Attractive Alternative Technology Research Articles

Oxidative removal of dissolved manganese(II) by peroxymonosulfate: Non-radical mechanism and influencing factors

In this study, the oxidative removal of Mn(II) by peroxymonosulfate (PMS) was investigated. PMS was found to be a more efficient oxidant than chlorine for Mn(II) oxidation. Weak autocatalysis kinetics were observed in PMS/Mn(II) system suggesting that the Mn(II) oxidation consisted of both homogeneous (direct oxidation) and heterogeneous (amorphous MnO2 catalytic oxidation) processes. Homogeneous oxidation of Mn(II) by PMS showed strong pH dependency with apparent second-order rate constants of 3.1–249.9 M−1s−1 at pH 7.0–9.0. Stoichiometry of PMS to Mn(II) was about 1:1 suggesting a two-electron transfer pathway (O transfer), which was further confirmed by the XPS analysis results. However, the change in the coordination structure of Mn(II) was found to greatly affect the oxidation rate and mechanism of Mn(II). Complexion with inorganic or organic ligands could inhibit the oxidation rate of Mn(II) and alter the oxidation mechanism from two-electron to one-electron pathway. Furthermore, coexisting metal ions such as Ca(II), Zn(II), and Fe(II)/Fe(III) ions could greatly accelerate the oxidation of Mn(II) by PMS and chlorine by promoting the heterogeneous oxidation process. Oxidative removal of Mn(II) by PMS was more efficient than chlorine in real waters (56 %–100 % versus 12 %–17 %). The combination of PMS oxidation with coagulation could further increase the removal efficiency from 56 % to 92 %. These findings highlight that PMS oxidation is an attractive alternative technology for Mn(II) removal and may also provide a fundamental understanding of the Mn materials-based advanced oxidation processes.

Flexible CO2 capture for open-cycle gas turbines via vacuum-pressure swing adsorption: A model-based assessment

As energy systems require flexible and responsive power generators to combat network imbalances, CO2 post-combustion capture (PCC) technologies need to be capable of transient operation. However, currently only amine absorption has been investigated for its efficacy in Flexible-PCC.Within this study we develop and validate a vacuum-pressure swing adsorption (VPSA) process model, capable of processing 33.8 kg/s of exhaust flow from a small-scale open-cycle gas turbine (OCGT). The Flexible response scenario is based on realistic load changes of OCGTs during a 5-h period. To handle the size of flow the system is split into two identical two bed four step VPSA processes, both using Zeolite 13X as the adsorbent material. Included in the Flexible-VPSA operation is the start-up, ramping, and shutdown procedures. Flexible-VPSA showed minute deviations in CO2 purity and recovery rate, and despite the specific energy demand increasing, results show no technical limitations to transient operation. The Flexible VPSA simulations are compared against the benchmark MEA solvent, with both technologies performing similarly when processing highly transient flue gas flowrate. Thus, VPSA is potentially an attractive alternative technology for Flexible-PCC.

Switched-Beam Optimization for an Indoor Visible Light Communication Using Genetic Algorithm

Nowadays, Visible Light Communication (VLC) is an attractive alternative technology for wireless communication because it can use some simple Light Emitting Diodes (LEDs) instead of antennas. Typically, indoor VLC is designed to transmit only one dataset through multiple LED beams at a time. As a result, the number of users per unit of time (throughput) is relatively low. Therefore, this paper proposes the design of an indoor VLC system using switched-beam technique through computer simulation. The LED lamps are designed to be arranged in a circular array and the signal can be transmitted through the beam of each LED lamp with the method of separating the dataset to increase the number of simultaneous users for enhancing the indoor VLC. The coverage area is determined from the area where the communication can be performed at a location on the receiving plane with a Bit Error Rate less than or equal to the specified value based on coverage illuminance according to International Commission on Illumination (CIE) standards. In this paper, Genetic Algorithm is used to find the suitable solution for designing parameters to achieve maximum coverage area. The results show that a Genetic Algorithm can be used to find a suitable solution and reduce the computational time approximately 382 min in proposed scenarios.

Performance and mechanism of the separation of C8 α‐olefin from F‐T synthesis products using novel Ag‐DES

AbstractAs an attractive alternative technology for the separation of long chain olefin and paraffin, a novel silver‐based deep eutectic solvent (Ag‐DES) was prepared and utilized for 1‐octene/n‐octane separations. Comprehensive reactive extraction separation experiments were performed to highlight the Ag‐DES concentration and operating temperature discriminations using compounds with different ratio of 1‐octene/n‐octane. The novel Ag‐DES showed optimal separation performance regarding 1‐octene/n‐octane and possessed the highest levels separation selectivity in the range 3.57–16.11 with excellent circulation stability in our best knowledge. Furthermore, FT‐Raman measurements and quantum chemistry calculation were performed to elucidate the interaction mechanism of Ag‐DES in the separation of 1‐octene and n‐octane, which revealed that both chemical complexation and strong physical attraction existed in the complex of Ag‐DES and 1‐octene rather than n‐octane. A practical process was proposed for the separation of olefin and paraffin, which indicates that an advanced separation technology could largely reduce the energy consumption. This study lends important insight for the development of Ag‐DES reactive extraction separation process for the energy‐efficient long chain α‐olefins purification from F‐T synthesis products.

Sulfadiazine removal using green zero-valent iron nanoparticles: A low-cost and eco-friendly alternative technology for water remediation

In this work, the effectiveness of green zero-valent iron nanoparticles (gnZVIs) for the removal of the antibiotic sulfadiazine (SDZ) from water via adsorption and reduction was tested. Additionally, the effectiveness of this material as a catalyst for the Fenton and photo-Fenton processes was also investigated. This represents the first study concerning the use of gnZVIs for the degradation of a sulfonamide antibiotic. The results obtained indicate that gnZVIs were able to remove up to 58% of SDZ via adsorption and up to 69% via adsorption plus reduction using a SDZ/Fe3+ molar ratio of 1:61.6. Furthermore, gnZVIs showed strong effectiveness as a catalyst for the Fenton and photo-Fenton reactions, with complete SDZ removal in 8 h and 5 min, respectively, using a SDZ/Fe3+/H2O2 molar ratio of 1:38.4:38.4. These results demonstrate that the use of gnZVIs constitutes an attractive and potential alternative technology for water remediation, reducing environmental impact and operational costs.

Developing New Chemistries for Redox Flow Batteries (AORFBs)

Aqueous organic redox flow batteries (AORFBs) have emerged as an attractive alternative RFB technology because redox active organic molecule materials are synthetically tunable, sustainable, and potentially low cost. The presentation will cover our recent research efforts in developing viologen anolyte materials for both anion and cation exchange pH neutral AORFBs with a variety of catholyte materials including ferrocene, TEMPO, ferrocyanide and halides. The viologen AORFBs demonstrated outstanding battery performance including an energy density of up to 30.4 Wh/L, a power density up to 220 mW/cm2, energy efficiency up to 72% at 60 mA/cm2, and capacity retention up to 99.999% per cycle up to 1000 cycles, representing the most stable organic RFB reported to date. In addition, this presentation will discuss mechanistic understandings of investigated redox active molecules using a variety of spectroscopic tools. Particularly, the presentation emphasizes that fundamental understandings of redox active electrolytes at molecular level are crucial to develop new generations of redox flow batteries for large scale and dispatchable renewable energy storage.

Effect of Ammonium Cations on the Diffusivity and Structure of Hydroxide Ions in Low Hydration Media

Anion exchange membrane (AEM) fuel cells are an attractive alternative technology to the acidic proton exchange membrane-based fuel cells. Conduction of hydroxide ions in AEMs creates an alkaline operating environment that allows using platinum-free catalysts, while still maintaining the performance needed for commercial application (e.g., the automotive industry). However, this technology is very sensitive to the behavior of hydroxide ions under low hydration conditions because of the consumption of water near the cathode. We use molecular dynamics simulation to investigate the behavior of two model quaternary ammonium cations used in AEM technologies at low hydration states in the presence of hydroxide anions. Both systems show the existence of an interesting ion complex—water-bridged hydroxide pair—that surprisingly involves two hydroxide anions in close proximity that is found to be highly stable. We use these new insights to explain the observed change in diffusivity of hydroxide and water from high ...

Developing New Chemistries for Redox Flow Batteries

Aqueous organic redox flow batteries (AORFBs) have emerged as an attractive alternative RFB technology because redox active organic molecule materials are synthetically tunable, sustainable, and potentially low cost. The presentation will cover our recent research efforts in developing viologen anolyte materials for both anion and cation exchange pH neutral AORFBs with a variety of catholyte materials including ferrocene, TEMPO, ferrocyanide and halides. The viologen AORFBs demonstrated outstanding battery performance including an energy density of up to 30.4 Wh/L, a power density up to 220 mW/cm2, energy efficiency up to 72% at 60 mA/cm2, and capacity retention up to 99.999% per cycle up to 1000 cycles, representing the most stable organic RFB reported to date. In addition, this presentation will discuss mechanistic understandings of investigated redox active molecules using a variety of spectroscopic tools. Particularly, the presentation emphasizes that fundamental understandings of redox active electrolytes at molecular level are crucial to develop new generations of redox flow batteries for large scale and dispatchable renewable energy storage.

Energy recovery from cross-linked polyethylene wastes using pyrolysis and CO2 assisted gasification

High-temperature gasification is an attractive alternative technology for clean energy production from plastic wastes and provides a sustainable pathway for their disposal. Waste cross-linked polyethylene (XLPE) offers good potential energy recovery source because of its high energy density of around 47 MJ/kg that can be converted to syngas using pyrolysis or gasification. CO2 assisted gasification can provide clean and efficient syngas that can be converted further to valuable products. This can effectively decrease the carbon foot-print from the utilization of polyethylene wastes. This paper examines pyrolysis and CO2 assisted gasification of XLPE waste with focus on the kinetics, product yield and syngas yield properties (yield of carbon monoxide, hydrogen, and hydrocarbon) at different temperatures. Pyrolysis experiments were carried out to estimate the impact of the gasifying agent over pyrolysis. Pyrolysis and CO2 assisted gasification were conducted at several temperatures in the range 973 K to 1173 K in steps of 50 K. The results were compared with high-, medium-, low-density polyethylene as well as ultra-high molecular weight polyethylene. Higher temperatures provided increased syngas yields from pyrolysis. The activation energy of pyrolysis from single-step kinetic analysis of TGA data revealed increases with an increase in branching and cross-linking. The reaction profiles of the single step of all the samples (except medium density polyethylene) were found to be closely represented by the Avrami-Erofeev models. Results also revealed that gasification generated more syngas, hydrogen, and energy than pyrolysis. Gasification consumed the CO2 to generate syngas with a mass-specific heating value similar to natural gas suggesting efficient utilization of both CO2 and XLPEs for clean and efficient energy production.

Old habits die hard: Using the energy cultures framework to understand drivers of household-level energy transitions in urban Zambia

This paper contributes to the literature on household energy transitions by highlighting the case of household cooking in urban Lusaka, Zambia. Through 32 targeted sector expert and household level interviews, we use the “Energy Cultures Framework” to identify normative, material and practice related determinants of the dominant cooking culture(s). We find that cooking behaviour is determined and self-reinforced through everyday social interactions, such as expectations of food taste, the practice of purchasing charcoal, and the ability to undertake daily chores in combination with cooking. The current dominant cooking culture(s) meets little resistance but is reinforced by external factors such as national policy regulation, lack for attractive alternative technologies and accessible charcoal markets. We also explore what might drive change of the dominant cooking culture(s) and find that perceptions vary notably between households and sector experts. While households generally recognise that a change in cooking culture is complex to bring about - as it is determined by a multitude of intertwined “softer” factors - sector experts consistently highlighted “harder” determinants of cooking behaviour such as fuel availability, fuel price and the cost of alternatives as the main triggers of change. This mismatch in understanding of how change is enabled about suggests that top-led interventions to diversify cooking behaviour have much to gain from further considering how norms, practices and material culture determine dominant energy culture(s) in a society.

A novel 3D three/five-input majority-based full adder in nanomagnetic logic

In recent decades, complementary metal–oxide–semiconductor (CMOS) downscaling has faced some serious challenges such as undesired leakage current densities and high power dissipation. One of the most attractive and promising alternative technologies to CMOS is nanomagnetic logic (NML), which is based on nonvolatile ferromagnetic computing states. In this paper, a novel full adder cell is suggested by providing a feedback loop to a special multilayer nanomagnetic majority voter, which switches between three- and five-input majorities periodically. This solution also represents an example revealing the potential of NML for circuit designs that are not accessible using other technologies such as CMOS or quantum-dot cellular automata (QCA). This capability comes from the combination of a clocking system and the nonvolatile behavior of NML. The correct operation of the new full adder cell is verified using the MQCA Verilog library. Comparisons with other state-of-the-art full adders show significant improvements in terms of density and simplicity.

Study on the Migration Characteristics of Sodium and Chlorine in Chemical Looping Process of ZhunDong Coal with Hematite Oxygen Carrier

ZhunDong coal is the largest coal resource in China but is characterized by high sodium and chlorine content. Chemical looping combustion with hematite as oxygen carrier is an attractive alternative technology for ZhunDong coal conversion without severe slagging and fouling problems. However, the influence of the chemical looping process for the migration characteristics of sodium and chlorine is not clear. Especially with the presence of hematite, it is bound to have a great influence on the migration of sodium and chlorine. For better controlling slagging and fouling problems caused by sodium and chlorine migration, it is necessary to study the migration paths of sodium and chlorine in the chemical looping process. Experimental results and analysis show that the migration characteristics and path of sodium and chlorine in the chemical looping process are different at different temperature ranges. However, some common grounds could be found. The releasing form of chlorine in the chemical looping process ...

Optimal rainwater tank design for control of particulate contaminants

AbstractRainwater systems, which collect rainfall from the roof surface, are an attractive alternative technology, and one of the cleanest water resources. Microorganisms can be treated by disinfection processes or by inducing a biofilm, but particulate matter can only be easily removed with effective storage tank design parameters. In this study, therefore, the effects of rainwater tank design parameters on the treatment of particulate contaminants are analyzed. The J-type inlet pipe seems to maintain stable rainwater quality by suppressing the resuspension of bottom sediments during rainfall inflow. The intermediate wall can prevent sediment from spreading to the whole storage tank, and provide functions such as securing the stable water quality of the outflow area and managing sediment flow to the inflow region. The baffles can simplify tank management such as sediment drainage and tank cleaning by leading to more sedimentation of particles in the unit area. Based on the water quality monitoring results of pH, biochemical oxygen demand (BOD), suspended solids (SS), and turbidity at the field scale, it is possible to supply a certain quality of water by optimizing tank design parameters alone even if particulate contaminants flow into the rainwater tank.

Developing New Chemistry for Redox Flow Batteries

Aqueous organic redox flow batteries (AORFBs) have emerged as an attractive alternative RFB technology because redox active organic molecule materials are synthetically tunable, sustainable, and potentially low cost. The presentation will cover our recent research efforts in developing two electron storage viologen molecules as anolyte materials for AORFBs. These viologen anolytes in neutral NaCl solutions have a theoretical capacity up to 96.5 Ah/L in H2O and exhibit a low reduction potential down to -0.78 V vs NHE. The neutral aqueous flow battery demonstration of two two-electron storage viologen molecules with (ferrocenylmethyl)trimethylammonium chloride (FcNCl) delivered up to 1.38 V cell voltage, and outstanding battery performance including a power density up to 130 mW/cm2, capacity retention up to 99.99% per cycle, and energy efficiency up to 65% at 60 mA/cm2. When paired with a TEMPO catholyte, a 1.72 V total organic RFB was also demonstrated. In addition, a fundamental study of the redox couple of [Fe(CN)6]4+/3+ in different supporting electrolytes with pH from 7 to 14 will be presented. We found that the redox couple functions best at neutral or near neutral conditions in RFBs. The entire presentation emphasizes that fundamental understandings of redox active electrolytes at molecular level are crucial to develop new generations of redox flow batteries for large scale and dispatchable renewable energy storage.

Screw pyrolysis technology for sewage sludge treatment

Sewage sludge quantities have grown continuously since the introduction of the European Directive (UWWTD 91/271/EEC) relating to the treatment of urban wastewater. In the present, most of the sewage sludge is combusted in single fuels incineration plants or is co-fired in waste incineration or coal power plants. The combustion of sewage sludge is a proven technology. Other treatments, such as fluidized bed gasification, were successfully adopted to produce suitable syngas for power production. Besides, the number of large wastewater treatment plants is relatively small compared to the local rural ones. Moreover, alternative technologies are arising with the main target of nutrients recovery, with a special focus on phosphorus. The aforementioned issues, i.e. the small scale (below 1MW) and the nutrients recovery, suggest that pyrolysis in screw reactors may become an attractive alternative technology for sewage sludge conversion, recovery and recycling. In this work, about 100kg of dried sewage sludge from a plant in Germany were processed at the newly developed STYX Reactor, at KIT. The reactor combines the advantages of screw reactors with the high temperature filtration, in order to produce particle and ash free vapors and condensates, respectively. Experiments were carried out at temperatures between 350°C and 500°C. The yield of the char decreased from 66.7wt.% to 53.0wt.%. The same trend was obtained for the energy yield, while the maximum pyrolysis oil yield of 13.4wt.% was obtained at 500°C. Besides mercury, the metals and the other minerals were completely retained in the char. Nitrogen and sulfur migrated from the solid to the condensate and to the gas, respectively. Based on the energy balance, a new concept for the decentral production of char as well as heat and power in an externally fired micro gas turbine showed a cogeneration efficiency up to about 40%.

Impact of spintronic memory on multicore cache hierarchy design

Spintronic memory [spin-transfer torque-magnetic random access memory (STT-MRAM)] is an attractive alternative technology to CMOS since it offers higher density and virtually no leakage current. Spintronic memory continues to require higher write energy, however, presenting a challenge to memory hierarchy design when energy consumption is a concern. This study motivates the use of STT-MRAM for the first-level caches of a multicore processor to reduce energy consumption without significantly degrading the performance. The large STT-MRAM first-level cache implementation saves leakage power. Moreover, the use of small level-0 cache regains the performance drop due to STT-MRAM long write latencies. The combination of both reduces the energy-delay product by 65% on average compared with CMOS baseline. The proposed STT hierarchy also shows good scalability over the CMOS with a few benchmarks which scale significantly better. The PARSEC and Splash2 benchmark suites are analysed running on a modern multicore platform, comparing performance, energy consumption and scalability of the spintronic cache system to a CMOS design.

Molybdenum sulphides on carbon supports as electrocatalysts for hydrogen evolution in acidic industrial wastewater

Microbial electrolysis cells (MECs) are an attractive future alternative technology to generate renewable hydrogen and simultaneously treat wastewaters. The thermodynamics of hydrogen evolution in MECs can be greatly improved by operating the cathode at acidic pH in combination with a neutral pH microbial anode. This can easily be achieved with acidic industrial wastewaters that have to be neutralised before discharge. For the hydrogen evolution reaction (HER) in acidic wastewater, efficient and inexpensive catalysts are required that are compatible with the often complex chemical composition of wastewaters. In this study, molybdenum sulphides (MoSx) on different carbon supports were successfully used for hydrogen evolution in different acidic media. At first, the cathodes were screened by linear sweep voltammetry in sulphuric acid (pH 0) or phosphate buffer (pH 2.2). After this, the overpotentials for H2 production of the best cathodes and their long term performances (⩾1week) were determined in acidic industrial wastewater (pH 2.4) obtained from a plant mainly producing cellulose acetate. For the most promising MoSx cathodes, the overpotentials for HER (at 3mAcm−2) were only ∼40mV higher than for a platinum electrode. Most importantly, the catalytic efficiency of the MoSx electrodes improved in the wastewater over time (7–17days), while Pt electrodes were found to be slowly deactivated. Thus, MoSx emerges as an affordable, efficient and especially durable electrocatalyst for HER in real acidic wastewaters and this could be an important contribution to take energy production from wastewaters in the form of hydrogen towards practical applications.

Bio-Based Succinate Production from Arundo donax Hydrolysate with the New Natural Succinic Acid-Producing Strain Basfia succiniciproducens BPP7

Bio-based succinic acid production from lignocellulosic biomass is one of the attractive and prominent alternative technologies to overcome issues associated with the utilization of fossil sources. In this context, it is necessary to find new microorganisms that are able to efficiently ferment this recalcitrant feedstock. The ecological approach developed in this study enabled the isolation of Basfia succiniciproducens BPP7 from a complex rumen ecosystem. This new wild-type strain was able to synthesize up to 6.06 ± 0.05 g/L of succinate (corresponding to 0.84 ± 0.017 g of succinate per gram of consumed glucose + xylose and to 0.14 ± 0.001 g of succinate per gram of glucans + xylans present in the biomass before hydrolysis) from Arundo donax hydrolysate in separate hydrolysis and fermentation (SHF) experiments. Higher titers of succinic acid were obtained through the optimization of growth conditions. The optimal medium composition identified on the smaller scale was then used for 2.5-L batch experiments, which used A. donax hydrolysate and yeast extract as the main C and N sources, respectively. A maximal titer of 9.4 ± 0.4 g/L of succinic acid was obtained after 24 h. The overall results clearly demonstrate the potential of B. succiniciproducens BPP7 for succinate production.

Low Area Complexity Demultiplexer Based on Multilayer Quantum-dot Cellular Automata

Nanoscience and nanotechnology involve the ability to see and to control individual atoms and molecules. A quantum-dot cellular automata(QCA) is one of the attractive alternative technology among nanotechnology solutions. Demultiplexer is used in communication systems to convert the serial data to the parallel data. A demultiplexer receives the output signals from the multiplexer. For that reason, it is important components for making integrated circuit. This work target is designing a high optimized demultiplexer in QCA framework. We proposed designs of 1:2 and 1:4 demultiplexer and the simulation results reveal that our proposed designs have significant improvements, such as low complexity and power consumption aspects.

Mesoscopic Perovskite Light-Emitting Diodes.

Solution-processed hybrid bromide perovskite light-emitting-diodes (PLEDs) represent an attractive alternative technology that would allow overcoming the well-known severe efficiency drop in the green spectrum related to conventional LEDs technologies. In this work, we report on the development and characterization of PLEDs fabricated using, for the first time, a mesostructured layout. Stability of PLEDs is a critical issue; remarkably, mesostructured PLEDs devices tested in ambient conditions and without encapsulation showed a lifetime well-above what previously reported with a planar heterojunction layout. Moreover, mesostructured PLEDs measured under full operative conditions showed a remarkably narrow emission spectrum, even lower than what is typically obtained by nitride- or phosphide-based green LEDs. A dynamic analysis has shown fast rise and fall times, demonstrating the suitability of PLEDs for display applications. Combined electrical and advanced structural analyses (Raman, XPS depth profiling, and ToF-SIMS 3D analysis) have been performed to elucidate the degradation mechanism, the results of which are mainly related to the degradation of the hole-transporting material (HTM) and to the perovskite-HTM interface.