This report deals with converting the agriculture waste (rice straw) to environmental cleaner materials (biochar) using airless pyrolysis followed by eco-friendly activation. The biochar (p-Biochar) ...obtained after pyrolysis step (poorly active material) was activated using wet attrition method to give m-Biochar (highly active materials). The both p-Biochar and m-Biochar were characterized in detail and utilized for MB and CV dye removal from aqueous solution. Various parameters affecting the adsorption process such as dye concentration, adsorbent dose, contact time, temperature, NaCl dose and pH were investigated. The adsorption isotherm was well fitted using Langmuir isotherm, and the maximum adsorption capacity is 90.91 and 44.64 mg/g, for MB and CV dyes, respectively. The contact time data obtained showed that the two dyes were poorly adsorbed over p-Biochar. The equilibrium was reached quickly in 15 min for MB dye and 20 min for CV dye using the m-Biochar, and removal percent was 94.45 and 92.70% for MB and CV dyes, respectively. Moreover, the kinetic isotherm presented very well fitted by pseudo-second-order model. In addition, the adsorption percent increases with further increasing the pH value. Finally, we observed that m-Biochar highly adsorbs the MB dye compared with the CV dye over all experimental conditions.
Multifunctional membrane technology has gained tremendous attention in wastewater treatment, including oil/water separation and photocatalytic activity. In the present study, a multifunctional ...composite nanofiber membrane is capable of removing dyes and separating oil from wastewater, as well as having antibacterial activity. The composite nanofiber membrane is composed of cellulose acetate (CA) filled with zinc oxide nanoparticles (ZnO NPs) in a polymer matrix and dipped into a solution of titanium dioxide nanoparticles (TiO2 NPs). Membrane characterization was performed using transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and Fourier transform infrared (FTIR), and water contact angle (WCA) studies were utilized to evaluate the introduced membranes. Results showed that membranes have adequate wettability for the separation process and antibacterial activity, which is beneficial for water disinfection from living organisms. A remarkable result of the membranes’ analysis was that methylene blue (MB) dye removal occurred through the photocatalysis process with an efficiency of ~20%. Additionally, it exhibits a high separation efficiency of 45% for removing oil from a mixture of oil–water and water flux of 20.7 L.m−2 h−1 after 1 h. The developed membranes have multifunctional properties and are expected to provide numerous merits for treating complex wastewater.
Distributed Ledger Technology (DLT) has emerged as one of the most disruptive technologies in the last decade. It promises to change the way people do their business, track their products, and manage ...their personal data. Though the concept of DLT was first implemented in 2009 as Bitcoin, it has gained significant attention only in the past few years. During this time, different DLT enthusiasts and commercial companies have proposed and developed several DLT platforms. These platforms are usually categorized as public vs private, general purpose vs application specific and so on. As a growing number of people are interested to build DLT applications, it is important to understand their underlying architecture and capabilities in order to determine which DLT platform should be leveraged for a specific DLT application. In addition, the platforms need to be evaluated and critically analyzed to assess their applicability, resiliency and sustainability in the long run. In this paper, we have surveyed several leading DLT platforms and evaluated their capabilities based on a number of quantitative and qualitative criteria. The comparative analysis presented in this paper will help the DLT developers and architects to choose the best platform as per their requirement(s).
To obtain the synergistic antimicrobial potential of nano-composites conjugated with graphene oxide (GO), an alternative approach was developed throughout the hybridization of chitosan (CS) or ...ethylene diamine tetraacetic acid (EDTA) with GO. The synthesized GO-nanocomposites were identified by XRD, HRTEM, SEM, FTIR, Zeta potential, and Raman spectroscopy. The antimicrobial activity of GO, GO-CS, and GO-EDTA was investigated against some pathogenic bacteria and Candida sp. Results showed that nano-composites looked flattened and clear, with some lines and folds on the exterior part. SEM images show the basic morphology of GO which owns remarkable holes, crevasses, and indeclinable internal structure. GO-EDTA and GO-CS possess a promising antimicrobial activity against all pathogenic microbes. In-vitro ZOI result verified that they exhibited activity against Escherichia coli (22.0 mm for GO-EDTA and 11.0 mm for GO-CS), Staphylococcus aureus (15.0 mm for GO-EDTA and 10.0 mm for GO-CS) and Candida albicans (22.0 mm for GO-EDTA and 16.0 mm for GO-CS). Microbial cells may be ultimately-damaged when they interact with GO-based nanocomposites due to different mechanisms such as oxidative and membrane stress and wrapping isolation. This work provides revolutionary GO-nanocomposites for increasing the antimicrobial activity against some pathogenic microbes with a cost-effective and eco-friendly approach.
► The soil–tool interaction model developed can simulate the soil cutting process of a simple soil engaging tool. ► Cohesive agricultural soils can be defined using the PFC
3D parallel bond model ...with dashpot. ► The calibrated particle stiffness was 6
×
10
3
N
m
−1 for coarse soil and 2
×
10
4
N
m
−1 for fine soil.
The discrete element method (DEM) has been recognized as an effective tool to simulate soil–tool interactions. However, most existing discrete element models were for cohesionless soils, and in those models there were limited discussions on selections and calibrations of model parameters. In this study, a soil–tool interaction model was developed using a commercial DEM software, Particle Flow Code in Three Dimensions (PFC
3D). In the model, soil particles were defined with the basic PFC
3D model particles, which consisted of balls with cohesive bonds between balls. The model parameters, bond normal and shear strengths, were determined based on intrinsic stresses of soil. The most sensitive model parameter, ball normal stiffness, was calibrated for two contrast soils: coarse and fine soils. The calibrations were performed through comparing the draught forces of a simple soil engaging tool simulated with the PFC
3D soil–tool interaction model and those estimated with the Universal Earthmoving Equation. The calibrated ball normal stiffness is 6
×
10
3
N
m
−1 for coarse soil and 2
×
10
4
N
m
−1 for fine soil.
Spinel nickel-cobalt sulfide (NiCo2S4) supported on reduced graphene oxide (rGO) was fabricated through a facile one-step hydrothermal method for energy storage applications. The distribution of the ...NiCo2S4 nanoparticles on the rGO surface was found to improve the supercapacitive performance of the assembled device. The NiCo2S4/rGO nanocomposite exhibits outstanding electrochemical behavior with a capacity (C)/specific capacitance (Cs) of 536 C g−1/1072 F g−1 at a current density of 1 A g−1. To further investigate the electrochemical behavior of the NiCo2S4/rGO nanocomposite, a hybrid supercapacitor (HSC) was constructed utilizing a NiCo2S4/rGO positive electrode and an activated carbon (AC) negative electrode. The assembled NiCo2S4/rGO//AC HSC results in outstanding specific energy (Es) of 41.52 Wh kg−1 at a specific power (Ps) of 1067 W kg−1 relative to previously reported NiCo2S4-based supercapacitors (SCs). The HSC had an Es of 36.51 Wh kg−1 at a Ps of 2065 W kg−1. Additionally, excellent cycling stability of 82% capacitance retention after 3000 repeated charge/discharge cycles was accomplished. These realized results confirm that the NiCo2S4/rGO nanocomposite is a suitable electrode material for SCs.
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•NiCo2S4/rGO nanocomposite was prepared using a one-step hydrothermal method as an electrode for a hybrid supercapacitor.•NiCo2S4 nanoparticles are homogeneously distributed and tightly anchored to the surface of the wrinkled rGO.•NiCo2S4/rGO nanocomposite exhibited a specific capacitance of 1072 F g−1 at a current density of 1 A g−1.•NiCo2S4/rGO//AC hybrid supercapacitor showed specific energy of 41.52 W h kg−1 at a specific power of 1067 W kg−1.
An overview of the successes and failure of the computerized glow curve deconvolution (CGCD) and the peak shape methods in describing the glow peaks generated from the fundamental one trap-one ...recombination center (OTOR) model was discussed. Also, the existing method, and a new developed one, to test the applicability of the existing thermoluminescence (TL) expressions to describe the glow peaks were discussed. The new TL expressions deduced by Kitis and Vlachos (17 G. Kitis, N.D. Vlachos, Radiat. Meas. 48 (2013) 47–54) were tested in the cases in which the other existing TL expressions failed. The results showed that the error in the calculated activation energy (E) using the existing expressions may reach up, in some cases, to 50%. While, using the new TL expressions, the error in the calculated E did not exceed 0.5%.
•The successes and failure of the CGCD and peak shape methods were discussed.•The deduced TL expressions based on the Lambert W function were tested.•A comparison between the existing and the new deduced TL expressions was made.•The error of E calculated using the existing expressions may reach up to 50%.•The error of E calculated using the new deduced expression did not exceed 0.5%.
The purpose of the current work is to investigate the effect of the scatter data and the background noise level on the uncertainty of the thermoluminescence (TL) measurements. The Monte-Carlo (MC) ...algorithm has been used to simulate the scattering data and the background noise signal in TL glow-curve. Under the simulation and experimental parameters used in the present study, a new general criterion for the minimum measurable dose has been established. It has been found from the results that the TL measurements, using either the peak maximum or the peak integral, can be conducted with an uncertainty level $<\pm 10\%2\sigma $ when the TL signal is at least 10 times greater than the background noise signal. It has also been found that the same criterion can be used for the evaluation of the kinetics parameters of the TL glow-peak using either the peak fitting or the peak shape methods.
Developing and designing novel electrodes for photocatalytic water splitting using computational analysis has become a crucial interest recently through bulk and surface calculations of the ...investigated materials. Doping wide band gap metal oxides has proven to be an efficient method for optical properties enhancement and band gap engineering. Herein, first-principles calculations were employed to investigate the possibility to engineer the optical and structural properties of SrSnO3 perovskite as a potential catalyst for photo-driven hydrogen production. Specifically, the synergistic effect of hydrogen doping and oxygen vacancies (OV) on the optoelectronic properties of SrSnO3 was for the first time investigated and discussed in detail. The interstitial hydrogen defects (Hi) are energetically favorable compared with the substitutional hydrogen defects. Mono- and co-hydrogen occupied oxygen vacancies sites were further examined. Interstitial hydrogen doping was found to introduce a shallow defect state below the conduction band minimum (CBM) forming a band tailing and increasing the dielectric constant. Thus, it could be used in gate dielectric applications. The created defect states upon doping were found to depend directly on the defect site and the defect concentration. At high concentration of oxygen vacancies defect, the HOV-OV structural configuration showed localized and shallow defect states with a band gap of 1.3 eV below the CBM. It also considerably increased the dielectric constant with optical absorption enhancement, compared to the pristine SrSnO3 counterpart. With optimum Gibbs free energy of hydrogen evolution reaction (HER) and theoretical band gap straddling of the oxygen and hydrogen evolution potentials, low exciton binding energy, and high permittivity, the HOV-OV structure is an ideal novel candidate catalyst for photocatalytic water splitting.
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•Thermodynamic and optoelectronic characteristics of several H defects in SrSnO3.•HOV-OV exhibited the narrowest bandgap energy among other defects (1.3 eV).•HOV-OV showed enhanced visible light response compared to the pristine SrSnO3.•(001) HOV-OV surface facilitates water and hydrogen adsorption compared to SrSnO3.•HOV-OV defected SrSnO3 is endorsed to be used in photocatalytic water splitting.
•A numerical solution for the trap-depth distribution model has been proposed.•Comparisons between the analytical and numerical solutions have been made.•The analytical assumptions could not be ...considered in the numerical solution.•At low doses, the analytical expressions cannot predict the peak characteristics.
The theoretical assumptions of the analytical expressions characterizing the thermoluminescence glow-peak arising from a continuous trap-depth distribution have been investigated. The sets of the differential equations governing the electrons’ transitions within a continuous trap-depth distribution during the irradiation and heating stages have been numerically solved. The analytical expressions are essentially based on a theoretical assumption that correlates the concentrations of the trapped electrons with the distribution of the trap depths in the bandgap. This correlation could not be considered in the numerical solution, since the irradiation stage is entirely independent of the trap depth. Thus, the final values of the instantaneous trap-filling functions of the irradiation stage do not depend on the trap depth, but rather on the trap capacity and the trapping probability coefficient. Consequently, in the numerical solution, the distribution of the trap depths and the distribution of the trapped electrons are independent. This inconsistency between the numerical solution and the analytical expression has led to differences in the shape of the thermoluminescence glow peaks resulting from the same trap-depth spectrum.
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