Jun 2020, Volume 14 Issue 3

Cover illustration

  • (Cyrine Ayed, Wei Huang, Kai A. I. Zhang, pp. 397‒404)
    A hybrid material consisting of a covalent triazine framework and mesoporous silica was designed and used as visible light-active, highly efficient, stable and reusable photocatalyst in water. Due to the high surface area and the added hydrophilic properties by silica, the hybrid material demonstrated excellent adsorption of organic molecules in water, leading not only to high photocatalytic performance of the hybri [Detail] ...

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    Colin A. Scholes

    Membrane technology holds great potential in gas separation applications, especially carbon dioxide capture from industrial processes. To achieve this potential, the outputs from global research endeavours into membrane technologies must be trialled in industrial processes, which requires membrane-based pilot plants. These pilot plants are critical to the commercialization of membrane technology, be it as gas separation membranes or membrane gas-solvent contactors, as failure at the pilot plant level may delay the development of the technology for decades. Here, the author reports on his experience of operating membrane-based pilot plants for gas separation and contactor configurations as part of three industrial carbon capture initiatives: the Mulgrave project, H3 project and Vales Point project. Specifically, the challenges of developing and operating membrane pilot plants are presented, as well as the key learnings on how to successfully manage membrane pilot plants to achieve desired performance outcomes. The purpose is to assist membrane technologists in the carbon capture field to achieve successful outcomes for their technology innovations.

    Ximei Zhao, Matthias Rudolph, Abdullah M. Asiri, A. Stephen K. Hashmi

    This review summarizes recent advances in the field of gold-catalyzed synthesis of pharmaceutically relevant aza-heterocycles via in situ generated α-imino gold carbene complexes as intermediates.

    Yichen Liu, Yongli Li, Andreas Hensel, Juergen J. Brandner, Kai Zhang, Xiaoze Du, Yongping Yang

    Emulsion is a disperse system with two immiscible liquids, which demonstrates wide applications in diverse industries. Emulsification technology has advanced well with the development of microfluidic process. Compared to conventional methods, the microfluidics-based process can produce controllable droplet size and distribution. The droplet formation or breakup is the result of combined effects resulting from interfacial tension, viscous, and inertial forces as well as the forces generated due to hydrodynamic pressure and external stimuli. In the current study, typical microfluidic systems, including microchannel array, T-shape, flow-focusing, co-flowing, and membrane systems, are reviewed and the corresponding mechanisms, flow regimes, and main parameters are compared and summarized.

    Jayshree Ashree, Qi Wang, Yimin Chao

    Despite all major breakthroughs in recent years of research, we are still unsuccessful to effectively diagnose and treat cancer that has express and metastasizes. Thus, the development of a novel approach for cancer detection and treatment is crucial. Recent progress in Glyconanotechnology has allowed the use of glycans and lectins as bio-functional molecules for many biological and biomedical applications. With the known advantages of quantum dots (QDs) and versatility of carbohydrates and lectins, Glyco-functionalised QD is a new prospect in constructing biomedical imaging platform for cancer behaviour study as well as treatment. In this review, we aim to describe the current utilisation of Glyco-functionalised QDs as well as their future prospective to interpret and confront cancer.

    Qiaofei Pan, Yinglin Yu, Dong Chen, Genlong Jiao, Xiaowen Liu

    Transdermal delivery offers several advantages in drug distribution, including convenience, painless administration, avoidance of first-pass metabolism, and ease of termination. However, the natural protective barriers of the skin, such as the stratum corneum, the topmost layer of skin, limit the systemic absorption of external therapeutics via transdermal delivery. Therefore, extensive application of transdermal delivery in medical treatment has been limited. Over the past few years, many formulation strategies and physical technologies, therefore, have been developed to enhance transdermal delivery. This review summarizes various formulation strategies proposed for transdermal delivery and their application in medical treatment.

    Yawen Yao, Sabine Rosenfeldt, Kai Zhang

    Herein, phloroglucinol tristearate (PhgTS) was used to study the crystallization process due to its unique symmetric structure containing a benzene ring and three aliphatic chains. Spherulites of crystallized PhgTS from four solvents under diverse conditions were analyzed in detail and their formation process was studied. Maltese cross is shown by PhgTS spherulites obtained from aprotic solvents via polarized optical microscopy. In comparison, no Maltese cross can be observed from branch-like crystals formed from protic solvents. Independent on the microscaled morphology, lamellae were found to be the basic blocks constructing both PhgTS spherulites and branch-like crystals, which were formed predominantly by stacked PhgTS molecules. Although differential characters of the solvents did not affect the formation of lamellas, the solvents played a crucial role in the formation of self-assembled microscaled morphologies. In particular, the morphologies of spherulites were strongly affected by the concentration of PhgTS solutions, surrounding temperature and evaporation rate of solvents. Generally, a higher concentration of PhgTS led to more homogeneous spherulites, a lower evaporation rate resulted in more compact spherulites, and a higher surrounding temperature generated preferentially more ring-banded spherulites of PhgTS.

    Cyrine Ayed, Wei Huang, Kai A. I. Zhang

    Covalent triazine frameworks (CTFs) have been recently employed for visible light-driven photocatalysis due to their unique optical and electronic properties. However, the usually highly hydrophobic nature of CTFs, which originates from their overall aromatic backbone, leads to limitations of CTFs for applications in aqueous media. In this study, we aim to extend the range of the application media of CTFs and design hybrid material of a CTF and mesoporous silica (SBA-15) for efficient photocatalysis in aqueous medium. A thiophene-containing CTF was directly synthesized in mesopores of SBA-15. Due to the high surface area and the added hydrophilic properties by silica, the hybrid material demonstrated excellent adsorption of organic molecules in water. This leads not only to high photocatalytic performance of the hybrid material for the degradation of organic dyes in water, but also for efficient photocatalysis in solvent-free and solid state. Furthermore, the reusability, stability and easy recovery of the hybrid material offers promising metal-free heterogeneous photocatalyst for broader applications in different reaction media.

    Guoxing Chen, Marc Widenmeyer, Binjie Tang, Louise Kaeswurm, Ling Wang, Armin Feldhoff, Anke Weidenkaff

    A series of novel dense mixed conducting ceramic membranes based on K2NiF4-type (La1–xCax)2 (Ni0.75Cu0.25)O4+δ was successfully prepared through a sol-gel route. Their chemical compatibility, oxygen permeability, CO and CO2 tolerance, and long-term CO2 resistance regarding phase composition and crystal structure at different atmospheres were studied. The results show that higher Ca contents in the material lead to the formation of CaCO3. A constant oxygen permeation flux of about 0.63 mL·min1·cm2 at 1173 K through a 0.65 mm thick membrane was measured for (La0.9Ca0.1)2 (Ni0.75Cu0.25)O4+δ, using either helium or pure CO2 as sweep gas. Steady oxygen fluxes with no sign of deterioration of this membrane were observed with increasing CO2 concentration. The membrane showed excellent chemical stability towards CO2 for more than 1360 h and phase stability in presence of CO for 4 h at high temperature. In addition, this membrane did not deteriorate in a high-energy CO2 plasma. The present work demonstrates that this (La0.9Ca0.1)2(Ni0.75Cu0.25)O4+δ membrane is a promising chemically robust candidate for oxygen separation applications.

    Siming Chen, Yue Wu, Geoffrey W. Stevens, Guoping Hu, Wenshou Sun, Kathryn A. Mumford

    Focused beam reflectance measurement (FBRM) and 13C nuclear magnetic resonance (13C NMR) analysis were used to study the precipitation process of CO2-loaded potassium glycinate (KGLY) solutions at different CO2 loadings, during the addition of ethanol as an antisolvent at a rate of 10 mL·min−1. The volume ratio of ethanol added to the KGLY solution (3.0 mol·L−1, 340 mL) ranged from 0 to 3.0. Three solid-liquid-liquid phases were formed during the precipitation process. The FBRM results showed that the number of particles formed increased with CO2 loading and ethanol addition for CO2-unsaturated KGLY solutions, whilst for CO2-saturated KGLY solution it first increased then decreased to a stable value with ethanol addition. 13C NMR spectroscopic analysis showed that the crystals precipitated from the CO2-unsaturated KGLY solutions consisted of glycine only, and the quantity crystallised increased with CO2 loading and ethanol addition. However, a complex mixture containing glycine, carbamate and potassium bicarbonate was precipitated from CO2-saturated KGLY solution with the maximum precipitation percentages of 94.3%, 31.4% and 89.6%, respectively, at the ethanol volume fractions of 1.6, 2.5 and 2.3.

    Mahboube Ghahramaninezhad, Fatemeh Mohajer, Mahdi Niknam Shahrak

    Post-synthetic functionalization or modification has been regarded as a promising strategy to treat surfaces of adsorbents for their applications in targeted adsorption and separation processes. In this work, a novel microporous adsorbent for carbon capturing was developed via functionalization of zeolitic imidazolate framework-91 (ZIF-91) to generate a hard/hard (metal-oxygen) structure named as lithium-modified ZIF-91 (ZIF-91-OLi compound). To this purpose, the ZIF-91 compound as an intermediate product was achieved by reduction of ZIF-90 in the presence of NaBH4 as a good reducing agent. Afterwards, acidic hydrogen atoms in the hydroxyl groups of ZIF-91 were exchanged with lithium cations via reaction of n-BuLi compound as an organo lithium agent through an appropriate procedure. In particular, the as-synthesized ZIF-91-OLi operated as an excellent electron-rich center for CO2 adsorption through trapping the positive carbon centers in the CO2 molecule. DFT calculations revealed that the presence of lithium over the surface of ZIF-91-OLi adsorbent plays an effective role in double enhancement of CO2 storage via creating a strong negative charge center at the oxygen atoms of the imidazolate linker as a result of the lithium/hydrogen exchange system. Finally, the selectivity of CO2/N2 was investigated at different temperatures, revealing the ZIF-91-OLi as a selective adsorbent for industrial application.

    Simon Roussanaly, Monika Vitvarova, Rahul Anantharaman, David Berstad, Brede Hagen, Jana Jakobsen, Vaclav Novotny, Geir Skaugen

    This paper compares the techno-economic performances of three technologies for CO2 capture from a lignite-based IGCC power plant located in the Czech Republic: (1) Physical absorption with a Rectisol-based process; (2) Polymeric CO2-selective membrane-based capture; (3) Low-temperature capture. The evaluations show that the IGCC plant with CO2 capture leads to costs of electricity between 91 and 120 €·MWh−1, depending on the capture technology employed, compared to 65 €·MWh−1 for the power plant without capture. This results in CO2 avoidance costs ranging from 42 to 84 €·tCO2,avoided−1 , mainly linked to the losses in net power output. From both energy and cost points of view, the low-temperature and Rectisol based CO2 capture processes are the most efficient capture technologies. Furthermore, partial CO2 capture appears as a good mean to ensure early implementation due to the limited increase in CO2 avoidance cost when considering partial capture. To go beyond the two specific CO2-selective membranes considered, a cost/membrane property map for CO2-selective membranes was developed. This map emphasise the need to develop high performance membrane to compete with solvent technology. Finally, the cost of the whole CCS chain was estimated at 54 €·tCO2,avoided−1 once pipeline transport and storage are taken into consideration.

    Dawid P. Hanak, Vasilije Manovic

    Renewable energy sources and low-carbon power generation systems with carbon capture and storage (CCS) are expected to be key contributors towards the decarbonisation of the energy sector and to ensure sustainable energy supply in the future. However, the variable nature of wind and solar power generation systems may affect the operation of the electricity system grid. Deployment of energy storage is expected to increase grid stability and renewable energy utilisation. The power sector of the future, therefore, needs to seek a synergy between renewable energy sources and low-carbon fossil fuel power generation. This can be achieved via wide deployment of CCS linked with energy storage. Interestingly, recent progress in both the CCS and energy storage fields reveals that technologies such as calcium looping are technically viable and promising options in both cases. Novel integrated systems can be achieved by integrating these applications into CCS with inherent energy storage capacity, as well as linking other CCS technologies with renewable energy sources via energy storage technologies, which will maximise the profit from electricity production, mitigate efficiency and economic penalties related to CCS, and improve renewable energy utilisation.

    Shinji Kanehashi, Colin A. Scholes

    Polymeric membrane-based gas separation has found wide applications in industry, such as carbon capture, hydrogen recovery, natural gas sweetening, as well as oxygen enrichment. Commercial gas separation membranes are required to have high gas permeability and selectivity, while being cost-effective to process. Mixed matrix membranes (MMMs) have a composite structure that consists of polymers and fillers, therefore featuring the advantages of both materials. Much effort has been made to improve the gas separation performance of MMMs as well as general membrane properties, such as mechanical strength and thermal stability. This perspective describes potential use of MMMs for carbon capture applications, explores their limitations in fabrication and methods to overcome them, and addresses their performance under industry gas conditions.