Ion-selective membranes enable electrochemical water purification and resource recovery. Effective molecular design must balance preferential target-ion uptake, rapid transport, and limited water crossover under changing feed and electrical conditions. This review examines how fixed charge, hydration, pathway connectivity, and ion-specific interactions govern transport in charged polymers, microporous materials, recognition membranes, selective surface layers, and covalent organic frameworks. Hydration reshapes transport pathways, making their hydrated dimensions and connectivity more informative than dry pore size alone. Strong binding can favor uptake while slowing release and passage, so selective uptake need not yield selective flux. Designs that partly decouple charge density from swelling or binding affinity from mobility offer ways to balance discrimination and throughput. Practical deployment requires reproducible selectivity, resistance, and water-transport properties across large-scale membrane production. Transport-state retention then requires maintaining these properties as polymer chemistry, hydration, and interfaces evolve during operation. Evaluating them together connects molecular design, manufacturing quality, and durability to current efficiency, product purity, concentration, recovery, and energy consumption in complex feeds.
This review critically evaluates polymer-blend and metal-organic-framework (MOF)-based mixed-matrix membranes (MMMs) for H2/CO2 separation, with emphasis on the relationship between membrane chemistry, polymer–filler interfaces, filler loading, operating conditions, transport mechanisms, and practically relevant separation performance. Unlike a purely descriptive survey, the review separates evidence obtained for H2/CO2 from results for other gas pairs, compares H2 permeability/permeance and H2/CO2 selectivity where directly reported, and identifies when apparent gains are limited to ideal-gas testing or low-pressure conditions. The discussion covers conventional H2/CO2 separation technologies, solution–diffusion and molecular-sieving mechanisms, PSF- and PEI-based membranes, composite and mixed-matrix architectures, Maxwell/Bruggeman/Lewis–Nielsen/Pal permeability models, and the role of CFD in membrane-module design. Particular attention is given to MOF family, interfacial compatibility, loading-dependent agglomeration, plasticization, mixed-gas competition, long-term stability, hollow-fiber scale-up, and techno-economic constraints. The resulting synthesis shows that high filler loading alone does not guarantee superior H2/CO2 performance; interface control, thin selective layers, realistic mixed-gas testing, and stable operation at elevated temperature and pressure are more decisive for translation to pre-combustion hydrogen purification.
The high temperature water-gas shift (HT-WGS) reaction is a central conversion step in ammonia production since it boosts the hydrogen yield and reduces the carbon monoxide content in the synthesis gas mixture before subsequent purification and ammonia synthesis. The industrial reactor was analyzed numerically with COMSOL Multiphysics 6.2. A three-dimensional model was created by combining momentum transport, heat transfer, multicomponent species transport, heterogeneous reaction kinetics, and intraparticle diffusion in porous Fe-Cr catalyst pellets under realistic adiabatic plant operating conditions. The novelty of the approach lies in combining industrial plant validation with simultaneous representation of reactor scale transport and pellet -scale diffusion-reaction processes. The model predictions were compared with the measured axial temperature profile and outlet gas composition obtained from the industrial plant. The model accurately predicted plant data with MAE = 3.50 K, R2 = 0.950 (temperatures), and MAPE = 5.30% (outlet content). The validated model was used to examine velocity, temperature, pressure, gas-composition, gas–pellet concentration, and intraparticle concentration profiles. A parametric analysis was performed to evaluate the effects of inlet temperature and steam-to-CO ratio on CO conversion. The pressure profile demonstrated an approximately linear decrease across the catalyst bed, dropping from 30 to 28.35 bar. The mole fractions of CO and H2O dropped along the reactive bed, while CO2 and H2 rose. Increasing the inlet temperature enhanced CO conversion from about 38.5% at 618 K to around 71% at 653–658 K, while increasing the steam-to-CO ratio from 4.0 to 6.0 improved anticipated conversion from approximately 50%–70%. The validated model is a valuable tool for assessing the operation of industrial HT-WGS reactors in ammonia producing facilities.
Microbial manufacturing is emerging as a complementary method to traditional metal processing using microorganisms and their metabolites as functional agents for selective dissolution, recovery, surface modification, and protective mineral formation. This review critically evaluates microbial manufacturing with a focused emphasis on sustainable metal recovery and surface modification and finishing, integrating mechanisms, quantitative performance, process intensification, scale-up, and techno-economic and life-cycle considerations. The reviewed processes are classified into two manufacturing functions: subtractive processing consisting of microbial or biogenic dissolution for metal recovery and controlled surface removal and constructive processing including extracellular-polymeric-substance-mediated biomineralization and functional surface formation. Recent intensified systems exhibit significant application-specific performance. The novelty of this review lies in integrating microbial metal recovery and surface engineering within a unified manufacturing-oriented framework that links biological mechanisms to manufacturing functions, engineering performance indicators, process intensification, scale-up, and techno-economic and life-cycle considerations. Rather than evaluating microbial processes solely through extraction efficiency or biological activity, the review assesses their manufacturing relevance in terms of selectivity, productivity, surface integrity, dimensional control, resource consumption, downstream processing, and industrial translation. However, the fact that microbial digestion functions under gentle conditions does not imply that it is intrinsically viable. Aeration, stirring, nutrient demands, water usage, retention duration, downstream separation, contaminant management, and process recycling can significantly influence both economic and ecological outcomes. The main challenge encountered in the analysis is the translation from biological feasibility to manufacturing reliability, especially for throughput, high solid processing, dimensional control, coating durability, repeatability, and pilot scale validation. Hence, this review proposes a manufacturing-oriented reporting framework and staged translation roadmap connecting mechanistic validation, process intensification, continuous or recycle operation, product qualification, and integrated techno-economic and life-cycle assessment. To summarize, data suggest that hybrid manufacturing is the most feasible near-term pathway by combining microbial or cell-free biogenic functions with known physical, chemical, and downstream operations to achieve selectivity, process control, productivity, and circular utilization of resources.
In recent decades, natural gas hydrate has emerged as a promising alternative energy resource, attracting worldwide attention in the petroleum and natural gas industry. Hydrate-based technologies have demonstrated considerable potential in various engineering applications, including natural gas exploitation, transportation, gas sequestration, and seawater desalination. However, the industrial application of these technologies is severely constrained by insufficient understanding of hydrate formation kinetics, especially in complex multiphase systems. This paper is built upon published experimental data and aims to characterize the driving force for hydrate growth by accounting for temperature and pressure. Accordingly, a kinetic model for hydrate growth driven by chemical potential is proposed. The model considers the influencing factors of diffusion, temperature, and hydrate surface area. The model’s accuracy is verified against experimental data, and the results indicate that it can effectively predict hydrate growth rates in both oil–water suspensions and gas–water systems with high reliability. When compared with experimental data, the hydrate growth rate in oil–water dispersed emulsion systems, the deviation of the present model is 2.7%–7.6%, while for gas–water systems, the model’s calculated deviation is 2.35%–2.89%. This work provides a valuable reference for interpreting hydrate growth mechanisms and offers technical support for the optimization of hydrate-based engineering applications in the petroleum and natural gas industry.
