Increase In Co Concentration Research Articles

Soapnut extract mediated synthesis of nanoscale cobalt substituted NdFeB ferromagnetic materials and their characterization

Neodymium iron boron (NdFeB) permanent magnets have high energy product with suitable magnetic and physical properties for an array of applications including power generation and motors. However, synthetic routes of NdFeB permanent magnets involve critical procedures with high energy and needs scientific skills. Herein, we report on soapnut extract mediated synthesis of nanoscale cobalt substituted NdFeB (Co-NdFeB) permanent magnetic powders (Nd: 15%, Fe: 77.5%, B: 7.5% and Co with molar ratios: 0.5, 1, 1.5 and 2). A 10 ml of 10% soapnut extract was added to 90 ml of respective chemical composition and heated to 60 °C for 30 min and aged for 24 h. The dried powder was sintered at 500 °C for 1 h. The characterization of the prepared nanoscale Co-NdFeB magnetic powders was done using the techniques such as Dynamic Light Scattering (DLS for size and zeta potential measurements), X-ray diffraction (XRD) for structural determination, Scanning electron microscopy (SEM) with energy dispersion spectroscopy (EDS) for surface morphological and elemental analysis, Fourier transform infrared spectroscopy (FT-IR) for the identification of functional groups associated and hysteresis loop studies to quantify the magnetization. The results revealed that particles were in irregular and tubular shaped and highly stable (Zeta potential: −44.4 mV) with measured size <100 nm. XRD micrographs revealed a tetragonal crystal structure and FTIR showed predominant N–H and O–H stretching indicates the involvement of these functional groups in the reduction and stabilization process of Co-NdFeB magnetic powders. Hysteresis studies signify the effect of an increase in Co concentration.

Early-Stage Deactivation of Platinum-Loaded TiO2 Using In Situ Photodeposition during Photocatalytic Hydrogen Evolution

This work unravels a sudden deactivation of Pt/TiO2 (P25) during the initial stages of photocatalytic H2 evolution from aqueous solution that, until now, has gone unnoticed, using a unique combination of in situ photodeposition of Pt with an on-line gas detector system. Utilizing a set of techniques, including high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (DRS-UV-vis), X-ray powder diffraction (XRD), Raman spectroscopy, and physisorption, we were able to attribute this deactivation to a shift in mechanism, accompanied by an increase in CO concentration. Key to this phenomenon is the ratio of Pt atoms to oxygen vacancies, which were created through ultrasonic pretreatment and in situ UV irradiation in the bulk and surface, respectively. We also observed a potential additional contribution to the deactivation by encapsulation of the Pt nanoparticles, indicating that strong metal–support interaction (SMSI) may ind...

Hydrophilic zeolite sorbents for In‐situ water removal in high temperature processes

AbstractAn attractive approach to reduce anthropogenic emission of carbon dioxide (CO2) would be to valorize it into value‐added products (e.g. alcohols or dimethylether) by chemical recycling. However, in most of these important reactions, water is produced as a byproduct that limits CO2 conversion thermodynamically and can lead to the deactivation of catalysts. Water removal in sorption‐enhanced reaction process (SERP) would allow the overcoming of these drawbacks and several zeolites (SOD, LTA, and FAU) have been selected to assess their potential to adsorb water in‐situ at high temperatures. This work aims to study the water adsorption capacity and kinetics in a large temperature range of 25–250 °C and evaluate the potential of the selected adsorbents for in‐situ water removal in the reverse water gas shift (RWGS) reaction. For all zeolites, the water uptake showed an important decrease at higher temperatures but the capacity at 250 °C was still significant. While the poor adsorption kinetics of SOD limit its use, FAU‐13X powder gave better results than LTA‐4A, which were confirmed by a more important increase of CO concentration at the exit of the reactor for the RWGS reaction. Transient adsorption data obtained in this study were fitted by a double stretched equation and the kinetic constants were determined. These results are essential to model and design an efficient SERP process and determine the optimal reaction conditions.

Magnetism and magnetooptics features of Zn1-xCoxOy thin films grown by pulsed laser deposition

The results of a comprehensive study of structural, magnetic and magneto-optical properties of 10–262 nm thick Zn1-xCoxOy films (x = 0–0.3) grown on c-sapphire substrates by pulsed laser deposition (PLD) method are present. It is revealed that all of the synthesized Zn1-xCoxOy films possess a wurtzite structure with the following lattice parameters: a = 3.2495 Å, c = 5.2329–5.2485 Å. It is detected that ferromagnetic properties of Zn1-xCoxOy films at room temperature vary non-monotonically with the increase of Co concentration. The strongest ferromagnetic signal is observed in the Zn0.87Co0.13Oy film due to the largest number of metallic Co clusters formed in the sample. A further increase of dopant concentrations in the films leads to the oxidation of metallic Co and the development of the paramagnetic Co3O4 phase which result in the decrease of the ferromagnetic signal. It is determined that specific magnetic characteristics of Zn1-xCoxOy samples do not depend on the film thickness. Characteristics of transversal Kerr effect pertaining to cobalt concentration in Zn1-xCoxOy films as well as thickness of the samples are studied for the first time. The correlation between the amplitude of the magneto-optical signal and the magnetization value of the films is established.

Street-service-level approach towards the calculation of CO emission in Malang City, Indonesia

Malang has shown an annual vehicle growth of 15%. However, it is an umfortunate fact that 32% of 44 main streets are identified as having low service level, according to a local transportation ranking report. Such condition results in the decline of average vehicle velocity, approaching to the level of velocity (v) = 0; or in other words, street saturation degree could reach >1. The condition is not proportional to the increase of CO concentration in Malang in 2013-2014 as shown in the result of Evaluation of City Air Quality in 2014 which jumped from 3000 µm/m3 in 2013 to almost 5000 µm/m3 in 2014. This study was aimed at evaluating the extend to which street-service-level variables influence the production of CO emission from motorized transportation activity in an urban street in Malang. Gatot Subroto Street is chosen as a case study according to Multi Criteria Analysis. Furthermore, the street-service-level variables being evaluated include vehicle volume, velocity, side friction, effective roadside width and effective street width. Through a qualitative statistical analysis approach using a multiple linear regression analysis, the result suggests that vehicle volume and side friction are the most dominant factors (Xi) that significantly influence CO emission loads (Y).

Magnetic Properties and Photocatalytic Behavior of Co Co-doped BiFeO3:Er

The multiferroic materials Bi0.95Er0.05Fe1−xCox O3 (x = 0, 0.01, 0.03, and 0.05) are synthesized by solvothermal method. X-ray diffraction pattern is used to confirm the formation of rhombohedral crystal structure. TEM images show agglomerated nanosize particles. With the concentration of Co, a red shift is observed in the charge transfer transition of O2p-Fe3d band and band gap decreases. At higher concentration of Co, the saturation magnetization enhances and coercivity also varies with the concentration of Co. The photocatalytic degradation of methylene blue is evaluated under the visible light with the assistance of H2O2. With the increase in Co concentration, the photocatalytic activity decreases. The main species responsible for the degradation is found out using scavengers like ammonium oxalate, silver nitrate, p-benzoquinone, and tert-butyl-alcohol. The possible mechanism for the degradation of dye is explained.

Air pollution and short-term clinical outcomes of patients with acute myocardial infarction.

Ambient air pollution is well-known to be a serious risk factor for cardiovascular diseases, stroke, and death. However, the association between air pollutants (AP) exposure and short-term clinical outcomes in acute myocardial infarction (AMI) patients (pts) has not been elucidated well. In the present study, 37880 AMI pts were enrolled from October 2005 to December 2013 in a nationwide large-scale, prospective, multicentre Korea AMI registry (KAMIR registry; http://www.kamir.or.kr). We obtained data on AP (e.g., NO2 , SO2 , CO, O3 and PM10 ) from the Korean National Institute of Environmental Research (NIER; http://www.nier.go.kr). Clinical endpoints included death, recurrent myocardial infarction (Re-MI), any revascularization and composite of all-cause death and Re-MI. Exposure to AP is defined as the average exposure to AP within 24hours before AMI admission. We observed that a 0.01 part per million (ppm) increase in NO2 concentration, 0.001ppm increase in SO2 concentration, and 0.1ppm increase in CO concentration each increased the risk of total death by 9.7% (95% CI, 6.2%-13.4%), 1.9% (95% CI, 0.3%-3.6%), and 2.1% (95% CI, 0.5%-3.9%), respectively. Exceptionally, O3 decreased the risk of total death by 0.6% (95% CI -0.2% to -1.0%) per 0.01ppm increase. PM10 was not related to any cardiovascular events. AP were each stratified into five quintiles according to ranges of AP levels. After adjusting analysis for risk variables, only high quintiles (Q4, Q5) of NO2 were positively associated with total death, cardiac death and MI, while SO2 , CO, O3 and PM10 were shown to be not related to any cardiovascular events at all levels. In AMI patients, each AP and its concentration has shown a different effect to short-term mortality and cardiovascular events.

Reduction of Oxide Mixtures of (Fe2O3 + CuO) and (Fe2O3 + Co3O4) by Low-Temperature Hydrogen Plasma

The paper presents experimental results pertaining to the reduction of oxide mixtures namely (Fe2O3 + CuO) and (Fe2O3 + Co3O4), by low-temperature hydrogen plasma in a microwave hydrogen plasma set-up, at microwave power 750 W and hydrogen flow rate 2.5 × 10−6 m3 s−1. The objective was to examine the effect of addition of CuO or Co3O4, on the reduction of Fe2O3. In the case of the Fe2O3 and CuO mixture, oxides were reduced to form Fe and Cu metals. Enhancement of reduction of iron oxide was marginal. However, in the case of the Fe2O3 and Co3O4 mixture, FeCo alloy was formed within compositions of Fe70Co30, to Fe30Co70. Since the temperature was below 841 K, no FeO formed during reduction and the sequence of Fe2O3 reduction was found to be Fe2O3 → Fe3O4 → Fe. Reduction of Co3O4 preceded that of Fe2O3. In the beginning, the reduction of oxides led to the formation of Fe–Co alloy that was rich in Co. Later Fe continued to enter into the alloy phase through diffusion and homogenization. The lattice strain of the alloy as a function of its composition was measured. In the oxide mixture in which excessive amount of Co3O4 was present, all the Co formed after reduction could not form the alloy and part of it appeared as FCC Co metal. The crystallite size of the alloy was in the range of 22–30 nm. The crystal size of the Fe–Co alloy reduced with an increase in Co concentration.

Effects of cobalt substitution on the physical properties of the perovskite strontium ferrite

Structural, electronic and magnetic properties of the perovskites SrFe1-xCoxO3 (x = 0, 0.25, 0.50, 0.75 and 1) are investigated using generalized gradient approximation (GGA) and GGA with Hubbard potential within the frame work of spin-polarized density functional theory (DFT). The calculated structural parameters and geometries are consistent with the experimental results and observed decrease in the lattice constants with increase in Co concentration. The bonding nature is visualized through electron charge densities and confirms that the bond between Sr−Fe/Co is ionic, Fe/Co−O is covalent and Co−Fe is metallic. Band profiles comparison and electrical properties reveal that these compounds are metallic. It is observed that the magnetic interaction is anti-ferromagnetic at Fe rich side while ferromagnetic for Co substituted compounds. The transition of anti-ferromagnetism to ferromagnetism is explained through exchange interactions.

Studies on Dilute Magnetic Semiconducting Co-Doped CdS Thin Films Prepared by Chemical Bath Deposition method

The Co-doped CdS polycrystalline thin films were deposited onto the glass substrates by chemical bath deposition method. All the deposited films were characterized for structural, surface morphology, elemental, optical and magnetic properties using X-ray diffractometer, scanning electron microscopy (SEM), energy dispersive X-ray, UV–Vis. NIR spectrometer and Vibrating sample magnetometer before and after doping. The thin films exhibit hexagonal wurtizite structure with (0 0 2) preferential orientation and the calculated crystallite size is 29 and 18 nm for pristine and Co-doped CdS films respectively. X-ray photoelectron spectroscopy (XPS) analysis showed the presence of Cd, S and Co peaks along with O 1s peak. The studies revealed that the surface Cd atoms of films are found to be bound either to S atoms or O atoms. SEM images showed grainy surface for pristine which gets modified under Co doping. Energy dispersive analysis using X-rays confirmed the presence of Cd, S and Co in the films. From optical transmittance spectra, the bandgap was estimated and found to be varying from 2.4 to 2.27 eV with the increase of Co concentrations. The room-temperature ferromagnetic behavior was exhibited by Co-doped CdS films.

Influence of defects on electrical properties of electrodeposited co-doped ZnO nanocoatings

We present a systematic investigation of the electrical properties of undoped and Co-doped ZnO nanostructures at room temperature as an extensive study of the role of defects in ZnO. The ZnO nanostructures were fabricated by the electrodeposition method at low bath temperature (80 °C) and the Co concentration was varied from 0.01 to 0.2 mM. Electrical properties of the undoped and Co-doped ZnO nanostructures were studied in detail. The carrier concentration increases while the mobility reduces with increase in Co-concentration. The resistivity increases with an increase in Co-concentration and the reason is correlated with the defects in ZnO. In order to understand more details of the role of defects in the present I–V characteristic behavior of the Co-doped ZnO, high temperature vacuum annealing of ZnO sample was carried out. Electrical, optical and magnetic properties of the high temperature vacuum annealed ZnO were studied in detail. Photoluminescence spectroscopy (PL) results revealed more information of the defect levels which act as scattering centers for the carriers. Co-doping as well as annealing at high temperature in vacuum environment tunes the defects in ZnO and which influence the optical, magnetic and electrical behavior of the ZnO nanostructures.

Changes of HbCO in the Blood of Rats with Different CO Concentration and Inhalation Time

To explore the change rules of behavioral characteristics, survival time and saturation of carboxyhemoglobin （HbCO） in different CO concentration to provide experimental basis for the cases of CO poisoning death in forensic practice. Total 160 SD rats were randomly divided into four groups. CO with the concentration of 1 250 mg/m³, 3 750 mg/m³, 6 250 mg/m³ were continuously and respectively replenished in a self-made toxicant exposure equipment until rats died from poisoning. In different CO concentration, the behavioral characteristics and survival time of poisoning rats were observed and recorded. The saturation of HbCO in heart blood was detected by spectrophotometric method. Organs such as brain, heart, lung and liver, and heart blood were obtained via autopsy and histopathological observation was performed. The behavioral characteristics of CO poisoning rats were limp and slow response. There were a gradual decrease of survival time and an increase of HbCO saturation in rats with the increase of CO concentration. Three rats in CO concentration of 1 250 mg/m³ group showed lower saturations of HbCO than the lethal dose and this situation hasn't been found in other groups. The animal model of CO poisoning established under different CO concentration has the advantages such as simplicity and good repeatability, which lays a foundation to the further study for CO and other inhaled toxic gas in the research of forensic sciences.

Preparation and enhanced ferromagnetic properties in Co doped BiFeO3 nanoparticles prepared by sol–gel method

ABSTRACTBiFe1-xCoxO3 (x = 0, 0.05, 0.10, 0.15, 0.20, and 0.25) nanoparticles were prepared by a sol–gel method. A single-phase perovskite structure was formed in the pure BiFeO3 particles. The secondary phase of Bi25FeO40 was observed in Co doped samples and the phases of CoFe2O4 were observed in BiFe0.8Co0.2O3 and BiFe0.75Co0.25O3. The average crystal size of pure BiFeO3 is about 84 nm and that was reduced from 84 nm to 49.7 nm with increasing Co content. Optical band gaps of BFCO nanoparticles decrease with the increase of Co concentration. The enhancement of room-temperature ferromagnetism was obtained in the Co doped BiFeO3 particles.

Structural, morphological and magnetic properties of Zn1−xCoxO prepared by sol—gel and hydrothermal method combined**Project supported by the 46th Institute of China Electronics Technology Group Corporation (No. 0231182346).

Cobalt-doped ZnO powder samples were prepared by sol—gel and hydrothermal method combined. The prepared powder samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron paramagnetic resonance (EPR) and vibrating sample magnetometry (VSM). XRD patterns show that all the samples have a single pure phase with wurtzite structure suggesting that Co2+ occupied Zn2+ sites in the ZnO crystal lattice. SEM images show that crystal grains of cobalt-doped ZnO are hexagonal cone or spheroidal. EPR pattern shows that all of the samples possess oxygen vacancy. Measurement of magnetism indicates that all the samples exhibit room temperature ferromagnetism (RTFM) embedded in a dominant diamagnetic or paramagnetic signal. The dominant signal turns from diamagnetic to paramagnetic with the increase of Co concentration. The magnetic behavior can attribute to defects and Co doping.

Study of oxidation for gas mixture of H 2 S and CH 4 in a non-premixed flame under oxygen deficient condition

Oxidation process of gas mixture of hydrogen sulfide (H2S) and methane (CH4) in a non-premixed flame and formation of COS and CS2 has been studied under oxygen deficient condition. Premixed fuel consisting of H2S and CH4 with constant molar ratios (1:1) was injected and air was varied from the stoichiometric to the fuel rich condition (equivalence ratio, Φ = 2) to determine the influence of Φ upon the oxidation manner. The flame could be divided into three sections namely initial oxidation, intense combustion and post-flame section. Oxidation competition between H2S and CH4 was observed at the first section wherein H2S conversion, mainly via partial oxidation, was superior to that of CH4. Initial CH4 conversion involved partial oxidation and interaction with sulfur species which contributed to productions of COS and CS2. Formation of SO2 was witnessed at the second section together with significant increase in concentrations of CO, H2 and C2H2. However, the productions of these combustibles were favored by higher temperature and fuel rich condition and likely to be maintained under anoxic environment in the post-flame section. The CS2 and COS concentration profiles suggested a tight relationship between its conversion path and the O2 level downstream.

Synthesis and characterization of CoxNi1‐xFe2O4 samples by solution combustion method using glycine as fuel

Nano sized CoxNi1‐xFe2O4(0≤x≤1) samples were prepared by solution combustion method using glycine as fuel, maintaining a fuel to oxidizer ratio of 0.8. PXRD and FTIR analysis confirms the formation of the spinel phase. Non spherical and highly crystalline nature of the sample was revealed by HRTEM analysis. Lattice parameters of all samples calculated after Rietveld refinement and their variation are in accordance with Vegard's law. DC magnetization study indicates a transformation from soft to hard magnetic phase on increase in Co concentration. Saturation magnetization of nickel ferrite samples match well with that of bulk samples, while the pure cobalt ferrite sample has a lower saturation magnetization compared to that of the bulk, which may be due to spin canting. Impedance measurements of the samples give general trend shown by ferrite material which is in accordance with Koop's phenomenological theory. The study shows that the magnetic and electric properties of nickel ferrite nanoparticles can be easily tailored using a simple solution combustion method in the fuel lean condition with glycine as fuel.

Reaction characteristics of KOH-modified copper manganese oxides catalysts for low-temperature CO oxidation in the presence of CO2

Binary copper manganese oxides catalysts supported on different activated carbons were prepared using the co-precipitation and high-pressure impregnation methods. The catalysts were further modified by KOH to mitigate the adverse effect of CO2 on their CO oxidation performances. The as-synthesized catalysts were characterized by N2 adsorption–desorption, X-ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. The effects of support and synthesis method, CO concentration, CO2 concentration, gas hourly space velocity (GHSV), and particle size on CO oxidation performances of the catalysts were investigated. The nature of the different activated carbon supports showed no significant effect on their CO oxidation performances. By contrast, the high-pressure impregnation method was conducive to more effective loading and uniform dispersion of the active components on the support and therefore to benefit the catalyst enhanced CO oxidation performances. Under the given experimental conditions, CO oxidation conversion decreased with the increase of CO concentration, CO2 concentration, GHSV, and particle diameter.

Durability of Electrodeposited Ni-Fe-Co-C Anodes for Alkaline Water Electrolysis

IntroductionWe have been studying more than a quarter of century for supply of renewable energy in the form of methane via electrolytic hydrogen generation using carbon dioxide as the feedstock. Although we created cathodes and anodes for direct seawater electrolysis, the energy efficiency was not sufficient. For immediate industrialization, we are concentrating our current effort on alkaline water electrolysis, creating efficient cathodes and anodes. The present work aimed to determine the composition of active Ni-Fe-Co-C alloy anodes prepared by electrodeposition and to examine the durability for continuous electrolysis at a high current density of 6000 Am-2 in 4.5 M KOH at 90°C. Experimental Procedures The substrate for electrodeposition was a chemically etched Ni plate. Electrodeposition was carried out at a current density of 300 Am-2 for 10 min in 1.14 M NiSO4-0.189 M NiCl2-0.49 M H3BO3-0.104 mM CH3(CH2)11OSO3Na solutions containing various concentrations of FeSO4, CoSO4 and lysine, the pH of which was adjusted at 1.5 by the addition of 18 M H2SO4. Lysine was added as the carbon source. The composition of metallic elements in the electrodes was analyzed by electron probe microanalysis, and carbon was chemically analyzed by combustion infrared absorption method. The solution used for oxygen evolution was 4.5 M KOH at 90oC. The activity of the anodes was evaluated from galvanostatic polarization curves measured by the current density rise every 1 min. The potential rise due to the solution resistance at high current densities was corrected by the current interruption technique. Potentiodynamic polarization curves were also measured at a potential sweep rate of 0.52mV-1 for comparison. Results and Discussion As-deposited alloys were used for examination of oxygen evolution activity. Ni was a stable anode but less active for industrial electrolysis. The addition of Co ion and lysine to the deposition electrolyte containing Ni ion enhanced the oxygen evolution activity, but the activity of Ni-Co-C alloys was not yet sufficiently high. Ni-Fe-Co-C alloys deposited showed significantly high activity for oxygen evolution. An increase in Fe content in the alloy was more effective than the increase in Co content for enhancement of oxygen evolution activity. Thus, an increase in Co concentration in deposition electrolytes did not largely change the activity because the increase in Co content in the alloy resulted in the decrease in the content of Fe. The addition of lysine to the deposition electrolytes containing Ni, Fe and Co ions enhanced the oxygen evolution activity. The highest activity was attained at 0.2 M lysine in the deposition solution, but further increase in lysine concentration was not effective. An increase in lysine concentration led to asymptotic increase in the C content in the Ni-Fe-Co-C alloys up to about 6 at%. The deposition electrolyte to form the most active Ni-Fe-Co-C alloy for oxygen evolution was 1.33M Ni-0.072M Fe-0.018M Co-0.2M lysine solution. When the Ni-Fe-Co-C alloy prepared from this electrolyte was used for oxygen evolution at a current density of 6000 Am-2 for 800 h, the mass loss was about 5 % of the original mass. The galvanostatic polarization potential of as-deposited Ni-Fe-Co-C alloy measured by the current density rise every 1 min was in the active region at lower current densities, but the potential shifed to the oxygen evolution region at higher current densities. Once the specimen was polarized in the oxygen evolution region, the potential was stayed in the oxygen evolution region even when the current density was lowered. After oxygen evolution at 6000 Am-2 for long period of time, the potential stayed in the oxygen evolution region regardless of current densities. In fact, the dissolution current density estimated from the mass loss by polarization at 6000 Am-2 for 800 h even on the assumption of Fe dissolution in the form of Fe6+ as FeO4 2- was only 4.5 x 10-3 Am-2 that is less than one-millionth of oxygen evolution current. Consequently, the active Ni-Fe-Co-C alloy anode thus prepared is sufficiently stable maintaining the passive state in the severe environment for oxygen evolution at 6000 Am-2 in a concentrated KOH solution at 90°C for long period of time. Conclusion The active oxygen evolution anode in alkaline water electrolysis for hydrogen production was created. The addition of Fe, Co and C to Ni enhanced the oxygen evolution efficiency in 4.5 M KOH solution at 90°C. The Ni-Fe-Co-C alloy thus prepared kept the passive state during electrolytic oxygen evolution at 6000 Am-2 for a long period of time.

Investigations on absorption, photoluminescence and magnetic properties of ZnO: Co nanoparticles

We have investigated the consequences of cobalt (Co) incorporation with different doping concentrations (0, 2, 4 and 6 %) on structural, optical and magnetic properties of ZnO nanoparticles. The results of X-ray diffraction spectra (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) pattern of single particle, energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared (FT-IR) authenticate the substitution of cobalt and hexagonal crystal structure without any secondary phase formation of all the samples under investigation. The ultraviolet–visible (UV–Vis) absorption study indicates that increase in Co concentration improves the visible region absorption (550–700 nm). The absorption edge of Co-doped ZnO shifts towards visible region with increase in Co concentration. The band gap of samples shows a red shift with increase in Co percentage. The photoluminescence (PL) study of the samples indicates that Co doping shifts the intense peak position of ZnO from violet to blue colour. The weak emission peak at 572 nm is also observed in all the samples. The emission is represented by chromaticity diagram. The room temperature magnetic properties have been studied using vibrating sample magnetometer (VSM). The room temperature magnetisation curve shows that an increase in Co concentration increases the linear behaviour of M–H loop. The magnetic susceptibility results indicate that all the samples have Curie–Weiss behaviour. The coercive field (Hc) and the remanence magnetisation (Mr) increase with Co doping concentration. Fig. M–H curve of pure and cobalt-doped ZnO nanoparticles at 300 K. Inset (a) shows absorption spectra, and inset (b) shows the emission spectra of Zn1−x Co x O nanoparticles.

Performance and emissions assessment of n-butanol–methanol–gasoline blends as a fuel in spark-ignition engines

The sleek of using alternatives to gasoline fuel in internal combustion engines becomes a necessity as the environmental problems of fossil fuels as well as their depleted reserves. This research presents an experimental investigation into a new blended fuel; the effects of n-butanol–methanol–gasoline fuel blends on the performance and pollutant emissions of an SI (spark-ignition) engine were examined. Four test fuels (namely 0, 3, 7 and 10 volumetric percent of n-butanol–methanol blends at equal rates, e.g., 0%, 1.5%, 3.5% and 5% for n-butanol and methanol, in gasoline) were investigated in an engine speed range of 2600–3400r/min. In addition, the dual alcohol (methanol and n-butanol)–gasoline blends were compared with single alcohol (n-butanol)–gasoline blends (for the first time) as well as with the neat gasoline fuel in terms of performance and emissions. The experimental results showed that the addition of low content rates of n-butanol–methanol to neat gasoline adversely affects the engine performance and exhaust gas emissions as compared to the results of neat gasoline and single alcohol–gasoline blends; in particular, a reduction in engine volumetric efficiency, brake power, torque, in-cylinder pressure, exhaust gas temperature and CO2 emissions and an increase in concentrations of CO and UHC (unburned hydrocarbons) emissions were observed for the dual alcohols. However, higher rates of n-butanol–methanol blended in gasoline were observed to improve the SI engine performance parameters and emission concentration. Oppositely the higher rates of single alcohol–gasoline blends were observed to provide adverse results, e.g., higher emissions and lower performance than those of lower rates of single alcohol. Finally, dual alcohol–gasoline blends could exceed (i.e. provide higher performance and lower emissions) single alcohol–gasoline blends and pure gasoline at higher rates (>10vol.%) in the blend and, in turn, it is recommended to be used at high rate conditions.