Optimal Solvent Design for Extractive Distillation Processes: A Multiobjective Optimization-Based Hierarchical Framework

The effect of disinfectants and antiseptics on co- and cross-selection of resistance to antibiotics in aquatic environments and wastewater treatment plants

The outbreak of the SARS-CoV-2 pandemic led to increased use of disinfectants and antiseptics (DAs), resulting in higher concentrations of these compounds in wastewaters, wastewater treatment plant (WWTP) effluents and receiving water bodies. Their constant presence in water bodies may lead to development and acquisition of resistance against the DAs. In addition, they may also promote antibiotic resistance (AR) due to cross- and co-selection of AR among bacteria that are exposed to the DAs, which is a highly important issue with regards to human and environmental health. This review addresses this issue and provides an overview of DAs structure together with their modes of action against microorganisms. Relevant examples of the most effective treatment techniques to increase the DAs removal efficiency from wastewater are discussed. Moreover, insight on the resistance mechanisms to DAs and the mechanism of DAs enhancement of cross- and co-selection of ARs are presented. Furthermore, this review discusses the impact of DAs on resistance against antibiotics, the occurrence of DAs in aquatic systems, and DA removal mechanisms in WWTPs, which in principle serve as the final barrier before releasing these compounds into the receiving environment. By recognition of important research gaps, research needs to determine the impact of the majority of DAs in WWTPs and the consequences of their presence and spread of antibiotic resistance were identified.

Topology-Based Initialization for the Optimization-Based Design of Heteroazeotropic Distillation Processes

Distillation-based separation processes, such as extractive or heteroazeotropic distillation, present important processes for separating azeotropic mixtures in the chemical and biochemical industry. However, heteroazeotropic distillation has received much less attention than extractive distillation, which can be attributed to multiple reasons. The phase equilibrium calculations require a correct evaluation of phase stability, while the topology of the heterogeneous mixtures is generally more complex, comprising multiple azeotropes and distillation regions, resulting in an increased modeling complexity. Due to the integration of distillation columns and a decanter, even the simulation of these processes is considered more challenging, while an optimal process design should include the selection of a suitable solvent, considering the performance of the integrated hybrid process. Yet, the intricate mixture topologies largely impede the use of simplified criteria for solvent selection. To overcome these limitations and allow for a process-based screening of potential solvents, the current work presents a topology-based initialization and optimization approach for designing heteroazeotropic distillation processes. The systematic initialization enables an efficient evaluation of different solvents with different mixture topologies, which is further exploited for optimization-based sensitivity analysis and multi-objective optimization. Three case studies are analyzed with about 170 individually optimized process designs, including stage numbers, feed locations, phase ratios, and heat duties.

Screening for New Efficient and Sustainable-by-Design Solvents to Assist the Extractive Fermentation of Glucose to Bioethanol Fuels

The production of bioethanol fuels using extractive fermentation increases the efficiency of the bioconversion reaction by reducing the toxic product inhibition. The choice of appropriate solvents to remove the bioethanol product without inhibiting the fermentation is important to enable industrial scale application. This work applies computer-aided molecular design technologies to systematically screen a wide variety of candidate solvents to enhance the separation, also considering the microorganisms that perform the fermentation. The performance of the candidates was evaluated using a rigorous process simulator for extractive fermentation, assisted by functional group-contribution (QSPR/QSAR) models for the prediction of various solvent properties, including toxicity and life cycle impacts. The solvent designs generated through this approach can provide powerful insights on the kind of molecular structures and functionalities that satisfy the process objectives and constraints, as well the desired sustainability features.

Two-stage particle separation channel based on standing surface acoustic wave

Microfluidic technology has great advantages in the precise manipulation of micro and nano particles, and the collection method of micro and nano particles based on ultrasonic standing waves has attracted much attention for its high efficiency and simplicity of structure. This paper proposes a two-stage particle separation channel using ultrasound. In the microfluidic channel, two different sound pressure regions are used to achieve the separation of particles with positive acoustic contrast factors. Through numerical simulation, the performance of three common piezoelectric substrate materials was compared qualitatively and quantitatively, and it was found that the output sound pressure intensity of 128°YX-LiNbO3 was high and the output was stable. At the same time, the influence of the number of electrode pairs of the interdigital transducer and the electrode voltage on the output sound wave is studied. Finally, 15 pairs of electrode pairs are selected, and the electrode voltages of the two sound pressure regions are 2.0V and 3.0V respectively. After selecting the corresponding parameters, the separation process was numerically simulated, and the separation of three kinds of particles was successfully achieved. This work has laid a certain theoretical foundation for rapid disease diagnosis and real-time monitoring of the environment in practical applications. This article is protected by copyright. All rights reserved.

Applications of Multi-Objective Optimization to Industrial Processes: A Literature Review

Industrial processes provide several of the products and services required for society. However, each industry faces different challenges from different perspectives, all of which must be reconciled to obtain profitable, productive, controllable, safe and sustainable processes. In this context, multi-objective optimization has become a powerful tool to aid the decision-making mechanism in the synthesis, design, operation and control of such processes. The solution to the mathematical models provides the necessary tools to asses the system performance in terms of different metrics and evaluate the trade-offs between the objectives in conflict. The number of applications of multi- objective optimization in industrial processes is ample and each application has its own challenges. In the present literature review, a broad panorama of the applications in multi-objective optimization is presented, including future perspectives and open questions that still need to be addressed.

Particle separation in microfluidics using different modal ultrasonic standing waves

Microfluidic technology has great advantages in the precise manipulation of micro and nano particles, and the separation of micro and nano particles based on ultrasonic standing waves has attracted much attention for its high efficiency and simplicity of structure. This paper proposes a device that uses three modes of ultrasonic standing waves to continuously separate particles with positive acoustic contrast factor in microfluidics. Three modes of acoustic standing waves are used simultaneously in different parts of the microchannel. According to the different acoustic radiation force received by the particles, the particles are finally separated to the pressure node lines on both sides and the center of the microchannel. In this separation method, initial hydrodynamic focusing and satisfying various equilibrium constraints during the separation process are the key. Through numerical simulation, the resonance frequency of the interdigital transducer, the distribution of sound pressure in the liquid, and the relationship between the interdigital electrode voltage and the output sound pressure are obtained. Finally, the entire separation process in the microchannel was simulated, and the separation of the two particles was successfully achieved. This work has laid a certain theoretical foundation for the rapid diagnosis of diseases in practical applications.

Multiobjective Optimization of Mixed-Integer Linear Programming Problems: A Multiparametric Optimization Approach

Industrial process systems need to be optimized, simultaneously satisfying financial, quality and safety criteria. To meet all those potentially conflicting optimization objectives, multiobjective optimization formulations can be used to derive optimal trade-off solutions. In this work, we present a framework that provides the exact Pareto front of multiobjective mixed-integer linear optimization problems through multiparametric programming. The original multiobjective optimization program is reformulated through the well-established ϵ-constraint scalarization method, in which the vector of scalarization parameters is treated as a right-hand side uncertainty for the multiparametric program. The algorithmic procedure then derives the optimal solution of the resulting multiparametric mixed-integer linear programming problem as an affine function of the ϵ parameters, which explicitly generates the Pareto front of the multiobjective problem. The solution of a numerical example is analytically presented to exhibit the steps of the approach, while its practicality is shown through a simultaneous process and product design problem case study. Finally, the computational performance is benchmarked with case studies of varying dimensionality with respect to the number of objective functions and decision variables.

Simulation studies of n-heptane/toluene separation by extractive distillation using sulfolane, phenol, and NMP

Simulation studies of n-heptane/toluene system were performed using Aspen Plus. The comparative study of different entrainers: N-Methyl-2-Pyrrolidone (NMP), Phenol, and Sulfolane for separation of this system was done. Sensitivity analysis was carried out to optimize flowsheets. The criteria to determine the appropriate solvent for the said system included, the total cost calculated by the Aspen Process Economic Analyzer, amount of the solvent consumed, cost of the solvent, and purity obtained during the separation process. For the given system, sulfolane was found to be the appropriate solvent.

Optimization of Solvent and Extractive Distillation Sequence Considering Its Integration with Reactor

The integration of reaction and extractive distillation system is beneficial for reducing the process cost. A systematic method is proposed to identify the optimal solvent, solvent-to-feed ratio, extractive distillation sequence and reactor operating conditions based on the integration of reactor and extractive distillation. The non-key component matrix method is used to generate the extractive distillation sequences. The proposed method can be used to evaluate different solvents, solvent-to-feed ratios, as well as the extractive distillation sequences; the optimal extractive distillation parameters corresponding to the minimum total annualized cost (TAC) can be identified considering different operating conditions. For the selective hydrogenation of benzene to cyclohexene process, the minimum total annualized cost of unit desired product, 4.01 $·kmol−1, is achieved when the reactor’s inlet temperature is 333 K, solvent N-Formylmorpholine and sequence S2 are employed, and the solvent-to-feed ratio is 4.

Computational design of heterogeneous catalysts and gas separation materials for advanced chemical processing

Functional materials are widely used in chemical industry in order to reduce the process cost while simultaneously increase the product quality. Considering their significant effects, systematic methods for the optimal selection and design of materials are essential. The conventional synthesis-and-test method for materials development is inefficient and costly. Additionally, the performance of the resulting materials is usually limited by the designer’s expertise. During the past few decades, computational methods have been significantly developed and they now become a very important tool for the optimal design of functional materials for various chemical processes. This article selectively focuses on two important process functional materials, namely heterogeneous catalyst and gas separation agent. Theoretical methods and representative works for computational screening and design of these materials are reviewed.

Systematic Selection of Green Solvents and Process Optimization for the Hydroformylation of Long-Chain Olefines

Including ecologic and environmental aspects in chemical engineering requires new methods for process design and optimization. In this work, a hydroformylation process of long-chain olefines is investigated. A thermomorphic multiphase system is employed that is homogeneous at reaction conditions and biphasic at lower temperatures for catalyst recycling. In an attempt to replace the toxic polar solvent N,N-dimethylformamide (DMF), ecologically benign alternatives are selected using a screening approach. Economic process optimization is conducted for DMF and two candidate solvents. It is found that one of the green candidates performs similarly well as the standard benchmark solvent DMF, without being toxic. Therefore, the candidate has the potential to replace it.