ChemEngineering, Volume 9, Issue 5 (October 2025) – 22 articles

The rising dependence on fossil fuels has intensified greenhouse gas emissions, necessitating the development of renewable energy alternatives. Biogas is a sustainable fuel source; however, its low energy density hinders direct commercial application. This study explores the potential of upgrading biogas to biomethane (Bio-CNG) via CO₂ methanation, using Aspen Plus v14.0 simulations and techno-economic analysis. Equilibrium studies revealed that optimal conditions of 300–400 °C, 1–5 bar, and a H₂/CO₂ ratio of 4 achieve CO₂ conversion above 99%, methane selectivity exceeding 92%, and near-complete suppression of CO formation. The developed process flowsheet delivered a methane-rich stream (>92% CH₄ + H₂) with high yield. Economic evaluation showed that at optimal conditions, the process achieves a positive net present value (NPV) of $12.2 million (1 bar) and $1.7 million (5 bar) and a payback period as low as 0.92 years (1 bar) or 5.6 years (5 bar), depending on the pressure scenario. These results demonstrate that biogas upgrading through CO₂ methanation is not only technically feasible but also economically competitive, supporting its integration into existing energy systems and contributing to the transition toward renewable fuels. Full article

Crude oil emulsions continue to pose significant challenges across production, transportation, and refining due to their inherent stability and complex interfacial chemistry. Their persistence is driven by the synergistic effects of asphaltenes, resins, acids, waxes, and fine solids, as well as operational factors such as temperature, pH, shear, and droplet size. These emulsions increase viscosity, accelerate corrosion, hinder catalytic activity, and complicate downstream processing, resulting in substantial operational, economic, and environmental impacts—underscoring the necessity of effective demulsification strategies. This review provides a comprehensive examination of emulsion behavior, beginning with their formation, classification, and stabilization mechanisms and progressing to the fundamental processes governing destabilization, including flocculation, coalescence, Ostwald ripening, creaming, and sedimentation. Separation techniques are critically assessed across chemical, thermal, mechanical, electrical, membrane-based, ultrasonic, and biological domains, with attention to their efficiency, limitations, and suitability for industrial deployment. Particular emphasis is placed on hybrid and emerging methods that integrate multiple mechanisms to improve performance while reducing environmental impact. By uniting fundamental insights with technological innovations, this work highlights current progress and identifies future directions toward greener, more efficient oil–water separation strategies tailored to diverse petroleum operations. Full article

Coffee drying in humid regions is frequently hindered by high rainfall and elevated relative humidity during peak harvest, prolonging drying times and risking microbial spoilage and quality deterioration. This study introduces a novel framework in which low-temperature drying is reframed as a gas–solid dehydration reaction, promoted by a catalyst analog represented by regenerable desiccants integrated into the inlet air stream to lower the humidity ratio (ΔY) and intensify the evaporation driving force. Two adsorbents, silica gel type A and zeolite 13X, were evaluated using a coupled reactor model linking fixed-bed adsorption kinetics with tensorial heat–mass transport in a 70 kg batch of parchment coffee arranged in a 0.20 m thick bed. Drying simulations from 53% to 12% (wb) at 40, 45, and 50 °C showed time reductions of 35–37% with silica gel and 44–57% with zeolite, yielding kinetic promotion factors of up to 2.3× relative to the control. Breakthrough analysis supported a dual-bed alternation strategy, with regeneration at ≤130 °C for silica and moderately higher for zeolite. A nomograph was developed to scale desiccant requirements across airflow and ΔY targets. These results confirm the feasibility and scalability of desiccant-assisted drying, providing a modular intensification pathway for farm-scale coffee processing. Full article

Conventional wastewater treatment methods typically achieve 70–90% removal efficiency for organic pollutants. However, the global wastewater crisis—with 80% of wastewater discharged untreated—demands innovative solutions to overcome persistent challenges in nutrient removal and resource recovery. This review presents the first systematic analysis of technology integration strategies for algal wastewater treatment, examining synergistic combinations of biofilm reactors, nano-enhancement, artificial intelligence, and 3D printing technologies. Individual technologies demonstrate distinct performance characteristics: algal biofilm reactors achieve 60–90% removal efficiency with biomass productivity up to 50 g/m²/day; nano-enhanced systems reach 70–99% pollutant removal; AI optimization provides 15–35% efficiency improvements with 25–35% energy reductions; and 3D-printed architectures achieve 70–90% removal efficiency. The novel integration framework reveals that technology combinations achieve 85–95% overall efficiency compared to 60–80% for individual approaches. Critical challenges include nanomaterial toxicity (silver nanoparticles effective at 10 mg/L), high costs (U.S. Dollar (USD) 50–300 per m² for 3D components, USD 1500+ per kg for nanomaterials), and limited technological maturity (TRL 4–5 for AI and 3D printing). Priority development needs include standardized evaluation metrics, comprehensive risk assessment, and economic optimization strategies. The integration framework provides technology selection guidance based on pollutant characteristics and operational constraints, while implementation strategies address regional adaptation requirements. Findings support integrated algal systems’ potential for superior treatment performance and circular economy contributions through resource recovery. Full article

The flaring of associated gas in oil and gas operations contributes significantly to greenhouse gas emissions and represents a loss of valuable hydrocarbon resources. While amine absorption is widely applied for acid gas removal, the use of supercritical carbon dioxide (sc-CO₂) for flare gas treatment remains largely unexplored, despite its proven selectivity for hydrocarbons in other industries such as natural product extraction and polymer processing. Conventional flare gas treatment methods face trade-offs: amine absorption achieves high acid gas removal efficiency but offers limited selectivity for heavier hydrocarbons, whereas sc-CO₂ extraction enables efficient recovery of higher hydrocarbons but does not fully remove acid gases. This study addresses these gaps by evaluating three two-stage flare gas treatment configurations—dual-stage amine absorption, dual-stage sc-CO₂ absorption, and a hybrid of sc-CO₂ followed by amine absorption—using Aspen HYSYS V12.1 simulations, with recycling processes considered in each case. The dual-stage sc-CO₂ process achieved nearly complete hydrocarbon recovery (100%) and complete H₂S removal, but CO₂ remained at elevated concentrations in the treated gas. The dual-stage amine process completely removed CO₂ and H₂S, though with higher energy demand for solvent regeneration. The hybrid configuration combined the advantages of both approaches, achieving complete H₂S removal, 100% hexane recovery, 95.02% methane recovery, and a drastic reduction in CO₂ concentration (to 0.0012 mole fraction). These results demonstrate that integrating sc-CO₂ with amine absorption resolves the trade-off between hydrocarbon selectivity and acid gas removal, establishing a technically viable pathway for flare gas utilization with potential application in gas-to-liquids (GTL) and carbon management strategies Full article

This paper discusses the efficiency of ultrasonic-assisted bitumen extraction from bituminous sands of the Beke deposit (Mangistau region, Kazakhstan) using alkaline aqueous solutions. The process parameters, including ultrasonic frequency (22 kHz), power (up to 1500 W), solution pH (>12), and optimal NaOH concentration (1 wt.%) were optimized to achieve a maximum bitumen recovery of 98 wt.% within 8 min. The most effective sand-to-solution mass ratio was determined as 1:2, while the optimal process temperature was 75 °C. The application of ultrasound significantly enhances cavitation and reagent penetration, enabling efficient separation of bitumen with minimal chemical usage. Fourier-transform infrared (FTIR) spectroscopy and GC–MS analyses revealed the presence of aromatic hydrocarbons, paraffinic and naphthenic structures, as well as sulfur- and oxygen-containing functional groups (e.g., sulfoxides, carboxylic acids). These characteristics suggest moderate maturity and a high degree of aromaticity of the organic matter. Despite suitable thermal and compositional properties, the extracted bitumen exhibits a relatively low stiffness and softening point, indicating the need for additional upgrading (e.g., oxidation) prior to use in road construction. Although standard rheological tests (e.g., dynamic shear rhinometry) were not conducted in this study, the penetration and softening point values suggest a relatively soft binder, possibly unsuitable for high-temperature paving applications without modification. Future research will focus on rheological evaluation and oxidative upgrading to meet the ST RK 1373-2013 specification requirements. Full article

This study presents an integrated approach to processing the heavy fraction of coal tar (HFCT) using oil shale (OS) from Shubarkol Komir JSC to simultaneously increase the yield of valuable hydrocarbon fractions and extract rare and dispersed trace elements. The lack of data on the effect of shale on the process and the kinetics of multi-component “tar + shale” systems limits the development of effective technologies. TG/DTG analysis was combined with the Friedman, Ozawa–Flynn–Wall, and Šesták–Berggren methods for the first time to evaluate the role of oil shale (OS). It was shown that the addition of 13% OS provides a sustained reduction in activation energy (~85–86 kJ/mol) and optimal conditions for hydrometallization. At 420 °C, an initial H₂ pressure of 4 MPa, and a reaction time of 60 min, the yield of light fractions reaches 62.6%, and the solid residue concentrates Ti, Mo, Ge, and other rare and dispersed elements reach up to 66,000 g/t in total. The possibility of extracting Ge using the Purolite C100 sorbent has also been confirmed. The novelty of the study lies in demonstrating the donor–catalytic effect of shale and the practical prospects of solid residue as a secondary mineral raw materials. Full article

This study systematically investigates the solvent-dependence of copper(II) extraction using di-2-ethylhexyl phosphoric acid (D2EHPA) across a range of polar and non-polar diluents, including chloroform, dichloromethane, carbon tetrachloride, cyclohexane, 1-octanol, and methyl isobutyl ketone (MIBK). Through analysis of extraction constants and distribution coefficients at varying pH levels, it was demonstrated that solvent polarity and dipole moment critically influenced the coordination geometry and extraction efficiency of the Cu(II)-D2EHPA complex. Notably, the highest extraction efficiencies were exhibited by 1-octanol and cyclohexane. A solvent-dependent structural transition was revealed by Ultraviolet–Visible (UV) spectroscopic evidence: tetrahedral coordination was dominated in polar media, while square planar geometries prevailed in non-polar environments. These findings establish a direct correlation between diluent properties and the extractant’s performance, offering a mechanistic framework for optimizing industrial-scale copper recovery processes. The insights gained highlight the importance of solvent selection in tailoring metal extraction systems for specific applications. Full article

This study investigates the enhancement of polyvinylidene fluoride (PVDF) membranes with polyethylene glycol (PEG) to improve their efficacy in treating tofu wastewater through the ultrafiltration (UF) process. PVDF membranes with varying PEG concentrations of 0, 0.5, 1, and 1.5% in the dope solution were produced, characterized via FTIR, mechanical strength, porosity, and contact angle measurements, and evaluated in wastewater treatment at varying pressures of 3, 4, and 5 bar in the UF process. The incorporation of PEG increased the membrane’s porosity from 28.2% for M-0 to 43.5% for M-1.5. The contact angle decreased from 65.3° for M-0 to 53.3° for M-1.5, indicating an increase in hydrophilicity. Elongation increased from 36.0% for M-0 to 113.5% for M-1.5; however, the tensile strength decreased from 11.8 MPa for M-0 to 5.4 MPa for M-1.5. Although PEG-modified membranes demonstrated enhanced flux, with values of 6.3 L∙m⁻²∙h⁻¹ for M-0 and 15.7 L∙m⁻²∙h⁻¹ for M-1.5 at a pressure of 5 bar, pure PVDF membranes (M-0) showed greater rejection rates for chemical oxygen demand (COD), total dissolve solid (TDS), total suspended solid (TSS), and turbidity at 3 bar, achieving values of 66.3%, 41.6%, 99.6%, and 99.1%, respectively. Following ultrafiltration, the pH and TDS levels conformed to Indonesian government guidelines; however, the COD levels were non-compliant, indicating the need for additional treatment. The findings suggest that PVDF/PEG ultrafiltration membranes are suitable for pre-treatment; however, nanofiltrationor reverse osmosis may be necessary to meet the stringent regulatory standards for tofu wastewater treatment. The modified M-1.5 membrane is recommended as the primary ultrafiltration membrane for tofu wastewater treatment due to its superior flux, prior to nanofiltration or reverse osmosis, to comply with the stringent regulatory standards established by the Government of the Republic of Indonesia. Full article

Steady-shear rheology and surface activity of surfactant–polymer solutions were investigated experimentally. Four different polymers were studied as follows: cationic hydroxyethyl cellulose, nonionic hydroxyethyl cellulose, nonionic guar gum, and anionic xanthan gum. The influence of the following four surfactants on each of the polymers was determined: nonionic alcohol ethoxylate, anionic sodium lauryl sulfate, cationic hexadecyltrimethylammonium bromide, and zwitterionic cetyl betaine. The interaction between cationic hydroxyethyl cellulose and anionic sodium lauryl sulfate was extraordinarily strong, resulting in dramatic changes in rheological and surface-active properties. The consistency increased initially, reached a maximum value, and then fell off with the further addition of surfactant. The surface tension of surfactant–polymer solution dropped substantially and exhibited a minimum value. Thus, the surfactant–polymer solutions were much more surface-active compared with pure surfactant solutions. The interaction between anionic xanthan gum and cationic hexadecyltrimethylammonium bromide was also strong, resulting in a substantial decrease in consistency. The surfactant–polymer solution became less surface-active compared with pure surfactant solution due to the migration of surfactant from solution to polymer. The interactions between other polymers and surfactants were weak to moderate, resulting in small to modest changes in rheological and surface-active properties. Surface activity of surfactant–polymer solutions often increased due to the formation of complexes more surface-active than pure surfactant molecules. Full article

Crude hemp (Cannabis sativa L.) seed oil (HSO) has a high degree of unsaturation, which has increased its interest in many industrial applications, especially epoxy-resin production. Crude HSO is refined to remove impurities and pigments; however, refining after epoxidation (post-epoxidation refining) also removes impurities and side products, similar to the vegetable oil refining process. Therefore, this study evaluates if it is worth refining crude HSO before epoxidation (pre-epoxidation), and to what extent pre-refining (before epoxidation) is needed to maintain yield and quality. Crude, degummed, and bleached HSOs were epoxidized at 60 °C for 5.5 h using amberlite 120H+ solid catalyst. The cumulative recovery yield, oxirane, conversion, color, and other quality parameters were analyzed before and after epoxidation of HSOs. Results showed that the recovery yield pre- and post-epoxidation of the epoxidized hempseed oils (EHSOs) ranged from 74 to 85%, with the bleached EHSO having the lowest yield. The oxirane content and epoxy conversion ranged from 8.4 to 8.6% and 99.5%, respectively. There was a significant decrease (approximately 99%) in the chlorophyll color content after epoxidation for samples that were not bleached initially with bleaching earth. Hydrogen peroxide was very effective in bleaching the HSO. Other quality parameters did not show any significant benefit from pre-epoxidation bleaching of the HSO. Therefore, it is recommended to directly epoxidize crude HSO or degummed HSO. Full article

The depletion of high-grade copper ore reserves in Kazakhstan, coupled with the increasing proportion of refractory ores and the high costs of extraction and processing, necessitates the development of efficient and economically viable technological solutions. In this context, biogeotechnology has gained considerable attention. Recently, alternative approaches based on the use of natural organic compounds—so-called bioreagents—have been introduced into the field of bioleaching. The present study aimed to investigate the effect of amino acids, aliphatic alcohols, and alcohol-based industrial by-products, used as bioadditives, on the bioleaching of copper. The results demonstrated that the influence of amino acids on copper bioleaching decreased in the following order: glycine > leucine > cysteine > histidine > asparagine. Furthermore, the addition of fusel oils, a mixture of aliphatic alcohols, to the bioleaching pulp enhanced copper recovery, achieving extraction efficiencies exceeding 90%. Full article

Direct air capture (DAC) has recently gained interest as a carbon dioxide removal (CDR) method to reduce atmospheric CO₂. DAC is mainly studied through standalone separation technologies, especially adsorption and absorption. Hybrid DAC, combining separation technologies, is rarely investigated and is the main topic of this work. This study investigates hybrid DAC using adsorption for pre-concentration up to a few percent or tens of percent depending on the case studied and membrane separation to concentrate the CO₂ stream to high purity (>90%). Adsorption regeneration by temperature swing adsorption (TSA) and vacuum thermal swing adsorption (VTSA) are compared, and VTSA regeneration achieved higher pre-concentration outlet CO₂ purity (15–30%) than TSA regeneration (1–10%). Membrane separation is studied depending on inlet CO₂ purity and outlet-required purity (90 or 95%), which influence the energy requirement and cost of capture. For all cases studied, the cost of capture remained high (>1700 €/tCO₂) with a high energy requirement (>2 MWh_e/tCO₂ and >27 GJ/tCO₂). The adsorption pre-concentration step accounted for the majority (>80%) of the energy requirement and cost of capture, and future work should be focused on preferentially improving adsorption step performance. Full article

Coal ash is a promising secondary resource for rare earth element (REE) recovery, yet efficient processing under environmentally benign conditions remains challenging. This study demonstrates that tartaric acid, when combined with MgSO₄ as a salt additive, enables effective extraction of light REEs (La, Ce, Nd). REE recoveries improved from ~40% without salt to nearly 65% under optimized conditions. Kinetic modeling indicated a surface-reaction–controlled mechanism with activation energies of 20–22 kJ/mol, consistent with SEM evidence of particle erosion and size reduction. These findings highlight the potential of organic-salt leaching systems as alternatives to mineral acid processes, offering both effective REE recovery and reduced environmental impact. Full article

The majority of downhole monitoring methods currently available for well cement projects, which are used to assess the quality of cement placement and monitor well integrity over time, are primarily qualitative in nature and rely on surface signs. Obviously, there is a need for a practical quantitative downhole monitoring method to ensure proper cement placement and long-term performance. One potential resolution to address this enduring problem would involve enhancing the designs of the cement slurry and transforming the cement into durable downhole logging equipment, thereby facilitating real-time observation of operations. To address this issue, in this work, carboxylated styrene butadiene rubber (XSBR) polymer-treated cement was used to understand the gas migration and fluid loss mechanism. The experimental findings indicate that the electrical resistivity of polymer-treated cement is significantly influenced by applied loads and stresses. The unconfined compressive strength test with XSBR-blended cement showed a significant improvement from 22.5 MPa to 33.31 MPa when XSBR increased from 0% to 3%. Additionally, in the high pressure and high temperature (HPHT) chamber, the latex polymer used as a migration additive control, the total fluid loss is found to be about 59.2 mL under 30 min of testing. Also, to emulate the accuracy, nonlinear predictive models based on the resistivity index correlation were developed to forecast polymer-treated cement performance for all the tests performed in this study. Hence, the utilization of polymer-treated cement systems proves to be a valuable method for monitoring the placement and post-placement performance of cement, as well as for visualizing real-time operational issues associated with cementing. This will also allow operators to provide immediate solutions, saving time and operational costs. Full article

Aluminum is the most used non–ferrous metal. It can be recycled saving several natural resources, but generates large amounts of residues with a complex composition—still containing a valuable amount of aluminum, although also including contaminant compounds. The laboratory-scale valorization of an industrial aluminum residue is here used as a powerful didactic resource in Inorganic and Analytical Chemistry and related fields such as Chemistry, Chemical Engineering, Environmental Engineering, Materials Engineering, and related university degrees, since concepts like acid-base properties (particularly amphoterism), redox reactions, speciation diagrams, or solubility–precipitation concepts are applied. The students are encouraged to look for information on the topic, to teamwork, and to elaborate a well-written laboratory report. At the same time, this laboratory work introduces them to advanced laboratory techniques and to incorporate concepts of Circular Economy and various Sustainable Development Goals, educating the students with respect to the environment. Although focused on University studies, this manuscript also contains excellent ideas for secondary teachers to motivate STEM vocations, particularly for Chemistry and Chemical and Environmental Engineering, and is also ideal for being included in the preparation of future Secondary School teachers. Full article

The aim of this study was to establish a method named simultaneous determination for the content of four fatty acids in Coix seeds and provide a reference for the quality control of this type of medicinal ingredient. The contents of four fatty acids in Coix seeds were determined via gas chromatography, and the method was subsequently validated. The linear ranges of palmitic acid, stearic acid, oleic acid and linoleic acid were 282.50–2825.00, 262.00–1572.00, 425.20–2976.75 and 304.50–1218.00 µg/mL, respectively. The RSD values of precision, repeatability and stability were less than 3.00% (n = 6), with recoveries of 98.82–102.05% (RSD 2.22–4.60%, n = 6). The contents of palmitic acid, stearic acid, oleic acid and linoleic acid in the 24 batches of Coix seeds were 0.11–0.32%, 0.06–0.08%, 0.35–1.17% and 0.31–0.73%, respectively. Oleic acid had the highest content, followed by linoleic acid, palmitic acid, and stearic acid. The detection method established in this experiment was implemented rapidly and accurately, was reproducible, and could simultaneously determine the contents of four fatty acids in Coix seeds. This study provides a reference for evaluating the quality of Coix seeds obtained from different habitats. Full article

Crystallization is one of the approximately twenty unit operations and is considered to be among the most important due to the large number of chemical compounds it produces, as well as due to the enormous quantities of these substances being manufactured around the world. This article aims to present a mathematical model for the shortcut design of a cooling crystallization unit consisting of the crystallizer and auxiliary equipment, such as an evaporator with its preheater and condenser, a heat pump that acts as the cooling system of the crystallizer, and a crystallizer pressure regulator modeled as an expansion valve. The model estimates an extensive series of variables, including mass and volume flow rates of the streams, heat duties of each piece of equipment, sizing variables such as heat transfer areas of heat exchangers and volumes of the vessels, and product flow rates for each specific feed. It embraces equations for the calculation of a series of stream properties, such as density, specific heat capacity, and latent heat of vaporization. For the sizing of the crystallizer, which is the main equipment of the unit, both flow rates and crystallization kinetics are taken into account. The latter is estimated by experimental data taken in a laboratory crystallizer and includes the crystal’s growth rate as a function of residence time. Full article

Prolonged exposure to landfill leachate can weaken the impermeability of liner systems, leading to leachate leakage and the contamination of surrounding soil and water. To improve loess impermeability to enable its use as a liner material, this study uses synthetic landfill leachate to investigate its effects on loess permeability via a series of laboratory tests. This study focused on the influence of varying dosages of calcium lignosulfonate (CLS) on loess permeability, along with its capacity to adsorb and immobilize heavy metal ions. Microscale characterization techniques, including Zeta potential analysis, X-ray fluorescence spectroscopy (XRF), and scanning electron microscopy (SEM), were employed to investigate the impermeability mechanisms of CLS-modified loess and its adsorption behavior toward heavy metals. The results indicate that the permeability coefficient of loess decreases significantly with increasing compaction, while higher leachate concentrations lead to a notable increase in permeability. At a compaction degree of 0.90, the permeability coefficient was reduced to 8 × 10⁻⁸ cm/s. In contrast, under conditions of maximum leachate concentration, the permeability coefficient rose markedly to 1.5 × 10⁻⁴ cm/s. Additionally, increasing the dosage of the compacted loess stabilizer (CLS) effectively reduced the permeability coefficient of the modified loess to 7.1 × 10⁻⁵ cm/s, indicating improved impermeability and enhanced resistance to contaminant migration. With the prolonged infiltration time of landfill leachate, the removal efficiency of Pb²⁺ gradually decreases and stabilizes, while the Pb²⁺ removal efficiency of the modified loess increased by approximately 40%. CLS-modified loess, through multiple mechanisms, reduces the fluid flow pathways and enhances its adsorption capacity for Pb²⁺, thereby improving the soil’s protection against heavy metal contamination. While these results demonstrate the potential of CLS-modified loess as a sustainable landfill liner material, the findings are based on controlled laboratory conditions with Pb²⁺ as the sole target contaminant. Future work should evaluate long-term performance under field conditions, including seasonal wetting–drying and freeze–thaw cycles, and investigate multi-metal systems to validate the broader applicability of this modification technique. Full article

As academic institutions expand, the proliferation of laboratories dealing with hazardous chemicals has risen. While the physicochemical characterization equipment employed in these academic chemical laboratories is widely recognized, its usage presents a notable risk to researchers at various levels. This paper presents a simplified approach for evaluating the effects of the implementation of prevention investments in regard to working with nanomaterials on a lab scale. The evaluation is based on modeling the benefits (avoided accident costs) and costs (safety training), as opposed to an alternative (not investing in safety training). Each scenario analyzed in the economic evaluation reflects a different level of risk. The novelty of this study lies in its objective to provide an economic assessment of the benefits and returns from safety investments—specifically training—in a chemical laboratory, using a framework that integrates qualitative insights to explore and define the context alongside quantitative data derived from a cost–benefit analysis. The Net Present Value (NPV) was evaluated. The results of the cost–benefit analysis demonstrated that the benefits exceed the cost of the investment. The findings from the sensitivity analysis highlight the significant influence of insurance benefits on safety investments in the specific case study. In this case study, the deterministic analysis yielded a Net Present Value (NPV) of €280,414.67, which aligns closely with the probabilistic results. The probabilistic NPV indicates 90% confidence that the investment will yield a positive NPV ranging from €283,053 to €337,356. The cost–benefit analysis results demonstrate that the benefits outweigh the costs, showing that with an 87% training success rate, this investment would generate benefits of approximately €6328 by preventing accidents in this study. To the best of the researchers’ knowledge, this is the first study to evaluate the influence of safety investment through an economic evaluation of laboratory accidents with small-angle X-ray scattering during the physicochemical characterization process of engineered nanomaterials. The proposed approach and framework are relevant not only to academic settings but also to industry. Full article

Process designs based on deterministic simulations without considering parameter uncertainty or variability have a high probability of failing to meet specifications. In this work, uncertainty and global sensitivity analyses were applied to a biogas upgrading membrane process implemented in the COCO simulator (CAPE-OPEN to CAPE-OPEN), considering both controlled and non-controlled scenarios. A user-defined model code was developed to simulate gas separation membrane stages, and a preliminary study of membrane parameter uncertainty was performed. In addition, a unit generating combinations of uncertainty factors was developed to interact with the simulator’s parametric tool. Global sensitivity analyses were carried out using the Morris method and Sobol’ indices obtained by Polynomial Chaos Expansion, allowing for the ranking and quantification of the influence of feed variability and membrane parameter uncertainty on product streams and process utilities. Results showed that when feed variability was ±10%, its effect exceeded the uncertainty of the membrane parameters. Uncertainty analysis using the Monte Carlo propagation method provided lower and upper tolerance limits for the main responses. Relative gaps between tolerance limits and mean product flows were 8–9% at a feed variability of 5% and 14–18% at a feed variability of 10%, while relative tolerance gaps resulting from composition were smaller (0.4–1.2%). Full article

Bioethanol from sugarcane bagasse is a promising second-generation biofuel due to its abundance as a sugar industry by-product. Herein, enzymatic hydrolysate obtained from sugarcane bagasse pretreated with optimized hydrothermal alkaline sulfite (HAS) was evaluated for its fermentability using Saccharomyces cerevisiae PE-2 and Scheffersomyces stipitis CBS 5773. The HAS pretreatment achieved a high delignification rate (63%), resulting in a cellulose- and hemicellulose-enriched substrate (55% and 27%, respectively). While the cellulose content remained relatively constant, hemicellulose content was reduced by 25%, with significant removal of acetyl groups (80%) and arabinan groups (39%). The pretreated bagasse exhibited high digestibility, applying 10 FPU (filter paper unit) cellulase together with 10 CBU (cellobiose unit) β-glucosidase per gram of dry bagasse in the hydrolysis step, yielding 72% glucan and 66% xylan conversion within 72 h. The resulting hydrolysate was efficiently fermented by S. cerevisiae and S. stipitis, achieving ethanol yields of 0.51 and 0.43 g/g of sugars, respectively. The fermentation kinetics were comparable to those observed in a synthetic medium containing pure sugars, demonstrating the effectiveness of HAS pretreatment in generating readily fermentable, carbohydrate-rich substrates. HAS pretreatment enabled improved conversion of sugarcane bagasse into fermentation-ready sugars, constituting a potential resource for bioethanol synthesis applying both S. cerevisiae and S. stipitis in the future. Full article