Chemical Engineering Tools Research Articles

Identifying Variables Influencing Traditional Food Solid-State Fermentation by Statistical Modeling.

Solid-state fermentation is widely used in traditional food production, but most of the complex processes involved were designed and are carried out without a scientific basis. Often, mathematical models can be established to describe mass and heat transfer with the assistance of chemical engineering tools. However, due to the complex nature of solid-state fermentation, mathematical models alone cannot explain the many dynamic changes that occur during these processes. For example, it is hard to identify the most important variables influencing product yield and quality fluctuations. Here, using solid-state fermentation of Chinese liquor as a case study, we established statistical models to correlate the final liquor yield with available industrial data, including the starting content of starch, water and acid; starting temperature; and substrate temperature profiles throughout the process. Models based on starting concentrations and temperature profiles gave unsatisfactory yield predictions. Although the most obvious factor is the starting month, ambient temperature is unlikely to be the direct driver of differences. A lactic-acid-inhibition model indicates that lactic acid from lactic acid bacteria is likely the reason for the reduction in yield between April and December. Further integrated study strategies are necessary to confirm the most crucial variables from both microbiological and engineering perspectives. Our findings can facilitate better understanding and improvement of complex solid-state fermentations.

Application of (bio) chemical engineering concepts and tools to model genetic regulatory circuits, and some essential central carbon metabolism pathways in living cells. Part 4. Applications in the design of some Genetically Modified Micro-Organisms (GMOs)

In the first part of this work, the general Chemical and Biochemical Engineering (CBE) concepts and rules are briefly reviewed, together with the rules of the control theory of Nonlinear Systems (NSCT), all in the context of (i) deriving deterministic Modular Structured Kinetic Models (MSDKM) to describe the dynamics of metabolic processes in living cells, and (ii) of Hybrid Structured Modular Dynamic Models (HSMDM) (with continuous variables, linking the cell-nano-scale MSDKM state variables to the macro-scale state variables of the bioreactor dynamic model). Thus, in the HSMDM model, both prediction quality and its validity range are improved. By contrast, the current (classical/default) approach in bioengineering practice for solving design, optimization, and control problems based on the math models of industrial biological reactors is to use unstructured Monod (for cell culture reactor) or simple Michaelis-Menten (if only enzymatic reactions are retained) global kinetic models by ignoring detailed representations of metabolic cellular processes. By contrast, as reviewed, and exemplified in the second part of this work, an accurate and realistic math modelling of the dynamic individual GERMs (gene expression regulatory module), or genetic regulatory circuits (GRC), and cell-scale CCM (central carbon metabolism) key-modules can be done by only using the novel holistic ’Whole-Cell Of Variable-Volume’ (WCVV) modelling framework, under isotonic/homeostatic conditions/constraints introduced and promoted by the author. An example was given in the same Part 2 for the case study of a dynamic model for the oscillating glycolysis coupled with the Tryptophan (TRP) oscillating synthesis in the E. coli cells.

The silver lining of antibiotic resistance: Bacterial-mediated reduction of tetracycline plant stress via antibiotrophy

The reuse of water using effluents containing antibiotics from anthropogenic activities has been mainly linked to the development of antibiotic resistance. However, we report that the development of bacterial tolerance promotes plant growth. In the present study, we aimed to evaluate the efficiency of inoculation of a new antibiotic-degrading bacterium, Erwinia strain S9, in augmenting the tolerance of pea (Pisum sativum L.) plants to tetracycline (TET) (10 and 20 mg/L). Physiological parameters such as tissue elongation and biomass, as well as relative water content, were remarkably lower in plants exposed to TET than in the control. The inhibitory effects of TET were associated with reduced CO2 assimilation, stomatal conductance, transpiration, dark respiration, and light saturation point (LSP). High concentrations of TET-induced oxidative stress are attested by the overproduction of superoxide radicals (O2•−), hydrogen peroxide (H2O2), and hydroxyl radicals (HO•), resulting in increased malondialdehyde content and cell death. The high activity of antioxidant enzymes such as catalase, ascorbate peroxidase, and guaiacol peroxidase validated the proposed mechanism. Under TET stress conditions, supplementation with Erwinia strain S9 was beneficial to pea plants through osmotic adjustment, increased nutrient uptake, gas exchange optimization, and increased antioxidant activities. Its presence not only ensures plant survival and growth during antibiotic stress but also degrades TET via significant antibiotrophy. This strategy is a cost-effective environmental chemical engineering tool that can be used to depollute wastewater or to improve crop resistance in rhizofiltration treatment when treated wastewater is reused for irrigation.

Comprehensive study of three configurations coproducing synthetic fuels and electricity from palm residue via Fischer-Tropsch process

The continuous date production growth in Tunisia is accompanied by a larger agriculture residue. This residue could contribute to meeting the national targets for renewable energy.The main objective of this research is to investigate coproducing synthetic fuels and electricity from Tunisian Palm Residue via a Fischer-Tropsch process. Three different configurations were considered: Base case, Auto-Thermal-Reforming case, and Power case. Various chemical engineering tools were applied including process design, simulation as well as energy and exergy analyses.The results obtained showed that the Auto-Thermal-Reforming case proves to be more efficient in terms of Fischer-Tropsch liquid fuels productivity under our recommended conditions: oxygen to carbon ratio of 1 and steam to carbon ratio of 2.25. The rise of burned fraction in power case leads to lower chemical conversion efficiency. The best energetic performance is attributed to the power case. This process promotes the production of electricity in expenses of liquid fuels. It presents an increase by 3 times of the equivalent conversion efficiency compared to the Auto-Thermal-Reforming case. The exergetic efficiency of the power case is 26.5%. The large portion of total exergy destruction belongs to the syngas section which should have the highest priority for thermodynamic improvement of the process.

Residence time distribution and flow pattern modeling of oilseeds in a pilot screw press

Mechanical expression is widely applied for oil recovery from oilseeds using continuous screw presses. Despite significant recent advances in the field of press design and automation, it remains difficult to predict the press performances based on the theoretical approaches, and more experimental investigations are needed to clarify and characterize the seeds flow and expression behavior in the press. Residence Time Distribution (RTD) is a frequently used tool in chemical engineering to characterize the material flow by simple tracer tests. In this paper, we explore the feasibility of using RTD for the screw presses, in order to check the flow patterns homogeneity and identify the possible deviations depending on the press geometry and the operating conditions. Both theoretical modeling and experimental investigation are conducted for two different screw press designs (Reinartz and Olexa), and at the different rotation speeds. An original and reliable experimental methodology was developed by using erucic acid as tracer in the form of pulse injection and gas chromatography as detection method. Experimental results coupled with statistical calculations showed the influence of the screw geometry and the rotation speed on the seeds flow inside the press. The matter displacement was much faster and the experimental residence time was very close to the theoretical one indicating more homogeneity and less dispersion in the Olexa arrangement in comparison to the Reinartz arrangement. The higher variance observed at lower rotation speed (2.4 rpm) suggested the presence of flow defects like mixing and axial dispersion in the press. To complete the experimental work, axial dispersion model was applied, and allowed obtaining the valuable information, such as axial dispersion degree and distribution functions. Obtained results can be very useful to predict the performance of existing screw presses and design more efficient industrial equipments.

Photoresponsive Molecular Switches and Machines

The field of photoactivatable molecular switches and machines is expanding rapidly with an ever increasing pace of progress. In response to the steeply growing attention and relevance of this topic, we have devoted a special issue of ChemPhotoChem to the field. The issue covers a variety of the most recent developments in light-controlled molecular switches and machines brought forward by leading researchers from across the globe. A diverse set of communications, articles, minireviews, and reviews deliver fresh insights into current hot topics, urgent problems to be solved, and the most important future prospects of the field of light-activated switches and molecular machines. One of the important current trends that is clearly identified in this issue is the expansion of structural space for photoresponsive switching architectures. While the most eminent and established photoswitches, such as azobenzenes, diarylethenes, or spiropyrans, are increasingly used for ever more complex functionalities and applications, new molecular motifs, such as metronidazole, arylazopyrazoles, phenoxyl–imidazolyl radical complexes, hydrazones or indigoid chromophores, have entered the stage. These systems expand the structure and property range of light-responsive molecular tools, and thus will be of high and complementing value for future developments and applications. Another venue where there has been an ardent recent effort in the field is in tackling the persisting deficiency of detailed knowledge about the excited-state processes that govern photoswitching events. A significant body of work is dedicated to the mechanistic understanding of fundamental photophysics behind these processes. Of particular interest are: i) the dynamic processes involved in interconverting ground/stable states into meta/bistable ones, ii) the specifics of the accompanying electronic and geometric changes in the excited state, and iii) the resulting differences in the properties of photochemically interconvertible multistates. It is evident that only a combination of clever chemical structure engineering and sophisticated analytical tools will be needed to solve these important problems. Applying the spatial and temporal resolution of light provides unique opportunities for the rational control of functionality at the molecular, supramolecular, and even larger scale. In this issue the breadth of photoswitch applicability is evident by the great variety of potential uses ranging from biological chemistry, polymers, and liquid crystals, to host–guest systems, molecular machines, and solar energy storage. This diversity of applications is made possible by the inherent properties of reversible light addressability: Creation of responsiveness at the molecular level, and the unique precision of the exerted control. In this manner greater complexity can be generated in a design-driven fashion at the smallest scales, and current developments are clearly headed towards a considerable increase in complexity. Taken together we believe that this issue will not only be an important source of inspiration for specialists, but more so will instill enthusiasm and curiosity about the power of light-addressable molecular systems in the general readership. We hope that the special issue will be as stimulating for chemists, biologists, physicists, and materials scientists as it is for us. Henry Dube received his diploma in chemistry from the LMU Munich in 2004 and his Ph.D. from the ETH Zurich in 2008 in the group of François Diederich. After a postdoctoral stay at the Scripps Research Institute in the group of Julius Rebek, Jr., he started his independent group at the LMU Munich in late 2011 with a Liebig Fellowship of the FCI. Since 2014 he is an Emmy-Noether group leader at the same institution. His research focuses on photochemistry, molecular machines, and supramolecular chemistry. Ivan Aprahamian received all of his degrees (B.Sc. in 1998, M.S. in 2000, and Ph.D. in 2005) from the Hebrew University of Jerusalem, Israel. He carried out his postdoctoral research in Professor Sir Fraser Stoddart′s group at UCLA, and then joined the faculty at Dartmouth College in 2008, where he became a full professor in 2019. His research focuses on hydrazone-based adaptive functional materials, including switches, sensors and fluorophores. Nobuyuki Tamaoki obtained his Ph.D. degree from Chiba University in Japan. After working as a researcher, a senior researcher and a group leader at Japanese government's research institutes including the National Institute of Advanced Industrial Science and Technology, he moved to Hokkaido University as a full professor in 2008. Currently he is also a director of the Green Nanotechnology Center of the University. His research interests include photochemistry, stereochemistry, organic synthesis, molecular switches and motors and self-assembled molecular systems.

Modelagem de um Reator Químico do Tipo PFR não Isotérmico com Jaqueta como Instrumento Didático no Ensino de Engenharia Química: Um Estudo de Caso

Modelagem de um Reator Químico do Tipo PFR não Isotérmico com Jaqueta como Instrumento Didático no Ensino de Engenharia Química: Um Estudo de Caso

Optimisation of metal extraction from chromium ore processing residue in New Jersey, USA

The feasibility of extracting metals from chromium (Cr) ore processing residue (COPR) was investigated. COPR samples collected from four sites in New Jersey, USA (sites A, B, C and D) were mixed with 15% carbon by weight with different percentages of sand to neutralise the basic oxide in COPR and heated under a reducing environment to extract metals. At 15% and higher sand additions, a pool of melted metal was formed underneath the slag for some test batches. In this research, knowing the chemical composition of COPR and the depth of melt, the chemical engineering tools of phase and viscosity diagrams were used to compute the type and amounts of additives needed to optimise and compute the temperature and duration of melt to achieve maximum metal separations. With optimisation, as much as 30% by weight of metal was extracted from the initial mass of COPR collected from sites C and D when those melting mixtures contained 20% or more sand by weight. On average, the metal phase contained ∼90% of combined amounts of iron (Fe), chromium and titanium (Ti).

Rate of Convergence of General Phase Field Equations in Strongly Heterogeneous Media Toward Their Homogenized Limit

Over the last few decades, phase field equations have found increasing applicability in a wide range of mathematical-scientific fields (e.g., geometric PDEs and mean curvature flow, materials science for the study of phase transitions) but also engineering ones (e.g., as a computational tool in chemical engineering for interfacial flow studies). Here, we focus on phase field equations in strongly heterogeneous materials with perforations such as porous media. To the best of our knowledge, we provide the first derivation of error estimates for fourth order, homogenized, and nonlinear evolution equations. Our fourth order problem induces a slightly lower convergence rate, i.e., $\epsilon^{1/4}$, where $\epsilon$ denotes the material's specific heterogeneity, than established for second order elliptic problems (e.g., [V. Zhikov, Dokl. Math., 73 (2006), pp. 96--99, https://doi.org/10.1134/S1064562406010261.]) for the error between the effective macroscopic solution of the (new) upscaled formulation and the so...

The Arrhenius Equation is Still a Useful Tool in Chemical Engineering

The Arrhenius equation correlates the rate of a chemical reaction with the corresponding activation energy, reaction time and reaction temperature, where the latter is measured in Kelvin. Although ...

Continuous flow-microwave reactor: Where are we?

This article presents the different microwave continuous reactors existing, which are reported in literature to carry out chemical synthesis with a more efficient way. It shows how the methods and tools of chemical engineering can be useful and necessary to define, characterize and optimize the microwave reactors. This review scans continuous microwave reactors, by describing the different types of microwave technologies used (multimode, single-mode, coaxial or guided transmission …). It then focuses on the various existing reactor geometries and on the control of the electromagnetic field homogeneity. The problem of temperature measurement and overall instrumentation is also addressed (input power, reflected power, continuous adaptation …).This review scans the most efficient microwave continuous flow reactors existing in the literature and highlights how the microwave technology is used as well as chemical engineering tools. It points out the reactors geometries, the control of the electromagnetic field and the measurement of the physical parameters (Temperature, microwave power, etc.).Finally, the scale-up of continuous-flow microwave reactors is examined through the existing lab-scale and semi industrial pilot plants described in literature.

Determination of Gibbs energies of formation in aqueous solution using chemical engineering tools

Standard Gibbs energies of formation are of primary importance in the field of biothermodynamics. In the absence of any directly measured values, thermodynamic calculations are required to determine the missing data. For several biochemical species, this study shows that the knowledge of the standard Gibbs energy of formation of the pure compounds (in the gaseous, solid or liquid states) enables to determine the corresponding standard Gibbs energies of formation in aqueous solutions. To do so, using chemical engineering tools (thermodynamic tables and a model enabling to predict activity coefficients, solvation Gibbs energies and pKa data), it becomes possible to determine the partial chemical potential of neutral and charged components in real metabolic conditions, even in concentrated mixtures.

The dissipation rate of news in online mass media evaluated by chemical engineering and process control tools

Basic chemical engineering and processes control tools were utilized to describe the flow of news information in the Internet. Data on the news coverage of scientific articles provided by Altmetric were analyzed for six chemistry journals. The timecourse of the news was modeled using linear system dynamics, resulting in an interpretable description of the timescales involved. The model was additionally tested by applying it to the flow of nonscientific news information. An investigation on the distribution of news items per scientific article further identified online news generation as a preferential growth process. The model results allowed a discussion on scientific impact in public media and an analysis on how this impact can be influenced by authors and journals. In respect to the field of engineering, the work shows that traditional ChemE and process control tools developed for the abstraction of physical and chemical systems can also be utilized to describe social and information related processes. © 2015 American Institute of Chemical Engineers AIChE J, 62: 1104–1111, 2016

ChemInform Abstract: Engineering in Direct Synthesis of Hydrogen Peroxide: Targets, Reactors and Guidelines for Operational Conditions

AbstractReview: 150 refs.

Engineering in direct synthesis of hydrogen peroxide: targets, reactors and guidelines for operational conditions

The demand for hydrogen peroxide is booming since it is considered as one of the most environmentally friendly and versatile chemical oxidants available and has a wide range of applications. The annual market, close to 3000 kt per year being produced via the auto-oxidation process (with 2-ethyl anthraquinone (traditional) or amyl anthraquinone for mega-plants), is mostly supplied by the company Solvay (30%), followed by Evonik (20%) and Arkema (13%). Nevertheless, the dream of a direct synthesis process is close to a century old and it has gained momentum in research efforts during the last decade with more than 15 groups active in the world. In this review, we focus the discussion on the targets, e.g. plant tonnage, the reactors and the most feasible industrial operational conditions, based on our experience and point of view using the chemical engineering tools available. Thus, direct synthesis can be competitive when on-site production is required and capacities less than 10 kt per year are demanded. The total investment cost should be approximately 40.3 ± 12.1 MM$ (in 2012) for a 10 kt per year size process to be comparable to the traditional process in terms of costs. Moreover, all kinds of reactors used are hereby discussed emphasizing the pros and cons; the most common ones are batch and semi-continuous modes of operation. However, at the moment, demonstrations of continuous operations as well as carefully determined kinetics are needed in order to scale up the process. Finally, operational conditions, including the catalyst composition (active metal, oxidation state and support), promoters (halides and acids–pH–isoelectric point), solvents, pressure and temperature need to be carefully analysed. In our opinion, as we try to show here, H2O2 direct synthesis is a competitive process and is ready for larger scale demonstration. Also, more than a hundred patents within the area support this claim, although the barriers of technology demonstration and further licensing are still pending.

Synthetic Biology Innovation Will Spur More Efficient Chemical Engineering

Synthetic biology is a new tool in chemical engineering that has already shown success in developing bio-based alternatives to chemicals typically derived from petroleum. A recent technical advance in synthetic biology stands to make this the design and development method of choice for chemical engineers.

Problem-solving and concept integration using a computational tool in first-year undergraduate chemical engineering

A computational MATLAB Tool with examples based on typical Chemical Engineering (ChE) problems has been designed. The Tool is intended to assist students with the development of problem-solving skills and to encourage cross-course learning in the first-year ChE curriculum. The Tool is module-based, with each module consisting of problems from a first-year ChE course. Each of the problems is solved with emphasis placed on the specific problem-solving methodology followed to reach the solution and includes an application of MATLAB, the programming language taught in the first-year ChE computational programming course. Extension problems for additional practice are also included. The Tool has been specifically designed for first-year students to help them develop their programming skills early in their education and to encourage connections between the first-year ChE courses. The Tool has been used by first-year ChE students and their feedback is presented. A copy of the MATLAB Tool can be obtained by contacting the corresponding author.

Thermodynamic Property Slopes from Primary Measurements

This paper lists the values of slope properties of entropy, enthalpy and exergy along isotherms, isochors, isobars and isentropes in terms of properties that can be primarily measured, namely pressure, volume, temperature, their slopes derivable from equations of state and one of the specific heats in the ideal gas state. It is also shown that all these slopes can be expressed in terms of a coefficient of thermal expansion and isothermal compressibility as well. These could be useful as an educational tool in chemical and mechanical engineering.

Exploratory analysis of excitation–emission matrix fluorescence spectra with self-organizing maps—A tutorial

Large datasets are common in chemical and environmental engineering applications and tools for their analysis are in great demand. Here, the outputs of a series of fluorescence spectroscopy analyses are utilised to demonstrate the application of the self-organising map (SOM) technique for data analysis. Fluorescence spectroscopy is a well-established technique of organic matter fingerprinting in water. The technique can provide detailed information on the physico-chemical properties of water. However, analysis of fluorescence spectra requires the application of robust statistical and computational data pre-processing and analysis tools. This paper presents a tutorial for training engineering postgraduate researchers in the use of SOM techniques using MATLAB ®. Via a tutorial, the application of SOM to fluorescence spectra and, in particular, the characterisation of organic matter removal in water treatment, is presented. The tutorial presents a step-by-step example of the application of SOM to fluorescence data analysis and includes the source code for MATLAB ®, together with presentation and discussion of the results. With this tutorial we hope to popularise this robust pattern recognition technique for fluorescence data analysis and large data sets in general, and also to provide educational practitioners with a novel tool with which to train engineering students in SOM.

Independent research as a teaching tool in graduate chemical reaction engineering. Case study: Modelling isomerization of unsaturated fatty acids with catalyst deactivation

Chemical reaction engineering is one of the most important courses in any chemical engineering program, dealing with many fundamental concepts that can be applied in a variety of fields related to chemical engineering. Given the broad variety of backgrounds of the students in graduate programs, teaching complex reaction engineering applications is challenging. In this paper, we report on our experience in including a robust and flexible research component in a graduate reaction engineering course. It is suggested that open research questions allow students to become familiar with course content, as well as with other tools required in their graduate programs, thesis writing and later careers. Steps in implementing the research component are presented together with details found to be helpful in designing a successful reaction engineering course. In addition, a representative research project in which a batch reactor was designed for the isomerization of unsaturated fatty acids is presented as a case study.