Covalent organic frameworks (COFs) are an emerging class of crystalline porous polymers with highly tuneable structures and functionalities. COFs have been proposed as ideal materials for applications in the energy-intensive field of molecular separation due to their notable intrinsic features such as low density, exceptional stability, high surface area, and readily adjustable pore size and chemical environment. This review attempts to highlight the key advancements made in the synthesis of COFs for diverse separation applications such as water treatment or the separation of gas mixtures and organic molecules, including chiral and isomeric compounds. Methods proposed for the fabrication of COF-based columns and continuous membranes for practical applications are also discussed in detail. Finally, a perspective regarding the remaining challenges and future directions for COF research in the field of separation has also been presented.

Covalent organic frameworks for separation applications.

Material recycle/reuse is one of the key strategies in reducing the consumption of fresh resources in the process industries. Over the past decade, several techniques have been developed to reduce the consumption of specific material utilities such as water and hydrogen. To date, none of the published techniques provides a noniterative, systematic, and graphical technique for identifying a target for minimum usage of the fresh resources ahead of detailed design of the recycle/reuse network. In this paper, we present a rigorous graphical targeting approach to minimize the use of fresh resources by using segregation, mixing, and direct recycle/reuse strategies. First, the problem is formulated mathematically to provide a systematic basis for its solution. Then, dynamic programming techniques are employed to derive the mathematical conditions and characteristics of an optimal solution strategy. These conditions and characteristics are transformed into a graphical form that can be readily used to identify rig...

Rigorous graphical targeting for resource conservation via material recycle/reuse networks

Material recycle/reuse is one of the key strategies in reducing the consumption of fresh resources in the process industries. Over the past decade, several techniques have been developed to reduce the consumption of specific material utilities such as water and hydrogen. To date, none of the published techniques provides a noniterative, systematic, and graphical technique for identifying a target for minimum usage of the fresh resources ahead of detailed design of the recycle/reuse network. In this paper, we present a rigorous graphical targeting approach to minimize the use of fresh resources by using segregation, mixing, and direct recycle/reuse strategies. First, the problem is formulated mathematically to provide a systematic basis for its solution. Then, dynamic programming techniques are employed to derive the mathematical conditions and characteristics of an optimal solution strategy. These conditions and characteristics are transformed into a graphical form that can be readily used to identify rigorous targets for minimum usage of fresh resources. The graphical technique is also useful in locating a material recycle/reuse pinch point, which provides insightful information on the use of fresh resources, the discharge of unused materials, and the relationships between process streams (sources) and units (sinks). Several test problems are solved to illustrate the ease, rigor, and applicability of the developed targeting technique.

/pdf/process-design-and-control-rigorous-graphical-targeting-for-4ipfvxa6rh.pdf

PROCESS DESIGN AND CONTROL Rigorous Graphical Targeting for Resource Conservation via Material Recycle/Reuse Networks

Water network synthesis has been an active area of research for the past one and a half decades. Many think that the technology reached a mature stage in the late 1990s, especially for the insight-based technique based on pinch analysis. The only review for the field dates back to 2000. However, many new papers published in this century reveal that new research gaps are found and more works were carried out to address the limitations of the “old” techniques. The main objective of this review is to provide a state-of-the-art overview of the insight-based techniques developed in the 21st century, particularly those developed for single impurity network of the fixed flow rate problems. Comparisons were also made between these recent techniques and those developed for the fixed load problems in the past century. Various flow rate targeting techniques developed for water reuse/recycle, regeneration, and wastewater treatment are reviewed in detail, along with the network design techniques that achieve the estab...

/pdf/state-of-the-art-review-of-pinch-analysis-techniques-for-3379g4mv9m.pdf

State-of-the-Art Review of Pinch Analysis Techniques for Water Network Synthesis

This work presents the water cascade analysis (WCA) as a new technique to establish the minimum water and wastewater targets for continuous water-using processes. The WCA is a numerical alternative to the graphical water targeting technique known as the water surplus diagram. The WCA is to the water surplus diagram in water pinch analysis (WPA) as problem table analysis (PTA) is to the grand composite curves in heat pinch analysis. By eliminating the tedious iterative steps of the water surplus diagram, the WCA can quickly yield accurate minimum water targets, pinch point locations, and water allocation targets for a maximum water recovery (MWR) network, thereby offering a key complementary role to the water surplus diagram in the synthesis of water network. As in the case of the water surplus diagram, the WCA is not limited to mass-transferâ€“based operations and is applicable to a wide range of water-using operations.

Targeting the minimum water flow rate using water cascade analysis technique

A new graphical targeting method for water minimisation

Refinery hydrogen management for clean fuels production

This paper presents new methods for targeting the minimum capital costs of mass exchange networks. Three cases are considered: a single mass separating agent (MSA), non-overlapping MSAs, and overlapping MSAs. New graphical tools, the y-x composite curve plot and the y-y* composite curve plot, have been introduced for this purpose and these allow the minimum exchanger sizes to be predicted before any design. The new capital cost targets can be traded off against the established operating cost targets by varying the minimum composition difference, in order to optimize the total annual cost (supertargeting). A design technique has been developed which allows the targets to be closely approached. The new targeting and design techniques have been extended to a wide range of Mass Exchange Network Synthesis (MENS) problems which will be considered in Part II of this paper.

Supertargeting for Mass Exchange Networks: Part I: Targeting and Design Techniques

It is possible to minimize industrial resource consumption by establishing eco-industrial resource conservation networks (RCN) between different plants. The establishment of these networks requires the satisfaction of quality criteria for material properties deemed significant by an industry. It also necessitates cooperation among the different firms based on the satisfaction of individual cost or resource consumption goals. Furthermore, there may be varying degrees of incomplete information regarding the process data of the participating plants. Eco-industrial RCNs may also be topologically constrained with respect to the number of links connecting different plants. These design aspects are incorporated in the optimization model through fuzzy mixed integer linear programming (FMILP) or fuzzy mixed integer non-linear programming (FMINLP). Case studies from literature involving water integration and hydrogen recovery are used to illustrate the methodology. The model is able to identify the topologically co...

Fuzzy optimization of topologically constrained eco-industrial resource conservation networks with incomplete information

The second part of this paper applies the techniques developed in the first part to four literature examples, featuring among them multiple mass separating agents (MSAs), multiple components being transferred, regeneration of one of the MSAs, and reactive mass exchange with non-linear equilibrium relationships. In all but the simplest example, the designs developed using these techniques had total annual costs (TACs) which were significantly less than those previously obtained when optimizing the problems using MINLP and state-space methods. In all cases the targets obtained by supertargeting before design were closely approached in design, indicating that these targets may meaningfully be used to screen alternative design options.

Nick Hallale

Papers

A new graphical targeting method for water minimisation

Refinery hydrogen management for clean fuels production

Supertargeting for Mass Exchange Networks: Part I: Targeting and Design Techniques

Fuzzy optimization of topologically constrained eco-industrial resource conservation networks with incomplete information

Supertargeting for Mass Exchange Networks: Part II: Applications