Zeta potential (ZP) is a parameter that expresses the electrochemical equilibrium between particles and liquids like in nanoparticle (NP) colloidal solutions with applications in medicine, pharmaceuticals, chemical production, mineral processing, and water and soil purification. Smoluchowski's theory applies to the ZP particles that are larger the interfacial layer but neglects surface conductivity. The Debye-Hückel theory correctly approximates the concentration of ions in a double layer but fails to account for the dependence of ZP on the concentration of counterions. Determining ZP of NPs is essential to proper NP characterization. For instance, developing well-defined therapeutic-relevant nanoformulations needs information on NPs size, surface charge, stability and agglomeration behaviour. This approach has many practical challenges, from inadequate knowledge of operating standards to sampling, data interpretation and good laboratory practice for the experiments replicability. However, in drug delivery research, very little literature can provide a clear, succinct explanation of these techniques. Looking for specific guidelines to overcome frequently encountered problems during ZP measurements. This article explores factors influencing colloidal particle stability. Measurement criteria such as applied voltage, number of measurements, electrophoretic mobility (EPM), size distribution, surface shape, temperature, viscosity, particle concentration, zeta potential, nanoparticles, colloidal suspension, electrophoretic mobility, and pH.

Poly(methyl methacrylate) (PMMA) is a versatile polymer with a forecast market of 4 Mtons/y by 2025, and 6 USD billion by 2027. Each year, 10% of the produced cast sheets, extrusion sheets, or granules PMMA end up as post-production waste, accounting for approximately 30 000 tons/y in Europe only. To guide the future recycling efforts, we investigated the risks of depolymerization process economics for different PMMA scraps feedstock, capital expenditure (CAPEX), and regenerated MMA (r-MMA) prices via a Monte-Carlo simulation. An analysis of plastic recycling plants operating with similar technologies confirmed how a maximum 10 M USD plant (median cost) is what a company should aim for, based on our hypothesis. The capital investment and the r-MMA quality have the main impacts on the profitability. Depending on the pursued outcome, we identified three most suitable scenarios. Lower capital-intensive plants (Scenarios 4 and 8) provide the fastest payback time, but this generates a lower quality monomer, and therefore lower appeal on the long term. On 10 or 20 years of operation, companies should target the very best r-MMA quality, to achieve the highest net present value (Scenario 6). Product quality comes from the feedstock choice, depolymerization, and purification technologies. Counterintuitively, a plant processing low quality scraps available for free (Scenario 7), and therefore producing low purity r-MMA, has the highest probability of negative net present value after 10 years of operation, making it a high-risk scenario. Western countries (especially Europe), call for more and more pure r-MMA, hopefully comparable to the virgin material. With legislations on recycled products becoming more stringent, low quality product might not find a market in the future. To convince shareholders and government bodies, companies should demonstrate how funds and subsidies directly translate into higher quality products (more attractive to costumers), more economically viable, and with a wider market.

Process simulation software designs equipment, simulates operations, optimizes a plant's configuration (heat exchangers network, for example), estimates operating and capital expenses, and serves as an educational tool. However, mastering the theoretical background minimizes common mistakes such as applying an incorrect thermodynamic method, selecting improper algorithms in the case of tear systems, and setting irrational system specifications. Engineers and researchers will exploit this tool more often in the future as constant advancements in simulation science as well as new models are released continually. Process simulators make it easier to build digital twins and thus will facilitate the implementation of the industry 4.0 guidelines. We highlight the mathematical and technical features of process simulators, as well as the capabilities and the fields of application. A bibliometric map of keywords from articles citing Aspen+, Aspen plus, Hysys, and Pro/II indexed by Web of Science between 2017 and 2020 identified the main research clusters, such as design, optimization, energy or exergy, biomass; H 2 and CO 2 capture, thermodynamics; and separations and techno-economic analysis.

Research has focused on nanoparticle (NP) aggregation and transport behavior in saturated granular porous media, but few studies have looked at the effect that temperature variability associated with winter conditions will have on engineered NPs.

Methane is the second highest contributor to the greenhouse effect. Its global warming potential is 37 times that of CO2. Flaring-associated natural gas from remote oil reservoirs is currently the only economical alternative. Gas-to-liquid (GtL) technologies first convert natural gas into syngas, then it into liquids such as methanol, Fischer–Tropsch fuels or dimethyl ether. However, studies on the influence of feedstock composition are sparse, which also poses technical design challenges. Here, we examine the techno-economic analysis of a micro-refinery unit (MRU) that partially oxidizes methane-rich feedstocks and polymerizes the syngas formed via Fischer–Tropsch reaction. We consider three methane-containing waste gases: natural gas, biogas, and landfill gas. The FT fuel selling price is critical for the economy of the unit. A Monte Carlo simulation assesses the influence of the composition on the final product quantity as well as on the capital and operative expenses. The Aspen Plus simulation and Python calculate the net present value and payback time of the MRU for different price scenarios. The CO2 content in biogas and landfill gas limit the CO/H2 ratio to 1.3 and 0.9, respectively, which increases the olefins content of the final product. Compressors are the main source of capital cost while the labor cost represents 20–25% of the variable cost. An analysis of the impact of the plant dimension demonstrated that the higher number represents a favorable business model for this unit. A minimal production of 7,300,000 kg y−1 is required for MRU to have a positive net present value after 10 years when natural gas is the feedstock.

Hazards and operability analysis (HAZOP) is one of a dozen-structured Process Hazards Analysis (PHA) methodologies that assess risks associated with operating processes to mitigate their consequences. HAZOP applies to all six stages of process design from discovery to decommissioning. Industry massively adopted PHA methodologies as a consequence of several industrial disasters in the 1970s that increased society's scrutiny of chemical operations. HAZOPs are conducted by multidisciplinary teams that rely on a set of guide words in combination with the system parameters to identify deviations from the design intent. The team discuss the causes and consequences of deviations, and the project owner modifies the process accordingly. It relies on heuristics rather than algorithms, so the formal structure gives practitioners the false sense that the analysis is comprehensive. Academic institutions increasingly apply PHAs to experimental work, but the scope of a HAZOP is often ill-suited for this environment as it requires dedicated personnel with particular expertise. Here, we outline the essential features of a HAZOP analysis for early career researchers engaging in process development for conditions that include, for example, high temperature, high pressure, toxic compounds (Hg, phosgene, CO), and potentially explosive and flammable mixtures like organic peroxides. Web of Science indexed over 100 000 documents that mention safety in 2021 and assigned 1500 to chemical engineering. A bibliometric analysis grouped them into five clusters: (1) lithium ion batteries and nanoparticles, (2) fire, simulation, and combustion, (3) models, risk, systems, and techniques (including HAZOP), (3) models, risk, systems, and techniques (including HAZOP), (4) water treatment, and (5) mechanisms and thermal runaway.

Pressure and temperature are the most important state variables for monitoring physicochemical processes to detect deviations that might lead to explosions and to verify levels, flow rate, and solids/gas hold-up. Pressure fluctuations in multiphase systems identify regime changes and flow anomalies. Pressure signals are the first indicator of a process upset and are tied into distributed control systems (DCS) to sound alarms when they drift to high or low and activate safety interlocks in the case of high, high-high, low, and low-low conditions. To maximize the information, it requires that pressure gauges (transducers) are installed and calibrated precisely. Pressure measuring devices include manometers, aneroid devices like bellows and Bourdon gauges, and electronic instruments-piezoresistive, piezoelectric, and capacitive. The electronic elements have the advantage of higher precision and faster response times to measure fluctuations. The Bourdon gauges are standard equipment for pressure regulators and are mounted on the exterior of vessels and pipes to facilitate visual inspections. Over two million articles indexed by the Web of Science Core collection mention pressure, and in 2021, chemical engineering ranks had over 7000 articles-only multidisciplinary material sciences and energy and fuels had more. A bibliometric analysis identified five research clusters: temperature, combustion, and kinetics; separation, membranes, and energy efficiency; carbon dioxide (capture and storage), water, and thermodynamics; methane, adsorption, and transport phenomena (e.g., diffusion and permeability); and modelling, optimization, and computational fluid dynamics (CFD).

Oxidative coupling of alcohols using methanol and ethanol, which can both be made renewable, is an attractive route to produce acrolein (propenaldehyde) in a single-step process. Currently acrolein is produced by direct oxidation of fossil propylene, and catalytic double dehydration of glycerol has been also investigated up to pilot scale. Although glycerol is an attractive feedstock, it suffers of several drawbacks. Addressing the limitations of both routes, the oxidative coupling of alcohols combines an exothermic oxidation and cross-aldolization. The best performing catalysts so far combine redox and acid/base sites. Reviewing the academic and patent literature, the present paper also addresses the economic analysis, to highlight the potential of this reaction at a yield from 70%, and at two different plant scales. The analysis has been made to guide further research, with the remaining technical problems to solve. Improved selectivity contributing to reduce the amount of equipment and the investment cost should be the prime target.