Dry Route Research Articles

Techno-economic analysis in the service of traditional ceramic industry. The first review

The traditional ceramics industry uses large amounts of raw materials and energy while significantly contributing to the CO2 footprint. The improvements, primarily in the first two areas, will contribute to sustainable development and answer the emerging questions of decreasing a gas-release footprint. These are topics of high importance considering European Union goals, and thus, on the contrary, there is yet only scarce available literature on the subject. This paper describes the state and future perspectives of the traditional ceramics industry through the techno-economic lens. Many options are detected that save resources (waste materials), energy consumption (reparation or modification of kilns, usage of dry pressing in ceramic tiles production, etc.), and control of flue gas composition (changing the fuel, etc.). Further intensified research is needed to widen the knowledge and compare the results. In the first place, the composition of flue gas should be determined by the same methods and presented using unified units. The lowest energy consumption and flue gas composition are determined in ceramic tiles production by the dry route. Using a downdraft gasifier of biomass in brick manufacturing increases the internal rate of return if a longer tunnel kiln is applied. The expected payback period is from 4 to 8 years.

Environmentally friendly p-type CTS-based thin-film thermoelectric generator

Cu-based sulphides are promising materials for environmentally friendly Te-free thermoelectric generators (TEGs). Cu2SnS3 (CTS) stands out for its electronic properties, stemming from its conductive Cu–S networks, especially in fully disordered cubic structural form. While wet chemical techniques are the most utilized for CTS synthesis, they introduce organic contaminants that reduce electronic connectivity between grains, limiting their performance as in-plane thin-film TEGs. We present a new method to improve the electronic properties of CTS thin films for thermoelectric applications involving three-step dry route synthesis of ball milling, thermal evaporation, and sulfurization of Cu2–Sn metallic precursors. Via this method, charge carrier concentration increased significantly, as estimated by Hall effect analysis, which was attributed to the Cu-poor stoichiometry, also confirmed via energy-dispersive X-ray spectroscopy (EDXS). Microstructural analysis by scanning electron microscopy (SEM) revealed micrometre-sized grains composed of even smaller crystalline domains, which X-ray diffraction (XRD) showed to be ~ 50 nm in diameter. When compared with literature results, our procedure leads to a fourfold enhancement in the thermoelectric power factor (PF=S2σ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$PF={S}^{2} \\sigma$$\\end{document}), determined through the Seebeck coefficient measurements (S\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$S$$\\end{document}) and electronic conductivity (σ) estimated by the van der Pauw technique. The CTS TEG has a power volume density of 2.3 μW K−1 cm−3, measured by a custom current–voltage–power (I–V–P) setup with varying load resistance. Results present a 100% increase in performance compared to ink-based techniques and were reproducible across three different batches. This strategy, improving the density of the CTS thin films, offers a new way to enhance Cu-based thin-film TEGs.

Investigation of the properties of Mg(OH)2 extracted from magnesium-rich brine via the use of an industrial by-product

Compared with magnesium oxide (MgO) produced through the dry route, the wet route production can lead to MgO with a high purity and reactivity. During this process, the use of chemical alkalis to precipitate the precursor, magnesium hydroxide (Mg(OH)2), is the highest contributor to cost and energy consumption. This study proposes a low-cost and sustainable way to recover Mg(OH)2 from simulated reject brine using concrete wash water (CWW). Mg(OH)2, with a purity of 94 % and a recovery degree of 98 % was synthesized at room temperature. Higher stirring speed and use of low pH CWW increased the impurity (CaCO3) content. The synthesized Mg(OH)2 showed a similar reactivity to MgO synthesized from reject brine with chemical bases due to its high specific surface area (102.8 m2/g). The calcination of the synthesized Mg(OH)2, led to MgO with a higher reactivity than similar ones obtained through the wet-route. Furthermore, the textural properties of Mg(OH)2 synthesized under different conditions were evaluated to establish a correlation between the reaction conditions and reactivity of Mg(OH)2. Increase in reaction temperature led to a small crystalline size, whereas the aging process resulted in the agglomeration of the synthesized Mg(OH)2, influencing its reactivity. The findings presented in this study can pave the way for the sustainable recovery of Mg(OH)2 and its direct use as a binder or as a precursor for the production of reactive MgO.

Life cycle assessment of magnesium phosphate cement production

Magnesium phosphate cement (MPC) is gaining attention in the field of rapid repair and coatings due to its superior qualities, yet little research has been done on the environmental impacts of MPC preparation. It's necessary to investigate its environmental implications for the sustainable development and application of MPC. This study develops a life cycle inventory of the production of MgO with three different production processes and the production of two phosphates and applies the inventory to conduct a life cycle assessment from cradle to gate for four scenarios of MPC production: Scenario 1 (S1) - dry route MgO and potassium dihydrogen phosphate (PDP) as raw materials; Scenario 2 (S2) - wet route MgO and PDP as raw materials; Scenario 3 (S3) - salt lake MgO and PDP as raw materials; Scenario 4 (S4) - dry route MgO and ammonium dihydrogen phosphate (ADP) as raw materials. Moreover, the sensitivity analysis and cost analysis of MPC are carried out. In order to comprehensively evaluate the low carbon properties of MPC, the carbon emissions of MPC and the commonly used rapid repair materials and coatings are compared. Results indicate S2 shows the highest carbon emission, and the global warming of S2 is 3.97%, 74.55%, and 1.41% higher than that of S1, S3, and S4, respectively. The environmental impact of MPC mainly comes from the production stage of MgO and phosphate (47%–67%). In three MgO production routes, S3 shows the best environmental performance. In two phosphates, S4 has a smaller impact on most impact categories. Sensitivity analysis also indicates that MgO and phosphate have a greater impact on the production of MPC. In addition, the cost of S2 is 2.91%, 0.37%, and 15.40% higher than that of S1, S3, S4, respectively, and S4 shows the best economic benefit. Furthermore, MPC has great advantages in rapid repair and coating, and can reduce carbon emissions by 12%–98% compared to other rapid repair materials and coatings.

HAXPES reference spectra of UO2 generated with Ga Kα x-ray source

HAXPES measurements were carried out using a Scienta Omicron HAXPES instrument to provide reference spectra for depleted uranium dioxide. High purity uranium dioxide, as confirmed by trace elemental analysis and x-ray diffraction, was synthesized via the integrated dry route from uranium hexafluoride. The material was fixed on double sided carbon tape for the analysis with charge control measures in place. The expanded energy range, using a Ga Kα x-ray source, presents core level photoelectrons not observed in traditional XPS. In addition, a region associated with the x-ray induced Auger transitions MNN is evident at binding energies only achievable with HAXPES. The reference spectra presented here act as the first in a line of proposed investigations into the comparison of XPS and HAXPES from surface to bulk as well as a fundamental understanding of the electronic structure of uranium materials.

Toward Large-Scale Production of Solid-State Batteries: Manufacturing Process Analysis and Cost Assessment for the Composite Cathode

In 2022 the lithium-ion battery (LIB) price has increased for the first time since its commercialization while LIBs are approaching their physicochemical energy limits.1,2 Therefore, next-generation or post LIB concepts are being intensively researched, solid-state batteries (SSBs) being evaluated to be among the most promising.3 While companies are already announcing ambitious large-scale production plans for SSBs, academic SSB research is still mainly confined to the laboratory-scale.4 The number of studies regarding SSB material scale-up, large-scale manufacturing or cost calculations is very limited.This work aims to address some of the named research gaps and reduce the knowledge gap between academia and industry. Particularly, the scaled cathode production and its cost assessment for sulfidic and oxidic SSBs are regarded. Therefor, suitable materials and processing pathways for giga-scale production of the composite cathode were ascertained by aggregating the data from a literature review, a patent analysis and expert interviews. Further, the cathode production cost was calculated by adapting the cost model of Duffner et al. (2021).5 Regarding the processing of sulfide-based SSB cathodes a wet and a dry production route is being distinguished . The wet route contains the identical process steps, as already established in LIB production, hence a quick adoption and rapid scale-up is feasible, which is expressed in the technology readiness level (TRL) of 6, the highest of all observed processes. However, challenges regarding densification and solvent compatibility must be solved beforehand. The dry route omits solvent compatibility problems. Next to equivalent challenges with densification, the scale-up of the newly implemented steps ‘dry mixing’ and ‘dry coating’ is currently limiting the large-scale potential, which is reflected in a lower TRL of 4. The scale-up of the oxidic SSB cathode production is still in its infancy (TRL 4), associated with limited processing know-how. The overall process chain will be similar to LIB production, but with the addition of a final co-sintering step, which is also the biggest barrier toward scale-up. Sintering process innovations are evaluated as promising by experts and could potentially enable low-cost, high throughput processing, but are still far from industrial scale.Cost calculations revealed that in the basic scenario, assuming a giga-scale production with state-of-the-art materials (cathode active material: NMC811, catholyte: Li6PS5Cl/Li7La3Zr2O12) while considering ascertained challenges, both SSB electrodes show significantly higher production cost than the LIB equivalent. Particularly, oxide-based cathodes show about three times the production cost of LIB cathodes (Figure 1a). By overcoming material and process challenges significant cost reductions are possible as simulated in an optimized future scenario (Figure 1b). The cost difference of LIB and oxidic SSB cathodes reduces to 16% and the dry process for sulfide-based cathodes even results in cost parity (~ 44 $ kWh1), showing the potential for cost competitiveness. The biggest drivers towards cost reduction are the increase of the cathode active material share and decreased prices of the solid electrolyte. On the process-level especially optimized mixing and drying for the sulfide-based cathode and a reduction of the sintering temperature below 500 °C for the oxide-based cathode lead to significant cost reductions. References J. Liu, Z. Bao, Y. Cui, E. J. Dufek, J. B. Goodenough, P. Khalifah, Q. Li, B. Y. Liaw, P. Liu, A. Manthiram, Y. S. Meng, V. R. Subramanian, M. F. Toney, V. V. Viswanathan, M. S. Whittingham, J. Xiao, W. Xu, J. Yang, X.-Q. Yang and J.-G. Zhang, Nat Energy, 4(3), 180–186 (2019).BloombergNEF, Lithium-ion Battery Pack Prices Rise for First Time to an Average of $151/kWh | BloombergNEF, https://about.bnef.com/blog/lithium-ion-battery-pack-prices-rise-for-first-time-to-an-average-of-151-kwh/ (2022). J. Janek and W. G. Zeier, Nat Energy, 8(3), 230–240 (2023). T. Schmaltz, T. Wicke, L. Weymann, P. Voß, C. Neef and A. Thielmann (2022).F. Duffner, L. Mauler, M. Wentker, J. Leker and M. Winter, International Journal of Production Economics, 232, 107982 (2021). Figure 1

Recycling MgO from the waste magnesium oxychloride cement (MOC): Properties, CO2 footprint and reuse in MOC

Recycled magnesia was prepared via using magnesium oxychloride cement (MOC)-based waste as the raw material instead of magnesite through calcination under the temperatures from 600 °C to 1000 °C. The effects of calcination temperature on the components, microstructures, and properties of recycled MgO, and its influence on the performance of MOC containing the recycled MgO were investigated. Results indicated that the reactivity of recycled MgO depended on the calcination conditions, the active MgO content approached 80 wt% through the calcination of MOC-based waste in the temperature range of 700 °C–900 °C. The MOC paste was prepared by using 30 wt% MgO recycled under 800 °C exhibited higher mechanical performance, denser microstructure and more stable volume. The carbon emissions of recycled MgO are 0.49 t/t of magnesia, which is only 31.2% of that emitted by the calcination of magnesite via conventional dry route. This study provides an efficient approach to reducing the consumption of non-renewable natural resources and the generation of construction waste to realize cleaner and sustainable production of reactive MgO.

Identification and Elemental Impurity Analysis of Heterogeneous Morphologies in Uranium Oxides Synthesized from Uranyl Fluoride Precursors.

The surface morphology characteristics of postenrichment deconversion products in the nuclear fuel cycle are important for producing nuclear fuel pellets. They also provide the first opportunity for a microstructural signature after conversion to gaseous uranium hexafluoride (UF6). This work synthesizes uranium oxides from uranyl fluoride (UO2F2) starting solutions by the wet ammonium diuranate route and a modification of the dry route. Products are reduced under a nitrogen/hydrogen atmosphere, with and without water vapor in the reducing environment. The crystal structures of the starting materials and resulting uranium oxides are characterized by powder X-ray diffraction. Scanning electron microscopy (SEM) and focused ion beam SEM with energy-dispersive X-ray spectroscopy (EDX) are used to investigate microstructural properties and quantify fluorine impurity concentrations. Heterogeneous distributions of fluorine with unique morphology characteristics were identified by backscatter electron imaging and EDX; these regions had elevated concentrations of fluorine impurities relating to the incomplete reduction of UO2F2 to UO2 and may provide a novel nuclear forensics morphology signature for nuclear fuel and U metal precursors.

Life cycle assessment of upcycling waste slag via CO2 pre-treatment: Comparative study of carbonation routes

Accelerated carbonation of industrial by-products such as yellow phosphorus slag (YPS) and basic oxygen furnace slag (BOFS) is an effective method to convert waste into valuable construction materials. Accelerated carbonation or CO2 sequestration can be conducted directly under dry or aqueous conditions. However, the slow reaction and low CO2 fixation efficiency of dry carbonation hinder the successful development of accelerated carbonation, whereas water consumption is the key challenge of aqueous carbonation for industrial applications. Therefore, this study evaluated the environmental impact of carbonation of YPS and BOFS via dry and aqueous routes, and upcycling these CO2-treated waste slags as cement replacements. The environmental impacts, including midpoint and endpoint impact, were quantified using life cycle assessment (LCA) by applying the ReCiPe methodology. The LCA results show that aqueous carbonation generates lower carbon emissions (11.3% and 214.0%) and human carcinogenic toxicity (2.4% and 0.2%) than dry carbonation for YPS and BOFS, but is accompanied by more serious impacts on mineral resource scarcity and water consumption. On the other hand, aqueous carbonation of BOFS generates lower (or even negative) carbon emissions than aqueous carbonation of YPS, and the same results can be found for human carcinogenic toxicity, mineral resource scarcity and water consumption. Sensitivity analysis shows that prolonged carbonation, particularly in the case of dry routes, results in very high carbon emissions. Apart from carbon emission benefits, using 20% aqueous carbonated YPS and 20% aqueous carbonated BOFS as cement replacements exhibited minimal impact of mechanical strength reduction, as compared with pure cement paste samples.

Chemical weathering processes generating the raw material used in porcelain stoneware industry in the São Paulo State, Brazil

The Paraná Sedimentary Basin (PSB) is an intracratonic basin located in the South America and some litostratigraphic units can be exploitable for different segments of non-metallic's industry. Brazil is one of the main producers in ceramic tiles market, specifically in the Santa Gertrudes Ceramic Pole (SGCP), São Paulo State. The Tatuí Formation is an Eopermian post-glacial marine unit from the PSB composed essentially of massive or laminated siltstones and pelites, interbedded with limestones and sandstones. These lithotypes are exploited and used as raw material to enhance the strength to porcelain stoneware industry in the São Paulo State, a product with greater added value in relation to the common “dry route” ceramic tiles produced in the SGCP. In order to understand the influence of the chemical weathering processes to generate the raw material used in the porcelain stoneware, we studied the mineralogy and geochemical characteristics of the weathered samples at two mines located in the city of Tatuí and compared the results with fresh rock collected nearby. The fresh rocks are composed of quartz, albite, microcline and muscovite. The weathered samples from the top of the weathering profiles are composed of kaolinite, illite, quartz, iron hydroxides and rare microcline, while the bottom horizons are richer in montmorillonite and feldspar. From the bottom to top layers, geochemical results indicate progressively enrichment of Al2O3, Fe2O3 and TiO2 and depletion of the other major oxides, trace elements (except for Ni, Th and U) and REE. The Chemical Index of Alteration (CIA) and Chemical Index of Weathering (CIW) values increased from the bottom to the top in the isalteritic saprolite. The weathering trends indicated the partial hydrolysis as the main chemical weathering process at both study areas. The chemical weathering reactions generated an added value ceramic product higher than the traditional clay materials exploited at SGCP due to the presence of montmorillonite and the low content of Fe2O3.

Effect of boron sources in the thermal behavior of a clay-based ceramics

Boron oxide sources as fluxing agents for clay-based materials have been a problem for the high solubility of these additives, however the dry milling-mixing-granulating route for clay based ceramics has been proposed and implemented with noticeable energetic advances.In the present study, the role of different boron oxide sources in the thermal behavior and sinterability of ceramic materials based on kaolinite clay was evaluated.Four boron sources were evaluated: Boric acid, borax, colemanite and ulexite. Four binary mixtures were made in a planetary mill to obtain uniform mixtures. For systematic comparison, the boron content added in all samples was 1 wt%. The thermal behavior evaluation of the mixtures was carried out by a multi-technique approach accompanied by textural, microstructural characterization complemented by a deep crystalline and non-crystalline phase evolution.Ulexite and borax presented the highest fluxing effect and colemanite has an even more moderate effect than boric acid. The observed microstructure was similar to other clay-based ceramics, with quartz grains, cristobalite and mullite embedded in the silica-based vitreous phase.The present study provides information for the additional design of clay-based materials with boron oxides as fluxing agents. The dry route alternative for using these agents was effective.

Effect of direct carbonation routes of basic oxygen furnace slag (BOFS) on strength and hydration of blended cement paste

Mineral carbonation of alkali solid wastes is envisaged to be an effective method to sequester CO2 and turn the wastes into more valuable end products. Steel slag generated from the steel-making industry contains a high content of calcium oxide, which is a potential medium to sequestrate CO2 via the carbonation process. In this paper, the influence of reaction parameters including solid to liquid ratio, CO2 flow rate, temperature, volume of water and carbonation time on aqueous carbonation of basic oxygen furnace slag (BOFS) in maximizing CO2 sequestration was determined. The structural and mineralogical changes of carbonated BOFS were also analyzed using thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. Using an optimized aqueous carbonation condition, about 16.35% of CO2 can be sequestered, which was obviously higher compared with dry carbonation (about 4.91%) at ambient conditions. Subsequently, the effect of replacing cement with carbonated BOFS (either by aqueous or dry route) on the micro-mechanical properties and hydration characteristics of blended cement paste was studied. The results demonstrated that as a small ratio of aqueous carbonated BOFS (10%-20%) blended in the cement paste they can accelerate the rate of early heat evolution during the first 24 h. On the contrary, as the carbonated BOFS ratio increased, the overall heat of hydration and mechanical strength were decreased. In comparison, BOFS carbonated by aqueous method is found to perform better in blended cement paste than its counterpart carbonated by dry method at the same replacement ratio due to the presence of a greater calcite content (acting as nucleation sites) in the aqueous carbonated BOFS.

Dry route process and wet route process for algal biodiesel production: A review of techno-economical aspects

In this study, two approaches for biodiesel production from microalgae, one through a dry route (using dried microalgae) and another through a wet route (using wet microalgae), are critically assessed. Analysis suggests that although both routes yield biodiesel of similar quality, there is a considerable difference in overall energy consumption, energy-intensive steps, and size of equipments for processing the same amount of lipids. This review depicts that both routes demand significant amount of energy, i.e. up to 120 MJ per kg of biodiesel that amounts to nearly three times the energy obtained from it. Also, the cost of production for one kg of biodiesel is high, i.e. up to $25 and $12 in dry and wet route respectively. This review article aims to present comprehensively and coherently the technical aspects of these two routes and their attributes in terms of energy consumption, manufacturing cost, and capital investment.

Fragmented fibre (including microplastic) pollution from textiles

The threat of microplastic (MP) pollution to our ecosystem is well established. The presence of natural, regenerated, and synthetic fragmented fibres (FF) and their abundance in terrestrial and aquatic environments has been extensively reported. All textiles release FF during their lifecycle, not limited to plastics, which find their way to the environment through different dispersal pathways. Beyond the nature of the polymer, the FF can also can be a carrier of hazardous chemicals. The ubiquitous nature of MPs (and FF) has widely placed them as one of the most enduring and pervasive anthropogenic pollutants. This review is focused on FFs generated and released from textiles during wet (predominantly laundering) and dry exposure conditions. A summary and critical analysis of the current methods to generate, collect, measure, and characterise FF from textile laundry effluent is presented. The impact of key parameters on the release of FF is summarised; including washing equipment/conditions, filtration procedures, characterisation techniques, and the effect of textile materials and structure. The results from key publications are tabulated for direct comparisons, this includes estimated number of FF released per washing cycle and length distribution profile. Though the wet route of release has gained more attention, the release through dry routes is also significant. Hence, a detailed overview of the collection and characterisation of FF from dry routes (atmospheric deposition and textile abrasion) was important. Finally, a comprehensive overview of latest research and industrially-applied mitigation strategies to limit the release of FF from textile sources during laundry is included. The impact of MPs (and FF) is briefly outlined covering the environment, human health and degradation. Improved plastics with reduced environmental impact, plastic recycling and reduced consumption are vital. Still, the release of FFs from textiles remains a challenge since their production is unintentional.

A two-stage processing of cherry pomace via hydrothermal treatment followed by biochar gasification

Poland is the EU’s largest producer of cherry, which largely is further processed. As a consequence, a problematic waste – cherry pomace – is generated as by-product. Among the new sustainable technologies for organic waste valorization particularly perspective are thermochemical methods, which can be divided into conventional one, i.e., dry route (e.g. pyrolysis, gasification) and wet route (i.e. hydrothermal treatment). Herein, we proposed a two-stage thermochemical processing route for the conversion of cherry pomace, i.e., hydrothermal treatment followed by CO2 gasification. Firstly, we transformed the feedstock into biochar via hydrothermal processing. The aim of this stage was to analyze the effect of processing temperature (200–350 °C) on the distribution of the yield of various groups of products. The residual biochar was obtained with the highest yield (33–57 wt%). Among the gas-phase products, the dominant constituent was CO2. The upgrading of the biochars through gasification with CO2 to ensure the sustainability of conversion was the subsequent step. The quality of the biochars was examined by infrared spectroscopy, proximate and ultimate analysis, SEM, and low-temperature nitrogen adsorption. The activation energy ranged between 668 and 732 kJ mol−1 for the gasification of the biochar prepared at 275 and 200 °C, respectively. It was found that biochars produced at different conditions exhibit various properties as a result of gradual degradation of the original components of the raw material and increase in aromaticity occurring with the increase in the processing temperature.

«Послать для своих великого государя дел...»: посольство Д.М. Голицына к Высокой Порте в 1701 году

Introduction. In January 1701, Prince D.M. Golitsyn was sent to Sultan Mustafa II for ratification of the Peace Treaty of Constantinople (July 3, 1700). He became the first Petrine diplomat sent to the Sublime Porte with the rank of grand ambassador. Methods and materials. The comprehensive study of archival sources (Russian State Archive of Ancient Acts), comparison of the data they contain with published materials make it possible to analyze the mission of Golitsyn in the context of the policy of Peter I towards the Ottoman Empire in the early 18th century. Analysis. Due to the hostilities by Narva, the dispatch of the embassy was delayed. The ambassador delivered the ratification of the peace treaty five months later than the agreed date. Golitsyn was the first Russian diplomat to wear a French dress during ceremonies at the Ottoman court. Besides, he not only followed the established ambassadorial custom, but also took into account the experience of his Western European colleagues. In addition to the ratification, Golitsyn had other tasks, the main of which was the conclusion of a trade agreement with the Sublime Porte. The conditions on which the ambassador was supposed to sign the agreement were fixed in a special instruction. The analysis of that instruction and reports of the ambassador showed that for Peter I the priority was not the development of mutually beneficial trade with the Ottoman Empire, but the opportunity to withdraw his fleet from the Azov to the Black Sea. Delivery of goods by Turkish ships or by dry route was considered only as an addition to the Russian Black Sea shipping. The conditions set in the instruction did not give to Golitsyn the opportunity to negotiate with the Sublime Porte, which categorically prohibited the entry of European ships into the Black Sea. Results. The sending of a grand ambassador by the tsar to the Ottoman sultan marked the transition of relations between the two states to a new level. Besides, a precedent was created for the reception of high-ranking Peter’s diplomats by the Sublime Porte.

Sequestration of CO2 by red mud with flue gas using response surface methodology

Energy demand is projected to increase throughout the globe in near future which necessitates the development of carbon capture and storage (CCS) technologies to avoid the harmful impacts of climate change. Direct mineral carbonation of alkaline solid wastes is one such technology that provides the benefit of being a permanent, cost effective and a promising on-site option, while improving the environmental quality of the waste. The present work attempts to study direct mineral carbonation of red mud (RM) with CO2 (concentration as in flue gas) by wet and dry route employing response surface methodology (RSM). Maximum reduction of about 18.5% in the concentration of CO2 was attained in wet carbonation conditions (65.1 ºC, 42.1 bar, L/S ratio of 0.53, 1 h) and the sequestration capacity of RM was found to be 15.5 g of CO2/kg, correspondingly. The models were found to be statistically significant (R2 value > 98.5%). Temperature and reaction time were found to influence the dry route. Meanwhile in wet route, temperature, pressure, liquid to solid (L/S) ratio and reaction time were all significant. The results demonstrated that RM could significantly sequester CO2 even from flue gas. The carbonation process was evidenced using Fourier-Transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM).

A comprehensive review on improving the production of rich-hydrogen via combined steam and CO2 reforming of methane over Ni-based catalysts

During the last few decades, the global energy requirement is soaring significantly due to the rise of global population and economic development. This resulted in colossal release of CO2 and CH4, emissions into the atmosphere referred as greenhouse gases (GHGs), which poses a detrimental effects for the environment. One of the sustainable solutions to curb emissions of GHGs into the atmosphere is efficient utilization of syngas in order to produce useful chemicals and fuels. A comprehensive review is presented to highlight the capability of Ni-based catalysts in methane reforming through the application of both steam and dry routes referred to as bi-reforming of methane (BRM). Ni-based catalysts were found to support favorable reaction activity as they are cheaper than many exorbitant catalysts. The metal used for catalyst support exhibits higher stability and thermal resistance with improved resistance to coke formation. This review entails recent progresses in the development of Ni-based catalysts along with physical and kinetic aspects of the BRM process.

Improving the sustainability of ceramic tile-making by mixing spray-dried and dry-granulated powders

Current trends in the ceramic industry see an increasing interest on porcelain stoneware, by which is possible to produce large tiles and slabs. These products are manufactured by spray-dried powders, which have excellent technological properties but require high energy and water consumption. Dry-processed granulates allow to reduce such a consumption, but suffer from a different technological behavior. A solution to improve the environmental sustainability of ceramic tile-making is mixing powders prepared by the wet and the dry routes. The technological features of industrially manufactured mixed powders was investigated (rheological properties, compaction response and firing behavior) in order to point out advantages and possible pitfalls. Dry-processed and spray-dried granulates exhibit different distributions of size, shape and moisture that reflect on distinct rheological and compaction behaviors. Mixed powders show a more or less accentuated deviation from linearity between the end terms. This fact makes possible to add up to ∼50% dry granulates by keeping the technological properties close to current industrial bodies. Sparings of water, energy and CO2 emission for the milling and granulation stages are estimated for a mix 50% spray-dried and 50% dry-processed powders.

Carbon nanowalls functionalization for efficient O2 reduction catalyzed by laccase using design of experiment

An enzymatic biofuel cell cathode was elaborated by nano-structuration and functionalization of graphite using two consecutive plasma treatments before immobilization of laccase as a biocatalyst to perform oxygen reduction reaction (ORR) by direct electron transfer ((DET). Nano-structuration of graphite surfaces by synthesis of vertical graphen-like carbon nanowalls (CNWs) was performed by microwave excited plasma enhanced chemical vapor deposition (PECVD). Atmospheric pressure plasma jet (APPJ) system was then used to functionalize chemically the CNWs surface via a rapid and dry route. A partial fractional design evidenced two significant parameters of the APPJ treatment in terms of ORR current density: the treatment time and the inter-distance between the plasma jet and the surface of the carbon material. With the optimized APPJ treatment parameters, a four-fold enhancement of the ORR current density (-440 ± 70 μA/cm2) could be obtained on CNWs, compared to graphite electrodes. The best current density obtained was about −1 mA/cm2 with oxidized laccase covalently immobilized on the electrode without any agitation of the solution, confirming the main importance of enzyme orientation on the electrode surface for efficient DET transfer, the relevance of electrode nanostructuration and the advantage of covalent linking of the protein on the electrode surface.