Journal of Chemical Engineering and Energy Materials

Abstract Corrosion in Naphtha Hydro treating (NHT) units poses a significant challenge to the long-term reliability and economic performance of petroleum refineries. These units operate under severe conditions—high temperatures, elevated hydrogen pressures, and the presence of corrosive species such as hydrogen sulfide (H₂S), organic acids, and chlorides—which create an aggressive environment for materials of construction. This study investigates the key operational factors that influence corrosion rates in an NHT unit using a six-month dataset from a hypothetical refinery scenario. Data collected includes reactor temperature and pressure, feed sulfur content, amine inhibitor dosage, and field-measured corrosion rates from corrosion coupons installed in critical locations. Statistical analysis revealed strong positive correlations between corrosion rate and both feed sulfur content (r = 0.81) and reactor temperature (r = 0.74), while amine inhibitor dosage showed a moderate inverse relationship (r = -0.66). A multiple linear regression model was developed to predict corrosion rate as a function of these parameters, with an R² value of 0.83, indicating high predictive accuracy. Corrosion hotspots were identified at the reactor inlet and in the cold zones of heat exchangers, suggesting the need for targeted monitoring and material upgrades in those areas. The study concludes that optimizing feed quality, maintaining appropriate inhibitor dosing, and deploying real-time corrosion monitoring can significantly mitigate corrosion risk. The findings provide a quantitative foundation for corrosion risk assessment in NHT units and offer actionable insights for improving operational safety and asset longevity in hydro processing environments.

Abstract The production of polymers, particularly PVC and its related copolymers, requires stringent control of operating conditions to minimize occupational exposure to VCM. In industrial practice, VCM synthesis is typically conducted in fully closed systems, which effectively reduce atmospheric emissions and worker exposure. Nevertheless, due to its high flammability, VCM vapor poses a significant fire and explosion hazard. Accidental releases under pressure can also result in frostbite because of rapid depressurization. Furthermore, the potential for long–range vapor dispersion necessitates rigorous control of potential ignition sources and strict adherence to process safety protocols.
In this study, a comprehensive and rigorously validated process model for VCM production was developed using Aspen Plus. The balanced process, which integrates both direct chlorination and oxychlorination routes, was simulated to determine an optimized, energy–efficient, and industrially feasible configuration. Detailed molecular kinetic models were incorporated for all major reactor units, accounting for both primary and secondary reaction pathways. The thermodynamic framework was based on the modified SRK equation of state, ensuring accurate vapor–liquid equilibrium representation for multi-component systems. Model validation against published plant-scale data showed excellent agreement in conversion, selectivity, and yield predictions. The developed simulation framework provides a robust foundation for future work on process optimization, heat integration, and safety analysis in large-scale VCM production plants.

Abstract 3D printing has emerged as a transformative technology in the field of prosthetics, enabling the rapid production of patient-specific devices with enhanced customization and reduced costs. Among various materials used in additive manufacturing, polylactic acid (PLA), a biodegradable and biocompatible thermoplastic derived from renewable resources, has gained significant attention in prosthetic applications. PLA-based materials offer a combination of lightweight structure, adequate mechanical strength, and environmental sustainability, making them suitable for creating both temporary and functional prosthetic components. This paper explores the role of 3D-printed PLA in prosthetics, comparing it with traditional manufacturing methods such as molding and machining, which are often time-consuming, expensive, and less customizable. The study highlights key properties of PLA, including ease of processing, dimensional stability, and potential for modification through fillers or reinforcement to meet specific functional requirements. Furthermore, it discusses critical parameters in 3D printing, such as layer height, infill density, and post-processing, that influence the performance of PLA prosthetics. Case studies demonstrate the successful implementation of PLA-based 3D-printed prosthetic hands, orthotic devices, and other medical applications, emphasizing their accessibility and adaptability. Despite limitations such as brittleness and temperature sensitivity, technological advancements in composite PLA and hybrid printing methods promise to overcome these challenges. This review concludes by examining future trends, including reinforced PLA composites, integration of smart technologies, and positioning PLA as a sustainable, cost-effective, and versatile material for next-generation prosthetic solutions.

Abstract Seawater electrolysis has emerged as a compelling pathway for green hydrogen production, enabling the use of Earth’s most abundant water resource while preserving limited freshwater reserves. However, direct seawater splitting remains fundamentally more complex than conventional electrolysis in purified media due to chloride-induced corrosion, chlorine evolution, inorganic scaling, and membrane and catalyst degradation in a multicomponent electrolyte. Recent advances in electrocatalyst design and system engineering are beginning to close this gap. Strategies such as chloride-tolerant and self-protective OER catalysts, layered double hydroxides with tailored anion intercalation, single-atom and noble-metal-modified active sites, and nanostructured HER catalysts with anti-fouling architectures have significantly improved activity, selectivity, and durability in saline environments. In parallel, system-level innovations—including anion-exchange and asymmetric membrane configurations, multi-chamber and buffered-cell architectures, hybrid anodic reactions that bypass oxygen evolution and suppress chlorine formation, and integrated pre-treatment and flow management—have enabled stable, chlorine-suppressed operation in real or simulated seawater for thousands of hours at practically relevant current densities in a limited number of prototype systems. This review consolidates the rationale for seawater splitting, compares indirect (desalination-coupled) and direct approaches, analyzes key degradation and selectivity challenges, and highlights recent breakthroughs in materials and reactor design that are pushing seawater electrolysis toward technological viability. Finally, the broader environmental and infrastructural implications are discussed, underscoring seawater electrolysis as a promising route to scalable green hydrogen that decouples clean energy deployment from freshwater consumption.

Abstract Water splitting is a key route to green hydrogen but is limited by the sluggish oxygen evolution reaction (OER), which requires high overpotentials and leads to substantial energy losses. Replacing OER with more thermodynamically favorable anodic reactions can lower the cell voltage while valorizing waste streams. Among these, the urea oxidation reaction (UOR) is especially attractive because urea is abundant in fertilizers, industrial effluents, and human/animal urine, and its electrooxidation is much easier than OER: the equilibrium potential of UOR coupled with cathodic hydrogen evolution is ~0.37 V vs RHE (and as low as ~0.07 V based on recent thermodynamic analyses), compared to 1.23 V for OER. Over the past decade, significant progress has been made in elucidating UOR mechanisms and developing high-performance electrocatalysts—particularly Ni-based (oxy)hydroxides, layered double hydroxides, chalcogenides, phosphides, and phosphate-based materials, often supported on carbon, MXenes, or other conductive scaffolds—which can drive UOR at technologically relevant current densities with markedly reduced cell voltages while simultaneously removing urea from wastewater or urine. This review examines UOR as a viable anodic process for hydrogen production, covering thermodynamic and mechanistic fundamentals, design principles and major catalyst families (with emphasis on structure–activity relationships), electrolyzer architectures that couple UOR with hydrogen evolution (alkaline urea electrolysis, direct urine electrolysis, and solar-biased systems), and recent operando and theoretical insights into active sites and reaction pathways. Finally, techno-economic and environmental aspects are assessed, remaining challenges—including catalyst stability, selectivity, poisoning, and carbonate scaling—are identified, and future directions toward practical urea-assisted hydrogen technologies are proposed.

Abstract Ciprofloxacin is a widely detected fluoroquinolone antibiotic whose high chemical stability and low biodegradability contribute to its persistence in aquatic environments. In this study, a magnetically recoverable g-C₃N₄/Fe₃O₄ heterostructured nanocomposite was developed and examined as a UV-C-activated photocatalyst for ciprofloxacin degradation in water. To elucidate the governing process parameters, the effects of initial ciprofloxacin concentration

(5–120 mg L⁻¹), catalyst dosage (0.05–0.25 g L⁻¹), and solution pH (4–10) were systematically evaluated using a central composite design in conjunction with response surface methodology (RSM). Photocatalytic experiments were carried out under UV-C irradiation (254 nm) at lamp powers of 10, 20, and 40 W.

The experimental results were adequately captured by quadratic models, yielding coefficients of determination (R²) of 0.8371, 0.8372, and 0.882 for the three irradiation systems, respectively. Analysis of variance confirmed the statistical significance of the fitted models and revealed no significant lack-of-fit at the 95% confidence level. Among the investigated variables, catalyst dosage and solution pH exerted the most pronounced influence on photocatalytic performance, whereas excessive initial ciprofloxacin concentrations adversely affected mineralization efficiency due to photon attenuation and inner-filter effects.

Numerical optimization indicated that maximum COD removal was achieved at an initial ciprofloxacin concentration of approximately 8.0 mg L⁻¹, a catalyst dosage of 0.23 g L⁻¹ g-C₃N₄/Fe₃O₄, and near-neutral pH. Under these optimized conditions, COD removal efficiencies of 82.3%, 90.8%, and 98.6% were obtained for the 10, 20, and 40 W UV-C systems, respectively, showing good agreement with experimental validation. The observed enhancement in photocatalytic activity is primarily attributed to improved charge carrier separation at the g-C₃N₄/Fe₃O₄ interface and more efficient utilization of incident UV-C photons. Overall, these findings highlight the potential of magnetically separable g-C₃N₄/Fe₃O₄ for the removal of persistent pharmaceutical contaminants and demonstrate the effectiveness of RSM as a practical tool for process optimization prior to scale-up.