Title: Modification of wheat gluten with citric acid to produce superabsorbent materials Authors
Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 10, 2013
Publication Date: February 20, 2013
Citation: Chiou, B., Jafri, H.H., Cao, T., Robertson, G.H., Gregorski, K.S., Imam, S.H., Glenn, G.M., Orts, W.J. 2013. Modification of wheat gluten with citric acid to produce superabsorbent materials. Journal of Applied Polymer Science. 129:3192-3197. Interpretive Summary: Most commercial superabsorbent materials are derived from synthetic polymers. These polymers can absorb hundreds of times their weight in water and are widely used in the hygiene industry. However, the use of petroleum-based polymers has several drawbacks. One is that the polymers are produced from a non-renewable resource. Another is that these synthetic polymers are not biodegradable, which leads to persistence and accumulation in the environment. We have developed a natural and biodegradable superabsorbent material from the reaction between wheat gluten and citric acid. This material can absorb up to 78 times its weight in water. This provides an environmentally-friendly alternative to petroleum-based materials.
Technical Abstract: Wheat gluten was reacted with citric acid to produce natural superabsorbent materials able to absorb up to 78 times its weight in water. The properties of the modified gluten samples were characterized using Fourier Transform Infra-red (FTIR) spectroscopy, thermogravimetric analysis, and water uptake. The reaction between gluten and citric acid was examined for gluten:citric acid ratios of 0.38:1 to 0.75:1 at temperatures from 100'C to 130'C. More citric acid reacted for samples containing higher citric acid concentrations and at higher temperatures. FTIR analyses indicated the presence of carboxylate groups on the modified gluten samples, which resulted in modified samples having higher water uptake values than neat gluten. The sample with a gluten:citric acid ratio of 0.5:1 and reaction temperature of 120'C had the largest water uptake value. Also, all modified gluten samples had lower thermal stability than neat gluten.