Showing papers in "Journal of The Taiwan Institute of Chemical Engineers in 2021"
TL;DR: A novel approach to the prediction of transport behaviours of multiphysics systems, offering significant reductions in the computational time and cost is put forward, based on machine learning techniques that utilize the data generated by computational fluid dynamics for training purposes.
Abstract: Comprehensive analyses of transport phenomena and thermodynamics of complex multiphysics systems are laborious and computationally intensive. Yet, such analyses are often required during the design of thermal and process equipment. As a remedy, this paper puts forward a novel approach to the prediction of transport behaviours of multiphysics systems, offering significant reductions in the computational time and cost. This is based on machine learning techniques that utilize the data generated by computational fluid dynamics for training purposes. The physical system under investigation includes a stagnation-point flow of a hybrid nanofluid (Cu−Al2O3/Water) over a blunt object embedded in porous media. The problem further involves mixed convection, entropy generation, local thermal non-equilibrium and non-linear thermal radiation within the porous medium. The SVR (Support Machine Vector) model is employed to approximate velocity, temperature, Nusselt number and shear-stress as well as entropy generation and Bejan number functions. Further, PSO meta-heuristic algorithm is applied to propose correlations for Nusselt number and shear stress. The effects of Nusselt number, temperature fields and shear stress on the surface of the blunt-body as well as thermal and frictional entropy generation are analysed over a wide range of parameters. Further, it is shown that the generated correlations allow a quantitative evaluation of the contribution of a large number of variables to Nusselt number and shear stress. This makes the combined computational and artificial intelligence (AI) approach most suitable for design purposes.
107 citations
TL;DR: In this article, a diesel engine is operated in RCCI mode with gaseous fuels viz. CNG as a primary fuel and a blend of diesel and Karanja biodiesel (BD20) as pilot fuel.
Abstract: Heterogeneous combustion in a diesel engine is noisier, uncontrolled and more polluting. This can be achieved with a strategic approach of a reactivity-controlled compression ignition (RCCI) mode engine that operates with low and high reactive fuel combinations. In the present work, a diesel engine is operated in RCCI mode with gaseous fuels viz. CNG as a primary fuel and a blend of diesel and Karanja biodiesel (BD20) as pilot fuel. This research aims to determine the operating limits of CNG fuel for less noisy combustion and clean exhaust. Further, relative air-fuel ratio (λ), cycle to cycle variations, combustion noise and emissions were studied for full load operation. The CRDI engine is optimized for diesel operation with a split injection strategy. The knock limits for CNG as the primary fuel are obtained. The combustion noise increases at a higher energy share by CNG. Also, higher values of HC and CO emissions are observed. This may be due to higher energy share values, flame speed and octane number of CNG fuel. Further, NOx emissions and smoke are decreased. The CNG induction of 10 ms with 90% ES can be noted as a knock limit for 3.5 kW power. The highest BTHE of 24.2% and least BSFC 0.3 kg/kWhr reported by 60%ES of LRF is better than diesel and KBD20 fuel. An optimum 60% energy share of CNG is observed for clean combustion and emissions strategy using the RCCI mode of a modified diesel engine.
84 citations
TL;DR: In this article, a mixture of 3-aminopropyl-triethoxysilane (APTES) with the biomass Ayous wood sawdust (AW) was used to remove reactive blue 4 (RB-4) from water.
Abstract: Background Biomass-based materials present low sorption capacity. In order to overcome this disadvantage, chemical modification of these materials is required. Methods Hybrids of biomass-based materials were obtained by reacting (25%-200% weight) 3-aminopropyl-triethoxysilane (APTES) with the biomass Ayous wood sawdust (AW), obtaining the hybrid materials AW@APTES-0.25, AW@APTES-0.50, AW@APTES-1.0, AW@APTES-1.5, and AW@APTES-2.0, that were characterized by hydrophobic/hydrophilic balance, CHN elemental analysis, surface area, TGA, FTIR, and pHpzc. Significant findings For screening purposes, the five materials were tested as adsorbents to remove reactive blue 4 (RB-4) from water. The results showed that AW@APTES-0.5 attained the maximum removal of RB-4. The kinetics and equilibrium data were suitably fitted by the nonlinear General-order kinetic (GO) and Liu equilibrium adsorption models. The maximum amount adsorbed of RB-4 dye was 415.1 mg g − 1 using AW@APTES-0.5 (50 °C). An increase in the Qmax value of AW@APTES-0.5 concerning unmodified AW attained up to 21.6 times. The ΔG° and ΔH° indicated that the adsorption processes of RB-4 onto adsorbents are endothermic and spontaneous, and the magnitude of enthalpy of adsorption (25.10 kJ mol−1) is compatible with the electrostatic attraction mechanism. The adsorbents’ applicability for treating simulated dye effluents showed an excellent efficiency attaining 98.66% removal of the effluent.
70 citations
TL;DR: In this article, the authors used analytical hierarchy process (AHP) decision-making approach to select the best alternative for running a PV unit among individual PV usage and pure water-based PV/T technologies.
Abstract: The foremost alternative for running a PV unit is chosen among five items using analytical hierarchy process (AHP) decision-making approach. Two items are individual PV usage and pure water based PV/T system, and three other ones are, Al2O3, TiO2, and ZnO nanofluid based PV/T technologies. The experimental data gathered throughout a year for a 250 W multicrystalline module is utilized to obtain the results. Energy yield, electrical and thermal efficiencies, payback period, and CO2 reduction are the decision-making criteria, while reliability is added to them to have a broader insight from the performance. According to the results, with the gained score of 33.1 out of 100, ZnO nanofluid based PV/T system is the best alternative. It has annual energy production and average electrical and thermal efficiencies of 632.5 kWh, 14.65, and 47.63%, respectively. Moreover, it can reduce CO2 emission by 853.8 kg and enjoy the reliability of 0.986388, which is the highest one among the alternatives. Additionally, this alternative offers a payback period of 5.12 years, which is around 10% lower than the main rival, i.e., TiO2 nanofluid based PV/T system. Utilizing pure water PV/T is also found much better than Al2O3 one because of economic issues.
68 citations
TL;DR: In this paper, the authors studied the natural convection of the CuO-water nanoliquid in a rectangular cavity with fins attached to the insulated wall and porous media, and derived the Navier-Stokes equations for heat transfer and entropy generation for distinct Rayleigh numbers (103−105), Darcy numbers (10−2−10−4), and Hartmann numbers (0, 10, 20).
Abstract: The oily water from various sources in combined cycle power plants is collected in oil/water separator in which the oil separates from water due to the density difference. The idea of the presented geometry is taken from conventional oil/water separators. This paper studies the natural convection of the CuO-water nanoliquid in a rectangular cavity with fins attached to the insulated wall and porous media. Discretion of Navier-Stokes equations is done by Finite Element Method and assumptions are laminar, steady and incompressible flow. Heat transfer performance and entropy generation are investigated for distinct Rayleigh numbers (103–105), Darcy numbers (10−2–10−4), and Hartmann numbers (0, 10, 20). Different sizes of the fins are also studied to show consequences of fin size on heat transfer in cavity. This is the first time that these parameters and their impacts on Nusselt number and entropy generation are studied for a conventional oil/water separator cavity. Corollaries demonstrate that increasing Rayleigh number and Darcy number improves heat transfer performance and average Nusselt number. Nevertheless, Hartmann number has a reverse effect with average Nusselt number. Finally, a new equation for average Nusselt number is developed with regard to Rayleigh number, Hartmann number, and Darcy number.
65 citations
TL;DR: In this article, a hybrid nanofluid containing Fe2O3-TiO2 (50:50) nanoparticles suspended in water basefluid has been used to improve the convective heat transfer in aluminum tube automotive radiator.
Abstract: Nanofluids have emerged as potential prospect coolant in heat transfer applications Hybrid nanofluid is recently developed class of nanofluids having two different types of nanoparticles suspended in the base fluid In this research, a novel hybrid nanofluid containing Fe2O3-TiO2 (50:50) nanoparticles suspended in water basefluid has been used to improve the convective heat transfer in aluminum tube automotive radiator Three hybrid nanoparticle concentrations (0005 vol%, 0007 vol% and 0009 vol%) were tested Effect of inlet temperature and fluid velocity on heat transfer rate was examined by varying the inlet temperature from 48 °C to 56 °C and flowrate from 11 LPM to 15 LPM Heat transfer rate increased by a maximum of 267% at 56 °C inlet temperature, 15 LPM flowrate and 0009 vol% nanoparticle concentration At aforementioned operating conditions, Nusselt number increased by 2003% Increase in inlet temperature from 48 °C to 56 °C increased the heat transfer rate by 8% Past 0009 vol% concentration, nanoparticle clogging diminished the stability of hybrid nanofluid which results in overall performance deterioration
65 citations
TL;DR: In this article, the effectiveness of using copper oxide (CuO) nanoparticles in a solar-assisted hot process stream was investigated using transient-based numerical approaches, the efficacy of loading CuO nanoparticles at 0.1 vol% into water on collector heat gain was examined.
Abstract: Background Flat plate solar collectors (FPSCs) can meet the needs of low-temperature process industries by providing a hot flow stream. In this regard, the addition of nanoparticles can improve the energy-saving potential of the FPSCs. In this study, the effectiveness of using copper oxide (CuO) nanoparticles in a solar-assisted hot process stream was investigated. Methods Using transient-based numerical approaches, the efficacy of loading CuO nanoparticles at 0.1 vol.% into water on collector heat gain was examined. Using effectiveness–NTU method, the nanofluid efficacy was challenged by adding a two-pipe heat exchanger to diminish heating power usage in a hot process stream. Findings The results revealed that if a water-filled solar-assisted hot process stream was used, the energy-saving will be 670, 383 and 225 kWh m 2 . year at 60, 120 and 240 lit hr under Najran climate conditions. Taking into account energy-saving of 712, 415.5 and 242.5 kWh m 2 . year for nanofluid, it was found that incorporating CuO into a solar-assisted hot process stream has been successful. Owing to using CuO, the effectiveness of the solar-assisted hot process stream was improved within the range of 6-12.8%.
54 citations
TL;DR: In this article, rice straw (RS), an agricultural waste, is used to prepare activated carbon (AC) with a two-step process of carbonization and KOH activation, which has a high specific surface area (SSA) of 2651 m2g-1 with hierarchical pore structure.
Abstract: Environmental-friendly and low-cost biomass-derived materials have been attracted many attentions to produce porous activated carbon (AC) with high surface area for supercapacitor (SC) application. In this study, rice straw (RS), an agricultural waste, is used to prepare ACs with a two-step process of carbonization and KOH activation. As-produced AC has a high specific surface area (SSA) of 2651 m2g-1 with hierarchical pore structure. In order to enhance the performance of SC, nitrogen-doping strategy is carried out to increase nitrogen functional groups in the AC using melamine as a precursor. The SSA of the nitrogen-doped AC is 2537 m2g-1 and the capacitance of 324 F/g is achieved using nitrogen-doped AC at a current density of 0.5 Ag-1 in 6 M KOH aqueous electrolyte. The capacitance retention is 95% after 10,000 charge and discharge cycles at a current density of 5.0 Ag-1. In addition, ionic liquid is employed as the electrolyte for the supercapacitor. The energy density of 48.9 Wh/kg at a power density of 750 W/kg can be achieved using EMI-TFSI electrolyte. We think that the proposed method can be used for a variety of biomass for preparation of ACs with high specific surface area and nitrogen functional groups for the energy storage applications.
53 citations
TL;DR: In this paper, the authors studied the magnetic nanofluid dynamics along a nonlinear porous stretching sheet with Arrhenius chemical kinetics and wall transpiration and solved the emerging momentum, thermal energy and nanoparticle concentration ordinary differential conservation equations numerically with a hybrid technique combining Successive Linearization and Chebyshev Spectral Collocation.
Abstract: Background Emerging applications in nanomaterials processing are increasingly featuring multiple physical phenomena including magnetic body forces, chemical reactions and high temperature behavior. Stimulated by developing a deeper insight of nanoscale fluid dynamics in such manufacturing systems, in the current article, we study the magnetic nanofluid dynamics along a nonlinear porous stretching sheet with Arrhenius chemical kinetics and wall transpiration. Appropriate similarity transformations are employed to simplify the governing flow problem. Methods The emerging momentum, thermal energy and nanoparticle concentration ordinary differential conservation equations are solved numerically with a hybrid technique combining Successive Linearization and Chebyshev Spectral Collocation. A parametric study of the impacts of magnetic parameter, porous media parameter, Brownian motion parameter, parameters for thermophoresis, radiation, Arrhenius function, suction/injection (transpiration) and nonlinear stretching in addition to Schmidt number on velocity, temperature and nanoparticle (concentration) distribution is conducted. A detail numerical comparison is presented with different numerical and analytical techniques as a specific case of the current investigation. Findings Increasing chemical reaction constant parameter significantly decreases nanoparticle concentration magnitudes and results in a thickening of the nanoparticle concentration boundary layer. Enhancing the values of activation energy parameter significantly increases the nanoparticle concentration magnitudes. Increasing thermophoresis parameter elevates both temperature and nanoparticle concentration. Increasing radiation parameter increases temperature and thermal boundary layer thickness. Enlarging Brownian motion parameter (smaller nanoparticles) and Schmidt number both depress the nanoparticle concentration.
51 citations
TL;DR: In this paper, an inspection of the free convection of nanofluid as well as entropy generation inside a porous cavity loaded with nano-encapsulated phase change materials (NEPCMs) was performed.
Abstract: Background The exploration of natural convection which is one the substantial types of convective heat transmission in various applications for instance heat exchangers and geothermal systems along with nanofluids (Nanofluids have greater thermal conductivity in comparison to the conventional fluids) engrossed all researchers’ attention. Methods This study is dedicated to the inspection of the free convection of nanofluid as well as entropy generation inside a porous cavity loaded with nano-encapsulated phase change materials (NEPCMs). The wavy bottom section of the enclosure may be subject to a constant heat flux due to the transmitted sunlight comes from a parabolic trough solar collector. The volumetric heat source/sink is comprised in the governing equation. The robust finite element method (FEM) is deployed to handle the transformed governing equations. Findings The numerical simulation of the streamlines and isotherms associated with velocity distribution for diverse factors are displayed. Further, the significant behavior of the contributing parameters on the Nusselt and Bejan numbers are represented. The results demonstrate that the various profiles of wavy bottom section could affect the heat transmission features as well as fluid flow remarkably. Furthermore, it is noteworthy that all the profiles of entropy enhance with increasing the amplitude with respect to the increasing undulation number for the existence of various Rayleigh number.
50 citations
TL;DR: In this article, the simulation of two alternative processes for the coupled production of metallic iron nanoparticles and the necessary reducing agent: hydrated hydrazine and sodium borohydride.
Abstract: This study deals with the simulation of two alternative processes for the coupled production of metallic iron nanoparticles and the necessary reducing agent: hydrated hydrazine and sodium borohydride. After carrying out a sensitivity analysis to identify the optimal operating conditions for each process, the results have been interpreted in the light of energy and exergy analysis. The study demonstrated that the sodium borohydride-based iron nanoparticles production is more profitable than the hydrazine-based one, because of a higher exergy efficiency as a consequence of lower exergy destruction value. The total heat duty required for the borohydride-based process was only 1.1 MWh with respect to 5 MWh for the hydrazine-based one. Conversely, cooling water and total power consumptions for the latter process are significantly lower than for the former one (2.33 t/h versus 26.87 t/h, and 2 kWh versus 88.7 kWh, respectively). Furthermore, as reported in the literature, the hydrazine-based process allows to produce high purity iron nanoparticles, since hydrazine is transformed completely in N2 during the process. Both processes were designed to produce 1765 kg/d of iron and the same amount of produced reducing agent was also stored as secondary product of the plant.
TL;DR: In this article, a porous enclosure containing three circular cylinders with magnetic field effects was investigated using finite element approach, where the cylinders are arranged in horizontal arrangement in the middle of cavity height, and the active hot central cylinder can move along the vertical central axis while other cold cylinders are considered fixed.
Abstract: In this numerical contribution, hybrid nanofluid flow behavior, thermal characteristics, and entropy generation analysis through a porous enclosure containing three circular cylinders with magnetic field effects were investigated using finite element approach. The cylinders are arranged in horizontal arrangement in the middle of cavity height, and the active hot central cylinder can move along the vertical central axis while other cold cylinders are considered fixed. The cylinders are enclosed by an adiabatic wavy cavity loaded with Cu-Al2O3-water. The results are discussed for the scrutinized parameters e.g., Rayleigh number (Ra), Darcy number (Da), Hartmann number (Ha), relative position of the hot cylinder (δ), and concentration in volume of nanoparticles (ϕ). It was inferred that the thermal-natural convective flow and overall heat transmission were reinforced by boosting Ra and Da, and lowering Ha. Changing the relative position of the hot cylinder has a remarkable effect on nanoliquid flow patterns, convective heat transfer and entropy generation characteristics.
TL;DR: In this paper, the unique characteristics of the nanosized silver thiocyanate structure motivated the researchers to apply it as an effective agent nanoparticles additive in Diesel/Biodiesel fuel blends.
Abstract: The unique characteristics of the nanosized silver thiocyanate structure motivated the researchers to apply it as an effective agent nanoparticles additive in Diesel/Biodiesel fuel blends. Nanostructure of silver thiocyanate was measured by High resolution transmission electron microscope giving nano diameter between the values of 7.23:7.98 nm. The engine test has been achieved using 200, 400, and 600 ppm nanoparticles of silver thiocyanate additives to the blends of D50B50 (50%diesel & 50% biodiesel by volume). The tested blends are subjecting to a continuous stirring by using a mechanical movement pump to enhance the harmony of the nano-solid inside the blended fuel. During the engine test, the obtained fuel blends are stable and steady and the engine is running smoothly at fixed speeds of 1400 RPM and loads variation. The nanoparticles silver thiocyanate act as an oxygenated contributing catalyst. However, the existence of the extra oxygen inside the engine cylinder participates in reducing the unburned hydrocarbon emissions. The obtained results showed that the 400-ppm nanosized silver thiocyanate comparatively presents a better performance, combustion, and emission with respect to another tested dos. Unburned hydrocarbons and smoke emissions were dramatically reduced by adding the silver thiocyanate nanoparticle, which has working as combustion exciter that enhances the heat release rate process inside the DI-engine cylinder.
TL;DR: In this article, the effects of the porous media on both thermodynamic and hydrodynamic characteristics of the system, i.e., velocity profiles and the pressure drop, were investigated numerically.
Abstract: Photovoltaic-thermal (PVT) collectors, are useful systems to absorb solar energy and convert that to electrical and thermal energy. However, to make the best out of solar irradiation, it is vital to improve the thermal and energy efficiencies of such systems. Porous metal foams are suggested to be utilized in the present study for cooling of the PV cells and increase the thermal and electrical efficiencies. Moreover, the effects of various parameters, such as porous layer thickness, solar heat flux, and Reynolds number on these efficiencies are investigated numerically. Results mainly focus on the effects of the porous media on both thermodynamic and hydrodynamic characteristics of the system, i.e., velocity profiles and the pressure drop. The results indicated that the usage of porous media can improve both efficiencies (between 3 and 4% for the electrical and between 10 and 40% for the thermal efficiency) with a subsequent pressure loss. But for cases with a thickness of more than half of the channel height, it has a negative effect. In the best condition, Rp=0.5, the overall efficiency reaches up to 95%, however, in this case, the pressure drop rises considerably (up to 600 Pa), which causes destructive effects on the system and imposes additional costs.
TL;DR: In this article, the impact of non-dimensional fusion temperature on the free convection of conducting nanofluid within a porous enclosure filled with nano-encapsulated phase change materials (NEPCMs).
Abstract: The present study encountered the impact of non-dimensional fusion temperature on the free convection of conducting nanofluid within a porous enclosure filled with nano-encapsulated phase change materials (NEPCMs). The enclosure is equipped with two parallel fins that have ability to move in both directions such as vertically as well as horizontally. In particular the particles are structured as core-shell with phase change materials. The phase change of the materials is obtained from the solid to liquid and absorbs the surrounding temperature in the hot region and releases in the cold region. The governing transformed equations are tackled by using the Finite Element Method (FEM). The numerical simulation of the isotherms, streamlines and heat transfer coefficient ratio along with velocity distribution for various parameters are presented. These are affecting a key role on the average and local Nusselt number as well as on the local Bejan number. However, the measure outcomes are; both the longitudinal and transverse velocity profiles boost up with an augmented Rayleigh number; however, the weaker flow field is generated for the increasing Hartmann number.
TL;DR: In this paper, the reduced graphene oxide-supported bimetallic palladium-zero-valent-iron (Pd/nZVI/rGO) composites were synthesized using a facile one-step liquid-phase reduction method.
Abstract: In this study, the reduced graphene oxide-supported bimetallic palladium-zero-valent-iron (Pd/nZVI/rGO) composites were synthesized using a facile one-step liquid-phase reduction method. Physicochemical and textural properties as well as chemical composition of the as-prepared composites were firstly characterized. Transmission electron microscopy (TEM) and X-ray diffractometry (XRD) analysis revealed that the presence of rGO sheets prevented the aggregation of Pd/nZVI nanoparticles and retarded the transformation of iron corrosion products from magnetite/maghemite to lepidocrocite, inducing such nanoparticles to be dispersed more homogeneously. In addition, the loading of Pd/nZVI nanoparticles could avoid the stacking of rGO sheets effectively. The synthesized Pd/nZVI/rGO composites were then used to remove antibiotic oxytetracycline (OTC) from aqueous solutions. It was found that the introduction of an optimal amount of rGO into Pd/nZVI nanoparticles enhanced significantly OTC removal. In particular, the presence of 5 wt.% of rGO in Pd/nZVI/rGO composite (dose, 0.1 g/L) exhibited the highest OTC removal of 96.5% (initially, 100 mg/L) after 60-min reaction at pH 5.0 and 25°C. The removal of OTC by Pd/nZVI/rGO composite was contributed by adsorption process, Fenton-like reactions, and reduction reactions. The Pd/nZVI/rGO composites exhibited better reusability than pristine nZVI particles. The pathways of OTC degradation over Pd/nZVI/rGO nanocomposite were also proposed.
TL;DR: In this paper, the adsorption of methylene blue (MB) dye using an aquatic plant, Azolla pinnata (AP), was modelled using several various supervised machine learning (ML) algorithms, aiming to accurately predict the advertisersorption capacity under various experimental conditions.
Abstract: Background In this study, the adsorption of methylene blue (MB) dye using an aquatic plant, Azolla pinnata (AP) was modelled using several various supervised machine learning (ML) algorithms, aiming to accurately predict the adsorption capacity under various experimental conditions. Methods The ML algorithms used in this study are the artificial neural network (ANN), random forests (RF), support vector regression (SVR), and instance-based learner (IbK). The SVR algorithm was trained using three kernels: radial basis function (RBF), Pearson VII universal kernel (PUK), and polynomial kernel (PolyK). The experimental data (adsorbent dosage, pH, ionic strength, initial dye concentration, and contact time) served as input for training the algorithms and with the adsorption capacity as the output. The performance of the algorithms was optimised based on the values of correlation coefficient (R) and fine-tuned using several error functions (e.g. mean absolute error, root mean square error, and non-linear chi-squared). Findings The best performing ML algorithm in this study is SVR-RBF which achieves the highest value in R (0.994) and has the lowest error.
TL;DR: In this article, the amplitude of the baffle could be changeable while its undulation number is fixed at 2, which is a significant thermal management aspect subject to various industrial applications.
Abstract: Background Free convection and second law scrutiny of nano-encapsulated phase change material (NEPCM) suspension along with entropy production inside a circular cold cylinder involving a wavy hot baffle is a significant thermal management aspect subject to various industrial applications. Phase change material (PCM) undergoes a solid-liquid phase mutation at a particular fusion temperature, and absorbs/releases an appreciable amount of energy because of the latent heat of phase mutation. Hence, NEPCMs would be prospective owing to their capability to enhance the working liquids’ performance, keeping the system at a particular cooling temperature. Methods In order to simulatethe free convection along with entropy generation of NEPCMs inside a circular cold cylinder entails a wavy hot baffle under CattaneoChristov heat flux model(Altered Fourier theory) and magnetic field, the finite element method (FEM) could be utilized to solve the governing equations. In this study, the amplitude of baffle could be changeable while its undulation number is fixed at 2. Findings Amplifying Raylegh number intensifies streamlines, isotherms, horizontal and vertical velocities, total entropy generation whittles down local Bejan number. Higher magnetic field strength is responsible for slow movement of NEPCMs and augments local Bejan number. Growth of baffle size yields squeezes the streamlines, horizontal and vertical velocities and intensified tilted isotherms.
TL;DR: In this paper, the authors analyzed the Casson fluid unsteady flow over a permeable flat plate in the presence of inclined magnetic field and heat transfer of fluid with the effect of thermal radiation.
Abstract: The inclined magnetohydrodynamic (MHD) unsteady flow and heat transfer of Casson hybrid nanofluid (HNF) due to porous stretching sheet is investigated. In the present paper we analyze the Casson fluid unsteady flow over permeable flat plate in the presence of inclined magnetic field and heat transfer of fluid with the effect of thermal radiation. The conservation of mass, conservation of momentum and thermal equations are non-dimensional into the system of nonlinear ODEs by taking the suitable similarity transformation. An exact analytical solution is obtained for velocity. The energy equation in the presence of inclined magnetic field and radiation is a differential equation with variable coefficients, which is transformed to an incomplete gamma function using a new variable and using the Rosseland approximation for the radiation. The governing differential equations are solved analytically and the effects of various parameters on velocity profiles, skin friction coefficient, temperature profile and wall heat transfer are presented graphically. There is an enhancement in heat transfer and pressure drop by usage of HNF. The variations in velocity and temperature profiles with respect to different various pertinent physical parameters. An increase of the mass transpiration (suction) parameter intensity increases the skin friction, which consequently improves the heat transfer enhancement and reduces the HNF temperature. Furthermore, the skin friction coefficient increases due to mass suction and MHD in the stretching sheet, whereas the rate of heat transfer decays. The results have possible technological applications in liquid-based systems involving stretchable materials.
TL;DR: In this paper, a core-shell design of Fe3O4@SnO2 was prepared, doped with silver nanoparticles (Fe3O 4@snO2/Ag) and later laden into three-dimensional graphene oxide hydrogel (rGH) forming 10% rGH-Fe 3O4/SnO 2/Ag, which was synthesized using chemical reduction methods and utilized in the degradation of 2,4 dichlorophenol as a target pollutant in the solution.
Abstract: In this study, a core-shell design of Fe3O4@SnO2 was prepared, doped with silver nanoparticles (Fe3O4@SnO2/Ag) and later laden into three-dimensional graphene oxide hydrogel (rGH) forming 10% rGH-Fe3O4@SnO2/Ag, which was synthesized using chemical reduction methods and utilized in the degradation of 2,4 dichlorophenol as a target pollutant in the solution. Fourier Transform Infrared Spectroscopy/FTIR spectra, Raman spectroscopy, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy, X-ray diffraction, Photoluminescence spectra, Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy were some of the standardized characterization techniques utilized. 2,4 dichlorophenol (2,4-DCP) was quickly adsorbed by three-dimensional 10% rGH-Fe3O4@SnO2/Ag composite and rapidly degraded by Fe3O4@SnO2/Ag nanoparticles under sunlight irradiation, indicating that superb synergies between adsorption-photocatalysis degradation could significantly improve the pollutant degradation performance. The maximum adsorption capacity of 10% rGH-Fe3O4@SnO2/Ag was 14.90 mg/g after 30 min. According to the results, the percent degradation efficiency of 2,4-DCP in Fe3O4@SnO2/Ag-rGH was not only high i.e. 93.8% via the synergy amongst adsorption-photocatalytic degradation, but also the percent degradation efficiency of 2,4-DCP was 85% after 5 repetitive cycles, which signified a high synergistic effect between Fe3O4@SnO2/Ag nanoparticles and 3D graphene. A corresponding pathway for 2,4-DCP photodegradation was suggested, such as 2,4 -dichlorophenol, formic, acetic, or oxalic acid as the main intermediate compounds. The experimental results of radical species trapping showed the photo-generated holes exhibiting an important role in promoting both direct oxidation of 2,4-DCP and production of ·O2 radicals. Therefore, 10% rGH-Fe3O4@SnO2/Ag composite revealed that it has a photocatalyst with high degradation activity, facile recyclability and easy magnetic separation for its potential wide application in the water treatment.
TL;DR: In this article, an Ag-Mg-MOF was synthesized through a one-step approach using solvothermal technique and the as-synthesized Bimetallic MOFs were characterized by TEM, SEM, EDS, XRD, FTIR and N2 adsorption.
Abstract: Removing of heavy metal ions from aqueous solutions has become a serious challenge from both biological and environmental viewpoints. Recently, metal-organic frameworks (MOF) including two metal ions in its framework have been enhanced as promising structure in the capture of various hazardous and toxic substances. Herein, Ag-Mg-MOF were synthesized through a one-step approach using solvothermal technique. Then, the as-synthesized Bimetallic MOFs were characterized by TEM, SEM, EDS, XRD, FTIR and N2 adsorption. The as-synthesized Ag-Mg-MOF samples were used for heavy metal removal. The results showed that the adsorption of cadmium, lead and Cupper ions on MOF was improved by the pH increasing. The experimental data were examined through Freundlich and Langmuir models. The fabricated Ag-Mg MOFs exhibit enhanced decontaminant performance toward Cu2+, Cd2+and Pb2 ions in terms of high adsorption capacities, Pb2+ (350 mg/g)> Cd2+ (270 mg/g)> Cu2+ (202 mg/g), and ultrafast kinetics compared to the monometallic Mg-MOF. FT-IR spectra of adsorbed pyridine methods and non-aqueous potentiometric titration were used for measuring surface acidity of the prepared MOF. It was observed that the surface acidity and the catalytic activity were increased in bimetallic MOF compared to monometallic MOF. The catalytic results of the formation of free solvent 14-aryl-14-Hdibenzo[a,j]xanthene compound by Ag-Mg MOF showed a high yield at a lower time. Also, the prepared MOF catalysts still preserved their initial catalytic activity even after the 4th run. The results of this work demonstrate that the novel Ag-Mg MOFs nanocatalysts have great potential for applications in environmental protection, especially in heavy metal ions removal present in wastewaters and in the synthesis of pharmacologically and biologically active compound.
TL;DR: In this article, the synthesis, characterization, and evaluation of inhibiting performance of two xanthene derivatives, namely 3-oxo-3H-spiro[isobenzofuran-1,9′-xanthene]-3′,6′-diyl (3-dibenzoate) (NAR2), on mild steel immersed in 1-M HCl solution are performed.
Abstract: The synthesis, characterization, and evaluation of inhibiting performance of two xanthene derivatives, namely 3-oxo-3H-spiro[isobenzofuran-1,9′-xanthene]-3′,6′-diyl (3-dibenzoate) (NAR2) and 3-oxo-3H-spiro[isobenzofuran-1,9′-xanthene]-3′,6′-diyl (3-diacetate) (NAR3) on mild steel immersed in 1 M HCl solution are performed. The in vivo tests were carried out to confirm the non-toxicity of NAR2 and NAR3. The solutions corrosive was analyzed using UV visible Spectroscopy. The recorded spectra confirm the adsorption capacity of these molecules on the surface of iron and thereby a formation of Fe–inhibitor complex film. A combination of Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX) Spectroscopy were performed to characterize the surface of mild steel, with and without the NAR2 or NAR3 inhibitors; and Electrochemical techniques were evaluated (EIS) to determine the corresponding corrosion inhibition efficiencies of NAR2 and NAR3. The Density Functional Theory (DFT)- based total energy calculations and Monte Carlo simulations were also performed to get further theoretical insights into the inhibition mechanism. The obtained results confirmed that both organic inhibitors exhibit non-toxicity, with an inhibition efficiency of 93% and 89% for NAR2 and NAR3 at 10−4 M concentrations, respectively. Also, the both inhibitor function as mixed (cathodic and anodic) type inhibitors, displace water molecules from mild steel, and form an heterogeneous films on the mild steel surface to protect against corrosion.
TL;DR: In this article, the authors used pure potato starch (PPS) purified from waste potato starch, was recovered and used to obtain a bilayer PPS-3APTMS-PLA film, the polylactic acid (PLA) was employed with PPS by casting method.
Abstract: In this work, pure potato starch (PPS) purified from waste potato starch, was recovered and used. PPS was modified by 3-APTMS (3-(aminopropyl) trimethoxy silane) to manufacture a crosslinked film. To obtain a bilayer PPS-3APTMS-PLA film, the polylactic acid (PLA) was employed with PPS-3APTMS by casting method. The resulting materials, PPS-3APTMS and PPS-3APTMS-PLA were characterized by attenuated total reflectance fourier transform infrared (ATR-FTIR), x-ray Diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA). The silane-doped bilayer films have more thermal stability compared to PPS. The mechanical, solubility, swelling, water vapor permeability, optical properties and biodegradability under controlled compost conditions were examined. When the tensile strength of the PPS, PPS-3APTMS and PPS-3APTMS-PLA films were evaluated, the tensile strength (TS) were to 1.017±0.35 MPa, 1.437 ± 0.19 MPa and 10.918 ± 1.30 MPa, respectively. The PPS and PPS-3APTMS films were not elongation at break, while it was found about 21.94 ± 9.48 for the bilayer PPS-3APTMS-PLA film. The solubility, swelling, water vapor permeability, and transparency decreased for bilayer films. The water vapor permeability of PPS, PPS-3APTMS and PPS-3APTMS-PLA films were obtained as 31.69±0.4 × 10−7 g s−1 m−1 Pa−1, 28.96±0.4 × 10−7 g s−1 m−1 Pa−1, and 14.26±0.3 × 10−7 g s−1 m−1 Pa−1, respectively. Then, the biodegradability of films was performed under controlled compost conditions for 46 days according to ISO-14,855 standard. The biodegradation of PPS, PPS-3APTMS and PPS-3APTMS-PLA was also calculated as 9.30%, 5.45% and 5.08%. Biodegradation of PPS-3APTMS film decreases compared to PPS. Furthermore, the biodegradation value of bilayer film, PPS-3APTMS-PLA, was also decreased due to the slower degradation tendency of PLA. The contribution to the reusability of waste starch and the modifying of starch for food packaging and coating applications are the novelty aspects of the current study.
TL;DR: In this paper, the influence of acid leaching sequences in RHA extraction on green silica purity and surface area was investigated, and the results showed that the acid-leaching process is believed to increase the silica extracted from rice husk ash (RHA).
Abstract: The acid leaching process is believed to increase the silica extracted from rice husk ash (RHA). This study intended to investigate the influence of acid leaching sequences in RHA extraction on green silica purity and surface area. The sequences were RHA leaching (T1), aged gel leaching (T2), dried product leaching (T3), and without leaching as a control. The T1 sequence has been proven to improve the green silica purity and surface area reaching 96.44% and 400.69 m2/g, respectively. For T2 and T3 sequences, the green silica has a much lower surface area and purity compared to T1. The values were 87.69% and 55.49 m2/g for T2 as well as 62.46% and 11.40 m2/g for T3. Without acid leaching, the purity and surface area of green silica significantly reduced to 56.94% and 5.72 m2/g. This study concludes that green silica from T1 sequence has successfully obtained high purity, high surface area, and indicates an amorphous and mesoporous particle. It is suitable to be utilized as an industrial silica gel for moisture adsorber which more sustainable and greener process.
TL;DR: In this paper, a glucose-based functionalized carbon dots (FCDs) was synthesized through a facile one-pot hydrothermal method, and its optimal corrosion inhibition efficiency exceeds to 88% at 70ppm.
Abstract: Background This work aims at developing some environmental-friendly corrosion inhibitors for copper in neutral solution. Methods A glucose-based functionalized carbon dots (FCDs) was synthesized through a facile one-pot hydrothermal method. The inhibition performance of FCDs was firstly researched systematically on copper in neutral 3.5 wt% NaCl solution by potentiodynamic polarization curves, electrochemical impedance spectroscopy and scanning vibrating electrode technique. The above electrochemical results show that FCDs is an effective corrosion inhibitor for copper in neutral solution, and its optimal corrosion inhibition efficiency exceeds to 88% at 70 ppm. The protective performance of FCDs depends on the coverage of adsorption film on copper surface. Its adsorption isotherm is in accordance with Langmuir adsorption model, involving both physisorption and chemisorption. Atomic force-distance curve directly quantifies the adhesion force between the adsorption film and copper surface. Significant finds The adsorption and anticorrosion mechanism of FCDs in neutral solution is proposed, which could provide theoretical guidance for design and synthesis of nanomaterial corrosion inhibitor.
TL;DR: In this article, the removal of Basic Blue 9 (BB9) dye was evaluated by using four different wastewater treatments, and the results showed that all the treatments provided high removal of BB9 with an efficiency of 83.26%.
Abstract: The presence of synthetic azo dyes in water can affect human health and the environment. Conventional treatments are not suitable to remove these synthetic dyes, as most of them have complex structures. In this work, the removal of Basic Blue 9 (BB9) dye was evaluated by using four different wastewater treatments. Biological treatment consisted of a process with microorganisms immobilized in sodium alginate. Chemical treatment was evaluated using ozone. Electrochemical treatment was carried out by electro-Fenton (EF) process using a parallel plate reactor and a carbon cathode. A reactor packed with activated carbon was used as a physical treatment. For each process, BB9 concentration was adjusted based on the removal capacity of the wastewater treatment used. Efficiency was evaluated using absorbance. Immobilized microorganisms degraded 6.61 mg/L within 120 min with an efficiency of 99%. Ozone oxidation degraded a BB9 concentration of 914.7 mg/L with an efficiency of 99% in 100 min. In the electrochemical process, the electrolysis lasted 180 min, where 5.3 mM H2O2 was electrogenerated and a concentration of 29.26 mg/L was degraded in 40 min with a removal efficiency of 97.7%. The physical treatment (adsorption) removed 7.85 mg/L of BB9 with an efficiency of 83.26%. According to the results, all the treatments provided high removal of BB9. Considering that the selection of wastewater treatment is highly dependent on operating expenses, a cost analysis is also presented for the wastewater treatments used.
TL;DR: In this article, ZnO/Bi4O5I5I2 (20%) nanocomposites were constructed through refluxing procedure and the Nyquist plot, transient photocurrent response, and photoluminescence analyses affirmed enhancement in carrier segregation efficiency in the fabricated nanocompositionite.
Abstract: In the present work, ZnO/Bi4O5I2 nanocomposites were constructed through refluxing procedure. The Nyquist plot, transient photocurrent response, and photoluminescence analyses affirmed enhancement in carrier segregation efficiency in the fabricated nanocomposite. The results exhibited that the ZnO/Bi4O5I2 (20%) nanocomposite demonstrates the best efficiency for the degradation of various pollutants, as compared to the single samples under visible light. The photoactivity of the ZnO/Bi4O5I2 (20%) photocatalyst is nearly 8.09, 26.1, 8.18, 10.4, and 19.2-times premier than that of the ZnO for decontamination of fuchsine, MB, MO, RhB, and phenol respectively. Furthermore, the ameliorated ability of the ZnO/Bi4O5I2 (20%) system is 2.45, 3.25, 2.28, 2.96, and 2.84 times higher relative to the ZnO/BiOI (20%) photocatalyst in elimination of fuchsine, MB, MO, RhB, and phenol, respectively. The boosted efficiency is because of the extension of absorption towards visible area, enhanced surface area, and more charge segregation in binary system. Moreover, with various quenchers, the outcomes of scavenging tests illustrated that ⦁O2−, ⦁OH, and h+ have considerable role in the photocatalytic removal process and the inhibition extent is as BQ > 2-PrOH > AO. Also, the ZnO/Bi4O5I2 (20%) nanocomposite possessed significant recycle efficiency, whose utilization had almost no significant change up to four consecutive cycles.
TL;DR: In this paper, an organic-inorganic perylene diimide modified BiO2-x (PDI/BiO2x) was synthesized, which can degrade various kinds of pollutants efficiently.
Abstract: Background Photocatalytic degradation of pollutants has the characteristics of high energy efficiency and no secondary pollution. In this paper, organic-inorganic perylene diimide modified BiO2-x (PDI/BiO2-x) was synthesized, which can degrade various kinds of pollutants efficiently. Method The samples were characterized by XRD, FTIR, SEM, DRS, PL and ESR. Results It was found that the introduction of PDISA effectively improved the separation efficiency and increased surface area of BiO2-x. When PD/BiO2-x catalyst was used to degrade RhB and MB, the degradation rates were increased by 21 and 18 times respectively. In addition, it could also degrade methyl orange and tetracycline hydrochloride. At the same time, the degradation rate still maintained 85% through five times recycle experiments.
TL;DR: In this paper, the retention capacities of Se (VI) and Se (IV) ions using S-72 sodalite are 149.5mg/g and 255 mg/g, respectively after an equilibration time of 300min and 360min.
Abstract: Muscovite flakes were applied in the synthesis of three types of sodalite with different morphologies by hydrothermal processes for 24 h, 48 h, and 72 h. The synthetic sample after 72 h (S-72) showed the best surface area (105 m2/g), morphological features, and ion exchange capacity (71.3 meq/100 g). The S-72 was applied for effective retention of both Se (VI) and Se (IV) ions in batch adsorption studies. The retention capacities of Se (VI) and Se (IV) ions using S-72 sodalite are 149 mg/g and 255 mg/g, respectively after an equilibration time of 300 min and 360 min. The kinetic assessment suggested Pseudo-second order behavior for the retention of both Se (VI) and Se (IV). The equilibrium studies of their retention reactions demonstrated Langmuir isotherm behavior and monolayer form for the homogeneously adsorbed Se (VI) and Se (IV) ions on the surface of sodalite. The Gaussian energies (> 8 KJ/mol), enthalpies (
TL;DR: In this article, a visible-light-responsive B-TiO2/CoTiO3 (denoted as BTiO 2/CTO) Z-Scheme heterojunction photocatalyst was successfully synthesized by a calcination method.
Abstract: A novel visible-light-responsive Black-TiO2/CoTiO3 (denoted as B-TiO2/CTO) Z-Scheme heterojunction photocatalyst was successfully synthesized by a calcination method. The obtained samples were attentively characterized by various techniques and measurement procedures to assess the morphological, optical, and structural properties. The B-TiO2/CTO nanocomposite exhibited the photocatalytic efficiency 99% after 20, 30, and 60 min for photodegradation of Rhodamine B (RhB), Methylene Blue (MB), and Methyl Orange (MO), respectively. Furthermore, degradation efficiency was 82.4% for tetracycline (TC) as a pharmaceutical contaminant under B-TiO2/CTO nanocomposite. In all photocatalytic experiments, the nanocomposite activity was higher than that of B-TiO2 and CTO, which improved its performance due to more generation, separation, and transport of charge carriers, which was confirmed by PL, EIS, and photocurrent techniques. Furthermore, the specific surface area of the nanocomposite was slightly increased after the combining of B-TiO2 and CTO, resulting in an increase of active sites and photogenerated electron-holes. Trapping experiments revealed that ⦁OH, ⦁O2−, and h+ species play an important role in the degradation process. According to the results obtained in this work, the Z-Scheme mechanism was proposed that was more in line with the actual conditions of the photocatalytic process. Finally, a series of seven sequential cycles for dyes degradation was performed using B-TiO2/CTO nanocomposite without significantly reducing performance.