In this study the catalytic ability of green synthesized nickel oxide nanoparticles (NiO NPs) is investigated for degradation of methyl orange as a hazardous environmentally contamination in water. ...The NiO NPs was prepared at ambient conditions using the antioxidant content of
Punica granatum
L. (pomegranate) juice extract and their bio-reducing ability were studied in details. This process is entirely green process, free from toxic and hazardous solvent. The biosynthesized NiO NPs were in nano scale and their morphology, sizes, surface area and optical properties were characterized using field emission scanning electron microscope (FE-SEM), BET surface area analysis, thermogravimetric analysis, energy dispersive x-ray spectroscopy (EDX), X-ray diffraction (XRD) and ultraviolet–visible spectroscopy (UV–Vis). The biosynthesized NiO NPs were found to be active catalysts, particularly with the reducing agents for instance sodium borohydride, for the degradation of the toxic organic dyes such as methyl orange (MO) in contaminated water. The NiO NPs are stable and reusable for reducing MO to its leuco-form, in a short time, in an aqueous medium in the absence of reducing agents. This method is much cheaper than the other methods. The catalytic activity of NiO NPs can be explained by its small size, compared with the bulk materials, which produce numerous active sites due to its big surface area per unit volume.
Silver (Ag) nanoparticles (NPs) are perceiving remarkable progress during the past few periods due to its exclusive properties in many applications. Recently, green synthesis method of NPs is racing ...against traditional chemical and physical methods by avoiding the use of many toxic chemicals, and expensive devices. Accordingly, in this study, dry and fresh Portulaca‐oleracea L. leaf extract has been employed for producing AgNPs as a reducing, capping and stabilizing agents. This process is simple, eco‐friendly and green. UV–vis spectra showed the formation of AgNPs represented by the change of a colorless liquid to brownish solution. The crystallinity of the AgNPs, was confirmed by X‐ray diffraction (XRD). The contribution of the available functional groups of the leaf extract in the reduction and capping process of NPs was demonstrated using Fourier transform infrared spectroscopy (FTIR). This study showed that fresh Portulaca‐oleracea L. leaf extract provides better NPs in terms of stability, purity, degree of crystallinity and spherical shape. The biosynthesized AgNPs from both procedures were coated on the indium tin oxide (ITO) glass substrates to enhance the reflectivity property. It has been shown that the utilized AgNPs, from fresh Portulaca‐oleracea L. extract, has smaller size and negligeable agglomeration, consequently lower light transmittance.
• High purity, stable and spherical Ag NPs have been synthesized from simple, rapid, safe, and one pot green method using fresh and dry Portulaca oleracea leaf extracts.
• Fresh and dry P. oleracea leaf extracts have been utilized as reducing, capping, and stabilizing agents.
• This study showed that fresh P. oleracea leaf extract is a better medium to produce NPs that possess higher purity, stability, degree of crystallinity, and spherical shape.
• This process can scale up economic viability with high‐quality products from different tunable bandgap.
The goal of the current article is investigating the nanomaterial stream and its thermal features on a cylinder which is porous. Nanofluid viscosity and the efficient thermal conductivity are ...computed by KKL equation. In such method, impact of Brownian movement is incorporated. The governing PDEs will be decreased to an ODEs set with the adequate ones utilizing resemblance transformation, numerically resolved by fourth-order Runge–Kutta method. Results for flow as well as heat transfer specifications are acquired to different amounts of the nanoparticle mass fraction,
Re
, suction factor and various forms of nanofluid. In this study, such results illustrate that a nanoparticle presence in the basis fluid can alter the flow model. Based on the achievements,
Nu
is a growing function of fraction of nanoparticle,
Re
and suction factor.
Zinc oxide (ZnO) nanorods have been extensively investigated, owing to their extraordinary applications in numerous fields, spatially microchip technology, solar cells, sensors, photodetectors, ...photocatalysts and many others. Recently, using ZnO nanorods, as photocatalysts, are receiving increasing attention in environmental defense applications. This mini review summarizes some remarkable applications for ZnO nanorods. First, the various chemical and physical procedures that were used to produce ZnO nanorods are identified through symmetric matrices and heterogeneous structures, then the authors explain how to use these methods to produce ZnO nanorods. This mini review, also, discusses the applications of ZnO nanorods in many fields, especially in field release, emission properties, and electron transference. Last but not least, the appropriate conclusions for future research using ZnO nanorods have been successfully explained.
The objective of this paper is to study the entropy generation and natural convection of water- Al2O3 nanofluid in an inclined cavity which consists of two connected inclined triangular enclosures ...under a horizontal magnetic field. The horizontal diameter of the cavity is small in thickness and has the temperature Tc. Half of the bottom wall and also the right wall are at the temperature Th. The rest of the walls are adiabatic. The governing equations of the nanofluid flow are algebrized and solved using the FVFEM method. The effective parameters are 103<Ra<105, 0<Ha<40, 0°<γ<90°, and 0.00<φ<0.06. The results indicate that the rate of heat transfer increases by 12% and the entropy generation enhances by 13% through enhancing the Raleigh number. As the Hartmann number increases, the rate of heat transfer and the entropy generation decrease by 6.5% and 8%, respectively. The Bejan number also decreases for a higher Raleigh number and a lower Hartmann number. For a higher angle of the cavity, the average Nusselt number calculated on the right wall always reduces. Entropy generation decreases and Bejan number increases for a higher inclined angle.
Sustainable construction requires high-strength cement materials that additives with silica content could provide the requirements as well. In this study, the effect of the micro and nano-size of ...silica on the compressive strength of cement paste using different mathematical approaches is investigated. This study compares the strength of preferentially replaced cement pastes with microsilica (MS) and nanosilica (NS) incorporation by proposing several mathematical models. In this study, 205 data were extracted from the literature and analyzed. The modeling processes considered the most significant variables as input variables that influence the compression strength, such as curing time, which ranged between 3 and 90 days, the water-cement ratio, which varied between 0.4 and 0.85, and NS ranged between 0 and 15%. MS ranged between 0 and 40% based on the weight of cement. In this process, the compressive strength of cement paste modified with NS and MS was modeled using four different models, including the Linear Regression Model (LR), Nonlinear Model (NLR), Multi-Logistic Regression Model (MLR), and artificial neural network (ANN). The efficiency of the suggested models was evaluated using different statistical assessments, such as the Root Mean Squared Error (RMES), the Mean Absolute Error (MAE), Scatter Index (SI), Objective value (OBJ), and coefficient of determination (R2). The findings revealed that the ANN model conducted better performance for predicting compressive strength for cement paste than the other models based on the statistical assessment. In addition, based on the statistical assessment of the sensitivity of parameters, NS had more of an effect on the compressive strength of cement paste, with 6.3% more than MS.
Abstract
This research introduces a pioneering green method for synthesizing zinc oxide nanorods (ZnO NRs) on a glass substrate using Thymus kotschyanus plant extract. The study delves into the ...intricate effects of ammonium hydroxide and precursor concentrations on the morphology, size, alignment, and crystalline structure of ZnO NRs. Through systematic experimentation, it was found that specific concentrations of these substances play vital roles in the formation and properties of the nanorods. Notably, a low concentration of the precursor coupled with a high concentration of ammonium hydroxide led to well-aligned hexagonal ZnO NRs with a remarkable aspect ratio. Variations in these concentrations were also found to influence the length, diameter, and alignment of the nanorods. The findings were corroborated using a diverse array of analytical techniques, including transmission and scanning electron microscopy, x-ray diffraction, UV–vis spectroscopy, and energy-dispersive x-ray analysis. The UV–vis spectra provided further insights into the optical properties and band gap energy of the ZnO NPs, while EDX analysis confirmed the elemental composition. This work represents a significant advancement in eco-friendly nanomaterial synthesis, providing detailed insights into the controlled fabrication of aligned ZnO NRs. Its innovative approach and extensive investigation into influencing factors make it a valuable contribution to the field of nanoscience.
This paper presents exergo-economic and enviro-economic assessment of a novel building integrated photovoltaic thermal-compound sensible rotary heat exchanger (BIPVT-SRHX) system. The innovative ...BIPVT-SRHX system preheats/precools the outdoor air in winter/summer and generates electric power. The performance of the system are analyzed from the energy/exergy viewpoints for Kermanshah, Iran climatic conditions. Then, the multi-objective genetic algorithm (MOGA) optimization is used to optimize to determine the optimum values of geometric and operating parameters in order to maximize the annual average exergo-economic and enviro-economic aspects of the system. The considered geometric and operating parameters include the length, width and depth of the air channel located underneath the PV modules, the air mass flow rate, and the diameter, rotational velocity and length of the SRHX. Moreover, the annual performance of the optimized and non-optimized BIPVT-SRHX systems are compared. The results showed that the annual average exergo-economic and enviro-economic aspects of the optimized BIPVT-SRHX system are 0.0076 $/annum and 246.9 kWh/$, respectively. Furthermore, it was found that the annual average enviro-economic aspect, annual average exergo-economic aspect, and yearly sum of CO2 mitigation of the optimized BIPVT-SRHX system are respectively 36.8%, 23.1% and 37.7% higher than the non-optimized system.
•An innovative exhaust air energy recovery system consisting of a BIPVT and a SRHX.•Pre-heating/pre-cooling ambient air in winter/summer and producing electricity.•Genetic algorithm-based multi-objective optimization approach for BIPVT-SRHX system.•Optimization leads to a 36.8% increase in annual average enviroeconomic parameter.•Optimization leads to a 23.1% increase in annual average exergoeconomic parameter.
Current article outlines the latest research of high CNTs thermal conductivities and their nanofluids. Because of their exceptional structure and small size, carbon nanotubes has thermal properties ...enabling them to be an ideal material in the investigation of thermal controlling, both on the micro- and the macro-scales and low-dimensional phonon physics researches. Depending on the process parameters used in CNTs synthesis, the thermal conduction properties are notably affected by the alteration of the diameter, the chirality, the length, and the quality of CNTs. This review elucidates in details the necessity of thermal conductivity on several factors including the aspect of tubes, number of defects, morphology, atomic arrangement and the occurrence of impurities. Besides these factors, the dependence of thermal conductivity on chirality and temperature is also discussed. Several experimental investigations and theoretical models to estimate thermal conductivity of CNTs and their nanomaterial are also reviewed. This review also elucidates different models suggested by researchers for estimating properties of CNT-based nanofluids.
•High thermal conductivities of CNT are examined.•Thermal conduction properties are notably affected by the alteration of the diameter.•Dependence of thermal conductivity on temperature and chirality was discussed.
PDF
