Molten carbonate electrolysis cells have recently gained interest for the sustainable production of H2 or syngas to substitute fossil fuels. However, they can be also used for CO2 sequestration, as ...they pump it from one electrode inlet to the opposite electrode outlet. Thus, they can easily be applied to segregation of CO2 from H2 based fuels while also increasing the fuel heat of combustion for example after a steam reforming reactor.
To explore the use of molten carbonate electrolysis cell for this application, in this work the authors investigate the performance of the cell under different operating conditions in term of both operating temperature and fuel electrode gas composition. Polarization curves, gas crossover and electrochemical impedance spectroscopy are used to evaluate specific issues (high electrolyte losses due to water and temperature) or benefits (excess of H2O in regard to CO2 that allows for higher CO2 capture rate). After, a series of long-term tests at −150 mA cm−2 and 650 °C are performed to demonstrate long term stability. In particular, before electrolyte loss made the performance unstable, different cells are operated for about 1000 h with an average voltage of about 1.14 V demonstrating also the repeatability of such tests.
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•Molten carbonate electrolysis cells can be used for CO2 capture and H2 upgrading.•Different molten carbonate electrolysis cells were operated for performance study.•Long-term operations (1000 h) were successfully achieved with repeatability.
Understanding soil health condition is essential to the sustainability and stability of the entire ecosystem of farmland. The primary objective of this study was to improve the soil health index ...(SHI) based on principle component analysis (PCA) and develop a new analysis method for soil health assessment based on Meta-Analytic Hierarchy Process (Meta-AHP), which provides consistent minimum data sets (MDS), weight and scoring function for different locations, studies and management. The thirteen variables of MDS that exhibited sensitivity to management between organic and conventional soil were selected by meta-analysis. The indicator weight was assigned by a combination of experts scoring, AHP and meta-analysis. To test the applicability and sensitivity of the soil health assessment by Meta-AHP, a sixteen-year long-term test was assessed by the conventional SHI method (cSHI) and Meta-AHP. The results showed that similar evaluation results and significant positive correlations (**P < 0.01, n = 9) between the two evaluated methods were observed, and the results calculated using Meta-AHP had the best discrimination under different plant systems due to the higher F values when compared with the cSHI. This study developed a sensitive and consistent SH assessment framework that can be used applied to a variety of location, study, and soil management systems.
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•Meta-analysis improved the sensitivity of minimum data sets in soil health assessment.•Analytic Hierarchy Process could adjust weight for soil health assessment.•Accuracy of Meta-AHP method was testified by Long-term experiment of organic farming.
A systematic study is carried out to determine the optimum electrospinning preparation condition to prepare an adequate electrospun nanofibrous membrane (ENM) for direct contact membrane distillation ...(DCMD). A structural properties investigation of ENM was carried out because of the significant impact of its architectural structure, nanofiber diameter, inter-fiber space and ENM thickness, on DCMD performance. The morphology, hydrophobicity, mechanical properties, crystallinity and DCMD desalination were investigated. A long-term DCMD experiment (100h) was carried out using 30 g/L NaCl aqueous solution, both in the feed and permeate side of the optimum ENM membrane to evaluate its potential to produce drinkable water in case of lack of distilled water, for instance in a remote area, emergency situation, and/or portable system. In this case, drinkable water could be produced after 28 h with a permeate flux of 57.5 kg/m2.h and a salt rejection factor greater than 99.9%. Another long-term DCMD experiment (65 h) was conducted using 30 g/L NaCl aquesous solution as feed but at a higher temperature and distilled water as permeate to evaluate the desalination stability, wettability and scaling of the optimum ENM. A permeate flux of 58.5 kg/m2.h was obtained with a salt rejection factor greater than 99.9%.
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•Electrospinning parameters dictate the ENMs morphology, hydrophobicity, and porosity.•The nanofiber diameter and ENM thickness affect membrane properties and performance.•ENMs can be developed for long-term direct contact membrane distillation (DCMD) tests.•ENMs could be a good candidate for portable DCMD to produce drinkable water.•ENMs can be used for water production in remote areas and emergency situations.
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•The MnO2 nanowires were wrapped by the Ni(OH)2 nanosheets in the MnO2-Ni(OH)2 composites.•1.0 nwMnO2-1.0 @CP electrode showed cell voltage of 1.64 V and a low Tafel slope of 68 mV ...dec−1.•Faradaic efficiency of 96.2%kepton for 300 h.•The synergy between nwMnO2 and nsNi(OH)2 accompanies a lattice oxygen participant adsorbate evolving mechanism.
To improve and maintain the oxygen evolution reaction (OER) performance of MnO2 in water electrolysis for a long time, this study attempts to utilize Ni(OH)2 nanosheets (ns), which have excellent electrochemical properties. Nanocomposites of MnO₂ and Ni(OH)2 were directly grown on a carbon paper (CP) electrode using hydrothermal synthesis. The MnO2 nanowires (nw) appeared to be wrapped by the Ni(OH)2 nanosheets in the MnO2-Ni(OH)2 composites. The MnO2-Ni(OH)2 composite electrode exhibited better OER performance than the nwMnO2@CP or nsNi(OH)2@CP electrodes. In particular, in a 1.0 M KOH alkaline electrolyte, the 1.0 nwMnO2-1.0 nsNi(OH)2@CP electrode showed the highest OER performance with a cell potential of 1.64 V and Tafel slope of 68 mV dec−1 at a 10 mA cm−2 of current density (η = 0.41 V). The X-ray photoelectron spectroscopy of nwMnO2-nsNi(OH)2@CP before and after the OER revealed the formation of more oxygen vacancies, which served as OH-adsorption sites, leading to higher OER activity. The stability of the 1.0 nwMnO2-1.0 nsNi(OH)2@CP electrode was demonstrated through 300 h-OER long-term tests, which yielded a high Faradaic efficiency of 96.2%. The lattice oxygen transfer plays a significant role in enhancing the intrinsic activity of catalysts during OER. The synergy between nwMnO2 and nsNi(OH)2 accompanies a lattice oxygen participant adsorbate evolving mechanism.
A solid oxide short stack composed of 6 Ni‐YSZ supported cells, YSZ electrolyte and GDC‐LSC oxygen electrode has been tested for 10,700 hours in steam electrolysis. Initial degradation was followed ...by a global stabilization of the performance after lowering the current density, with a degradation rate below 0.5% kh−1.
Post‐test analysis has been conducted on two repeating units (RUs) to highlight the most significant microstructure alterations. Nickel depletion was observed in the hydrogen electrode close to the interface with the electrolyte. Formation of small pores in the electrolyte was detected along the grain boundaries. A consequent detachment related to this phenomenon was observed in proximity of the GDC compatibility layer. At the oxygen electrode side, the formation of a ∼1 µm dense mixed layer of GDC and YSZ was observed. Strontium from the LSC electrode migrated through GDC pores and reacted with YSZ, forming evident SrZrO3 inclusions. Distinct accumulation of silicon at the Ni/YSZ interface and chromium on the GDC barrier layer have been observed in both RUs. Despite this range of alterations observed, the stack degradation remained limited, testified from the fact that performance decay between 4,000 and 10,000 hours of operation was virtually nil.
Solid oxide fuel cells are thought to be capable of a wide range of fuels, but the direct utilization of hydrocarbon fuels increases the risk of carbon deposition at the anode. In this research, a ...novel full cell structure supported by porous Gd0.1Ce0.9O1.95 (GDC) skeleton is proposed and anode material Ba(Ce0.9Y0.1)0.8Ni0.2O3–δ (BCYN) is proposed to be impregnated on the skeleton to form a multi-functional anode. In the operating reductional atmosphere, Ni is reduced from the BCYN and provides electrochemical catalyticity, and BCYN can absorb water on its surface to prevent carbon deposition. 5% Cu is also applied to the anode to increase electron conductivity by impregnation, and it doubles the peak power density. The composite Ba(Ce0.9Y0.1)0.8Ni0.2O3–δ@CuO anode is evaluated and found to have good carbon deposition resistance with 3% humidified C2H6 in constant current operation for 120 h, and withstand 3% humidified CH4 in OCV condition for nearly 160 h.
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•The novel full cell structure supported by porous Gd0.1Ce0.9O1.95 skeleton.•Ba(Ce0.9Y0.1)0.8Ni0.2O3–δ is impregnated on skeleton to form multi-functional anode.•Cu is applied to the anode to increase electron conductivity by impregnation.•The anode has carbon deposition resistance withstand 3% humidified CH4 and C2H6.
Corrosion modules simulating the engineered barrier system were designed in this study for long-term-corrosion (LTC) testing of canister materials under aerobic and anaerobic conditions. The LTC ...module for aerobic conditions was designed as a bath-type container with flowing underground water extracted from the Korea Underground Research Tunnel. Five types of metallic disks, that is, rolled Cu, Type 304 stainless steel (SS), Titanium Grade 2 (Ti-G2), cast iron (CI), and Cu coating, were embedded into bentonite and maintained at different temperatures. After 3 years of testing under aerobic conditions, the corrosion rates of CI and Cu were estimated to be 1.9 μm/year and 550 nm/year, respectively. The SS and Ti-G2 exhibited a better corrosion rate of 6 nm/year. The LTC module for anaerobic conditions was developed in a vessel-type cylindrical container to allow it to settle in the boreholes. Four coin-shaped disks of each metal were embedded in bentonite, which was subsequently stacked in the cylindrical vessel. The vessels were placed in boreholes at a depth of 300 m. The Cu corrosion rate after 6 months of LTC testing under anaerobic conditions was 280 nm/year. Longer LTC tests will provide a more exact corrosion rate.
Increasing the efficiency of coal power plants requires raising the operating temperature above 650°C. However, coal ash can severely attack alloy materials at high temperature. For example, the ...corrosion rates of commercial Fe- and Ni-based alloys are generally greater than 2 mm/year at 750°C in the gas environment of oxy-fuel combustion. Thus, a critical study is needed to determine the effect of the constituents in the ash on corrosion and find an approach to reduce the corrosion rates in an ash-laden environment at high temperature. The role of CaO in the ash (typical of U.S. Western coal ash) has been investigated in laboratory exposure environments with various structural alloys. Detailed results are presented on weight change, scale thickness, internal penetration, microstructural characteristics of corrosion products, and the cracking of scales for the alloys after exposure at 750°C. The thermal stability of K3Al(SO4)3 under the environment of oxy-fuel combustion was determined by thermogravimetric analysis and differential thermal analysis. The reaction of this low melting temperature salt with the CaO-containing ash is discussed. In addition, we performed synchrotron nanobeam X-ray analysis to study the phase and chemical composition of the oxide layers on the alloy surface. Results from these studies are used to address the role of CaO in ash in the long-term corrosion performance of alloys.
Much attention has been recently focused on realizing, by chemical treatment, an artificial superhydrophobic surface with elevated roughness in order to achieve both self cleaning and antireflective ...effects because superhydrophobic surface with surface functionalization is believed to be effective for the self cleaning effect, mimicking a lotus leaf. Various hydrophobic, hydrophilic, superhydrophobic, and superhydrophilic glasses are evaluated by monitoring the variation of water contact angle (CA), optical transmittance, and photovoltaic performance under outdoor conditions for 12 weeks. Our results show a nanopatterned superhydrophilic glass without surface chemical treatment exhibits more efficient self cleaning and antireflective effects, leading to only 1.39% of drop of solar cell efficiency during an outdoor test for 12 weeks, while the solar cells with bare glass packaging and fluorinated superhydrophobic packaging show 7.79% and 2.62% of efficiency drop, respectively.
► Various glass surfaces are tested for self cleaning and antireflective properties. ► We examine the contact angle, optical transmittance, and photovoltaic performance. ► Directly patterned superhydrophilic glass shows the best performance after 12 weeks. ► Surface chemical treatment process is unnecessary.
An electrochemical remediation technology, referred to as Electrochemical Geo-Oxidation (ECGO) was tested in field to assess its potential to treat polychlorinated biphenyls (PCBs) contaminated ...sediments from New Bedford Harbor (NBH), Massachusetts. The primary objective was to evaluate the effectiveness of ECGO for reducing PCB levels under the anaerobic conditions typical of saturated and submerged sediments. The ECGO treatment of aerated and un-aerated (anaerobic) samples of the NBH sediments began on November, 2003 and lasted over four-years until early July, 2008. During 2003–2006 seven sampling events occurred, and the last sampling was done on March, 2010, about 20 months after the treatment power was turned off on July 12, 2008. Full PCB congener analyses (EPA 22 1668A) and partial PCB scans (EPA Method 8082) were performed on samples collected from the ECGO test cells and the control cell. At the end of the first 30-month period, the sample analyses indicated about 30% reduction in total PCB levels in un-aerated ECGO test cell compared to the control. The eighth and final sampling in March 2010 showed that total PCBs had been greatly reduced in the un-aerated test cell, from about 40,000 μg/kg (ppb) to 200 μg/kg (ppb). Conversely, PCB levels in sediments contained in the aerated ECGO test cell remained relatively unchanged compared to the pre-test level and control. This represented a greater than 90% reduction in total PCBs relative to the 2003 starting levels and the control sample average. The final results indicated that ECGO was effective at degrading PCBs in a reducing environment.
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