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91.
92.
《International Journal of Hydrogen Energy》2021,46(60):30976-30987
Palm oil mill effluent (POME) is a wastewater effluent that is generated from palm oil milling. Treatment of POME, especially using biological treatment methods, is a challenge as it contains high amounts of organic and sulfur compounds, and it is highly acidic. In this research, the effects of zero-valent iron (ZVI) on the enhancement of methane production from POME via anaerobic digestion were investigated. Furthermore, to identify the reactor operation modes that were suitable for the addition of ZVI, anaerobic digestion of POME was tested in three reaction configurations: batch reactor, fed-batch reactor, and continuous stirred-tank reactor (CSTR). In the batch mode, where acidic POME was fed with 16 g/L of ZVI dose just once, methane production increased by 74%. However, as the oxidation of ZVI under anaerobic conditions led to the production of hydroxyl ions, the pH of the medium continuously increased from approximately 7 to 9, which is not suitable for methanogenesis. In the fed-batch mode that involved intermittent feeding of acidic POME, the pH of the culture media was maintained at 6.8. This is because the extra hydroxyl ions generated from the oxidation reaction of ZVI tended to neutralize the acids in the feeding substrate. In addition, ZVI promoted the production of methane from POME and increased the average methane content in biogas from 62% to 76%. In the CSTR mode, which involved continuous feeding of acidic POME, ZVI increased methane production by 86% (from 1.79 to 3.32 L/day), methane content in biogas from 60 to 75%, and total chemical oxygen demand (tCOD) removal efficiency from 78 to 89 to 88–95%. Thus, the addition of ZVI can be a potential strategy for in-situ methane enrichment of biogas by anaerobic digestion of POME. This is because ZVI acts as a buffer for acid generation and provides extra electrons, ferrous ions, and ferric ions, which promote key microbial activities in the anaerobic digestion process. 相似文献
93.
《International Journal of Hydrogen Energy》2021,46(69):34449-34462
Three-dimensional Bödewadt flow (fluid rotates at a large enough distance from the stationary plate) of carbon nanomaterial is examined. Single walled and multi walled CNTs are dissolved in water and gasoline oil baseliquids. Darcy-Forchheimer porous medium is considered. Stationary disk is further stretched linearly in radial direction. Heat transfer effect is examined in presence of radiation and convection. Effect of viscous dissipation is accounted. Entropy generation rate is studied. By using adequate transformation (von Kármán relations), the flow field equations (PDEs) are transmitted into ODEs. Solutions to these ODEs are constructed via implementation of shooting method (bvp4c). In addition to Entropy generation rate, Bejan number, heat transfer rate (Nusselt number), skin friction and temperature of fluid are examined through involved physical parameters. Axial component of velocity intensifies with increment in nanoparticles volume fraction and ratio of stretching rate to angular velocity parameter while it decays with higher porosity parameter. Higher nanoparticles volume fraction and porosity parameter lead to decay in radial as well as tangential component of velocity. However it enhances with higher ratio of stretching rate to angular velocity parameter. Temperature of fluid directly varies with higher ratio of stretching rate to angular velocity parameter, radiation parameter, Eckert number, Biot number and nanoparticles volume fraction. Rate of Entropy generation is reduced with higher estimations of porosity parameter, nanoparticles volume fraction and radiation parameter. Skin friction coefficient decays with higher porosity parameter and ratio of stretching rate to angular velocity parameter. Intensification in porosity parameter, nanoparticles volume fraction and Biot number leads to higher Nusselt number. Prominent impact is shown by multiple-walled CNTs with gasoline oil basefluid than single-walled CNTs with water basefluid. 相似文献
94.
S. Pacanowski M. Wachowiak B. Jabłoński B. Szymański L. Smardz 《International Journal of Hydrogen Energy》2021,46(1):806-813
Pd/Mg bilayers and Pd/Al/Mg trilayers were prepared onto glass substrates at room temperature (RT) by UHV magnetron sputtering. Mixing effects at the Pd–Mg and Al–Mg interfaces were studied in-situ, immediately after deposition, by X-ray Photoelectron Spectroscopy (XPS). Additionally, the interfaces of the Pd/Al/Mg trilayer for the Al thickness equal to 1 nm were examined. Hydrogen absorption was monitored in-situ at RT by simultaneous resistivity and optical transmittance measurements. Formation of MgH2 phase was confirmed by ex-situ X-ray diffraction measurements. The XPS studies revealed rather sharp interface between Al and Mg layers. On the other hand, a significant interface mixing for the Pd/Mg bilayers and Pd/1 nm – Al/Mg trilayers was observed. Further studies showed that an additional layer of Al, deposited between magnesium and palladium layers, can significantly improve the hydrogen absorption kinetics at RT. The optimal thickness of the Al layer was found to be 0.5 nm. 相似文献
95.
We focused on the work function of metals as an index of ion binding property between metals and hydrogen and analyzed the relation between the standard entropy change of metal hydrides and the work function of metals (alloys). The standard entropy change of saline hydrides and metallic hydrides roughly increased with the work function. It was indicated that hydrogen storage alloys consist of metal elements A and B whose work functions are small and large, respectively. The standard entropy changes of alloy-based metal hydrides with different composition ratio ΔS0 linearly increased with the work functions of the alloys Wc. Wc also linearly increased with the bulk modulus Bc. Then, it was found that ΔS0 was proportional to the standard heat of formation ΔH0 because dWc/dBc, dΔS0/dWc and dΔH0/dBc are constant. 相似文献
96.
Yin Liu Zhecheng Wang Li Zhao Jun Zhou Yueqin Wang 《Journal of the American Ceramic Society》2019,102(11):6680-6687
xSrFe12O19/(1−x)NiFe2O4 composites (0 ≤ x ≤ 1.0) were synthesized by using a conventional solid-state synthetic route. The results show that magnetic hysteresis loops of the xSrFe12O19/(1−x)NiFe2O4 composites are similar to those of individual component ferrites, except for the 0.1SrFe12O19/0.9NiFe2O4 and 0.3SrFe12O19/0.7NiFe2O4, suggesting that the hard/soft magnetic phases are well exchange-coupled. The saturation magnetization, coercivity, and remanent magnetization of the xSrFe12O19/(1−x)NiFe2O4 composites are increased with increasing content of SrFe12O19, with maximal values of 42.1 Am2 kg−1, 78.7 kA m−1, 17.2 Am2 kg−1, respectively, as the content x is about 0.5. They are higher than those of the individual components, implying that interface coupling is present in the magnetic composites. The coercivity and remanent magnetization of the composites are increased initially with increasing sintering temperature and then show a downward tendency. For the component SrFe12O19 and NiFe2O4, the minimum reflection losses are −12.5 dB and −18.3 dB at match thicknesses of 2.5 mm and 2 mm, respectively. Compared with those of the component SrFe12O19 and NiFe2O4, the microwave absorption performances of the xSrFe12O19/(1−x)NiFe2O4 composites are improved remarkably, especially for the samples of x = 0.3 and x = 0.9. The minimum reflection losses values of the 0.3SrFe12O19/0.7NiFe2O4 composite are −31.6 dB (12.7 GHz) and −20.2 dB (13 GHz), while those of the 0.9SrFe12O19/0.1NiFe2O4 composites are −23.7 dB (16.3 GHz) and −33.5 dB (15.8 GHz), as the matching thicknesses are 2.5 mm and 2 mm, respectively. Therefore, the xSrFe12O19/(1−x)NiFe2O4 composites could be used as potential microwave absorption materials. 相似文献
97.
Zhuo Shi Ningning Dong Dingfeng Zhang Xiaofang Jiang Guanxin Du Shichao Lv Jiejie Chen Jun Wang Shifeng Zhou 《Journal of the American Ceramic Society》2019,102(7):3965-3971
The construction of nonlinear optical materials featuring asymmetric transmission of light is of great technological importance for various applications, including optical switching and optical power limiting. A significant challenge is the scalable fabrication of material candidates with good photochemical stability, high optical transmittance, and excellent optical limiting performance. Here, we present a nanocrystallization avenue for constructing hybrid optical limiting materials that exhibit ultrafast and robust optical limiting performance. The experimental results show that the controllable relaxation of a niobate glass may lead to the clustering of Nb-O units and contracting of the bandgap. It results in the notable improvement in nonlinear optical properties, including the enhanced saturation irradiance (380 GW/cm2), doubly increased nonlinear coefficient, and decreased limiting threshold (200 GW/cm2). Our results suggest a promising material that exhibits promising applications for protecting eyes and sensitive components from laser-induced damage. 相似文献
98.
Global decrease in crude oil resources and frequent crude oil leaks cause the energy crisis and ecological pollution. The absorption and release of leaked crude oil through absorption materials are a necessary process for environmental protection and recycling. In this article, a CO2-responsive olefin copolymer was obtained by copolymerization of styrene and an amine-containing olefin monomer. The structure of resultant copolymer was characterized by FTIR; thermal properties and CO2-responsive morphology changes were determined by DSC/TGA and SEM, respectively. Copolymers had certain absorption capacity for toluene with absorption rate up to 180.0%. The absorbed toluene could be released upon CO2 stimulation with desorption rate up to 84.6%. The CO2-responsive copolymer could be regenerated through a simple heating process and showed stable absorption–desorption performance even after being recycled for 4 times. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47439. 相似文献
99.
100.