Continuous Flow Stirred Tank Reactor Research Articles

Mathematical modeling and kinetics of batch and continuous electro-catalytic oxidation of pharmaceutical-contaminated wastewater

An accurate yet simple model is the key to the design and control of intricate electro-catalytic oxidation of pharmaceutical contaminated wastewater. For both batch and unsteady-state continuous flow stirred tank reactors (CSTR), batch reactor models have been used earlier. Further, these models do not correlate rate to the operating conditions, and consider pseudo-first/second-order kinetics. Here, first-principles models are proposed by formulating unsteady-state mass balances, modifying them to attain realistic final conditions, and incorporating fractional variable-order kinetics. Following integral analysis, analytical solutions are obtained. These are independently applicable to design, unlike a numerical solution. Nonlinear regression is performed to estimate the model parameters from the transient experimental data. The simulations yield markedly accurate model parameters together with a better fit to the experimental data of Ti/RuO2-mediated amoxicillin-trihydrate electro-oxidation, for CSTR and batch reactors. For the batch reactor, the operating conditions are varied one at a time. Their effects on the model parameters are elucidated based on the oxidant and transformation species formed. The computed optimum model parameters are: rate constant 3.318 × 10−3 mg−0.092 m1.276 min−1, order 1.092, initial rate 4.032 × 102 mg m−2 min−1, and final conversion 90.6% in 180 min. The corresponding operating conditions are: pH 2.0, feed 50 mg L−1, electrolyte 2 g L−1, and current 1 A. A simple generalized power-law correlation, associating rate to the operating conditions, is then estimated. Statistical analysis of these models using central composite design delivers R2 0.99, predicted R2 0.96, and optimum set close to the above. The corresponding sensitivity analysis and generalized correlation, both show applied current to be the most significant operating condition. The dynamic modeling approaches proposed here can be extended to model, control, and scale-up complex reaction systems.

Polynomial chaos expansions on principal geodesic Grassmannian submanifolds for surrogate modeling and uncertainty quantification

In this work we introduce a manifold learning-based surrogate modeling framework for uncertainty quantification in high-dimensional stochastic systems. Our first goal is to perform data mining on the available simulation data to identify a set of low-dimensional (latent) descriptors that efficiently parameterize the response of the high-dimensional computational model. To this end, we employ Principal Geodesic Analysis on the Grassmann manifold of the response to identify a set of disjoint principal geodesic submanifolds, of possibly different dimension, that captures the variation in the data. Since operations on the Grassmann require the data to be concentrated, we propose an adaptive algorithm based on Riemannian K-means and the minimization of the sample Fréchet variance on the Grassmann manifold to identify “local” principal geodesic submanifolds that represent different system behavior across the parameter space. Polynomial chaos expansion is then used to construct a mapping between the random input parameters and the projection of the response on these local principal geodesic submanifolds. The method is demonstrated on four test cases, a toy-example that involves points on a hypersphere, a Lotka-Volterra dynamical system, a continuous-flow stirred-tank chemical reactor system, and a two-dimensional Rayleigh-Bénard convection problem.

Increasing urine nitrification performance with sequential membrane aerated biofilm reactors

This study aimed to investigate whether separating organics depletion from nitrification increases the overall performance of urine nitrification. Separate organics depletion was facilitated with membrane aerated biofilm reactors (MABRs). The high pH and ammonia concentration in stored urine inhibited nitrification in the first stage and therewith allowed the separation of organics depletion from nitrification. An organics removal of 70 % was achieved at organic loading rates in the influent of 3.7 gCOD d−1 m−2. Organics depletion in a continuous flow stirred tank reactor (CSTR) for organics depletion led to ammonia stripping through diffused aeration of up to 13 %. Using an MABR, diffusion into the lumen amounted for 4 % ammonia loss only. In the MABR, headspace volume and therefore ammonia loss through the headspace was negligible. By aerating the downstream MABR for nitrification with the off-gas of the MABR for organics depletion, 96 % of the ammonia stripped in the first stage could be recovered in the second stage, so that the overall ammonia loss was negligibly low. Nitrification of the organics-depleted urine was studied in MABRs, CSTRs, and sequencing batch reactors in fed batch mode (FBRs), the latter two operated with suspended biomass. The experiments demonstrated that upstream organics depletion can double the nitrification rate. In a laboratory-scale MABR, nitrification rates were recorded of up to 830 mgNL−1 d−1 (3.1 gN m−2 d−1) with ambient air and over 1500 mgNL−1 d−1 (6.7 gN m−2 d−1) with oxygen-enriched air. Experiments with a laboratory-scale MABR showed that increasing operational parameters such as pH, recirculation flow, scouring frequency, and oxygen content increased the nitrification rate. The nitrification in the MABR was robust even at high pH setpoints of 6.9 and was robust against process failures arising from operational mistakes. The hydraulic retention time (HRT) required for nitrification was only 1 to 2 days. With the preceding organics depletion, the HRT for our system requires 2 to 3 days in total, whereas a combined activated sludge system requires 4 to 8 days. The N2O concentration in the off-gas increases with increasing nitrification rates; however, the N2O emission factor was 2.8 % on average and independent of nitrification rates. These results indicate that the MABR technology has a high potential for efficient and robust production of ammonium nitrate from source-separated urine.

Thermodynamics of Growth in Open Chemical Reaction Networks.

We identify the thermodynamic conditions necessary to observe indefinite growth in homogeneous open chemical reaction networks (CRNs) satisfying mass action kinetics. We also characterize the thermodynamic efficiency of growth by considering the fraction of the chemical work supplied from the surroundings that is converted into CRN free energy. We find that indefinite growth cannot arise in CRNs chemostatted by fixing the concentration of some species at constant values, or in continuous-flow stirred tank reactors. Indefinite growth requires a constant net influx from the surroundings of at least one species. In this case, unimolecular CRNs always generate equilibrium linear growth, i.e., a continuous linear accumulation of species with equilibrium concentrations and efficiency one. Multimolecular CRNs are necessary to generate nonequilibrium growth, i.e., the continuous accumulation of species with nonequilibrium concentrations. Pseudounimolecular CRNs-a subclass of multimolecular CRNs-always generate asymptotic linear growth with zero efficiency. Our findings demonstrate the importance of the CRN topology and the chemostatting procedure in determining the dynamics and thermodynamics of growth.

Industrial Scale Reactor Design for Al2O3 Production from Bauxite and Sodium Hydroxide Solution

The aim of this study is to design a reactor that can optimize the production of Al2O3 from the reaction between bauxite and sodium hydroxide solution on an industrial scale. The type of reactor used for the production of Al2O3 nanoparticles is a Continuous Flow Stirred – Tank Reactor (CSTR). The method used in this study is to perform computational analysis and calculation of the dimensions of the reactor and stirrer as well as the mass balance, using basic calculation with Microsoft Excel application. To produce Al2O3 nanoparticles on an industrial scale, three reactor units and three stirrers are required. Based on the calculation results, it is found that the first and second reactors have volume 2,9689 m3 with height 5,0424 ft and require a stirrer with six blades with an angle of 45owhich has power 50 Hp. The third reactor has volume 4,3387 m3 with height 9,0847 ft and requires one stirrer with six blades with an angle of 45o which has a power 75 Hp. The computational calculation results in this study can be used as an overview in designing a reactor to produce Al2O3nanoparticles from bauxite and sodium hydroxide solution on an industrial scale

ADM1-Based Modeling of Biohydrogen Production through Anaerobic Co-Digestion of Agro-Industrial Wastes in a Continuous-Flow Stirred-Tank Reactor System

Biological treatment is a promising alternative for waste management considering the environmentally sustainable concept that the European Union demands. In this direction, anaerobic digestion comprises a viable waste treatment process, producing high energy-carrier gases such as biomethane and biohydrogen under certain operating conditions. The mathematical modeling of this bioprocess can be used as a valuable tool for process scale-up with cost-effective implications. The scope of this work was the evaluation of the well-established Anaerobic Digestion Model 1 (ADM1) for use in two-stage anaerobic digestion of agro-industrial waste. Certain equations for the description of the metabolic pathways for lactate and bioethanol accumulation were implemented in the existing mechanistic model in order to enhance the model’s accuracy. The model presents a high estimation ability regarding the final product (H2 and biogas) reaching the same maximum value for the theoretical as the experimental data of these products (0.0012 and 0.0036 m3/d, respectively). The adapted ADM1 emerges as a useful instrument for designing anaerobic co-digestion processes with the goal of achieving high yields in fermentative hydrogen production, considering mixed biomass growth mechanisms.

Tailoring the active phase of CoO-based thin-film catalysts in order to tune selectivity in CO2 hydrogenation.

In this study, we prepared CoO-based thin films deposited on Kanthal steel wire gauze meshes by plasma-enhanced chemical vapor deposition. X-ray photoelectron spectroscopy (XPS) analysis revealed a structure characterized by a combination of cobalt oxide and metallic cobalt embedded within a carbon matrix. Our primary objective was to gain insights into the roles of Co0 and CoO in CO2 hydrogenation reactions. To achieve this, the performance of the thin-film CoO-based catalyst with an initial atomic ratio of CoO/Co0 at 10.2 was compared with two series of the thin-film catalysts that underwent pre-reduction processes at 350 °C for durations of 30 and 60 minutes, resulting in atomic ratios of CoO/Co0 at 3.1 and 1.1, respectively. Subsequently, catalytic tests were conducted in a continuous flow stirred tank reactor operating at temperatures ranging from 250 °C to 400 °C. Our findings indicate that CoO plays a significant role in activating the CO2 methanation reaction which can be due to the high hydrogen coverage of CoO, while Co0 is the active phase in the reverse water-gas shift reaction. Results highlight the importance of oxidized cobalt for hydrogen adsorption and dissociation in CO2 hydrogenation for CH4 formation.

A new reconstruction-based method using local Mahalanobis distance for incipient fault isolation and amplitude estimation

Faulty variable isolation and amplitude estimation are of great importance to support the decision-making for system maintenance but lack sufficient studies, especially concerning the challenge of incipient faults with tiny amplitude. The reconstruction-based contribution (RBC) idea is commonly used for faulty variable isolation and fault amplitude estimation but usually suffers from low accuracy performance when facing the incipient faults challenge due to the use of insensitive detection indexes. Therefore, this paper proposes an improved reconstruction-based approach using the highly sensitive index named local Mahalanobis distance (LMD) for incipient fault isolation and amplitude estimation. The novel RBC approach retains the advantages of LMD, e.g., high sensitivity to incipient faults, robustness to outliers, and ability to handle non-Gaussian data, and is also available for multiple faulty variables isolation. The performance evaluation of the proposed methods using the benchmark case of the Continuous-flow Stirred Tank Reactor (CSTR) process shows that this approach has high isolation and estimation accuracy for both single and multiple faults. Thanks to a comparative study, it can be highlighted that for both faulty variables isolation and fault amplitude estimation tasks, our proposal outperforms the state-of-the-art RBC-based methods using different detection indexes: the combined index of PCA, conventional Mahalanobis distance, and augmented Mahalanobis distance.

Seawater biodesalination treatment using Phormidium keutzingianum in attached growth-packed bed continuous flow stirred tank reactor

Water scarcity is increasing worldwide due to rising population which is creating opportunities to unlock alternative green desalination techniques for seawater, such as biodesalination. Therefore, this study presents the utilization of the Phormidium keutzingianum strain in an attached growth-packed bed reactor to treat seawater in real-time in a continuous-flow stirred tank reactor for biodesalination. Two reactors were designed and developed, in which zeolites were used as the support media for the attached growth. The experiment was conducted in an open outdoor environment with a continuous air flow rate of 3 mL/min and two hydraulic retention times (HRT) of 7 and 15 d. Parameters such as the pH, chloride ion concentration, total organic carbon (TOC), and optical density were monitored regularly. The pH change was not significant in either reactor and remained within the range of 7.25–8.0. Chloride ion removal was the most crucial component of biodesalination efficiency, with d 7 removal efficiencies of approximately 40% and 32% for reactors 1 and 2, respectively. Reactor 1 exhibited a TOC reduction of 36% within the first 10 d at a HRT of 7, and when the HRT was set to 15 d, a TOC removal efficiency of 89% was achieved on d 53. For reactor 2, a TOC removal efficiency of approximately 81% was achieved on d 11 at HRT 7, and it reduced to less than 50% at an HRT of 15. The chloride ion and TOC removal phenomena were similar in both reactors. The optical density (OD) showed low measurement recordings, ranging from 0.005 to 0.01, indicating low cell detachment in the seawater effluent. Therefore, using the attached growth method for the biodesalination of seawater is feasible. Furthermore, biomass harvesting in attached growth systems is easier than that in suspension growth systems.

Highly efficient and robust treatment of low C/N actual domestic sewage via integrated fermentation, partial-nitrification, partial-denitrification and anammox (IFPNDA)

For achieving efficient and robust treatment of domestic sewage with C/N around 2.8, this study innovatively developed an integrated fermentation, partial-nitrification, partial-denitrification and anammox (IFPNDA) process based on the Anaerobic Baffled Reactor and Continuous-flow Stirred Tank Reactor (ABR-CSTR) bioreactor. Desirable N-removal efficiency of 87.5 ± 2.1% was obtained without external organics, correspondingly effluent total nitrogen (TN) concentration reached 6.1 ± 0.7 mg/L. The N-removal stability was greatly facilitated by the effective linkage between partial nitrification (PN) process and partial denitrification (PD) process in emergency. Highly enriched hydrolytic bacteria (6.9%) and acidogenic bacteria (5.7%) in A1, especially Comamonas (2.8%) and Longilinea (3.5%), induced the significant increase of volatile fatty acids (VFAs) in domestic sewage. Thauera (6.1%) in A2 and Nitrosomonas (5.4%) in A3 acted as the dominant flora of nitrite supplies for anammox in IFPNDA process. Candidatus_Brocadia (2.4%) dominated the advanced nitrogen removal. The IFPNDA process exhibited much potential for achieving energy neutrality during wastewater treatment.

Phenanthrene removal from a spent sediment washing solution in a continuous-flow stirred-tank reactor

The issue of polycyclic aromatic hydrocarbons (PAHs) is widespread in marine sediments involving ecological systems and human health. Sediment washing (SW) has proven to be the most effective remediation approach for sediments polluted by PAHs, such as phenanthrene (PHE). However, SW still raises waste handling concerns due to a considerable amount of effluents generated downstream. In this context, the biological treatment of a PHE- and ethanol-containing spent SW solution can represent a highly efficient and environmentally-friendly strategy, but its knowledge is still scarce in scientific literature and no studies have so far been conducted in continuous mode. Therefore, a synthetic PHE-polluted SW solution was biologically treated in a 1 L aerated continuous-flow stirred-tank reactor for 129 days by evaluating the effect of different pH values, aeration flowrates and hydraulic retention times as operating parameters over five successive phases. A PHE removal efficiency of up to 75–94% was achieved by an acclimated PHE-degrading consortium mainly composed of Proteobacteria, Bacteroidota and Firmicutes phyla through biodegradation following the adsorption mechanism. PHE biodegradation, mainly occurring via the benzoate route due to the presence of PAH-related-degrading functional genes and a phthalate accumulation up to 46 mg/L, was also accompanied by a reduction of dissolved organic carbon and ammonia nitrogen above 99% in the treated SW solution.

Single CSTR can be as effective as an SBR in selecting PHA-storing biomass from municipal wastewater-derived feedstock

A key step for the production of polyhydroxyalkanoates (PHAs) from organic waste streams is the selection of a biomass with a high PHA-storage capacity (selection-step), which is usually performed in sequencing batch reactors (SBR). A major advancement would be to perform such selection in continuous reactors to facilitate the full-scale implementation of PHA production from municipal wastewater (MWW)-derived feedstock. The present study therefore investigates to what extent a simple continuous-flow stirred-tank reactor (CSTR) represents a relevant alternative to anSBR. To this end, we operated two selection reactors (CSTR vs. SBR) on filtered primary sludge fermentate while performing a detailed analysis of the microbial communities, and monitoring PHA-storage over long-term (∼150 days) and during accumulation batches. Our study demonstrates that a simple CSTR is as effective as an SBR in selecting biomass with high PHA-storage capacity (up to 0.65 gPHA gVSS−1) while being 50% more efficient in terms of substrate to biomass conversion yields. We also show that such selection can occur on VFA-rich feedstock containing nitrogen (N) and phosphorus (P) in excess, whereas previously, selection of PHA-storing organisms in a single CSTR has only been studied under P limitation. We further found that microbial competition was mostly affected by nutrient availability (N and P) rather than by the reactor operation mode (CSTR vs. SBR). Similar microbial communities therefore developed in both selection reactors, while microbial communities were very different depending on N availability. Rhodobacteraceae gen. were most abundant when growth conditions were stable and N-limited, whereas dynamic N- (and P-) excess conditions favoured the selection of the known PHA-storer Comamonas, and led to the highest observed PHA-storage capacity. Overall, we demonstrate that biomass with high storage capacity can be selected in a simple CSTR on a wider range of feedstock than just P-limited ones.

Influence of non-equilibrium and nonlinear sorption of 137Cs in soils. Study with stirred flow-through reactor experiments and quantification with a nonlinear equilibrium-kinetic model

This paper addresses the modelling of cesium sorption in non-equilibrium and nonlinear conditions with a two-site model. Compared to the classical Kd approach, the proposed model better reproduced the breakthrough curves observed during continuous-flow stirred tank reactor experiments conducted on two contrasted soils. Fitted parameters suggested contrasted conditions of cesium sorption between 1) equilibrium sites, with low affinity and high sorption capacity comparable to CEC and 2) non-equilibrium sites, with a fast sorption rate (half-time of 0.2–0.3 h), a slow desorption rate (half-time of 3–9 days) and a very low sorption capacity (0.02–0.04% of CEC). Comparison of EK sites densities with sorption capacities derived from the literature suggests that the EK equilibrium and kinetic sites might correspond to ion exchange and surface complexation of soil clay minerals respectively. This work stresses the limits of the Kd model to predict 137Cs sorption in reactive transport conditions and supports an alternative non-equilibrium nonlinear approach.

Peroxy Radical Autoxidation and Sequential Oxidation in Organic Nitrate Formation during Limonene Nighttime Oxidation.

Limonene is an abundant monoterpene released into the atmosphere via biogenic emissions and biomass burning. However, the atmospheric oxidation and secondary organic aerosol (SOA) formation mechanisms of limonene, especially during nighttime, remain largely understudied. In this work, limonene was oxidized synergistically by ozone (O3) and nitrate radicals (NO3) in a flow tube reactor and a continuous flow stirred tank reactor. Upon oxidation, many highly oxidized organic nitrates and nitrooxy peroxy radicals (RO2) were observed in the gas phase within 1 min. Combining quantum chemical calculations with kinetic simulations, we found that the primary nitrooxy RO2 (C10H16NO5) through NO3 addition at the more substituted endocyclic double bond and at the exocyclic double bond (previously considered as minor pathways) can undergo autoxidation with rate constants of around 0.02 and 20 s-1 at 298 K, respectively. These pathways could explain a major portion of the observed highly oxidized organic nitrates. In the SOA, highly oxidized mono- and dinitrates (e.g., C10H17NO7-8 and C10H16,18N2O8-10) make up a significant contribution, highlighting nitrooxy RO2 autoxidation and sequential NO3 oxidation of limonene. The same organic nitrates are also observed in ambient aerosol during biomass burning and nighttime in the southeastern United States. Therefore, the present work provides new insights into the nighttime oxidation of limonene and SOA formation in the atmosphere.

Dynamic adsorption of diclofenac onto a magnetic nanocomposite in a continuous stirred-tank reactor

In this study, a waste-based magnetic activated carbon (MAC) was used for the first time in a continuous-flow stirred tank reactor (CSTR). The aim was to evaluate the dynamic removal of diclofenac (DCF) from water and wastewater. Firstly, the breakthrough curves corresponding to DCF adsorption from distilled water at different feed flow rates and doses of MAC were determined. After selecting the most favourable conditions, namely 0.18 h L−1 flow rate and 400 mg L−1 of MAC, the effect of different aqueous matrices was studied, with the breakthrough curves evidencing a performance decline in wastewater in comparison with distilled water. Finally, the exhausted MAC was magnetically recovered, regenerated by microwave-assisted heating and applied in two subsequent adsorption cycles. The regeneration studies pointed to a decrease of the specific surface area and an improvement of the magnetic retrievability of MAC. After the first regeneration step, just mild effects were observed in the dynamic adsorptive performance of MAC. However, after a second regeneration step, the performance declined ca. 50%. Overall, the results highlight the feasibility of producing waste-based magnetic composites that simultaneously combine high adsorption efficiency under dynamic operation in a CSTR, with easy retrievability and successful one-stage regeneration for further reutilization.

Influent carbon to phosphorus ratio drives the selection of PHA-storing organisms in a single CSTR

Enriching a biomass with a high fraction of polyhydroxyalkanoate-storing organisms (PHA-storers) represents an essential step in the production of PHAs (bioplastics) from municipal wastewater using mixed microbial cultures. A major challenge is however to create selective growth conditions that are favourable to PHA-storers. Our study thus investigates to what extent the influent COD to phosphorus (COD:P) ratio can be used as a tool for the robust selection of PHA-storers in a single continuous-flow stirred-tank reactor (CSTR). Therefore, we operated five CSTRs in parallel, fed with synthetic wastewater (50% acetate - 50% propionate) with different COD:P ratios (200−1000 gCOD gP−1), and performed a detailed analysis of the microbial communities over long-term (30−70 solid retention times). Our study demonstrates that efficient and robust selection of PHA-storers can be achieved in a single CSTR at high influent COD:P ratios. The selective advantage for PHA-storers increases with the influent COD:P ratio, but only if growth conditions remain limited by both C-substrate and P. In contrast, selection performance deteriorates when COD:P ratios are too high and growth conditions are limited by P only. At an optimal COD:P ratio of 800 gCOD gP−1, a stable microbial community consisting of >90% PHA-storers and dominated by Pannonibacter sp. was selected in the long-term. Finally, our results suggest that high COD:P ratios provide a selective advantage to microorganisms with low cellular P requirements, explaining why different PHA-storers (i.e., Xanthobacter sp. vs. Pannonibacter sp.) were selected depending on the influent COD:P ratio (i.e., 200 vs. 800 gCOD gP−1). Overall, our results provide relevant insights for the development of a new approach for selecting PHA-storers, based on the use of a single CSTR and control of the influent COD:P ratio.

An incipient fault diagnosis methodology using local Mahalanobis distance: Fault isolation and fault severity estimation

Recently, a detection methodology based on anchor estimation and the Mahalanobis distance, named the local Mahalanobis distance (LMD) technique, has been proposed for incipient fault detection. As an extension, this paper proposes the LMD based faulty variable isolation and fault severity estimation methods to offer an integrated incipient fault diagnosis solution. The LMD technique has been proved to be highly sensitive to incipient faults, robust to outliers, and free of distribution assumptions. Within the LMD framework, the faulty variable is recognized by analyzing the relative position of faulty samples and their corresponding anchors. Then an analytical expression of fault severity derived from the LMD index is established for the fault severity estimation task. Performance evaluations of the proposed methods based on a benchmark case of the Continuous-flow Stirred Tank Reactor (CSTR) process are provided in this work. The result shows that even for tiny deviation, such as 5dB fault to noise ratio, the total isolation performance still achieves 100% accuracy, and the relative error of two tricky faults in the case of severity estimation is less than 10%. The comparison study of different methods indicates that our solution outperforms divergence based techniques and reconstruction based contribution (RBC) methods for the two tasks.

Photoreduction of Ni2+ under solar and artificial reactors on the hetero-junction (CuFe2O4/ZnO): Comparison between experimental and theoretical results

The photocatalytic Ni2+ reduction on the hetero-junction CuFe2O4/ZnO (1/1) in both plug flow reactor (PFR) and continuous flow stirred tank reactor (CFSTR), is optimized with respect to Ni2+ initial concentration (Co= 30 ppm), pH ~ 7 and liquid flow (100 mL min−1). The spinel CuFe2O4 and the wurtzite ZnO were prepared by nitrate route and characterized photoelectrochemically. The photoelectrochemical characterization predicts the injection of electrons from the spinel CuFe2O4 to the wurtzite ZnO which are subsequently transferred to adsorbed Ni2+ ions. To obtain high efficiencies, the optimal operating conditions for the kinetics of the reduction of the Ni2+ are determined and compared to the theoretical model. Under sunlight, the Ni2+ reduction is improved up to 96% because of the additional UV photons which activate ZnO. The Ni2+ reduction follows a pseudo-first order kinetic with a rate constant of 1.63 × 10−2 min−1 according to Langmuir-Hinshelwood. The photoactivity is slightly lowered; under artificial illumination for an optimum concentration of 30 ppm. The comparison with the theoretical model gave a reduction of 99% for a Ni2+ concentration of 30 ppm.

Design and Application of Hierarchical Multi-objective Predictive Control for Continuous Flow Stirred Tank Reactor

Design and Application of Hierarchical Multi-objective Predictive Control for Continuous Flow Stirred Tank Reactor

History Dependence in a Chemical Reaction Network Enables Dynamic Switching.

This work describes an enzymatic autocatalytic network capable of dynamic switching under out-of-equilibrium conditions. The network, wherein a molecular fuel (trypsinogen) and an inhibitor (soybean trypsin inhibitor) compete for a catalyst (trypsin), is kept from reaching equilibria using a continuous flow stirred tank reactor. A so-called 'linear inhibition sweep' is developed (i.e., a molecular analogue of linear sweep voltammetry) to intentionally perturb the competition between autocatalysis and inhibition, and used to demonstrate that a simple molecular system, comprising only three components, is already capable of a variety of essential neuromorphic behaviors (hysteresis, synchronization, resonance, and adaptation). This research provides the first steps in the development of a strategy that uses the principles in systems chemistry to transform chemical reaction networks into platforms capable of neural network computing.