Effect of graft copolymerization of fir sawdust lignocellulose with N-vinylpyrrolidone on adsorption capacity to tea catechins

Fir sawdust lignocellulose (FSL) adsorbent was copolymerized with N-vinylpyrrolidone (NVP) in four solvent systems so as to improve its adsorption capacity to tea catechins. It showed that the improvement of adsorption capacity to total catechins was influenced by the reaction solvent, ratio of azodiisobutyronitrile (AIBN) to NVP, ratio of NVP to FSL, reaction temperature and time. The optimum graft copolymerization conditions were: acetonitrile as reaction solvent, AIBN/NVP 0.04, NVP/FSL 0.2 at 70 °C for 6 h. Scanning electron microscopy revealed that the grafted-on NVP was deposited on the FSL surface and in the intercellular regions of the grafted FSL. Fourier transforms infrared spectrum showed that the FSL absorption band at 1634.87 cm−1 induced by –CO was shifted to around 1660 cm−1 and the absorption band was greatly strengthened after NVP grafting.