Assessment of graphitized coal ash char concentrates as a potential synthetic graphite source

Coal ash char concentrates from four countries (Portugal, Poland, Romania, and South Africa) were prepared, characterised, and graphitized under the scope of the Charphite project (Third ERA-MIN Joint Call (2015) on the Sustainable Supply of Raw Materials in Europe). Coal ash chars may be a secondary raw material to produce synthetic graphite and could be an alternative to natural graphite, which is a commodity with a high supply risk. The char concentrates and the graphitized material derived from the char concentrates were characterised using proximate analysis, X-ray fluorescence, X-ray diffraction (structural), Raman microspectroscopy, solid-state nuclear magnetic resonance, scanning electron microscopy, and petrographic analyses to determine if the graphitization of the char was successful, and which char properties enhanced or hindered graphitization. Char concentrates with a lower proportion of anisotropic particles and a higher proportion of mixed porous particles showed greater degrees of graphitization. It is curious to see that embedded Al2O3 minerals, such as glass and clay, influenced graphitization, as they most likely acted as catalysts for crystal growth in the basal direction. However, the graphitized samples, as a whole, do not compare well against a reference natural graphite sample despite some particles in select char concentrates appearing to be graphitized following graphitization.Fil: Badenhorst, Charlotte. University Of Johannesburg; SudáfricaFil: Santos, Cláudia. Universidad de Porto; PortugalFil: Lazaro Martinez, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; ArgentinaFil: Bialecka, Barbara. Central Mining Institute; PoloniaFil: Cruceru, Mihai. University Constantin Brancusi of Targu Jiu; RumaniaFil: Guedes, Alexandra. Universidad de Porto; PortugalFil: Guimarâes, Renato. Universidad de Porto; PortugalFil: Moreira, Karen. Universidad de Porto; PortugalFil: Predeanu, Georgeta. University Politehnica Of Bucharest; RumaniaFil: Suárez-Ruíz, Isabel. Consejo Superior de Investigaciones Científicas; EspañaFil: Cameán, Ignacio. Consejo Superior de Investigaciones Científicas; EspañaFil: Valentim, Bruno. Universidad de Porto; PortugalFil: Wagner, Nicola. University Of Johannesburg; Sudáfric

Thermal and Viscoelastic Responses of Selected Lignocellulosic Wastes: Similarities and Differences

Woody lignocellulosic biomasses comprise the non-edible parts of fruit trees. In recent years, the exploitation of this biomass has been widening in order to mitigate environmental issues. At the same time, this waste could be transformed into a value-added product (active carbon by pyrolysis, isolation of nanocellulose, oils or proteins). For either valorization path, a complete thermo-mechanical characterization is required. A detailed thermo-mechanical study (TGA, DSC, DMA) was performed on two types of lignocellulosic wastes, with and without kernels: on one side, the walnut shells (WS) and the pistachio shells (PsS) and, in the second category, the apricot seeds (AS), the date seeds (DS), and the plum seeds (PS). The results of the sample-controlled thermal analyses (HiRes TGA) evidenced a better resolution of the degradation steps of WS. Kinetic studies conducted also by conventional TGA (Flynn–Wall–Ozawa) and modulated TGA (MTGA) allowed us to make comparative reasonings concerning the degradation of the investigated biomasses. The DMA results revealed the effect of water traces and oil kernels on relaxation and supported the atypical DSC endotherm emphasized in the freezing temperature domain

An Eco-Friendly Modification of a Walnut Shell Biosorbent for Increased Efficiency in Wastewater Treatment

Herein, we report the performance of some low-cost biosorbents developed by environment-friendly modification of walnut shells. Two types of biosorbents were prepared by ecological modification of walnut shell surfaces: (1) biosorbents obtained by hot water treatment (WSH2O) and (2) biosorbents produced by mercerization (WSNaOH). Different techniques were used to evaluate the morphological, elemental, and structural modification of the biosorbents, by comparison with raw materials. These characterization techniques involved scanning electron microscopy (SEM) coupled with energy-dispersive X-ray analysis, and Fourier-transform infrared spectroscopy (FTIR). The biosorbents were employed for the removal of methylene blue (MB) and crystal violet (CV) cationic dyes (as model organic pollutants) from aqueous solutions. The kinetic adsorption data mainly followed the pseudo-first-order model. The maximum adsorption capacities of the produced biosorbents ranged from 102 to 110 mg/g and were observed at 330 K. Equilibrium data for adsorption were fitted to Langmuir and Freundlich isotherm models. The calculated values of thermodynamic parameters suggested that the investigated adsorption processes were exergonic (ΔG < 0) and exothermic (ΔH < 0). In addition, a possible valorization of the cost-effective and eco-friendly spent biosorbents was tested by performing secondary adsorption of the anionic dyes

Thermal Maturity and Kerogen Type of Badenian Dispersed Organic Matter from the Getic Depression, Romania

The aim of this study is to evaluate the thermal maturity of Upper Badenian (Middle Miocene) petroleum source rocks of the Getic Depression, Romania, and to characterize the dispersed organic matter using organic petrography associated with Rock-Eval pyrolysis. A total of 33 core samples of Upper Badenian source rocks from the central–southern part of Getic Depression was studied. The results show that most samples with values of total organic carbon (TOC) o%) ranging between 0.41% and 0.55%, and the values of Tmax between 409 °C and 443 °C. Optical microscopy with reflected white light and fluorescence blue light was used for identification of terrigenous macerals (vitrinite, liptinite as, resinite, cutinite, sporinite, and inertinite) associated with marine liptinite macerals (telalginite and lamalginite) showing yellow and bright–yellow epifluorescence

Undifferentiated Inorganics in Coal Fly Ash and Bottom Ash: Calcispheres, Magnesiacalcispheres, and Magnesiaspheres

During a study aiming to recover strategic elements and minerals from coal fly ash and bottom ash (RAREASH and CHARPHITE projects funded, respectively, by the 2nd ERA-MIN and 3rd ERA-MIN Programs of the European Union Commission), it was found that in coal fly ash and bottom ash from Romania and Poland, several morphotypes did not fit into the general fly ash classifications, unless grouped together as “undifferentiated inorganics”. However, the combination of reflected light optical microscopy under oil immersion, scanning electron microscopy, and X-ray microanalysis (SEM/EDS) showed that many of these morphotypes not only have distinctive petrographic patterns but are also characterized by a chemical assemblage dominated by Ca, Mg, and P. In this paper, a survey of the literature is presented together with several detailed studies of samples from the RAREASH and CHARPHITE projects from which the following nomenclature are proposed: “calcispheres” for spongy Ca-rich morphotypes, “calcimagnesiaspheres” for (Ca + Mg)-rich morphotypes with visible MgO nodules and/or periclase (MgO) exsolved from Ca aluminate-silicate glass, and “magnesiaspheres” divided into “magnesiaferrospheres” for (Mg + Fe)-rich morphotypes with magnesioferrite, and “magnesiaoxyspheres” for magnesiaspheres mainly composed of (Mg + Fe)-rich amorphous material with visible MgO nodules and/or periclase

Hydrothermal nitrogen doping of anthracene oil-derived activated carbons for wide voltage asymmetric capacitors

This work focused on the development of doping procedures to introduce nitrogen functionalities on an activated carbon derived from anthracene oil to be subsequently used on wide voltage asymmetric capacitors. For that, ammonia solution was used and different hydrothermal conditions applied. Tailoring the temperature treatment (120 and 180 °C), nitrogen-doped activated carbons (N-ACs) with different nitrogen content (5.6 and 4.1 at. %) and diverse speciation were obtained. N-ACs exhibited excellent capacitive behaviour and long-life cycle in a three-electrode cell using KOH aqueous solution as electrolyte. The significant capacitance value of 291 F g-1 at 0.2 A g-1 was achieved by the N-AC obtained at 180 °C. Furthermore, full carbon asymmetric supercapacitors incorporating N-ACs as negative electrodes were assembled, and an operating voltage window of 1.3 V in 6 M KOH solution established. As a result, high energy densities were achieved in the devices, particularly in that including N-AC-180. Electrochemical tests revealed that pyridinic and quaternary nitrogen species of N-ACs play a critical role in the excellent asymmetric supercapacitor electrochemical performance, including improvement of conductivity and specific capacitance

Incineration of Aviary Manure: the Case Studies of Poultry Litter and Laying Hens Manure

International audienceThe industrial incineration of aviary manure is still far from the concept of using its ash residuals for nutrient uptake by plants, and most of these materials are landfilled under futile fixed cost. Aviary manure includes poultry litter mixed with different aviary bedding materials or laying hens manure, which may be burned using other incineration technologies and conditions. This study aims to determine the comparative characterisation of P-rich ash residues sampled at Güres Energy (Turkey) fluidised bed combustion of laying hens manure and at Campoaves (Portugal)chain grate stoker combustion of rice husk poultry litter. The effect of different fuels and different combustion systems on P speciation in ash was investigated: the characterisation of global samples (bottom ash (BA), economiser fly ash (FAECO), cyclone fly ash (FACYC)) and respectivesize-fractions were done chemically (proximate and elemental analysis by X-ray fluorescence–XRF–and Inductively CoupledPlasma Mass Spectroscopy – ICP-MS), morphologically (detailed imaging and X-ray micro analysis by Scanning ElectronMicroscopy—Energy-Dispersive X-ray spectrometry–SEM−EDS) and mineralogically (X-ray diffraction–XRD). Phosphoruswas detected in Güres ashes mainly as hydroxyapatite crystals alongside with CaCO 3 relics and CaO, while Campoaves ashfractions contained P also as Na–K-Mg phosphate and major amounts of rice husk relics including unburnt char and silicaphases. Both Güres and Campoaves ashes are complex but the combustion of aviary manure under these setting conditionsappears to be promising for P recovery owing to their high P content and limited trace elements respecting the limitationsimposed by EU legislation for fertilisers applications

Green Synthesis of Advanced Carbon Materials Used as Precursors for Adsorbents Applied in Wastewater Treatment

Huge amounts of vegetable waste, mainly resulting from the food industry, need large areas for storage, as they could cause hazardous environmental impact, leading to soil and water pollution or to CO2 emissions during accidental incineration. This work was aimed at recycling certain lignocellulosic waste (walnut shells, kernels of peach, apricot, and olive) to design advanced carbon material precursors (ACMP) to be used for obtaining nano-powders with high applicative potential in pollution abatement. Both waste and ACMP were characterized using proximate and elemental analysis, and by optical microscopy. Complex characterization of raw materials by FTIR, TGA-DTG, and SEM analysis were carried out. The ACMP were synthetized at 600–700 °C by innovative microwave heating technology which offers the advantages of lower energy consumption using 3.3 kW equipment at laboratory level. The ACMP ash < 3% and increased carbon content of 87% enabled the development of an extended pore network depending on degassing conditions during heating. TEM analysis revealed a well-developed porous structure of the synthesized ACMP carbonaceous materials. Due to the presence of oxygen functional groups, ACMPs exhibit adsorption properties highlighted by an iodine index of max. 500 mg/g and surface area BET of 300 m2/g, which make them attractive for removal of environmental pollutants such as dyes having molecule sizes below 2 nm and ions with pore dimensions below 1 nm, widely used industrially and found in underground waters (NO3−) or waste waters (SO42−)

Poultry litter ash characterisation and recovery

International audienc