Hossam Mohammed Abdel-AzizRabie Saad FaragSoha Ali Abdel-Gawad
19页
查看更多>>摘要：Green synthesis approach was successful used extract was successful in preparing bimetallic zero-valent Iron/Copper nanoparticles [FB-nZVFe/Cu]. Scanning Electron Microscope [SEM], Fourier Transform Infrared Spectroscopy [FTIR], and Dispersive X-ray Spectroscopy [EDX] showing the synthesizing of FB-nZVFe/Cu. The removal efficiency of Caffeine [5mg L~(-1)] reached 86% under the conditions [0.2 g L -1, 45min, and pH 5]. The adsorption data are more appropriate by the Langmuir model [R~2=0.9987] with q_(max)=34.34mg g~(-1). Kinetic results showed that Caffeine uptake is following pseudo-second-order. Langmuir and pseudo-second-order are more appropriate in linear and nonlinear models. Overall, FB-Fe/Cu is a committed green substance for removal Caffeine from aqueous solutions. Functional parameters affect investigated using the Linear regression analysis, we found them to account for over 98% of the variables affecting the removal procedure.
查看更多>>摘要：Biochar adsorbents used to treat different heavy metals in water are efficient and low-cost. Appropriate raw materials, excellent selectivity and detailed adsorption mechanism are of important for research on biochar adsorbents. In this work, konjac starch was dispersed in polyvinylpyrrolidone (PVP) solution to prepare different sizes hydrophilic carbon spheres (HCSs) by hydrothermal synthesis method. Adsorption kinetics of the HCSs towards Pb~(2+) is described perfectly by the pseudo-second-order equation. With the temperature increasing, adsorption thermodynamics are more consistent with the Freundlich model. The calculated DG, DH and DS shows the adsorption of the HCSs towards Pb~(2+) is a spontaneous, endothermic and entropy increase process. In addition, HCSs have excellent selectivity for the adsorption of Pb~(2+) and Cu~(2+). HCSs prepared from konjac starch make full use of natural biomass resources, they can be used as a potential adsorbent material in treatment on heavy metal ion from water field.
查看更多>>摘要：During hydraulic fracturing in a high-methane coal seam, there is a water-displacing-methane effect. A pseudo triaxle experimental system, which is opposite to the name of true triaxial system, for the water-displacing-methane effect was created. First, cylindrical coal samples in a methane adsorption equilibrium state, spontaneously desorbed. And then water was injected into the coal samples. The following was shown: (1) The displacement methane volume gradually rises with an increase of injected water, while the displacement methane rate tends to rise at first before declining later. Simultaneously, the water-displacing-methane process is characterised by a time effect. The methane displacement lags behind water injection. (2) Competitive adsorption and displacement desorption between the water and methane will promote adsorption methane into free methane, while the pore pressure increase caused by water injection will turn free methane into adsorption methane. The net free methane of the combination action provides a methane source for the water-displacing-methane effect. (3) A pore pressure gradient, which provides a power source for the water-displacing-methane effect, is formed and reduces gradually at the front of the water seepage along the seepage direction. The increase in water pressure can rapidly improve the pore pressure gradient and boost the displacement methane volume as well as improve displacement methane efficiency. (4) A starting porosity pressure gradient and limit pore pressure exist in the process of water-displacing-methane. When the pore pressure gradient is less than the starting pore pressure gradient, there is free methane in the coal rock, but it cannot be displaced. When the pore pressure is between the starting pore pressure and the limit pore pressure, the free methane can be displaced. When the pore pressure is greater than the limit pore pressure, the methane is almost completely adsorption methane, and water cannot be used to disp
查看更多>>摘要：Liquid CO_2 phase transition fracturing (LCO_2-PTF) is an effective and economical technology used to improve the permeability of rock and coal. In this study, the working mechanisms of LCO_2-PTF were analysed and relevant equipment was designed to develop and promote the application of this technology. It utilized phase transition equipment (PTE) consisting of a liquid gas container, control unit for the current and gas volume, heating tube, and other components. LCO_2 blasting experiments were conducted in an airtight container to investigate the released energy, pressure, and other technical parameters. The application of LCO_2-PTF for enhancing gas drainage in coal mines was then evaluated. The results of a blasting experiment showed a maximum energy of 947.12 kJ and revealed that the releasing pressure could be easily changed by varying the plate and heat tube. The releasing pressure remained unchanged within an initial distance and then decreased exponentially. The blasting products were gaseous CO_2 and water vapor, with no sparks or flames. The surface temperature of the PTE ranged from 269.32 to 277.96 K. Application of LCO_2-PTF in coal mines with low permeability showed gas drainage 3.38 times higher than that achieved with conventional technologies, with methane concentration increasing from 55 to 89%. The attenuation coefficient of gas emissions dropped by 94% and the gas permeability coefficient of the coal body increased more than 23 times after fracturing. The shockwave of the high-pressure gas promoted the development and extension of cracks. The influence radius of the pre-cracking coal seam was 8.1 m, which is 6.75 times that of the original coal seam. The experimental results and the engineering applications indicate that LCO_2-PTF is a safe and effective technology to enhance gas drainage in coal mines.
查看更多>>摘要：Experimental investigations were undertaken to adsorb Brilliant Green (BG) a toxic dye from aqueous medium using activated carbon derived from the medlar nucleus (ACMN). The adsorption was used to remove BG using ACMN as bio-adsorbent to replace activated carbon still expensive. The prepared adsorbent was characterized by the BET surface area measurement, FTIR spectroscopy and X-ray diffraction. Various parameters such as the initial dye concentration (110-200 mg/L), adsorbent dose (1-6 mg/L), initial pH (2-9) and temperature (298-318 K) were studied to observe their effects on the BG adsorption. Batch studies were conducted in order to determine the optimal parameters required to reach the adsorption equilibrium. The maximum adsorption capacity of ACMN for the BG adsorption at 298 K was found to be 833.15 mg/g. The adsorption kinetic data were analyzed by using several kinetic models namely the pseudo-firstorder, pseudo-second-order, Elovich equation, intraparticules diffusion model. It was established that the adsorption obeys the pseudo-second-order kinetic model. The evaluation of thermodynamics parameters such as the free energy ΔGo (-10.584 to -6.413 kJ/mol), enthalpy ΔHo (36.439 kJ/mol) and the change of entropy (0.1438 kJ/mol K) indicated a spontaneous and endothermic nature of the reaction with a chemisorption process. The present adsorbent may be considered as an alternative for the better performance of the BG removal from aqueous medium.
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