Transformation details of poly(acrylonitrile) to poly(amidoxime) during the amidoximation process

During the amidoximation process, transformation details of poly(acrylonitrile) (PAN) to poly(amidoxime) (PAO) is critical for optimizing amidoximation conditions, which determine the physicochemical properties and adsorption capabilities of PAO-based materials. Although the optimization of amidoximation conditions can be reported in the literature, a detailed research on the transformation is still missing. Herein, the effect of the amidoximation conditions (i.e. temperature, time, and NH2OH concentration) on the physicochemical properties and adsorption capabilities of PAO was studied in detail. The results showed that the extent of amidoximation reaction increased with increasing temperature, time, and NH2OH concentration. However, a considerably high temperature (>60 degrees C) and a considerably long time (>3 h) could result in the degradation and decomposition of PAO's surface topologies and functional groups, and then decrease its adsorption capability for U(vi). The optimal amidoximation condition was 3 h, 60 degrees C and 50 g L-1 NH2OH. At this condition, the PAO obtained presented the highest adsorption capability for U(vi) under experimental conditions. These results provide pivotal information on the transformation of PAO-based materials during the amidoximation process.

Automated summary

The amidoximation process is crucial for optimizing the physicochemical properties and adsorption capabilities of PAO-based materials. Increased temperature, time, and NH2OH concentration lead to higher extent of amidoximation reaction, but excessively high temperature and long time can degrade PAO's surface properties and decrease its adsorption capability. The optimal condition for the highest U(vi) adsorption capability was found to be 3 h, 60 degrees C, and 50 g L-1 NH2OH.