October 5, 2016

Process turns wheat flour into CO2-capturing micropores

Pol_Co2 Vilas Pol, an associate professor in the School of Chemical Engineering and the School of Materials Engineering, is working to perfect a process that turns wheat flour into numerous tiny pores that capture carbon dioxide, representing a potential renewable technology to reduce the industrial emission of carbon dioxide into the atmosphere. (Purdue University image/John Underwood) Download image

WEST LAFAYETTE, Ind. – Researchers have shown how a process for the "carbonization" of wheat flour creates numerous tiny pores that capture carbon dioxide, representing a potential renewable technology to reduce the industrial emission of carbon dioxide into the atmosphere. 

"With increasing carbon dioxide emissions, global warming is accelerating, accompanied by abnormal climate changes," said Vilas Pol, an associate professor in Purdue University's School of Chemical Engineering and the School of Materials Engineering. "It is imperative to develop efficient methods for capturing carbon dioxide."

Purdue researchers developed a process that creates carbon compartments from wheat flour. Collaborating with researchers at Korea University in Seoul, South Korea, they studied carbon dioxide capture in these unique carbon compartments. The chemical compound potassium hydroxide was used to "activate" – or generate many small pores – in the wheat flour inside a furnace at 700 degrees Celsius.

The carbon dioxide is "adsorbed," or bound to the material's surface inside the micropores.

"The outstanding overall carbon dioxide adsorption performance indicates that potassium hydroxide-activated microporous carbon compartments can be a promising approach," said associate professor Ki Bong Lee from Korea University.

Dysart_CO2 Purdue doctoral student Arthur Dysart operates a system that measures the adsorption of gas molecules on a solid carbon surface. He is working on a team developing materials that capture carbon dioxide, a strategy aimed at reducing the effects of climate change. (Purdue University image/John Underwood) Download image

The researchers varied the ratio of potassium hydroxide to carbon until finding a formulation that performed the best.

Findings are detailed in a research paper appearing on Tuesday (Oct. 4) in the journal Scientific Reports. The paper was authored by researchers Seok-Min Hong and Eunji Jang, graduate students from Korea University; Purdue chemical engineering doctoral student Arthur D. Dysart; Pol; and Lee.

Findings showed the rate of carbon dioxide adsorption depends on the material's volume of micropores with a pore size less than .8 nanometers. The researchers also demonstrated that the material can be rapidly used over again to repeatedly capture carbon dioxide.

Future research will include work to adsorb larger quantities of carbon dioxide.

The research was supported by the National Research Foundation, the Basic Science Research Program and the Human Resources Development Program of the Korea Institute of Energy Technology Evaluation and Planning. Purdue University's carbon compartment development process was supported by the U.S. Department of Energy.

Writer: Emil Venere, 765-494-4709, venere@purdue.edu

Source: Vilas G. Pol, 765-494-0044, vpol@purdue.edu 

Note to Journalists: The research paper is available at http://www.nature.com/articles/srep34590 and from Emil Venere, 765-494-4709, venere@purdue.edu


CO2 Capture in the Sustainable Wheat-Derived Activated Microporous Carbon Compartments

Seok-Min Hong1, Eunji Jang1, Arthur D. Dysart2, Vilas G. Pol2 & Ki Bong Lee1

1Department of Chemical and Biological Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 136-713, Republic of Korea. 2School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907-2100, United States. Correspondence and requests for materials should be addressed to V.G.P. (email: vpol@purdue.edu ) or K.B.L. (email: kibonglee@korea.ac.kr)

Microporous carbon compartments (MCCs) were developed via controlled carbonization of wheat flour producing large cavities that allow CO2 gas molecules to access micropores and adsorb effectively. KOH activation of MCCs was conducted at 700 °C with varying mass ratios of KOH/C ranging from 1 to 5, and the effects of activation conditions on the prepared carbon materials in terms of the characteristics and behavior of CO2 adsorption, were investigated. Textural properties, such as specific surface area and total pore volume, linearly increased with the KOH/C ratio, attributed to the development of pores and enlargement of pores within carbon. The highest CO2 adsorption capacities of 5.70 mol kg−1 at 0 °C and 3.48 mol kg−1 at 25 °C were obtained for MCC activated with a KOH/C ratio of 3 (MCC-K3). In addition, CO2 adsorption uptake was significantly dependent on the volume of narrow micropores with a pore size of less than 0.8 nm rather than the volume of larger pores or surface area. MCC-K3 also exhibited excellent cyclic stability, facile regeneration, and rapid adsorption kinetics. As compared to the pseudofirst-order model, the pseudo-second-order kinetic model described the experimental adsorption data methodically.

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