Preparation and evaluation of nanocomposite sodalite/-Al2O3 tubular membranes for H2/CO2 separation

Nanocomposite sodalite/ceramic membranes supported on -Al2O3 tubular support were prepared via the pore-plugging hydrothermal (PPH) synthesis protocol using one interruption and two interruption steps. In parallel, thin-film membranes were prepared via the direct hydrothermal synthesis technique. The as-synthesized membranes were evaluated for H2/CO2 separation in the context of pre-combustion CO2 capture. Scanning electron microscopy (SEM) was used to check the surface morphology while x-ray diffraction (XRD) was used to check the crystallinity of the sodalite crystals and as-synthesized membranes. Single gas permeation of H2, CO2, N2 and mixture gas H2/CO2 was used to probe the quality of the membranes. Gas permeation results revealed nanocomposite membrane prepared via the PPH synthesis protocols using two interruption steps displayed the best performance. This was attributed to the enhanced pore-plugging effect of sodalite crystals in the pores of the support after the second interruption step. The nanocomposite membrane displayed H2 permeance of 7.97 107 mols1m2Pa1 at 100 C and 0.48 MPa feed pressure with an ideal selectivity of 8.76. Regarding H2/CO2 mixture, the H2 permeance reduced from 8.03 107 mols1m2Pa1 to 1.06 107 mols1m2Pa1 at 25 C and feed pressure of 0.18 MPa. In the presence of CO2, selectivity of the nanocomposite membrane reduced to 4.24.The Department of Science and Innovation Research Foundation (DSI-NRF) South Africa’s SARChI Clean Coal Technology.http://www.mdpi.com/journal/membranesam2021Chemical Engineerin

Update on current approaches, challenges, and prospects of modeling and simulation in renewable and sustainable energy systems

Modeling and simulation (M&S) is a well-known scientific tool that could be used to analyze a system or predict its behavior before physical construction. Despite being an established methodical tool in engineering, only a few review articles discussing emerging topics in M&S are available in open literature, especially for renewable and sustainable energy systems. This review critically examines recent advances in modeling and simulation in the energy sector, with few insights on its approaches, challenges, and prospects in selected renewable and sustainable energy systems (RSES). In addition, the concept of model validation in RSES is systematically discussed based on in-sample and out-of-sample approaches, while potential data sources with crucial elements for model validation in RSES are highlighted. Furthermore, three major groups of sustainable energy system models that play important roles in supporting national and international energy policies arepresented, to bring to light how the modeling of energy systems is evolving to meet its challenges in the design, operation, and control of RSES. This review also presents a comprehensive assessment of the current approaches, challenges, and prospects in modeling the behavior and evaluating the performance of RSES. Finally, areas that need further research and development in renewable and sustainable energy system modeling are also highlighted.https://www.elsevier.com/locate/rserpm2022Chemical Engineerin

Application of the Response Surface Methodology to Optimise the Leaching Process and Recovery of Rare Earth Elements from Discard and Run of Mine Coal

The supply shortage of rare earth elements (REEs) for use in numerous high-tech applications has become an incentive for the prospecting of REEs from coal and coal discard. In this study, an optimised leaching process for the recovery of REEs from coal using the Design Expert (DOE) is reported. Response surface methodology (RSM) was used to investigate the effect and to determine the optimal leaching parameters for the two non-calcined coal samples. An optimised REE leaching recovery of 18.95% and 41.35% was obtained for the non-calcined Run-of-Mine (ROM) coal and discard coal, respectively. This optimised recovery was obtained as the HCl concentration increased from 0.5 M to 2 M, leaching temperature increased from 30 °C to 50 °C, whilst the solid:liquid ratio decreased from 40 g/L to 10 g/L. Statistical analysis indicated that the leaching parameters studied were important and controlled the REE leaching recovery model. Optimisation results also indicate that the calcined coals at 700 °C have the highest leaching recovery of 94.73% (ROM) and 98.17% (discard), respectively. Calcination also increased the concentration of REEs in the ROM sample from 225 ppm to 347 ppm and discarded the sample from 245 ppm to 363 ppm at 700 °C. Given the effect of the lixiviants investigated, the leaching efficiency of HClO4 for REE recovery was significantly lower than HCl and HNO3 under optimal leaching conditions. The discard coal used in this study had a significantly higher potential for REE recovery than ROM coal because it had a higher REE abundance and greater recovery

Application of the Response Surface Methodology to Optimise the Leaching Process and Recovery of Rare Earth Elements from Discard and Run of Mine Coal

The supply shortage of rare earth elements (REEs) for use in numerous high-tech applications has become an incentive for the prospecting of REEs from coal and coal discard. In this study, an optimised leaching process for the recovery of REEs from coal using the Design Expert (DOE) is reported. Response surface methodology (RSM) was used to investigate the effect and to determine the optimal leaching parameters for the two non-calcined coal samples. An optimised REE leaching recovery of 18.95% and 41.35% was obtained for the non-calcined Run-of-Mine (ROM) coal and discard coal, respectively. This optimised recovery was obtained as the HCl concentration increased from 0.5 M to 2 M, leaching temperature increased from 30 °C to 50 °C, whilst the solid:liquid ratio decreased from 40 g/L to 10 g/L. Statistical analysis indicated that the leaching parameters studied were important and controlled the REE leaching recovery model. Optimisation results also indicate that the calcined coals at 700 °C have the highest leaching recovery of 94.73% (ROM) and 98.17% (discard), respectively. Calcination also increased the concentration of REEs in the ROM sample from 225 ppm to 347 ppm and discarded the sample from 245 ppm to 363 ppm at 700 °C. Given the effect of the lixiviants investigated, the leaching efficiency of HClO4 for REE recovery was significantly lower than HCl and HNO3 under optimal leaching conditions. The discard coal used in this study had a significantly higher potential for REE recovery than ROM coal because it had a higher REE abundance and greater recovery

The production of polyhydroxyalkanoates using volatile fatty acids derived from the acidogenic biohydrogen effluents : an overview

Biohydrogen production is regarded as the cleanest process of producing H2 due to its non-polluting features and its ability to valorize wastes. However, its industrialization remains stagnant due to the process barriers facing this technology. Research is now geared towards the beneficiation of acidogenic-derived metabolites to improve its competitiveness. The acidogenic effluents consist of chemical precursors known as volatile fatty acids (VFAs), which can serve as cheap substrates for polyhydroxyalkanoates (PHAs). PHAs are emerging as a potential replacement for petroleum-based plastics due to their environmental friendliness, biodegradability, and cost-effectiveness. This overview discusses the synthesis of PHAs using acidogenic-derived VFAs as a carbon source. It examines the setpoint parameters that affect the recovery of PHAs using VFAs that are obtained from acidogenic effluents. Furthermore, the challenges that hinder the industrialization of PHAs are elucidated. The paper concludes by providing suggestions that could fast-track the development of PHAs using waste effluents.https://www.sciencedirect.com/journal/bioresource-technology-reports2024-06-10hj2023Chemical Engineerin