An Excellent Bifunctional Adsorbent for Various Organic Acids and Aldehydes

Significance 

Lignocellulose is widely used in the production of organic acids and aldehydes. This can be attributed to the ease of degrading cellulose, hemicellulose, and lignin into constituent compounds that are beneficial in the production of a variety of fuels, chemicals, and materials. Currently, pretreatment approaches are used to produce organic acids and aldehydes from lignocellulose. However, the resulting products are in solution with other byproducts due to the additional side reactions. Therefore, efficient separation and purification techniques are highly desirable to obtain pure organic acids and aldehydes.

Presently, several separation methods have been developed. Interestingly, the adsorption method has attracted significant attention of researchers. It involves the use of adsorbents to adsorb aldehydes and organic solutions from sugar solutions. Considering the increasing demand for high-performance adsorbents, polyethylenimine have been recently identified as a promising solution for selectively and effectively recovering lignocellulose-derived aldehydes and organic acids from sugar solutions. Despite the remarkable improvements, polyethylenimine requires the use of membrane filtration that is highly disadvantageous.

To this note, Dr. Qiang Yang at Western Michigan University together with Dr. Troy Runge at the University of Wisconsin synthesized a reactive adsorbent for selective and efficient adsorption and separation of lignocellulose-derived organic acids and aldehydes from the sugar solution. In particular, the polyethyleneimine based insoluble adsorbent was modified through simple cross-linking. They further investigated the adsorption performance of the newly developed adsorbents. Their research work is currently published in the research journal, ACS Sustainable Chemistry and Engineering.

In brief, the authors commenced their research work by cross-examining the chemical modifications of polyethyleneimine to make insoluble adsorbents. They purposed to eliminate the use of filtration membranes. Next, by using cross-linked polyethylenimine adsorbent, they assessed the adsorption kinetics and isotherms of various samples of lignocellulose-derived organic acids and aldehydes. Finally, they explored the recoverability of the organic acids and aldehydes as well as the possibility of recycling the polyethylenimine adsorbents.

The authors observed that the developed cross-linked polyethylenimine adsorbent demonstrated effective selective adsorption and separation of lignocellulose-derived organic acids and aldehydes from the sugar solutions. In addition, they noted that the presence of salt favored the adsorption of aldehyde while acidic conditions were suitable for the adsorption of organic acids. Furthermore, it was worth noting that the addition of salts significantly enhanced the selective adsorption of aldehydes over organic acids.

In summary, Yang and Troy study successfully demonstrated the effectiveness of cross-linked polyethylenimine adsorbent in selective adsorption of lignocellulose-derived organic acids and aldehydes. Specifically, the process enabled recovery of organic acids and aldehydes which could be made into other useful chemicals. Consequently, they demonstrated the feasibility of the adsorbent especially in large scale application through separation and recycling. This is cost effective and economical. Altogether, the paper provides a foundation that will foresee the development of more efficient adsorbents for various applications.

About the author

Qiang Yang is an Assistant Professor in the Chemical and Paper Engineering at Western Michigan University. He got his Ph.D. in Biological Systems Engineering from University of Wisconsin-Madison. His research interest spans the areas of biorefinery, bioenergy and bioproducts.

Reference

Yang, Q., & Runge, T. (2019). Cross-Linked Polyethylenimine for Selective Adsorption and Effective Recovery of Lignocellulose-Derived Organic Acids and Aldehydes. ACS Sustainable Chemistry & Engineering, 7(1), 933-943.

Go To ACS Sustainable Chemistry & Engineering

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