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Carbon-free electrosynthesis of ammonia using water (H2 source) and air (N2 source) is promising technology to reduce the global CO2 emission resulting from the industrial ammonia production process (Haber-Bosch). In this study, electrocatalysis activity of non-noble metal perovskite-based catalyst (La0.75Sr0.25Cr0.5Fe0.5O3-δ-Ce0.8Gd0.18Ca0.02O2-δ, LSCrF-CGDC) for ammonia synthesis directly from air and water was explored. Ammonia was successfully from wet air (3%H2O) synthesized in a single-chamber type reactor. The highest ammonia formation rate and Faradaic efficiency of about 1.94×10-11 mol s-1 cm-2 and 2.01% were achieved at 375 oC and 1.2 V, respectively. The observed ammonia formation rate is higher than reported for an expensive noble metal-based catalyst (Ru/MgO). The obtained results indicated that the direct synthesis of ammonia from air and water is a promising technology for green and sustainable ammonia synthesis.

In this study, zinc ferrite magnetic nanoparticles (ZnFe2O4, ZFO MNPs) were employed as a sorbent for the removal of oil spill from water surfaces. ZFO MNPs were synthesized via a sol-gel process and characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). Both the apparent density and magnetic force were determined. ZFO MNPs presented a considerable magnetic force (40.22 mN) and an adequate density (0.5287 g/cm3), which are important for the magnetic separation and flotation. Four oil samples (gasoline engine oil, crude oil, used motor oil and diesel engine oil) were used to investigate the gravimetric oil removal capability of ZFO MNPs. The oil sorption capacities were found to be 23.00-6.13, 27.65-7.42, 22.62-7.01 and 30.54-9.93 g/g for crude, diesel engine, gasoline engine, and used motor oil, respectively. The current findings demonstrate that ZFO MNPs exhibit good properties (e.g., magnetic and density) and can be used as a sorbent for oil spill cleaning-up from water surfaces.

Purpose The main purpose of this paper is to investigate the adsorption properties of CoFe1.9Mo0.1O4 magnetic nanoparticles (CFMo MNPs) using, anionic dye “congo red (CR)” as a model of water pollutants. Design/methodology/approach The magnetic nano-adsorbent was synthesized via sol-gel process. Different techniques including; Fourier transform infrared spectroscopy, point of zero charge, scanning electron microscope and X-ray powder diffraction were used to characterize the prepared adsorbent. Adsorption experiments were conducted in batch mode under various conditions (contact time, shaking speed, initial dye concentration, initial solution pH, solution temperature and adsorbent amount) to investigate the adsorption capability of CFMo MNPs for CR. Findings The results showed that, CFMo MNPs could successfully remove more than 90% of CR dye within 20 min. Adsorption kinetics and isotherms were better described using pseudo-second-order (PSO) and Langmuir models, respectively. The maximum adsorbed amount (qmax) of CR dye was 135.14 mg/g. The adsorption process was found to be endothermic and spontaneous in nature as demonstrated by the thermodynamics ( ΔGo, ΔHoand ΔSo). Practical implications This study provided a good example of using an easily separated magnetic nano-adsorbent for fast removal of a very toxic organic pollutant, congo red, from the aquatic environment Originality/value The employment of Mo-doped cobalt ferrite for the first time for removing hazardous anionic dyes such as congo red from their aqueous solutions.

Purpose This paper aims to investigate the electrocatalytic activity of CoFe1.9Mo0.1O4-Ce0.8Gd0.18Ca0.02O2-δ composite (CFMo-CGDC) for the direct synthesis of ammonia from H2O and N2 under atmospheric pressure. Designs CoFe1.9Mo0.1O4 nanoparticles (CFMo NPs) were synthesized via a sol-gel method. CFMo NPs were characterized using X-ray diffraction (XRD), Brunauer–Emmet–Teller (BET) specific surface area measurement and scanning electron microscope (SEM). Double-chamber reactor was used to synthesize ammonia using H2O and N2 as precursors. The factors affecting the ammonia formation rate (applied voltage and temperature) were studied. Findings CoFe1.9Mo0.1O4 nanoparticles (CFMo NPs) were synthesized via a sol-gel method. CFMo NPs were characterized using XRD, Brunauer–Emmet–Teller (BET) specific surface area measurement and SEM. Double-chamber reactor was used to synthesize ammonia using H2O and N2 as precursors. The factors affecting the ammonia formation rate (applied voltage and temperature) were studied. Originality/value The usage of CFMo-CGDC composite as an electrocatalyst for the synthesis of ammonia directly from H2O and N2.

Surface technology provides an important and valuable insight into the practical and theoretical applications of a manufactured surface. Cutting conditions play an important role in assessment of functional performance for engineering surfaces. Also, there is an important relation between the surfaces geometry and the functional performance of the surface. The geometry of the surface has a large influences of the surface performance. Topography analysis is primarily concerned with describing a surface in terms of its features. Then the knowledge gained about the geometry of the surface is used to control the surface production process to predict the performance of the component in its functional environment. Roughness parameters which characterize machined surfaces affect on both culling conditions and functional performance. Previous researches introduced a relations between roughness parameters and functional performance of machined surfaces. In present study, three of the surface functional performance that are friction ,wear, and lubrication which known as the tribological properties are concerned. A hybrid Artificial Neural Network (ANN) is used for selection of optimal cutting conditions. Experimental study is made to obtain the required parameters for the constructed ANN. The experimental study is made on 65 specimens free cutting steel 37, 40 mm in diameter. The specimens are divided into three groups, one of them is machined by turning operation. The second group is machined by milling operation. The third group is machined by grinding operation. All specimen are machined at various cutting conditions (feed, speed, depth of cut). All specimens are measured using Mitutoyo Surf Test SJ201 that give the surface profile and some of roughness parameters of the measured surface as a result. A developed Matlab programs Sur/Test SJ201P and SRCP, are used to give a full assessment of surface roughness parameters from the resulted surface profile of the Mitutoyo SurfTest-S/201. An introduced neural network is modeled by computer programs written in Matlab®. Also, OSCC program made by Matlab© is developed for selection of optimal cutting conditions. The maximum difference between measured data and data obtained from introduced hybrid ANN is of ±0.25%.

In this study, Zn-substituted cobalt ferrite nanoparticles (CoFe1.9Zn0.1O4, CFZ) were successfully synthesized via a combined EDTA-citrate sol-gel process. The synthesized CoFe1.9Zn0.1O4 nanoparticles were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), point zero charge (pHpzc) and scanning electron microscopy (SEM). The adsorption experiments of methylene blue (MB) onto CFZ surface were conducted in batch mode. The experiments were conducted under different conditions (contact time, adsorbent dosage, initial pH solution, solution temperature and initial dye concentration). The experimental data were better fitted to pseudo-second-order (PSO) kinetic model (R2=0.9990). In addition, Langmuir isotherm (R2=0.9906) was the best model to describe the experimental adsorption data. The maximum adsorbed amount of MB (qmax) per unit mass of adsorbent was about 27.79 mg/g. The adsorption thermodynamics (i.e., ΔG°, ΔH°, ΔS°) revealed that the proposed adsorption process is feasible, spontaneous and exothermic in nature. The obtained results suggest that CFZ is a promising material used as an adsorbent for very toxic pollutants from aqueous solutions.

In the present study, Zn-doped cobalt ferrite (CoFe1.9Zn0.1O4) magnetic nanoparticles were successfully synthesized via sol-gel method. The prepared materials were characterized using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The apparent density and magnetic force of CoFe1.9Zn0.1O4 nanoparticles were determined. The results revealed that the prepared materials display an adequate density and considerable magnetic force. The gravimetric oil removal capability tests were also performed to investigate the oil absorption properties of CoFe1.9Zn0.1O4 nanoparticles using four types of oil samples (crude, diesel, gasoline and hydraulic oil) as water pollutant’s model. The oil removal capabilities of the prepared absorbent were found to be 13.72 ± 0.42-5.50 ± 0.53 g/g, 14.99 ± 0.95-8.86 ± 0.42 g/g, 18.23 ± 1.01-8.06 ± 1.26 g/g and 10.58 ± 0.49-5.24 ± 0.31 g/g for crude, diesel engine, gasoline engine and hydraulic oil, respectively. The results suggest that the prepared magnetic nanoparticles can be used as absorbent materials for removing oil spills from water surface.

In this study, the adsorption properties of spinel ferrite-based adsorbent, CoFe1.9Mo0.1O4 (CFMo), for removal of methylene blue (MB) from aqueous solution have been investigated. Sol-gel process was successfully employed to prepare CoFe1.9Mo0.1O4 magnetic nanoparticles. The synthesized adsorbent was characterized by Fourier transform infrared (FTIR), scanning electron microscope (SEM) and X-ray diffraction (XRD). The adsorption experiments were carried out at various operational conditions (solution pH, initial dye concentration, contact time, adsorbent dosage and temperature) to evaluate the potential adsorption property of CFMo magnetic nanoparticles. The results showed that, under the optimum adsorption parameters, approximately 95 % of MB dye can be removed. The adsorption data were better described by Langmuir isotherm model and the maximum amount of MB adsorbed was about 20.45 mg/g. Several adsorption kinetic models and thermodynamic parameters (∆Go, ∆Ho, ∆So) were used to fit the adsorption experimental data. The adsorption kinetics followed the pseudo-second-order model (PSO), while the thermodynamic parameters indicate that the proposed adsorption process was endothermic and spontaneous in nature. The obtained results suggest that CFMo is promising adsorbent material for removal of very toxic dyes from aqueous solutions.

Electrochemical synthesis of ammonia was investigated using a cobalt-free La0.6Sr0.4Fe0.8Cu0.2O3-δ-Ce0.8Sm0.2O2-δ (LSFCu-SDC) composite cathode and SDC-ternary carbonate composite electrolyte. La0.6Sr0.4Fe0.8Cu0.2O3-δ and Ce0.8Sm0.2O2-δ were prepared via combined EDTA-citrate complexing sol–gel and glycine nitrate processes, respectively, and characterised by X-ray diffraction (XRD). Ammonia was successfully synthesised from wet hydrogen and dry nitrogen under atmospheric pressure using Ni-SDC, SDC-carbonate and LSFCu-SDC composites as anode, electrolyte and cathode respectively. Ammonia formation was observed at 400, 425, 450 and 475 °C and the maximum rate of ammonia production was found to be 5.39 × 10−9 mol s−1 cm−2 at 450 °C and 0.8 V. The AC impedance measurements were recorded before and after the ammonia synthesis in the range of temperature 400–475 °C. The formation of ammonia at the N2 side together with stable current at 450 °C under constant voltage demonstrates that SDC-(Li/Na/K)2CO3 composite electrolyte exhibits significant proton conduction at a temperature around 450 °C.