Energetics of Electrochemically-mediated Amine Regeneration

Carbon dioxide capture by non-aqueous blend in rotating packed bed reactor: Absorption and desorption investigation

Limits to Paris compatibility of CO2 capture and utilization

Creating a bipolar electrode system for electrochemical advanced oxidative processes with efficient electricity consumption

In situ resource utilization (ISRU) is the practice of generating resources when humans are away from Earth. The goals of ISRU include the generation of rocket propellants, building materials, and life sustaining commodities from such resources as the Mars atmosphere, lunar regolith, and even trash. There are many technology options that are currently at different technology readiness levels. This talk will review some of the more mature ISRU technologies and show were electrochemical processes have the potential to be a better option. The generation of oxygen from lunar regolith has been demonstrated using hydrogen and carbothermal reduction processes. Electrolysis of regolith when it is molten or dissolved has the potential for increased yields. Propellant production on Mars can be achieved through capture of carbon dioxide from the Mars atmosphere and water from the Mars soil. The water is split to oxygen and hydrogen, which is used to reduce carbon dioxide to methane, resulting in production of methane and oxygen. The co-electrolysis of carbon dioxide and water can produce methane and oxygen in a single process vessel, reducing the complexity of the overall system. Recent work has shown that this can be done when carbon dioxide is dissolved in an ionic liquid. The same ionic liquid shows a high capacity for carbon dioxide uptake and can be used to collect carbon dioxide. Because ISRU systems are extremely mass constrained, there is a need for gas and water cleanup methods that do not use consumables. Some of the ISRU cleanup challenges and potential solutions, such as electro-dialysis to clean water, will be discussed.

The purpose of this study is the mathematical modelling of electromechanical processes to estimate the electricity consumption of an automated shuttle warehouse system. In the form of a system of two ordinary differential equations with initial conditions, it is proposed the mathematical model allowing to study the processes of electric energy consumption by an automated shuttle with direct current motors, which is used as the automation tools in modern warehouse systems for transporting goods between racks. The proposed mathematical model allows us to determine the angular velocity of the shuttle wheels and the current in the rotor windings of its driving electric motors for a given supplied electric voltage. The process of electric energy consumption is characterized by the current in the rotor windings of the driving electric motors of the shuttle and their supplied voltage. By means the proposed mathematical model, the process of energy consumption is researched for the automated shuttle accelerated from the state of the rest to achieving of the steady speed under an instantaneously supplied constant electric voltage. The considered example shows that the proposed model allows us to study both transient and steady processes of electric energy consumption by a shuttle with direct current motors when transporting goods between racks of a warehouse system.

An electrochemical process based on pH-swing has been proposed recently to regenerate spent alkaline absorbent from direct air capture (DAC). In this work, we experimentally investigated and theoretically simulated two optimization strategies to further reduce the energy consumption of such novel electrochemical process. First, partial vacuum was applied to the gas phase during CO2 desorption to increase the gas production rate. The energy consumption of the electrochemical cell decreased by 12 to 15% when the CO2 partial pressure in the gas phase was reduced from 0.9 to 0.3 atm. Second, phosphate and sulphate were tested as background electrolyte to the alkaline absorbent, reducing the energy consumption by minimizing the ohmic losses in the electrochemical cell. The optimal concentration for phosphate was 0.1 M, while the CO2 production rate was limited by either the total carbon feeding rate or the high acidifying solution pH at higher concentrations of phosphate. Moreover, due to the low pKa and high molar conductivity of sulphate compared to phosphate, sulphate addition showed an even lower energy consumption than phosphate addition. Finally, the lowest experimental energy consumption was 247 kJ mol−1 CO2 achieved with CO2 partial pressure of 0.3 atm and 0.1 M of sulphate addition at current density of 150 A m−2 while our mathematical model predicted a theoretical minimum energy consumption of 138 kJ mol−1 under the same condition. Overall, the investigated optimization strategies advanced the development of an energy-efficient electricity-driven process for direct air capture.

Influence of Bubbles on the Energy Conversion Efficiency of Electrochemical Reactors

The presence of carbon dioxide in the Malay Basin has often raised queries regarding its origin and distribution. Accumulations in the Malay Basin have been shown to originate from both organic and inorganic sources (Figure 1). Organic sources comprise the decomposition of organic matter with increasing as well as the cracking of hydrocarbon products at high temperatures. Inorganic sources include the thermal breakdown of calcareous shales and limestones, as well as the diagenetic reactions in siliciclastic rocks whereby carbonate minerals such as siderite, dolomite and calcite in clastic sediments react with silicates at temperatures greater than 320°C to generate carbon dioxide. In addition, carbon dioxide contents in both associated and non-associated gases in the Malay Basin can vary up to a maximum of 90%. Our studies indicate that it is erroneous to generalise that carbon dioxide occurrences increase with increasing depth. Another important observation is that low carbon dioxide percentages (less than 20%) do not necessarily indicate an organic origin. However, in most cases where the carbon dioxide contents are greater than 40%, more often than not, they are of inorganic origin. Modeling of the Malay Basin’s hydrocarbon and inorganic carbon dioxide generation was performed using personalised kerogen kinetic parameters and carbonate decompositional kinetic parameters of actual Malay Basin’s samples. The former were determined for the Bergading Deep-1 Group E coals, Beranang 6F- 18.1 Group I fluviodeltaic coaly shales and Bunga Raya-1 Group K lacustrine shales (Figure 2). For the assessment of carbon dioxide generation from carbonates, the decompositional kinetic parameters were determined for the Bunga Raya-1 Group M calcareous shales and limestones. These new kinetics data provide a better control on the results of the carbon dioxide generation modeling as they are specific to the Malay Basin samples. Additionally, predictions of carbon dioxide generation were also determined from modeling the diagenetic reactions within the penetrated sediments using the method of Cathles & Schoell (PGCE 2006). Three locations were selected for the carbon dioxide kinetics modeling, namely Bujang Deep, Angsi and Bunga Raya. Using the newly-acquired kinetic parameters, we were able, for the first time, to determine the timing of inorganic carbon dioxide generation and expulsion as well as its most likely origin in these areas. To ascertain the trapping feasibility of the generated carbon dioxide, the resulting timings were compared with the thermal subsidence and basin inversion of the Malay Basin which occurred between 21 Ma to 6 Ma, with peak trap formation at around 16 Ma. Based on the carbonate decompositional kinetics modeling, the carbon dioxide observed in Bujang Deep should have a mixed origin due to expulsion from the following: both the Group M calcareous shales and limestones at 21 Ma and 20 Ma, respectively (Figure 3), and from the Group K siliciclastic reactions at 14 Ma. The origins were validated by actual measured data whereby the Bujang δ13CCO2 fall within -3 to -6o/oo isotope values, indicating an inorganic origin. There are also carbon dioxide samples with isotope values of - 11.4 and -12.2o/oo, suggesting a mixed origin. The Dulang, Semangkok and Tangga fields located within the middle part of the Malay Basin also exhibit high carbon dioxide occurrences (Figure 1). In the Angsi area, the kinetics modeling indicated that the carbon dioxide encountered by the well should have a strong inorganic influence due to the thermal breakdown of the Group M limestones (Figure 4). Modeling indicated the timing of expulsion to be around 14 Ma. Carbon dioxide contributions may also be expected from the Group M calcareous shale but, since it was generated much earlier than the trap formation at 24 Ma, it is presumably lost. With the bottom temperature of the section being only at 200°C, the diagenetic reactions have not yet started. Traditionally, the carbon dioxide contents of Angsi-1 of less than 20% would be thought of as suggestive of an organic origin. However, the δ13CCO2 values range of between of -5 and -7o/oo tell a different story; these carbon dioxide gases are actually of inorganic origin. Kinetic modeling results corroborate with this indication, thus validating the model. The Bunga Raya kinetics modeling results suggest an inorganic origin for the carbon dioxide observed in the Bunga Raya-1 well, by virtue of being sourced from the Group M limestone at 2 Ma (Figure 5). Again, diagenetic reactions did not contribute to the carbon dioxide accumulation in Bunga Raya.

Most of the white sugar production is based on the clarification of sugarcane juice through sulfitation. In this work, alternative clarification technologies, namely ozonation and the electrochemical advanced oxidation process using the DSA® anode, are compared for the first time. In the first case, the effects of temperature and ozone concentration in the gas bubbled into raw sugarcane juice were investigated; for the electrochemical process, the effects of applied electric potential and temperature were considered. Central composite experimental designs were used to study the effects of these process variables on ICUMSA color removal, remaining sucrose content, rheology of the juice and energy consumption. For ozonation, the highest ICUMSA color removals at the end of 60 min were 75% (55 °C; 22.9 mg O3 L−1), 71.4% (33.7 °C; 14.5 mg O3 L−1), and 57.6% (55 °C; 14.5 mg O3 L−1), with energy consumptions of 532, 442 and 642 kWh m−3 order−1, respectively. In contrast, the highest ICUMSA color removal achieved by anodic electrooxidation was around 35%, at 33.8 °C and 18 V or 40 °C and 28 V, with 199 and 587 kWh m−3 order−1, respectively. In both cases, no losses of sucrose or appreciable variation in juice viscosity were observed. Considering equivalent clarification performances, the electrochemical process was shown to be more energy-efficient. Conversely, given the best performances achieved in each case, the clarification technologies studied did not reveal significant differences regarding energy consumption, sounding promising for industrial application, while further detailed process design and economic evaluation are needed.

The Direct Carbon Fuel Cell (DCFC), which uses solid carbon as fuel and molten carbonate as electrolyte, has had resurgence of interest due to very high electrochemical conversion efficiency (nearly 100%), no requirement of fuel reforming, and potential for CO2 capture and sequestration. At the cathode, carbon dioxide is converted into carbonate ions. The main reaction at the anode is generation of carbon dioxide from carbon and carbonate, viz.,(1) C + 2CO3 2- = 3CO2 + 4e-.The net cell reaction is oxidation of carbon to carbon dioxide. Additional reactions that may occur at the anode are (i) a two-electron reaction resulting in co-generation of carbon dioxide and carbon monoxide, viz.,(2) C + CO3 2- = CO2 + CO + 2e-,and (ii) the Boudouard reaction leading to conversion of carbon and carbon dioxide to carbon monoxide, viz.,(3) C + CO2 = 2CO2,the so-called “carbon corrosion” reaction. The performance of DCFC can be appreciably limited by this reaction.A one-dimensional macro-homogeneous kinetic model for a DCFC anode is developed in this study. We consider steady-state operation of a DCFC with uniform distribution of carbon and molten carbonate in the anode. The potential drop through the anode current collector, placed usually near the anode-electrolyte interface, is considered to be negligible. Given their small size, carbon particles are fully wetted in molten carbonate and the extent of the reverse Boudouard reaction is therefore negligible. For the characteristic pore diameters considered, there is substantial over-pressure in the thick slurry comprised of carbon particles and molten carbonate, permitting the reaction products to remain dissolved in the electrolyte. The reaction products are transported through the anode until they leave via gas channel at one end of the anode. In the thick slurry, the dominant mechanism for this transport is diffusion. The rates of reactions (1) and (2) are described by concentration- and temperature-dependent Butler-Volmer rate expressions. Each reaction is inhibited by its product(s).The conservation equations for electronic and ionic potentials are related to each other due to electro-neutrality. This is also the case with the conservation equations for electronic and ionic currents. The conservation equations for carbon monoxide and carbon dioxide are based on Fick’s law of diffusion. Numerical effort in solution of the four conservation equations can be reduced considerably by recognizing that only two of these are independent, as there are only two independent reactions. One therefore needs to solve only two boundary-value problems to determine the profiles of electronic potential, ionic potential, electronic current, ionic current, and product concentrations. The boundary conditions for the four variables depend on the configuration of a DCFC and location of the current collector in the anode, its distance from the anode-electrolyte interface. The external current density I is specified. The base values of the system parameters were obtained using information available in the published literature.Various microstructure and macrostructure parameters influence design and performance of a DCFC anode and these are considered in the model. Appropriate dimensionless parameters and variables are used to reduce the number of system parameters and variables via lumping. Five of the dimensionless parameters provide binary comparisons of resistances for reactions (1) and (2), ohmic resistance, and resistances for transport of the two reaction products. Various sets of the five dimensionless parameters are considered to examine the distribution of electronic and ionic potentials, electronic and ionic current densities, rates of reactions (1) and (2), and concentrations of carbon monoxide and carbon dioxide. Conditions under which reactions (1) and (2) occur throughout the anode, corresponding to a very effective anode, are identified. Conditions under which this is not the case are also investigated to see if there are specific benefits in constraining the two reactions to portion(s) of the anode. Besides generating spatial profiles of system variables for the anode, the kinetic model enables identification of polarization curves and power density versus current density plots. The optimum current density and the corresponding power density are influenced strongly by the relative importance of the five resistances. The effect of location of the anode current collector with respect to the anode-electrolyte interface is examined via few model simulations.

In today’s world, owing to industrial expansion, urbanization, the rapid growth of the human population, and the high standard of living, the utilization of the most advanced technologies is unavoidable. The enhanced anthropogenic activities worldwide result in a continuous increase in global warming potential, thereby raising a global concern. The constant rise in global warming potential forces the world to mitigate greenhouse gases, particularly carbon dioxide. Carbon dioxide is considered as the primary contributor responsible for global warming and climatic changes. The global anthropogenic carbon dioxide emissions released into the atmosphere can eventually deteriorate the environment and endanger the ecosystem. Combating global warming is one of the main challenges in achieving sustainable development. Carbon capture and storage is a potential solution to mitigate carbon dioxide emissions. There are three main methods for carbon capture and storage: post-combustion, pre-combustion, and oxy-fuel combustion. Among them, post-combustion is used in thermal power plants and industrial sectors, all of which contribute a significant amount of carbon dioxide. Different techniques such as physical and chemical absorption, physical and chemical adsorption, membrane separation, and cryogenic distillation used for carbon capture are thoroughly discussed and presented. Currently, there are various materials including absorbents, adsorbents, and membranes used in carbon dioxide capture. Still, there is a search for new and novel materials and processes for separating and capturing carbon dioxide. This review article provides a comprehensive review of different methods, techniques, materials, and processes used for separating and capturing carbon dioxide from significant stationary point sources.

Electrochemical processes offer R&D opportunities toward decarbonization and resource recovery for circular economics. Innovate material produced by advancing manufacture techniques further widens its applications. In this presentation, we will discuss electrochemical process designs and material innovation to address technical and economic challenges of separations in biochemical/ biofuel production, resources recovery, CO2 utilization and impaired water treatment. In separations, the electrically driven force enabling selective capture of charged species and/or in-situ aqueous pH manipulation provides high energy efficiency, low capital footprint and cost for industrial applications compared to other separation technologies, e.g., separations by pressure-driven, thermally driven and biological-related. The common practices known are electrodialysis (ED), electrodeionization (EDI), capacitive deionization (CDI), cation intercalation desalination (CID), and ion concentration polarization (ICP). In these techniques, concentrated ions are separated from the liquid energy use is correlated with the quantity of ions removed. Therefore, the selective target capture provides “fit-for-purpose” separations. Pressure-driven processes cannot tune salinity for fit-for-purpose quality desalination but are effective at organic and biological species removal that electrochemical processes are not able to do. Thermal-driven processes cannot tune salinity for fit-for-purpose quality but are effective at organic and biological species removal. Biological-related processes typically apply bioelectrochemical reactions via microbes and bacteria to drive the removal of ions from the solution. In biological processes, ions are removed from the water solution. The ability to produce fit-for-purpose water has not been explored with biological processes, but they can treat targeted organics and biologicals. Compared to the pressure-driven membrane separation technologies used most in industrial separations, applications of selective separations have increased in recent years and becomes important to address the challenges of technology adaptation to climate change. For examples, the production of biofuel and bio-products to reduce green-house gas emission from fossil fuel and the non-conventional water supply for water-energy nexus have required high energy efficient and cost effective separation technologies. Innovative electrochemical separations can provide transformational impacts in advancing selective separations for highly energy efficient, small capital footprints and low processing cost. It, thus, enables the paradigm-shift of using alternative fuels and water supplies for industrial applications. We will discuss the key process performance metrics, energy consumption and processing rate, of various electrochemical technologies applied in biorefinery, waste to energy and water energy nexus to separate charges species from “dilute” aqueous phase. The ions separation performance demonstrated from various aqueous streams include 1) Inorganic and organic salts removal/capture in lignin valorization. and from bioprocessing streams in biofuel production; 2) volatile fatty acid removal/capture as well as biogas purification from solid waste anaerobic digester for waste to energy; 3) selective desalination of hardness, alkalinity, silica, and ammonia from impaired water for cooling water supply; 4)Capture and delivery for CO2 utilization. Critical issues in process design and material property to achieve electrochemical separation rate and energy efficiency for economic viability will be discussed.

In the past few decades, membrane-based processes have become mainstream in water desalination because of their relatively high water flux, salt rejection, and reasonable operating cost over thermal-based desalination processes. The energy consumption of the membrane process has been continuously lowered (from >10 kWh m−3 to ~3 kWh m−3) over the past decades but remains higher than the theoretical minimum value (~0.8 kWh m−3) for seawater desalination. Thus, the high energy consumption of membrane processes has led to the development of alternative processes, such as the electrochemical, that use relatively less energy. Decades of research have revealed that the low energy consumption of the electrochemical process is closely coupled with a relatively low extent of desalination. Recent studies indicate that electrochemical process must overcome efficiency rather than energy consumption hurdles. This short perspective aims to provide platforms to compare the energy efficiency of the representative membrane and electrochemical processes based on the working principle of each process. Future water desalination methods and the potential role of nanotechnology as an efficient tool to overcome current limitations are also discussed.

This paper describes an electrochemical treatment process of hydrochlorothiazide (HDZ) under different conditions such as initial concentration, sodium chloride and applied voltage. In this present study, HDZ was treated by electrochemical oxidation process using graphite-PVC composite electrode as anode and Platinum (Pt) as cathode. All results were analyzed using liquid chromatography-time of flight/mass spectrometry (LC-TOF/MS). It was found that at high applied voltages, and high amounts of NaCl, the electrochemical treatment process was more efficient. The removal% of HDZ was 92% at 5 V after 60 min. From the obtained results, the electrochemical oxidation process of HDZ followed pseudo first order with rate constant values ranged between 0.0009 and 0.0502 min−1, depending on the experimental conditions. Energy consumption was also considered in this study, it was ranged between 0.9058 and 5.56 Wh/mg using 0.5, 0.3 and 0.1 g NaCl within interval times of (10, 20, 30, 40, 50, 60, 70, and 80 min). Five chlorinated and one non-chlorinated by-products were formed and analyzed in negative ionization (NI) mode during the electrochemical process. Due to the strong oxidizing potential of the chlorine (Cl2) and hypochlorite ion (ClO−), HDZ and its by-products were removed after 140 min. Furthermore, a novel synthesis of chlorothiaizde as one of the new by-products was reported in this present study. Toxicity was impacted by the formation of the by-products, especially at 20 min. The inhibition percentage (I%) of E. coli bacteria was decreased to be the lowest value after 140 min.

Carbon dioxide is one of the main if not the most potent greenhouse gases responsible for climate change. Scientists put great efforts to tackle this problem and carbon dioxide capture seems to be a promising solution. The present study proposes a novel method of carbon dioxide capture using black liquor, a side stream from the paper and pulp industry. Its content in sodium hydroxide makes it an attractive candidate for carbon dioxide capture via carbonation. The black liquor was prepared from oat husks, a non-woody biomass, using the soda-pulping process. To estimate its carbon dioxide absorption capacity, a mixture of nitrogen and carbon dioxide (70:30%) was sparged into a bubble column reactor and computational fluid dynamics simulations of this setup were used to evaluate the mixing process. The formation of carbonate and bicarbonate ions throughout the carbonation process was followed using a Fourier-Transform Infrared (FTIR) probe and a pH meter. The absorption capacity was measured from the weight increase of the reactor. It was found to be around 30 g of carbon dioxide/L of black liquor. The carbonate and bicarbonate species in black liquor before and after carbonation were further characterized with 13C Nuclear Magnetic Resonance (NMR), X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and optical microscopy. Using industrial side-streams might enable an economically feasible process without the need for production of virgin absorbents or their recovery. Furthermore, this capturing process, which is performed at atmospheric conditions might reduce the overall energy consumption. The results demonstrated that black liquor could be an attractive absorbent for carbon dioxide, paving the way for a circular and resource-efficient economy.