Chemical Engineering Approach Research Articles

Batch Emulsion Polymerization, a Chemical Engineering Approach

In industry latex products are usually produced in (semi-) batch emulsion polymerisation processes. Good chemical engineering is important to guarantee product quality and to minimise the energy consumption as well as the production of waste material. Our results reveal that sufficient emulsification is essential for the control of the polymerisation process. For the emulsifier used in this study, the colloidal stability of the polymer particles is mainly governed by the physico-chemical properties of the reaction mixture. Brownian coagulation appears to be the predominant mechanism.

Abstract B49: Using small molecule activators of PP2A to negatively regulate c-myc in small cell lung cancer

Abstract Treatment for small cell lung cancer (SCLC) is based on combination chemotherapy with a five-year survival of just 10-13% for patients with limited disease. A common molecular alteration in SCLC is the overexpression of MYC family oncogenes, occurring in 18-31% of SCLCs, and more commonly in chemo-refractory disease. Several FDA approved tricyclic antidepressants were recently shown to have efficacy in SCLC cell lines based on G-protein coupled receptor (GPCR) mediated effects, and a phase IIa trial is testing one of these compounds. A reverse chemical engineering approach was employed to remove GPCR pharmacology from the tricyclic family of compounds, generating a novel class known as SMAPs, small molecule activators of protein phosphatase 2A (PP2A). PP2A is a tumor suppressor with an established negative regulatory action on c-myc. Thus, it was hypothesized that SMAPs could represent a novel treatment approach in SCLC via activation of PP2A with downstream effects on targets including c-myc. A genetic signature score for SMAP efficacy predicted broad activity of these compounds in SCLC and identified myc family pathways as strongly correlated to IC50 in a panel of tumor cell lines. Incubation with the SMAP TRC-794 was shown to induce apoptosis in the SCLC cell lines H82 and H69 as seen by induction of annexin V as well as parp and caspace-3 cleavage. Loss of c-myc in the c-myc amplified cell line H82 was observed in a dose dependent manner at 24hrs. Loss of c-myc was observed by 6 hours of drug treatment in H82 and H2081 cells. Supporting a PP2A dependent mechanism, molecular effects on c-myc in H82 were partially reversed with the phosphatase inhibitor okadaic acid. IC50s for these cell lines were similar to those for a lung adenocarcinoma line with established in vivo sensitivity to TRC-794. TRC-1154, a more potent SMAP, was shown to produce statistically significant tumor growth inhibition compared to vehicle control in a xenograft model when orally dosed at 100mg/kg daily. In summary, SMAPs may represent a viable treatment approach in SCLC, possibly via a PP2A mediated negative regulation of c-myc. Citation Format: Benjamin Jonathan Wolpaw, Goutham Narla, Shashank Cheemalavagu. Using small molecule activators of PP2A to negatively regulate c-myc in small cell lung cancer. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr B49.

Residence time distributions in a co‐kneader: A chemical engineering approach

In this article, we have studied the residence time distributions (RTD) in a modular co‐kneader. Several papers have already addressed the co‐kneader modeling and operating mode but there is still a lack of experimental data on RTD. To investigate the RTD, we have used a colored tracer dispersed in polypropylene (PP) that was injected in the flow during the compounding of neat PP. The effect of operating parameters such as temperature, feed rate, and screw configuration was investigated, focusing on the influence of mixing and conveying elements in a zone where the polymer is molten. As can be expected, results on various screw configurations show that increasing the number of kneading elements makes the RTD longer. More interestingly, for a defined set of elements, their position does not change the experimental RTD. A chemical engineering approach was used to model the RTD, with an equation derived from a cascade of continuous stirred tank reactors. The model allows to retrieve an elementary RTD for each section of a defined type of elements and to propose a law for their combination in good agreement with experiments. POLYM. ENG. SCI., 55:1237–1245, 2015. © 2015 Society of Plastics Engineers

Chelation technology: a promising green approach for resource management and waste minimization.

Green chemical engineering recognises the concept of developing innovative environmentally benign technologies to protect human health and ecosystems. In order to explore this concept for minimizing industrial waste and for reducing the environmental impact of hazardous chemicals, new greener approaches need to be adopted for the extraction of heavy metals from industrial waste. In this review, a range of conventional processes and new green approaches employed for metal extraction are discussed in brief. Chelation technology, a modern research trend, has shown its potential to develop sustainable technology for metal extraction from various metal-contaminated sites. However, the interaction mechanism of ligands with metals and the ecotoxicological risk associated with the increased bioavailability of heavy metals due to the formation of metal-chelant complexes is still not sufficiently explicated in the literature. Therefore, a need was felt to provide a comprehensive state-of-the-art review of all aspects associated with chelation technology to promote this process as a green chemical engineering approach. This article elucidates the mechanism and thermodynamics associated with metal-ligand complexation in order to have a better understanding of the metal extraction process. The effects of various process parameters on the formation and stability of complexes have been elaborately discussed with respect to optimizing the chelation efficiency. The non-biodegradable attribute of ligands is another important aspect which is currently of concern. Therefore, biotechnological approaches and computational tools have been assessed in this review to illustrate the possibility of ligand degradation, which will help the readers to look for new environmentally safe mobilizing agents. In addition, emerging trends and opportunities in the field of chelation technology have been summarized and the diverse applicability of chelation technology in metal extraction from contaminated sites has also been reviewed.

Magnetic nanowire synthesis: A chemical engineering approach

Bimetallic one‐dimensional cobalt–nickel magnetic nanowires capped on both sides with conical heads were synthesized using the polyol process. Then, the process was scaled up to produce magnetic nanowires in sample aliquots of approximately 20 g. The scale‐up strategy involved improving the mixing reagents using either axial or radial mixing configurations and was experimentally validated by comparing the structural and magnetic properties of the resulting nanowires. The results indicated a connection between the flow patterns and the size and shape of the nanowires. When a Rushton turbine was used, shorter nanowires with unconventional small heads were obtained. Because the demagnetizing field is strongly localized near or inside these heads, the coercive field was enhanced nearly twofold. These results were confirmed by micromagnetic simulations using isolated nanowires. In addition, the development of flow patterns at the small and pilot scales was predicted and compared using three‐dimensional turbulent computational fluid dynamics simulations. © 2014 American Institute of Chemical Engineers AIChE J, 61: 304–316, 2015

Ferroelectric Sm-doped BiMnO3 thin films with ferromagnetic transition temperature enhanced to 140 K.

A combined chemical pressure and substrate biaxial pressure crystal engineering approach was demonstrated for producing highly epitaxial Sm-doped BiMnO3 (BSMO) films on SrTiO3 single crystal substrates, with enhanced magnetic transition temperatures, TC up to as high as 140 K, 40 K higher than that for standard BiMnO3 (BMO) films. Strong room temperature ferroelectricity with piezoresponse amplitude, d33 = 10 pm/V, and long-term retention of polarization were also observed. Furthermore, the BSMO films were much easier to grow than pure BMO films, with excellent phase purity over a wide growth window. The work represents a very effective way to independently control strain in-plane and out-of-plane, which is important not just for BMO but for controlling the properties of many other strongly correlated oxides.

Combinatorially Designed Lipid‐like Nanoparticles for Intracellular Delivery of Cytotoxic Protein for Cancer Therapy

An efficient and safe method to deliver active proteins into the cytosol of targeted cells is highly desirable to advance protein-based therapeutics. A novel protein delivery platform has been created by combinatorial design of cationic lipid-like materials (termed "lipidoids"), coupled with a reversible chemical protein engineering approach. Using ribonuclease A (RNase A) and saporin as two representative cytotoxic proteins, the combinatorial lipidoids efficiently deliver proteins into cancer cells and inhibit cell proliferation. A study of the structure-function relationship reveals that the electrostatic and hydrophobic interactions between the lipidoids and the protein play a vital role in the formation of protein-lipidoid nanocomplexes and intracellular delivery. A representative lipidoid (EC16-1) protein nanoparticle formulation inhibits cell proliferation in vitro and suppresses tumor growth in a murine breast cancer model.

Kinetic study of 4-nitrophenol photocatalytic degradation over a Zn2+ doped TiO2 catalyst prepared through an environmentally friendly aqueous sol–gel process

• Kinetic study of 4-NP photocatalytic degradation under artificial light was performed. • A pseudo-first order kinetic model was adjusted on the experimental data. • Apparent reaction rate constant and global apparent activation energy were estimated. • A mechanism was proposed to describe the reaction at a molecular scale. • Statistical validations of the pseudo-first order model was successfully performed. A kinetic study of the photocatalytic degradation of 4-nitrophenol (4-NP) under UV–visible light (330 nm < λ < 800 nm) has been performed via a rigorous chemical engineering approach over a Zn 2+ doped TiO 2 catalyst prepared through an environmentally friendly aqueous sol–gel process. The experiments have been performed at three temperatures to enable the global activation energy to be estimated. The influence of the illumination intensity has also been considered. The possibility of internal and external diffusion limitations has been studied and the results obtained demonstrated that there is no diffusional limitation during the photocatalytic degradation of the 4-NP using the selected catalyst. Therefore, the apparent specific reaction rate measured corresponds to the actual reaction rate of the chemical reaction. Parameter adjustments show that the kinetic model that provides the best fit to the experimental data corresponds to a first order reaction. A sequence of elementary steps has been considered and a pseudo-steady state approach based upon the stationary state hypothesis for reaction intermediates has been applied to obtain a kinetic rate expression in agreement with the experimental data. The mean values of the reaction rate constant found at 283 K, 288 K and 293 K are respectively equal to k ‾ 1 = 0.094 ± 0.003 m 3 h −1 kg catalyst - 1 ; k ‾ 2 = 0.119 ± 0.004 m 3 h −1 kg catalyst - 1 and k ‾ 3 = 0.150 ± 0.023 m 3 h −1 kg catalyst - 1 and the global activation energy of the degradation reaction was evaluated as 40 kJ mol −1 . A phenomenological kinetic mechanism is proposed to describe the reaction at a molecular scale. Finally, statistical validations and residuals analysis have been performed to confirm that the first order model is suitable to represent the 4-NP photocatalytic degradation over time. Such studies are essential to design a reactor for water pollutant degradation on an industrial scale.

Development of P22 viral capsid nanocomposites as anti-cancer drug, bortezomib (BTZ), delivery nanoplatforms.

Genetic and chemical engineering approaches are used to employ P22 viral capsids as nanoplatforms for developing an efficient delivery vehicle. Catechol ligands are chemically attached to the interior surface of P22 viral capsid for subsequent encapsulation of an anticancer drug, bortezomib (BTZ), through boronic acid-diol complexation. For targeted delivery, hepatocellular carcinoma (HCC)-targeting peptide (SP94, SFSIIHTPILPL) is synthesized and chemically conjugated to the exterior surface of the P22 viral capsid nanocomposites. Effective targeted delivery of synthesized P22 viral capsid nanocomposites is demonstrated by fluorescent cell imaging and the efficacy of delivered P22 viral capsid nanocomposites is evaluated using a cell viability assay.

Metal Recovery from Hydroprocessing Spent Catalyst: A Green Chemical Engineering Approach

The present study aims to develop an ecofriendly, chelant-assisted extraction methodology for significant recovery of heavy metals (cobalt (Co), molybdenum (Mo)) from hydroprocessing spent catalyst. Ethylene diamine tetraacetic acid (EDTA) was employed for metal mobilization in the extraction process. The possibility of internal and external mass transfer resistance was investigated to improve the diffusion rate of reactants, while kinetic aspects were studied to achieve thermodynamic equilibrium for the process. Percentage distribution of various protonation stages of EDTA was explored to understand the conjugate base and ligand precursor and to improve the effect of reaction pH on extraction efficiency. Extraction of 80.4% Co and 84.9% Mo was achieved at optimum reaction conditions. Selective precipitation of metals was attained according to maximum solubility of metal oxides at different pH regions. Efforts were also made to recycle the recovered EDTA, recovered support material, and extracted metals. ...

CO2chemical conversion to useful products: An engineering insight to the latest advances toward sustainability

In the fossil-fuel-based economies, current remedies for the CO2 reduction from large-scale energy consumers (e.g. power stations and cement works) mainly rely on carbon capture and storage, having three proposed generic solutions: post-combustion capture, pre-combustion capture, and oxy fuel combustion. All the aforementioned approaches are based on various physical and chemical phenomena including absorption, adsorption, and cryogenic capture of CO2. The purified carbon dioxide is sent for the physical storage options afterwards, using the earth as a gigantic reservoir with unknown long-term environmental impacts as well as possible hazards associated with that. Consequently, the ultimate solution for the CO2 sequestration is the chemical transformation of this stable molecule to useful products such as fuels (through, for example, Fischer–Tropsch chemistry) or polymers (through successive copolymerization and chain growth). This sustainably reduces carbon emissions, taking full advantage of CO2-derived chemical commodities, so-called carbon capture and conversion. Nevertheless, the surface chemistry of CO2 reduction is a challenge due to the presence of large energy barriers, requiring noticeable catalysis. This work aims to review the most recent advances in this concept selectively (CO2 conversion to fuels and CO2 copolymerization) with chemical engineering approach in terms of both materials and process design. Some of the most promising studies are expanded in detail, concluding with the necessity of subsidizing more research on CO2 conversion technologies considering the growing global concerns on carbon management. Copyright © 2013 John Wiley & Sons, Ltd.

Structure and function of abscisic acid receptors

The phytohormone abscisic acid (ABA) plays a crucial role in adaptive responses to environmental stresses, such as drought and high salinity, as well as in plant development, such as seed maturation and dormancy. PYR/PYL/RCAR has been identified as a bona fide ABA receptor (ABAR) that constitutes the core regulatory component of ABA signaling networks in plants. Here, we review recent structural and functional studies of the ABAR that have elucidated its activation mechanism, early signaling components, and physiological responses. A crucial event in the receptor's activation was found to be an open-to-closed conformational change in the gate loop of the receptor protein. More recent progress has provided strategies for controlling the gate's closure using chemical agonists or protein engineering approaches.

The dynamics of chemical reactors in porous media

Is ignition or extinction the fate of an exothermic chemical reaction occurring in a bounded region within a heat conductive solid consisting of a porous medium? In the spherical case, the reactor is modeled by a system of reaction-diffusion equations that reduces to a linear heat equation in a shell, coupled at the internal boundary to a nonlinear ODE modeling the reaction region. This ODE can be regarded as a boundary condition. This model allows the complete analysis of the time evolution of the system: there is always a global attractor. We show that, depending on physical parameters, the attractor contains one or three equilibria. The latter case has special physical interest: the two equilibria represent attractors ("extinction" or "ignition") and the third equilibrium is a saddle. The whole system is well approximated by a single ODE, a "reduced" model, justifying the "heat transfer coefficient" approach of Chemical Engineering.

ChemInform Abstract: Drug Development: Longer‐Lived Proteins

AbstractReview: 75 refs.

Large-scale synthesis of multi-walled carbon nanotubes in a continuous inclined mobile-bed rotating reactor by the catalytic chemical vapour deposition process using methane as carbon source

Multi-walled carbon nanotubes (CNTs) were produced in a continuous inclined mobile-bed rotating reactor by the catalytic chemical vapour deposition of methane on a bimetallic Ni–Mo/MgO catalyst whose activity remains constant in the course of time. Measurements performed on the continuous reactor were validated to ensure that the installation worked correctly and that measurements were precise enough. The performance of the reactor was simulated using a model based on the chemical reactor engineering approach. Hypotheses of the model were verified, and a kinetic study was performed to obtain a kinetic rate expression and to determine the catalytic activity as a function of time. The purity level of produced CNTs depends on the desired properties of the product, so the operating conditions are linked to the purity level that is required. A minimal purity level corresponds to high carbon production, and a maximal purity level corresponds to high specific productivity. It was shown that operating conditions had to be fixed to reach a given specific productivity or a given carbon production, and the optimized operating conditions leading to those two opposite purity level objectives were established.

Drug development: longer-lived proteins

Protein therapeutics represent a powerful class of clinically approved drugs for the prevention and treatment of various diseases. Once administered, the biological fate of protein therapeutics is governed by the body's various complex biochemical and biophysical clearance mechanisms, several of which may decrease the drug's circulation time and efficiency. In this tutorial review, we introduce the concepts of physiological protein clearance from the body, and describe several chemical modification and protein engineering approaches used to improve the life span of administered protein therapeutics.

Chemical engineering approach to regenerative medicine

AbstractThe intrinsically multi-factorial pathological trend of spinal cord injury is probably the most important reason behind the absence of efficient therapeutic strategies. Therefore, recent studies suggest the use of new tools combining the delivery of both cells and drugs. Systems which are able to perform multiple controlled delivery of different therapeutic agents have gained particularly strong interest. Hence, in order to avoid trial and error approaches, several studies were performed following the classic chemical engineering multiscale approach: tuning microchemistry to manipulate macro properties in order to satisfy specific medical needs as injectability, low stress on target tissues, ability to retain liquids, capability of carrying living cells, and possibility to control the delivery of drugs. In this framework we focused on injectable agarose-carbomer based hydrogels applying he results of our studies performed in the past two years: in vitro biocompatibility, physical chemical studies, drug delivery transport phenomena investigation, and in vivo biocompatibility in uninjured Brainbow mice.

A chemical engineering approach to cellulose substitution kinetics

A general kinetic model for the substitution of cellulose was developed. The model assesses the differences in the reactivity of the cellulose hydroxyl groups and a decrease in the reactivity as the substitution proceeds. The model predicts the detailed distribution of the different mono (2, 3, 6)-, di (23, 26, 36) – and trisubstituted (236) units as a function of the reaction time. The classical Spurlin distribution is obtained as a special case of the general model. Numerical strategies were developed for the solution and computer simulation of the model. Simulation results were shown to be valid for various reactivity ratios of the hydroxyl groups. The modelling concept was verified with experimental data obtained for carboxymethylation of cellulose in a slurry reactor. The detailed data, which revealed the non-uniform reactivities of the different hydroxyl groups and the decline of the substitution rate with time, were successfully described by the mathematical model.

Modelling the passage of food through an animal stomach: A chemical reactor engineering approach

Mathematical models have been extensively used in veterinary science to analyse data collected from experiments measuring the flow of digesta through the gastrointestinal tract (GIT) of ruminants. In this paper a classic two compartment digesta flow model is reformulated into a two compartment CSTR (continuous stir tank reactor) model. A segregated reactor model is then obtained by incorporating ‘non-mixing’ stagnant regions into the ideal CSTR model. The ability to incorporate non-ideal mixing into the model allows a more accurate representation of the conditions within the GIT. In analyzing this model our main focus is on the cumulative excretion curve, as this is used to estimate the mean residence time through the GIT. The mean residence time is an important indicator of animal nutrition, directly affecting the feeding strategy of an animal. The effects of stagnant regions in a ‘two stomach’ GIT model are investigated by comparing the cumulative excretion curve with that obtained from an equivalent ideal ‘two stomach’ GIT model. This comparison characterises a trend that non-ideal mixing delays the excretion of waste from the GIT. The effect upon the cumulative excretion curve of small changes in parameter values is then investigated. Small changes in the size of the first stomach, and the division of the initial digesta ingested between the ‘well-mixed’ and stagnant regions of the first stomach, are found to substantially effects the cumulative excretion of digesta from the GIT of a ruminant animal. This investigation is a good example of the applications of chemical engineering to a problem outside the traditional definition of the discipline. 2 In the nomenclature a subscript i refers to the ith compartment of the reactor.

Hydroformylation of 1-Octene Using [Bmim][PF6]−Decane Biphasic Media and Rhodium Complex Catalyst: Thermodynamic Properties and Kinetic Study

A chemical reaction engineering approach is reported to investigate the biphasic hydroformylation of 1-octene using [bmim][PF6] ionic liquid. It is based both on a process parameter investigation (temperature, concentrations, and pressures) and a thermodynamic study of the reaction medium (gas−liquid and liquid−liquid equilibria). Initial rate data show complex behavior with respect to operating parameters and are best described by a rate equation based on a mechanistic model. Complete reaction scheme including isomerization is then modeled accounting from the time dependent concentration of the organic substrates measured in organic phase and recalculated in ionic liquid phase from liquid−liquid equilibria.