Gossypol is a polyphenolic aldehydic compound extracted from cotton plants, and is toxic to monogastric animals as well as young ruminants. Cotton seed meal, as one of the main byproduct of cotton industry, is an important part of animal protein feed resources. However, the poisonous side effect of gossypol in cotton seed has a big challenge for its practical application.
A research group led by Prof. ZHANG Yagang at Xinjiang Technical Institute of Physics & Chemistry (XTIPC) of Chinese Academy of Sciences developed molecularly imprinted polymer (MIP) for selective recognition and adsorption of gossypol. Adsorption performances of these MIPs showed that the prepared MIPs achieved binding capacity as high as 564 mg g-1 for gossypol and had improved selectivity and excellent reusability. The study was published in Journal of Molecular Recognition.
Researchers prepared the molecularly imprinted polymers with gossypol as the template molecule and dimethylaminoethyl methacrylate (DMAEMA) as the functional monomer by bulk thermal polymerization. They revealed the morphology and microstructures of MIPs using scanning electron microscope (SEM) and Brunauer–Emmett–Teller (BET) method.
Adsorption kinetics and adsorption isotherms data of MIPs for gossypol were found to fit well with the pseudo-second-order model and Freundlich model. The two classes of binding sites existed in the gossypol-imprinted polymers. The binding sites in the MIP were heterogeneous, higher-affinity and the lower-affinity binding sites were both produced in MIPs.
Researchers evaluated the performances of MIPs by adsorption kinetics, adsorption isotherms, adsorption selectivity and reusability studies. Their results clearly showed that MIPs had favorable selectivity towards gossypol compared with non-imprinted polymers. It is notable that adsorption capacity of MIPs maintained above 90% after five regeneration cycles, indicating the prepared MIPs were recyclable and could be used multiple times.
The results demonstrated that the prepared gossypol molecularly imprinted polymers provided a green and alternative approach for the removal of gossypol from cotton seed meal.