Volume 40, Issue 5

In the portfolio of technologies available for net zero-enabling solutions, such as carbon capture and low-carbon production of hydrogen, membrane-based gas separation is a sustainable alternative to energy-intensive processes, such as solvent-based absorption or cryogenic distillation. Detailed knowledge of membrane materials performance in wide operative ranges is a necessary prerequisite for the design of efficient membrane processes. With the increasing popularization of data-driven methods in natural sciences and engineering, the investigation of their potential to support materials and process design for gas separation with membranes has received increasing attention, as it can help compact the lab-to-market cycle. In this work we review several machine learning (ML) strategies for the estimation of the gas separation performance of polymer membranes. New hybrid modelling strategies, in which ML complements physics-based models and simulation methods, are also discussed. Such strategies can enable the fast screening of large databases of existing materials for a specific separation, as well as assist in de-novo materials design. We conclude by highlighting the challenges and future directions envisioned for the ML-assisted design and optimization of membrane materials and processes for traditional, as well as new, membrane separations.

Wetted wires are a unique column internal with several advantages compared to spray and packed columns. These include near-perfect liquid distribution, extremely low pressure drops, and better heat or mass transfer due to droplet circulation. Currently, wetted-wire columns remain within the laboratory prototyping stage. The primary goal of this review is to present the current research on wetted-wire columns and to highlight the gaps that impede scale-up and commercialization. Initially, wetted-wire columns were proposed as an alternative to spray towers. However, wetted-wire columns occupy a space in between spray towers and packed columns. Therefore, wetted-wire columns should also be analyzed more like packed columns to increase the speed of technological translation. Wetted-wire column literature is presented by defining features (wire diameter, nozzle diameter, pitch, and material) and by performance indicators (operating range, pressure drop, hold-up, and separation efficiency). In addition, adjacent literature on wire-like structures is discussed.

Carbon capture continues to gain attention from researchers especially in light of alarming increase of greenhouse gases in the atmosphere in the recent decades. Among the available carbon capture technologies, both of physical and chemical adsorption is favourably seen with various applicable adsorbents successfully introduced. Such promising CO 2 adsorbent candidates include low-dimensional nanomaterials such as graphene, carbon nanotubes (CNTs) and fairly new MXenes. In this review, we will be covering the effects of various types of modifications and functionalization of these materials in enhancing the CO 2 adsorption capacities. This includes functionalization with oxygenated and protic functional groups, heteroatoms doping, defect engineering and surface modification. It is observed that doping of graphene, amine-functionalization of CNTs and surface termination modification of MXenes are some of the most widely researched strategies. Since MXenes are a recent addition in the field of CO 2 capture, we also covered some fundamental theoretical findings to introduce this new 2D nanomaterial to the readers. With this review, we aim to provide a better understanding on how modifications and functionalization process help to improve CO 2 uptake in order to help synthesis of high-performance adsorbents in the future.

Carbamazepine (CBZ) is a contaminant of emerging concern that is persistent in water and wastewater. At low concentrations, prolonged exposure to CBZ-containing water causes detrimental health effects to humans and may also have negative impacts on the environment. Here we critically review new treatment approaches to decrease CBZ concentrations in water and wastewater. First, we summarize the transformation pathways of CBZ in the aquatic environment and identify the corresponding products. Then, we describe the removal of CBZ and structurally-related pharmaceuticals by phototransformation, biotransformation, and adsorption processes, with an emphasis on the application of naturally- and biologically-derived nanoporous adsorbents, such as agricultural wastes, natural polymers, activated carbon, metal organic frameworks, silicas, and molecularly imprinted polymers. Biologically-derived activated carbons exhibited the highest adsorption capacities for CBZ, with adsorption predominantly occurring through hydrophobic and π–π interactions. CBZ was also effectively treated using titanium dioxide and other inorganic photocatalysts. This review not only provides a critical synthesis of state-of-the-art adsorption and degradation processes for CBZ and structurally-related pharmaceuticals, but also proposes knowledge gaps and future research directions.

The polymer obtained from hydrophilic monomers can be transformed into a hydrogel via cross-linking by different cross-linkers. Hydrogels are three-dimensional networks that can absorb several times their weight and swell in water/swelling media, improving the media’s viscosity as a thickener. The cross-linked poly(acrylic acid) microparticles prepared via precipitation polymerization technique are often synthesized by radical polymerization and have carboxylic functional groups in their structure, which make the hydrogel properties such as swelling capacity, particle morphology, and viscosity be controlled by physical factors such as solvent, neutralizer, pH , pK a , zeta potential, and ionic strength of the swelling media, as well as synthetic factors including comonomer, cross-linker, and network type. In this paper, the effects of crucial factors on the synthetic and swelling steps are elaborated to facilitate the achievement of poly(acrylic acid)-based xerogels having desirable rheological properties, such as swelling/viscosity optimization, which is the primary purpose of a thickener in any swelling media.