Addition of Mg–Nb oxides(e.g.MgNb_(2)O_(6),Mg4Nb_(2)O_(9),and Mg_(3)Nb_(6)O_(11))ameliorates H_(2)absorption/desorption kinetics of MgH_(2)as demonstrated in the current article.H_(2)desorption and absorption rates o...Addition of Mg–Nb oxides(e.g.MgNb_(2)O_(6),Mg4Nb_(2)O_(9),and Mg_(3)Nb_(6)O_(11))ameliorates H_(2)absorption/desorption kinetics of MgH_(2)as demonstrated in the current article.H_(2)desorption and absorption rates of the ball-milled MgH_(2)are evidently temperature-dependent,which points out that the prior rate increases with increasing temperature(593–673 K)and vice versa.Among the tested samples,MgH_(2)with Mg_(3)Nb_(6)O_(11)nanoparticles showed superior performance.The Johnson–Mehl–Avrami equation was employed to construct H_(2)desorption curves as well as find out reaction rate constants at different temperatures.The Arrhenius equation was fitted in the context to estimate the activation energy of the ball-milled MgH_(2)and MgH_(2)/Mg_(3)Nb_(6)O_(11)mixtures;for example,the values obtained were 127 and 88 kJ·mol^(−1),respectively.In addition,a novel experimental setup combining a hydrogen detector with a differential scanning calorimeter was used to confirm the H_(2)desorption properties of the ball-milled nanoparticles discussed based on the kinetic argument.展开更多
Microalgae cultivation in photobioreactors(PBRs)has emerged as a promising and sustainable approach to address various environmental and energy challenges,offering a multitude of benefits across diverse applications.R...Microalgae cultivation in photobioreactors(PBRs)has emerged as a promising and sustainable approach to address various environmental and energy challenges,offering a multitude of benefits across diverse applications.Recent developments in microalgae cultivation in photobioreactors have contributed substantially to the development and optimization of sustainable bioprocesses.This review presents a comprehensive analysis of recent innovations and breakthroughs in the field of microalgae cultivation,with a specific focus on their application in photobioreactors,aimed at paving the way for a greener future.This study in-depth examines the advantages of microalgae cultivation in photobioreactors,concentrating on its effectiveness in wastewater treatment,CO_(2)bioremediation,and the production of biofuels and high-value products.The review evaluates the effects of light,solar irradiation,temperature,nitrogen and phosphorus concentrations in culture media,CO_(2)concentrations,and pH on microalgae growth performance,including specific growth and biomass productivity.The study also examines open systems like unstirred ponds,raceway ponds,and circular ponds and closed systems like horizontal tubular,vertical bubble-column,airlift,flat panel,and plastic-bag photobioreactors,comparing their pros and cons.To optimize microalgae cultivation,key factors in photobioreactor design,including photosynthetic efficiencies,light/dark(L/D)cycles,CO_(2)concentrations,mass transfer,hydrodynamics behavior,and p H,are extensively investigated.In addition,the review outlines recent developments in large-scale photobioreactors and highlights the challenges and opportunities associated with photobioreactor scale-up and design parameter optimization,including genetic engineering and economic feasibility.This article is a vital resource for researchers,engineers,and industry professionals seeking sustainable bioprocesses and the application of microalgae-based technologies.展开更多
Understanding scale-up effects on the hydrodynamics of a liquid-solid circulating fluidized bed(LSCFB)unit requires both experimental and theoretical analysis.We implement multigene genetic programming(MGGP)to investi...Understanding scale-up effects on the hydrodynamics of a liquid-solid circulating fluidized bed(LSCFB)unit requires both experimental and theoretical analysis.We implement multigene genetic programming(MGGP)to investigate the solid holdup and distribution in three LSCFB systems with different heights.In addition to data obtained here,we also use a portion of data sets of LSCFB systems developed by Zheng(1999)and Liang et al.(1996).Model predictions are in good agreement with the experimental data in both radial and axial directions and at different normalized superficial liquid and solid velocities.The radial profiles of the solid holdup are approximately identical at a fixed average cross-sectional solid holdup for the three LSCFB systems studied.Statistical performance indicators including the mean absolute percentage error(6.19%)and correlation coefficient(0.985)are within an acceptable range.The results suggest that a MGGP modeling approach is suitable for predicting the solid holdup and distribution of a scaled-up LSCFB system.展开更多
文摘Addition of Mg–Nb oxides(e.g.MgNb_(2)O_(6),Mg4Nb_(2)O_(9),and Mg_(3)Nb_(6)O_(11))ameliorates H_(2)absorption/desorption kinetics of MgH_(2)as demonstrated in the current article.H_(2)desorption and absorption rates of the ball-milled MgH_(2)are evidently temperature-dependent,which points out that the prior rate increases with increasing temperature(593–673 K)and vice versa.Among the tested samples,MgH_(2)with Mg_(3)Nb_(6)O_(11)nanoparticles showed superior performance.The Johnson–Mehl–Avrami equation was employed to construct H_(2)desorption curves as well as find out reaction rate constants at different temperatures.The Arrhenius equation was fitted in the context to estimate the activation energy of the ball-milled MgH_(2)and MgH_(2)/Mg_(3)Nb_(6)O_(11)mixtures;for example,the values obtained were 127 and 88 kJ·mol^(−1),respectively.In addition,a novel experimental setup combining a hydrogen detector with a differential scanning calorimeter was used to confirm the H_(2)desorption properties of the ball-milled nanoparticles discussed based on the kinetic argument.
基金support received from Interdisciplinary Research Center for Refining and Advanced Chemicals,King Fahd University of Petroleum&Minerals,Dhahran,Saudi Arabia with funding grant and financial support for this work through project No.INRC2318
文摘Microalgae cultivation in photobioreactors(PBRs)has emerged as a promising and sustainable approach to address various environmental and energy challenges,offering a multitude of benefits across diverse applications.Recent developments in microalgae cultivation in photobioreactors have contributed substantially to the development and optimization of sustainable bioprocesses.This review presents a comprehensive analysis of recent innovations and breakthroughs in the field of microalgae cultivation,with a specific focus on their application in photobioreactors,aimed at paving the way for a greener future.This study in-depth examines the advantages of microalgae cultivation in photobioreactors,concentrating on its effectiveness in wastewater treatment,CO_(2)bioremediation,and the production of biofuels and high-value products.The review evaluates the effects of light,solar irradiation,temperature,nitrogen and phosphorus concentrations in culture media,CO_(2)concentrations,and pH on microalgae growth performance,including specific growth and biomass productivity.The study also examines open systems like unstirred ponds,raceway ponds,and circular ponds and closed systems like horizontal tubular,vertical bubble-column,airlift,flat panel,and plastic-bag photobioreactors,comparing their pros and cons.To optimize microalgae cultivation,key factors in photobioreactor design,including photosynthetic efficiencies,light/dark(L/D)cycles,CO_(2)concentrations,mass transfer,hydrodynamics behavior,and p H,are extensively investigated.In addition,the review outlines recent developments in large-scale photobioreactors and highlights the challenges and opportunities associated with photobioreactor scale-up and design parameter optimization,including genetic engineering and economic feasibility.This article is a vital resource for researchers,engineers,and industry professionals seeking sustainable bioprocesses and the application of microalgae-based technologies.
基金support provided by King Abdulaziz City for Science and Technology(KACST)through the Science&Technology Unit at King Fahd University of Petroleum&Minerals(KFUPM)for funding of this work,project No.NSTIP#13-WAT96-04,as part of the National Science,Technology and Innovation Plan.
文摘Understanding scale-up effects on the hydrodynamics of a liquid-solid circulating fluidized bed(LSCFB)unit requires both experimental and theoretical analysis.We implement multigene genetic programming(MGGP)to investigate the solid holdup and distribution in three LSCFB systems with different heights.In addition to data obtained here,we also use a portion of data sets of LSCFB systems developed by Zheng(1999)and Liang et al.(1996).Model predictions are in good agreement with the experimental data in both radial and axial directions and at different normalized superficial liquid and solid velocities.The radial profiles of the solid holdup are approximately identical at a fixed average cross-sectional solid holdup for the three LSCFB systems studied.Statistical performance indicators including the mean absolute percentage error(6.19%)and correlation coefficient(0.985)are within an acceptable range.The results suggest that a MGGP modeling approach is suitable for predicting the solid holdup and distribution of a scaled-up LSCFB system.
