Formation Of Undesirable Compounds Research Articles

Feasibility assessment of transition metal carbides applied to chemical looping reforming – A proof-of-concept for tungsten carbide

This paper is the first study to present an innovative technology for hydrogen and syngas production named Carbide Chemical Looping Reforming (CCLR). Nine different Transition Metal Carbides (TMC) were assessed in a thermodynamic study to evaluate potential materials to be applied in the system that could possibly form hydrogen and carbide when in the presence of methane. Out of all the materials, tungsten proved to be the best suitable due to its known high resistance to carbon deposits [1], low-temperature range to form carbides (at least 750 °C), no formation of undesired compounds, and considerably high hydrogen quality in syngas range. A sensitivity analysis is performed in order to assess the better conditions of temperature, pressure and methane ratio for the process to maximize the formation of hydrogen. A study of the heat balance between the air reactor and fuel reactor is shown to prove the system can work as an autothermal process and exclude external heat sources as well as an analysis of the carbon emission potential to prove the technology accounts for lower emission when compared to current technologies, such as Steam Methane Reforming and Steam Methane Reforming with Carbon Capture and Storage. Experimental thermogravimetric analysis showed a high formation of hydrogen and carbide in the system with high selectivity towards hydrogen/syngas reactions, proving the formation of carbides in a process and replicability of the system. Lastly, an economic assessment is performed with tungsten carbide to show that the application of tungsten in CCLR could achieve a competitive level to current technologies with a hydrogen cost price of USD 3.23, with the potential to be reduced even more depending on the process configuration.

Sulfur Interaction and Regeneration of CaMn0.775Ti0.125Mg0.1O2.9-δ Perovskite as Oxygen Carrier during Combustion of Sour Gas in a 500 Wth Chemical Looping Combustion Unit.

In the present study, the performance of a CaMn0.775Ti0.125Mg0.1O2.9-δ perovskite used as an oxygen carrier to burn sour gas with different H2S concentrations (up to 3000 vppm) in a continuous 500 Wth chemical looping combustion (CLC) prototype was investigated. After 29 h of sour gas combustion, the combustion efficiency had dropped by 18% in comparison with the reference test without sulfur addition. The characterization of the used particles of the perovskite confirmed that the presence of sulfur in the fuel gas had a poisonous effect through the formation of undesired compounds, such as CaSO4. The reactivity with CH4 and oxygen uncoupling capacity decreased, which could explain the decrease in the combustion efficiency. Two regeneration processes, one at high temperature (1273 K) and another one at low temperature (773-873 K), were carried out in a batch fluidized bed reactor to remove the amount of sulfur accumulated in the oxygen carrier particles. The detection of appreciable amounts of gaseous sulfur-based compounds (SO2 and H2S) during the experimentation and the postcharacterization results obtained through different techniques such as X-ray diffraction, ultimate analysis, and thermogravimetric analysis confirmed the effectiveness of both processes. Finally, the feasibility of implementation of the regeneration processes in a commercial CLC unit was thoroughly analyzed.

Electrochemically Modulated CO2 Removal from Oceanwaters

As the concentration of carbon dioxide is continuously increasing, there have been a lot of efforts to remove CO2 from various sources. While most of the attention has been focused on CO2capture at point sources followed by geological storage, interest in negative emission strategies also increased recently. One of the promising approaches for negative emissions is removing CO2 from ocean water. The world ocean is the largest carbon sink, containing 120 times higher concentration compared to the atmosphere. Therefore, by removing CO2 from ocean water, we can expect a reduction in CO2 concentration in the atmosphere.Considering that the CO2-reduced oceanwater should be returned to the ocean, the addition of chemicals, and the formation of undesirable compounds should be avoided. In this respect, the electrochemical approach can be a good choice because it does not require additional chemicals, and the control of voltage can tune the reactions in the system. Until now, several approaches have been made by using the electrodialysis process. However, the use of bipolar membrane for water dissociation makes this process expensive, making the application of this process sluggish.In this talk, we will present a new membrane-free approach based on electrochemical modulation of the pH to release the CO2 from ocean water. After removing CO2, the treated water is alkalized before being returned to the ocean. Using an electrochemical pH swing approach, we could successfully remove the CO2 from ocean water without employing expensive membrane or additional chemicals.

Electrical conductivity and performance evaluation of verjuice concentration process using ohmic heating method

AbstractThe verjuice sample (14.5 ± 0.2% total soluble solid [TSS] content) was concentrated (at 102 ± 2°C evaporation temperature) until reach 50% TSS content by applying ohmic heating at 13, 15, 17, and 19 V/cm voltage gradients. The total process times up to 50% TSS content were determined as 2,100, 1,500, 1,200, and 1,020 s for 13, 15, 17, and 19 V/cm, respectively. The electrical conductivity values increased until reach 32% TSS content and then showed a decrease until the final TSS content. The total energy consumption values increased as the voltage gradient decreased. The total power and specific water removal ratio (SWRR) values decreased as the voltage gradient decreased. The efficiency of ohmic heating assisted concentration process increased with the applied voltage gradient and it ranged from 71.27 to 75.22%. By evaluating the effects of ohmic heating conditions applied in the present study on total process time, total energy consumption, and process efficiency, 19 V/cm voltage gradients could be recommended to be optimum evaporation conditions of verjuice concentration in case of decreasing process time and higher energy efficiency.Practical applicationsFruit juices are generally concentrated to extend their shelf life. Therefore, for concentration purposes, various techniques, such as thermal evaporation, freezing methods, and membrane techniques, are applied in the fruit juice industry. This technique has some disadvantages, such as high energy requirements, the formation of undesirable compounds, high initial investment cost, and high failure rate to reach the desired total soluble solid content. The ohmic heating method, which is among the alternative heating methods, has advantages such as high energy efficiency, shorter processing time, higher product quality, and not causing wastewater. As a result of this study, it is thought that the verjuice samples were successfully concentrated up to 50% TSS content by using the ohmic heating method and this method can be used as an alternative method instead of the traditional method due to higher process efficiency and shorter process time.

The Nutritional and Safety Challenges Associated with Lupin Lacto-Fermentation.

A sustainable agriculture that can satisfy the ever-rising global demand for food and animal feeds is becoming a manifest necessity in the light of the growing population, and the security concerns in the increasing land-use for food/feed. There has been a recent growth of interest in the positive impact of the functional ingredients derived from plants on human health. The proposed beneficial effects of such ingredients span from a decrease in plasma glucose levels and in preventing hypertension, to controlling obesity, improving satiety and stabilizing plasma lipid homeostasis. Lupin is a sustainable crop that plays an important role in organic farming, thus, the interest in lupin as a protein source for human and animal nutrition has increased in recent years. The use of legumes as a source of protein is somewhat limited by the low digestibility of most plant proteins (Neves et al., 2006). Previous digestibility studies of protein obtained from legumes have shown interactions between antinutritional compounds, such as trypsin inhibitors and tannins, and the decreased proteolytic susceptibility of protein complexes, thereby decreasing the food value of plant proteins (Agte et al., 1998). The digestibility of lupin protein could be improved by lactic acid fermentation (Bartkiene et al., 2015). However, it should be noted that lactic acid fermentation is a traditional process for food and feed production that may also result in the formation of undesirable compounds (e.g., biogenic amines and D-lactate). Also, lupin exhibits useful techno functional properties allowing its use as an ingredient in the production of several palatable food products, such as biscuits, pasta, and bread (Lee et al., 2006; Guillamon et al., 2010; Jayasena and Nasar-Abbas, 2011, 2012; Bartkiene et al., 2013a, 2016b). For instance, the supplementation of wheat flour with the high-protein lupin flours can improve the nutritional quality of baked goods (Gomez et al., 2008). In addition, lupine does not contain gluten (a mixture of proteins found in wheat and related grains), thus, it could be used as a functional ingredient in gluten-free foods (Scarafoni et al., 2009). However, the use of lupin flour with a high protein content for the production of cereal products may cause problems associated with the formation of acrylamide (Bartkiene et al., 2013b, 2016a). The tolerable daily intake (TDI) levels of acrylamide for neurotoxicity were estimated to be 40 μg/kg per day and for cancer—2.6 μg/kg per day (Tardiff et al., 2010). Mitigation strategies propose modifying the product formulations or processing conditions, to minimize the pathways of acrylamide formation. For this reason, it is very important to assess the risk of new raw materials and technological procedures and to evaluate the safety parameters of the finished products.

A Novel Method for Judging Health/Degradation of Lithium-Ion Batteries

ABSTRACTA novel and fundamental method was reported to judge states of lithium ion batteries (LIBs) using the capacitance and the voltage of the cells that were estimated from the real-time currents and voltage characteristics of the cells. We measured the differential capacitance, that is, dQ/dV or delta Q/ delta V that is equal to the currents (I) divided by differential voltages (dV/dt) calculated from the current and the voltage characteristics of the cell during the charging/ discharging, where Q is the charge that flows through the cell, V is the voltage of the cell and t is time. It is thought that the capacitance decrease with the degradation of the cell because the effective area of the electrodes is decreasing due to formation of undesirable compounds. The differential capacitance in some specific voltage range for the LIBs was approximately directly proportional to the state of the degradation of the cell. Therefore, it is concluded that the novel method is very useful to judge the state of the LIBs.

Monitoring Chloride and Nitrite Ions in 2,4-Dichlorofluorobenzene Plant Effluent by CE

A capillary electrophoresis method was developed for the separation and determination of chloride and nitrite in the effluents obtained during the process development of the synthesis of 2,4-dichlorofluorobenzene. Monitoring chloride and nitrite in the process effluents is necessary to improve the yield, minimize the formation of undesirable compounds and also to reduce environmental pollution. A buffer consisting of boric acid, chromate and tetradecyltrimethylammonium bromide was used for the separation. Nitrate was used as the internal standard. Indirect UV detection was performed at 254 nm using chromate co-ion as a chromophore. The limit of detection of chloride and nitrite were 0.85 and 1.05 ppm, respectively. The intra- and inter-day variance values were less than 3% with correlation coefficients for the two target anions of >0.999. The recoveries for chloride and nitrite ranged from 99.24% to 101.56%. Chlorides and nitrites in the process samples were in the range of 0.08–0.16% and 0.18–0.28%, respectively. There was no interference from other peaks under the optimized electrophoretic conditions.

Review of quality factors on wine ageing in oak barrels

Oak barrels have an important effect on wine aroma, colour, and stability. In addition, the product undergoes spontaneous clarification. The quality of aged wine depends on many different factors, mainly the wood composition, wine composition and ageing time. First, we shall review the different studies carried out on the above-mentioned factors. In addition, we shall look at the works carried out on the formation of undesirable compounds (ethylphenols), which are mainly found in wine ageing in used barrels. Finally, studies made on the processes of sorption of some wine volatile compounds by wood and by lees and new methods of ageing wine in wood will be presented.