Green Chemistry Blog

Scientists from Singapore have employed an ionic liquid to fabricate polybenzimidazole (PBI) membranes for protein separation and water reuse.

PBI has been extensively investigated in the field of membrane separation technologies due to its high glass transition temperature, stable thermal properties and excellent chemical resistance in harsh environments.   One major drawback of PBI though is its low solubility.  Only a few highly polar and aprotic organic solvents are able to dissolve PMI (such as DMSO, DMF and N,N-dimethylacetamide), but these are relatively toxic and volatile.

Here, the team from the National University of Singapore led by Tai-Shung Chung found that 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) was able to dissolve PBI under much lower temperatures and pressures compared to traditional solvents.  The acetate anion of the ionic liquid could form hydrogen bonds with the PBI chains, effectively breaking the interchain bonding in PBI. Ultrafiltration membranes could then be made from the PBI-[EMIM]OAc solution by a non-solvent induced phase separation method, with the resulting membranes achieving a high separation factor. 

This article is free to access until the 27th April 2012!  Click on the link below to find out more…

Molecular interactions between polybenzimidazole and [EMIM]OAc, and derived ultrafiltration membranes for protein separation, Ding Yu Xing ,  Sui Yung Chan and Tai-Shung Chung, Green Chem., 2012, DOI: 10.1039/C2GC35134J  

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Scientists have developed an efficient peroxophosphotungstate-based polymer-immobilised ionic liquid phase catalyst for the epoxidation of allylic alcohols and alkenes.

Polyoxometalates (POMs) have been shown to be efficient Bronsted acid catalysts and selective oxidation catalysts in various important transformations.  Research in recent years has been focused on surface immobilisation of POMs in order to develop continuous flow process and improve the robustness and recyclability of the catalysts and to avoid or reduce catalyst leaching.

In this work, scientists from Newcastle University and Queen’s University, Belfast led by Simon Doherty, Julian Knight and Christopher Hardacre prepared a linear cation-decorated polymeric support with tuneable surface properties and microstructure by ring-opening metathesis polymerisation of a norbornene-based monomer with cyclooctene.  The resulting peroxophosphotungstate-based polymer-supported ionic liquid phase catalyst presented an efficient system for the epoxiadation of allylic alcohols and alkenes.  Importantly, the catalysts could be easily recovered and reused with only a slight reduction in performance. 

This article is free to access until the 19th April 2012!  Click on the link below to find out more…

An efficient recyclable peroxometalate-based polymer-immobilised ionic liquid phase (PIILP) catalyst for hydrogen peroxide-mediated oxidation, Simon Doherty, Julian G. Knight, Jack R. Ellison, David Weekes, Ross W. Harrington, Christopher Hardacre and Haresh Manyar, Green Chem., 2012, DOI: 10.1039/C2GC16679H

Scientists have developed a new strategy for grinding wood chips which leads to significant energy savings.

Wood is a source of biomass that can be converted into renewable fuels and chemicals.  However, it has been noticed that in pretreatment processes, the size of the wood chips or particles used affects their rates of dissolution.  Therefore most studies to-date have used pre-ground biomass, but the energy consumption for grinding untreated wood to powder is high and could be a process-limiting cost for the production of renewable chemicals and fuels. 

Tom Welton and colleagues from Imperial College London, UK, and the University of Natural Resources and Life Sciences, Vienna, Austria, have developed a new process where an ionic liquid is used to soak the wood chips in prior to grinding.  This step gave significant energy savings which was shown to be due to the lubricating properties of the ionic liquid rather than any physico-chemical modifications of the biomass. 

This article is free to access until the 10th April 2012!  Click on the link below to find out more…

Soaking of pine wood chips with ionic liquids for reduced energy input during grinding, Agnieszka Brandt, James K. Erickson, Jason P. Hallett, Richard J. Murphy, Antje Potthast, Michael J. Ray, Thomas Rosenau, Michael Schrems and Tom Welton, Green Chem., 2012, DOI: 10.1039/C2GC15663F

You may also be interested in these related articles which are also free to access for 2 weeks:

Ionic liquid pretreatment of lignocellulosic biomass with ionic liquid–water mixtures, Agnieszka Brandt, Michael J. Ray, Trang Q. To, David J. Leak, Richard J. Murphy and Tom Welton, Green Chem., 2011, 13, 2489-2499

The effect of the ionic liquid anion in the pretreatment of pine wood chips, Agnieszka Brandt, Jason P. Hallett, David J. Leak, Richard J. Murphy and Tom Welton, Green Chem., 2010, 12, 672-679

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