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The effects of acetone on the combustion, performance and emission characteristics of a diesel engine were investigated. This study focused on the advantages, disadvantages and limitations of using acetone in a diesel engine. Acetone as an oxygenated additive with a carbonyl functional group was blended with diesel fuel at different concentrations. The engine was operated at a constant speed of 2000 rpm and different loads. Low concentrations of acetone reduced the coefficient of variation (COV) and slightly increased the peak pressure and the heat release rate (HRR) at most loads. The emissions of CO and NOx were reduced besides a slight enhancement in the engine performance. Relatively high concentrations significantly increased the COV at both idle and full loads and depressed the peak pressure and HRR at full load. Acetone with relatively high concentrations caused instabilities in the diesel engine operation. [Display omitted] [ABSTRACT FROM AUTHOR]

The soot emission is an urgent problem that deserves extensive studies to suppress it. The smallest ketone was investigated in this study as a soot suppressor in a diesel engine. The fringe analysis approach was used to quantify the nanostructure characteristics of soot. At first, the image processing parameters were updated for this study, and their effects were explored and interpreted. Image resolution was found to be a crucial parameter in the image analysis process with a spatial resolution of 0.0417 nm/pixel as the best adjustment for the present study. The contrast-limited adaptive histogram equalization approach provided a perfect histogram equalization. A Gaussian low-pass filter with a standard deviation of 1.5 and a filter size of 11 produced the best results. The bottom hat transformation with a structuring element of a five pixels size and zero corners produced the best fringes' representation. A threshold level of 0.8 as Otsu's level provided a better nanostructure's representation. Second, the images of soot from acetone/diesel blends were analyzed using the updated parameters. The addition of acetone reduced the formation of soot in a diesel engine. The fringe length, tortuosity, intensity and alignment were all decreased, while fringe spacing was increased with acetone. [Display omitted] • The effects of C3 ketone on soot nanostructure were investigated in a diesel engine. • The image processing parameters were tuned for this study. • The effects of those parameters on soot nanostructure were explained. • The fringe length, tortuosity, intensity and alignment were decreased with acetone. • The fringe spacing and soot disorder was increased with acetone. [ABSTRACT FROM AUTHOR]

Abstract: It is known that extracellular biosynthesis of nano-particles could be highly advantageous for its synthesis in large quantities and easy downstream processing. Therefore, the present study aims to specify and determine the effective origin source for Ag-NPs produced by Escherichia coli strain S78, if it was culture broth, supernatant or cell pellet. The reduction of silver nitrate was determined by estimating the excreted amount of the enzyme nitrate reductase. Additionally, the produced silver from the specified corresponding production phase was characterized. Moreover, the antibacterial effect of produced Ag-NPs against both Gram positive and Gram negative bacteria was investigated. The results demonstrated that after 7days of incubation culture broth produced the highest yield of Ag-NPs followed by the cell-free supernatant. FTIR spectra, nitrate reductase assay and accumulation efficiency confirmed the extracellular production of Ag-NPs. The results also revealed that the produced Ag-NPs has got a good antibacterial activity against Gram negative, when compared with the Gram positive bacteria. In final conclusion, the Ag-NPs produced in the culture broth of strain S78 could be used successfully as an environmental friendly disinfector of water and wastewater against pathogenic microorganisms. [Copyright &y& Elsevier]

Abstract: Nano-poly (glycidyl methacrylate) cation exchange resin with sulphonate functionality content ranging from 1.77 to 4.00 (mmol/g) was prepared and examined in removal of cadmium ions from synthetic cadmium solution. Initial fast adsorption step was recognized at 15min where 90% of cadmium ions were adsorbed while equilibrium was reached within two hours. The equilibrium adsorption capacities ranged from 9.947 to 480mg/g of polymer as initial cadmium concentration increased from 100 to 5000ppm. The adsorption experiments for Cd2+ were conducted at various operating conditions. It was concluded that the sorption was considerably affected by initial cadmium concentration, solution pH and resin dose. Nevertheless, there was slight dependence of sorption on agitation speed, solution temperature and the sulphonation degree. The order of kinetic reaction was found to follow closely the second-order kinetic model and ion exchange mechanism played a significant role in all studied cadmium sorption systems. Moreover, the obtained results indicate that film diffusion governs the rate limiting process. [Copyright &y& Elsevier]

Abstract: Bacillus mojavensis strain 32A that exhibited 96.11% flocculation efficiency for clay suspensions was selected from other 15 comparative strains. Under growth condition, strain 32A was able to produce 5.2g/L of purified biopolymer. Its constituent was mainly polysaccharide and protein with proportional of 98.4–1.6% respectively. FTIR spectrum was confirming its chemical analysis. This biopolymer attain very fast sedimentation rate. The cost-effective biopolymer and CaCl2 dosages were 3mg/L and 5ml/L respectively that posed 89.7% flocculation efficiency. These dosages were suitable only for clay concentrations ⩽5g/L. The maximum flocculation efficiency of the biopolymer recorded at pH 1.0 of clay suspension. The too high (>75°C) or too low (<25°C) clay suspension temperature was unfavorable for the biopolymer flocculation performance. The biopolymer solution utilized high thermal stability over the temperature range of 5–60°C. Furthermore, its pH stability recorded at pH range of 5–9. [Copyright &y& Elsevier]

Abstract: Immobilized eggshell with a polymer mixture of alginate and polyvinyl alcohol was applied as a biocomposite adsorbent (ESC) for the adsorption of C.I. Remazol Reactive Red 198 from aqueous solution. ESC was characterized using XRD, TGA, FTIR and SEM. The Red dye adsorption onto the ESC was investigated in a batch system with respect to initial dye concentration, pH, contact time, agitation speed, solution temperature and biocomposite dosage. The prepared biocomposite exhibits high efficiency for red dye adsorption and the equilibrium states could be achieved in 3h for the different studied initial dye concentrations. The equilibrium isotherm study indicated that sorption data were analyzed and fitted well by both Langmuir and Temkin models compared to Freundlich model. The maximum monolayer dye adsorption capacity (at the optimum pH 1.0) was estimated to be 46.9mg/g at 22°C. The kinetic study revealed that pseudo-second order model fitted well the kinetic data, while both the intraparticle diffusion and Boyd kinetic model indicated that intraparticle diffusion was the main rate determining step in the biosorption process. The negative values of both the enthalpy (ΔH°) and Gibbs free energy (ΔG°) changes indicate exothermic as well as feasible and spontaneous nature of the biosorption process respectively. [Copyright &y& Elsevier]

Abstract: The goal of this batch-test kinetic study is to evaluate the effectiveness of the different prepared nano-zirconium vanadate ion exchangers for removing cesium, cobalt and nickel from aqueous solution. The prepared samples are characterized using X-ray diffraction, Scanning Electron Microscope and Specific surface area. Analysis of the respective rate data in accordance with three kinetic models is applied. It is revealed that the kinetics of cesium sorption onto the different prepared inorganic nano-zirconium vanadate ion exchangers can be described well by the second-order and Elovich kinetic model. However, cobalt and nickel sorption kinetics may be described by the first, second-order and Elovich kinetic models. It is established that the ion exchange mechanism plays a significant role in all studied cesium sorption systems and may participate with a small extent in the studied cobalt and nickel sorption systems. Moreover, the sorption systems are governed mainly by intraparticle diffusion. Finally, nano-zirconium vanadate produced from homogeneous precipitation is selected for investigating the kinetic effect of the agitation speed and the solution temperature on the different three ion removals. It is recognized that the activation energy and the thermodynamic parameters for the sorption systems of studied ion removal using the homogeneous precipitated nano-zirconium vanadate ion exchanger are determined. [Copyright &y& Elsevier]

Abstract: Sol–gel, homogeneous precipitation and hydrothermal synthesis are three different preparation techniques have been used as an attempt to synthesize nano-zirconium vanadate with properties suitable to be used as ion exchangers. The impact of the synthetic preparation variables such as the reactant concentrations, reaction temperature and reaction time on the ion exchange capacity of the produced ion exchanger has been considered for each preparation technique. One sample from each preparation technique having the largest ion exchange capacity has been selected to be physically and chemically characterized using various analytical techniques such as XRD, TGA, DSC, pH titration, FTIR and SEM in order to determine the properties of the ion exchanger produced from each technique. For all the studied ZrV samples it can be presumed that they have the ion exchange affinity sequences for alkali metal ions K>Na>Li, the order for the alkaline earth metals is Ba>Ca>Mg and their affinity for radioactive metals follow Cs>Sr. Moreover, the prepared materials are of high thermal and radiation stabilities. Also they have high chemical stabilities toward wide concentration ranges of acid, basic as well as polar solvents. It has been deduced from the X-ray analysis that ZrV produced from the sol–gel technique has an amorphous structural. While those produced from the homogeneous precipitation and hydrothermal synthesis techniques, in the nano-scale have semi-crystalline structural. Furthermore, SEM confirms that particle size of the all studied prepared ZrV samples have nano-diameters of range 50–60nm. Specific surface area of the three different prepared ion exchangers are found to be equal to 187, 192 and 320m2/g for sol–gel, homogeneous precipitation and hydrothermal, respectively. A tentative structural formula of Zr(OH)2(HVO4)2·2H2O has been proposed for all studied samples on the basis of on FTIR, DSC and TGA results. [Copyright &y& Elsevier]

Abstract: Harmful ions such as cesium, cobalt and nickel were removed from aqueous solutions using nano zirconium vanadate ion exchangers that prepared using three different techniques and their organic hybrids. Different processing parameters that affect on sorption efficiency were studied. All prepared ion exchangers and their composites have high uptake affinity for cesium removal. The removal capacities of the ion exchangers either the inorganic ones or those that immobilized decreased in the acidic media, in contrast to the alkaline that enhances the ion exchange process. Both the temperature and agitation were found to be appropriate for maximum ions removal. The sorption data obtained for equilibrium conditions have been analyzed using the linear forms of Freundlich, Langmuir and Dubinin–Radushkevich isotherms and the applicability of these isotherm equations to the sorption systems was compared by judging the correlation coefficients, R 2. It was established that the equilibrium isotherms models'' applicability follows the order: Langmuir>Freundlich>Dubinin–Radushkevich, in case of cesium removal using the different prepared inorganic ion exchangers. But the applicability for cobalt and nickel ions removal using the different prepared inorganic ion exchangers follows the order Freundlich>Langmuir>Dubinin–Radushkevich. The sorption processes for ions uptake using the different types of the prepared inorganic ion exchangers were found to be endothermic processes. [Copyright &y& Elsevier]

• 3D comprehensive modeling of a densely packed HCPV module is developed. • DA-HCPV module performance integrated with four quadrants MCHS is studied. • System performance with different inlet and outlet flow directions is analyzed. • Exergy analysis is done in order to introduce DA-HCPV/T system exergy efficiency. The dense solar radiation received by a high concentration photovoltaic module (HCPVM) causes a high cell temperature. In this module, multiple solar cells were electrically connected in both series and parallel. The higher temperature of the solar cell in the series string limits the generated power for the whole string. Therefore, it is crucial to employ a uniform cooling mechanism for higher electrical performance along with a longer lifespan. The uniform cooling is required to attain safe operating temperature and prevent the hot spot formation. Hence, in the current work, a four-compartment microchannel heat sink is proposed for the thermal management of HCPVM under high solar concentration of 1000 suns (1 sun = 1000 W/m2). A three-dimensional (3D) conjugate heat transfer model with exergy analysis is developed and validated. This model was used to investigate the effect of inlet and outlet orientation of four quadrants microchannel heat sink as a cooling method for HCPVM. Eight different orientations of parallel-flow and counter-flow conditions were investigated and compared in terms of temperature non-uniformity, module power, and exergy performance. The results showed that the inlet and outlet orientation was a key role affecting the module temperature non-uniformity. For the counter-flow operated heat sinks, the HCPVM can be operated under a temperature non-uniformity of 3.1 °C at total inlet module mass flowrate of 350 g/min and solar concentration ratio of 1000 suns. In addition, the attained HCPVM electrical, thermal, and overall exergy efficiency were 37.2%, 8.2%, and 45.4% respectively at the same conditions. [ABSTRACT FROM AUTHOR]

Abstract Recently, extraordinary attention has been given to the preparation of strong acid-doped polyaniline in distinct morphologies, such as nanofibers, nanotubes, and nanoflowers, while seeking proper and cheap energy polymeric materials. This work introduces the CO 2 -supported polymerization process as an advanced and novel polymerization technique to prepare rectangular cross-sectional self-assembled HCl-doped polyaniline nanotubes (HCl-PANNT) without the need to use any surfactants for the first time. Based on the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results, a rectangular cross-sectional HCl-PANNT with an average outer diameter and wall thickness of 110 and 35 nm, respectively, was prepared. Furthermore, X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) were employed to reveal the crystallinity and the chemical structure of the prepared polyaniline, respectively. Accordingly, the produced PANNT has a partial crystalline structure and emeraldine salt form. Moreover, the produced HCl-PANNT showed a high electrical conductivity of 1.5 S/cm. Graphical abstract Image Highlights • Strong acid-doped polyaniline nanotubes preparation is highly desired. • Compressed CO 2 was used for polyaniline nanotubes preparation without surfactants. • The synthesized nanotubes have a rectangular cross-sectional area. • The prepared polyaniline nanotubes have a significant electrical conductivity. • CO 2 -assisted polymerization is promising in advance polyaniline morphologies production. [ABSTRACT FROM AUTHOR]

• 3D heat transfer model for DL-MCHS coupled with thermal model for CPV/T are done. • Assessment of DL-MCHS potentials for CPV thermal management is achieved. • The DL-MCHS including the header design are considered in the CFD simulation. • Different solar concentration ratios and volumetric flowrates are considered. • Comparison between PF and CF orientations through DL-MCHS are performed. The concentrator photovoltaic (CPV) systems commonly endure high cell temperatures, which affect their overall performance. Besides, the high cell temperature could lead to physical damages within the whole system due to the induced thermal stresses. Therefore, an efficient cooling is mandatory to achieve a higher net output power from the CPV and safe operation. The current work's main purpose is to investigate the integration of double-layered microchannel heat sink (DL-MCHS) with CPV cell as thermal management device. A three-dimensional (3D) model is presented to investigate the performance of a CPV cooled by the DL-MCHS to figure out the ability to handle the effective heat dissipation under different terrestrial conditions. The parallel flow (PF) and counter flow (CF) cooling orientations were studied. Ethanol coolant is used to cool the CPV under different concentration ratios (CR) of 5, 10, 15, and 20 suns. The results show that the temperatures remarkably decreases with the inlet flowrate is increased. The counter flow operation (CF) achieved the best temperature uniformity index (T uni) when the coolant mass flowrate (V̇) ranged between 200 and 1200 ml/hr. Especially at CR 5 suns, the temperature uniformity index, T uni , enhanced to 99.87% at 1200 ml/hr. [ABSTRACT FROM AUTHOR]

• Novel hybrid HCPV/Membrane Distillation was developed and investigated. • Heat exchanger was utilized to couple HCPV/T with membrane distillation unit. • Two different modules, DCMD and AGMD, were studied and compared. • The proposed system showed promising results for electricity/water production. The present study introduces an innovative method for fresh water and electricity generation in the isolated regions. This proposed system couples a concentrated photovoltaic (CPV) unit with a membrane distillation (MD) unit. The CPV unit converts solar energy into electrical energy with conversion efficiency of about 40%. The rest is converted to thermal energy, which may cause cells degradation if temperature exceeds manufacturer limits. An intermediate fluid is used as a coolant which transfers the excess energy to the feed of the MD unit through a heat exchanger. The generated thermal energy in the HCPV cells is used as the driving force for the distillation phenomena in the MD unit. Numerical models were built to simulate the hybrid system. It was found that, at a solar radiation concentration ratio of 1000 suns, the coolant flow rate should exceed 150 g/min for a maximum cell temperature less than 349 K. This arrangement should produce 177 W electric power, and 308 W thermal heat transferred to the coolant. At these conditions, the feed inlet temperature reaches about 323 K, at which, the MD unit produces about 5.88 kg/m2.h of pure water, thus allowing the system to simultaneously produce electricity and pure water for isolated coastal regions. [ABSTRACT FROM AUTHOR]

High-pressure CO 2 -supported aniline polymerization was thoroughly investigated with a focus on the effect of acid doping on the morphology of the prepared polyaniline (PANI). The polymerization was conducted using HCl at three different concentrations and H 2 SO 4 as the doping agents. Self-assembled HCl-doped PANI nanoflowers (PANNFL) were synthesized for the first time by high-pressure CO 2 -supported polymerization in the presence of 2 M HCl. Furthermore, HCl-doped PANI nanotubes (HCl-PANNTs) and nanofibers (HCL-PANNFs), as well as sulfuric acid-doped PANI nanofibers (SUA-PANNFs), were successfully prepared by changing either the acidity of the reaction or the doping agent. With 0.1 M HCl doping, circular and rectangular cross-sectional HCl-PANNTs with a wall thickness of 40 nm were prepared. Upon increasing the acid concentration to 2 M HCl, the morphology of the PANI structures transformed from nanotubes to nanoflowers while retaining the same wall thickness. Further increasing the HCl concentration resulted in a mixture of nanosheet structures, and the amount of nanoflowers decreased. Additionally, 1.1 M H 2 SO 4 doping produced nanofibers (SUA-PANNF) with an average fiber diameter of 45 nm. All the prepared PANIs had partially crystallized structure in the emeraldine salt form. Additionally, the crystallinities of the prepared HCl-PANI structures were higher than that of the SUA-PANI structure. It was clearly observed that the type of acid dopant and the acid concentration affected the polymerization yield (PY) and could control the electrical conductivity (EC). The highest EC, i.e., 3.7 S/cm, was exhibited by PANI prepared with 5 M HCl. Image 10019203 • Doping acid type was studied in the High-pressure CO 2 polymerization for the first time. • Self-assembled HCl-doped polyaniline nanoflowers were prepared successfully. • Self-assembled polyaniline nanotubes and nanofibers were also prepared. • The electrical conductivity could be controlled by adjusting the doping acid concentration. • Increasing the doping acid concentration affect the polymerization yield negatively. [ABSTRACT FROM AUTHOR]

Highlights • A three-dimensional thermal model for HCPV/T system was developed. • Four distinct designs of jet impingement heat sinks were evaluated and compared. • Single jet impingement design achieved the best performance of the HCPV/T system. Abstract The high solar light concentration onto the photovoltaic cell leads to extremely high cell temperature, which significantly decreases the cell efficiency and degrades its lifetime due to the thermal stresses. One of the main challenges of these types of solar cells is to propose an efficient cooling technique that allows the cells to operate under its recommended operating conditions. Therefore, the focus of this study was to develop a comprehensive three-dimensional model for the high concentrator photovoltaic/thermal (HCPV/T) system. This model comprises a thermal model for a triple-junction solar cell integrated with a thermo-fluid model for four distinct designs of confined jet impingement heat sinks. The results showed that the cell electrical efficiency increased with the coolant flow rate, and sufficient temperature uniformity can be achieved by the jet impingement configurations. Additionally, the use of jet impingement configurations consumed a slight pumping power less than 1% of the generated power in the solar cell. The maximum local temperature of uncooled solar cell was predicted to reach 1360 °C under solar concentration ratio of 1000 Suns. Under the same conditions, the single jet design reduced the maximum local temperature to about 65 °C with coolant mass flow rate of 50 g/min. It should be noted that the thermal stress substantially decreased with the increasing coolant mass flow rate. Exergetic analysis showed that the single jet design attained the maximum total exergy efficiency of 53.25% at the flow rate of 25 g/min. [ABSTRACT FROM AUTHOR]

• A three-dimension model for high concentrator photovoltaic (HCPV) was developed. • The jet impingement/microchannel hybrid cooling scheme was studied for HCPV. • The hybrid schemes have a higher thermal performance and overall exergy efficiency. • Thermal stresses sufficiently decreased with increasing the inlet mass flow rate. An efficient cooling arrangement is mandatory to achieve a higher net output power from the high concentrator photovoltaic structures in addition to extending their lifetime. In the current study, five new heat sink designs for a jet impingement/microchannel hybrid cooling scheme were investigated and compared with a conventional jet impingement cooling scheme. These designs consisted of an arrangement of rectangular fins at the streamwise length of the heat sink. This resulted in a stepwise decrease in the corresponding channel width and hydraulic diameter. A comprehensive three-dimensional thermal and structure model was developed to investigate the capability of the proposed designs in terms of reduction of the cell temperature besides enhancement of the temperature uniformity. Based on the results, the hybrid cooling scheme exhibited promising cooling ability compared to the conventional jet impingement scheme. The results of the present study show that the hybrid cooling scheme is effective cooling system and it achieved the utmost possible reduction of solar cell temperature, under high solar concentration ratio of 1000 suns where the solar cell temperature reduces to 55 °C. When the inlet mass flow rate was increased to 50 g/min under the same conditions, a corresponding reduction in the cell temperature from 67.3 to 55 °C was observed for Case 4 of the hybrid scheme designs. In addition, there was a decrease from 82.3 to 63.2° C for Case 1 of the conventional jet impingement heat sink (HS). Under the hybrid cooling scheme, the electrical efficiency of the cell improved to 39.7% when the inlet mass flow rate was equal to 50 g/min for Case 4. Exergy analysis revealed that the hybrid scheme achieved an overall exergy efficiency of 53.5% at inlet mass flow rate of 25 g/min. [ABSTRACT FROM AUTHOR]