine functionalized graphene oxide (NAEP-GO) against carbon steel in 15% HCl which simulate oil well acidizing environment by weight loss (at ambient and higher temperatures) and electrochemical measurement experiments. The GO was synthesized using waste graphite, after which N,N′-Bis-(2-aminoethyl)piperazine was grafted onto the GO. Both the GO and NAEP-GO were characterized by FTIR, Raman and TEM techniques. The effect of concentration, temperature and time on the performance of the inhibitor was investigated in this study. The inhibitor efficiency was observed to increase with concentration and a maximum inhibition efficiency of 87% was observed for 25 ppm NAEP-GO at room temperature. The inhibitor exhibited excellent performance at the studied temperatures, however the performance decreases with increase in temperature. The inhibitor showed excellent efficiency of over 80% for all the studied immersion time. The PDP measurement revealed the NAEP-GO to acts predominantly as a cathodic-type inhibitor. The studied compound was observed to obey the Langmuir adsorption isotherm. SEM/EDS, AFM surface morphology and FT-IR analyses of the corrosion product after 24 h′ immersion in the NAEP-GO inhibited solution provide evidence of adsorption of NAEP-GO molecules on the steel surface to form the protective NAEP-GO film that blocked the steel surface from the aggressive acid attack. This study is of importance in solving two main environmental problems, corrosion and the problem of waste disposal as GO was prepared from waste graphite.

Facile preparation of N-S co-doped graphene quantum dots (GQDs) from graphite waste for efficient humidity sensing

In this work, graphene quantum dots (GQDs) were prepared from Graphitic waste. The resulting GQDs were evaluated for the potential application for resistive humidity sensors. The resistive humidity sensors were fabricated on the pre-patterned interdigital ITO electrodes using the three different concentrations (2.5, 5.0, and 10 mg) of GQDs in DMF. The GQDs films were deposited using the spin coating technique. The GQDs (10 mg/ml) based impedance sensors showed good sensitivity and lowered hysteresis as compared to the other ratios (2.5 and 5 mg) of the GQDs. The maximum calculated hysteresis of the GQDs (10 mg) based humidity sensor is around 2.2 % at 30%RH, and the minimum calculated hysteresis of the GQDs (10 mg/ml) based humidity sensor is approximately 0.79 % at 60 %RH. The response and recovery time found to be 15 s and 55 s, respectively. The interesting humidity-dependent resistive properties of these prepared GQDs make them promising for potential application in humidity sensing.

Development of a multi criteria decision analysis framework for the assessment of integrated waste management options for irradiated graphite

An integrated waste management approach for irradiated graphite was developed during the European Commission project ‘Treatment and Disposal of Irradiated Graphite and other Carbonaceous Waste’. This included the identification of potential options for the management of irradiated graphite, taking account of storage, retrieval, treatment and disposal methods. This paper describes how these options can be assessed using multi-criteria decision analysis (MCDA) for a case study relating to a generic power reactor. Criteria have been defined to account for safety, environmental, economic and socio-political factors, including radiological impact, resource usage, economic costs and risks. The impact of each option against each criterion has been assessed using data from the project and the wider literature. A linear additive approach has been used to convert the calculated impacts to scores. To account for the relative importance of the criteria, example weightings were allocated. This application has shown that MCDA approaches can be used to support complex decisions regarding irradiated graphite management, accounting for a wide range of criteria. Use of this approach by individual countries or organisations will need to account for the specific options, scores, weightings and constraints that apply, based on their national strategies, regulatory requirements and public acceptability.

Poly(methyl methacrylate)-graphene emulsion prepared via RAFT polymerization and the properties of NR/PMMA-graphene composites

Poly(methyl methacrylate) (PMMA)-graphene emulsion was prepared via reversible addition-fragmentation chain-transfer (RAFT) polymerization using a hydrophilic macro-RAFT agent. In addition, the graphene was prepared using waste graphite from a metal smelting industry to reduce the cost of polymer composites and be more eco-friendly. The graphene oxide (GO) was synthesized via the Hummers method and the modified Hummers method (without using sodium nitrate) and then modified to reduced (r)GO using L-ascorbic acid as the reducing agent. Transmission electron microscopy and zeta potential analyses revealed the PMMA attached to the graphene surface with a good stability. Moreover, the PMMA-graphene composites as the fillers in natural rubber latex could improve the mechanical properties and electrical conductivity of the composite films.

High-value utilization of graphite electrodes in spent lithium-ion batteries: From 3D waste graphite to 2D graphene oxide

The graphite electrodes of spent lithium-ion batteries (LIBs) have a good crystalline composition and layered structure, and the recovery potential is promising. However, the internal and external surfaces of the waste graphite are often polluted with various organic and inorganic impurities, which seriously restrict its high-value utilization. Herein, the microstructure and surface analysis of waste graphite at variable scales were carried out systematically to reveal the types and occurrence status of impurities and their influence on the preparation of graphene oxide (GO) using a modified Hummers method. The results show that the graphite surface contaminants are polyvinylidene fluoride binder, LiPF6 electrolyte and LiF residue from the solid electrolyte interface, while residual lithium (Li2CO3) and CuO were found to have invaded the crystal structure of graphite. Fortunately, the modified Hummers method can effectively remove these complicated associated impurities and prevent their re-contamination on the GO surface. More importantly, the modified Hummers method can not only destroy the longitudinal molecular bonds between graphite layers, but also splice them horizontally to form 2D GO, which is verified by high-resolution transmission electron microscope (HR-TEM) images. This paper provides theoretical support and practical guidance for the high-value utilization of waste graphite in spent LIBs.

Interfacial photothermal water evaporator based on nanoporous microwave‐expanded graphite and coconut waste fibers@recycled polystyrene as substrate

Interfacial photothermal water evaporator based on nanoporous microwave‐expanded graphite and coconut waste fibers@recycled polystyrene as substrate

Effective regeneration of high-performance anode material recycled from the whole electrodes in spent lithium-ion batteries via a simplified approach

Along with the extensive application of energy storage devices, the spent lithium-ion batteries (LIBs) are unquestionably classified into the secondary resources due to its high content of several valuable metals. However, current recycling methods have the main drawback to their tedious process, especially the purification and separation process. Herein, we propose a simplified process to recycle both cathode (LiCoO2) and anode (graphite) in the spent LIBs and regenerate newly high-performance anode material, CoO/CoFe2O4/expanded graphite (EG). This process not only has the advantages of succinct procedure and easy control of reaction conditions, but also effectively separates and recycles lithium from transition metals. The 98.43% of lithium is recovered from leachate when the solid product CoO/CoFe2O4/EG is synthesized as anode material for LIBs. And the product exhibits improved cyclic stability (890 mAh g−1 at 1 A g−1 after 700 cycles) and superior rate capability (208 mAh g−1 at 5 A g−1). The merit of this delicate recycling design can be summarized as three aspects: the utilization of Fe impurity in waste LiCoO2, the transformation of waste graphite to EG, and the regeneration of anode material. This approach properly recycles the valuable components of spent LIBs, which introduces an insight into the future recycling.

Ecofriendly synthesis of MWCNTs by electric arc in aqueous medium: Comparative study of 6B pencil and mineral graphite

AbstractThe production of carbon nanotubes (CNTs) by electric arc discharge (EA) usually applies pure mineral graphite (PMG) as the precursor electrode due to its high‐purity and conductivity. This work investigated the versatility of EA in aqueous medium for the production of CNTs by varying the electrodes purity degree. In this way, a variety of domestic and industrial graphite waste can be recycled into high‐quality CNTs by adjusting the EA parameters. CNTs were synthesized using 6B pencil (6BP, ~57% graphite) and their quality and quantity were compared to the PMG (99.995%) production. PMG led to short CNTs (ID/IG 0.266), while the synthesis with 6BP led to long CNTs (ID/IG 0.428). The 6BP CNTs showed elevated quality for application in the electronic, biomedical, and optical fields.