Review.7 – Highly Mesoporous Organic Aerogels Derived from Soy and Tannin

Green Chemistry, 14, 11, (2012) pp. 3099-3106

Authors: Gisele Amaral-Labat, Liudmila Grishechko, Andrzej Szczurek, Vanessa Fierro, Antonio Pizzi,   Boris Kuznetsov, and Alain Celzard

Green chemistry is the newest innovative research domain in the chemistry field. Based primarily on the development of alternative sustainable technologies and methods, green chemistry aims to eliminate or reduce the use of hazardous materials used in industrial, residential and commercial industries. This includes the design, manufacture, and application of the chemical substances.  Most aerogels supplied to consumers on the market are derived from toxic and often expensive carcinogenic compounds. In the article presented, researchers aim to produce a cost effective, environmentally friendly aerogel in hopes of eliminating the need and use of harsh chemicals.

Article Summary: The first organic aerogels derived from soy and tannin that are 91% natural have been developed by chemists. The process to create soy-tannin aerogels involves many steps which begins by the most critical step of denaturing the soy protein. This ensures the polar backbone amide and polar side-chain groups are exposed. Addition of small amounts of formaldehyde make the protein reactive towards copolymerization reaction with tannin. The next step is crosslinking the protein with flavonoid tannin at different pH levels, gel and cured at 85°C, and finally dried with supercritical CO₂.

Using the transient plane source (TPS) technique the resulting aerogels were tested for thermal transport properties, including thermal conductivity and thermal diffusivity. One of the most promising applications of aerogels is the use as thermal superinsulators. Aerogels have low densities and consist mostly of air and so have low thermal conductivity. The prepared aerogels were tested at 18°C, and gave thermal conductivities of 0.034 and 0.033 W/m•K.

Along with these thermal properties, researchers investigated the morphology, pore texture, and chemical structure using scanning electron microscope (SEM), envelope and helium pycnometry, nitrogen adsorption, nuclear magnetic resonance (NMR), and fourier transform infrared spectroscopy (FTIR).

 

Some interesting points about this journal article include:

• Soy-tannin aerogels are among the greenest organic aerogels on the market. This is due to their low cost, highly advanced mesopore texture, renewable character and good thermal insulative properties.

• Tannin is a biomolecule compound widely seen in many species of plants. It is considered an astringent which gives humans the dry and puckery feeling when drinking red wine or eating unripen fruit.

 

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