Extraction of theanine from waste liquid of tea polyphenol production was studied in aqueous surfactant two-phase system (ASTP) with cationic surfactant (CTAB) and anionic surfactant (SDS). Results indicate that the region of ASTP is narrow and there is only a two-phase region of cationic surfactant. The increase in concentrations of NaBr and Na

2

SO

4

are beneficial to the formation of ASTP. Theanine concentration in the bottom phase increases with increasing concentration of theanine

whereas the partition coefficient and extraction rate only change a little when the concentration of theanine is above 0.2 g·L

-1

. With the increase of SDS concentration

the phase ratio and the partition coefficient decrease

while the extraction efficiency of theanine increases and the concentration of theanine changes a little in the range from 2.4/7.5 to 2.8/7.2 for SDS/CTAB ratio. The temperature has a notable effect on the concentration of theanine in the bottom phase

partition coefficient and extraction rate of theanine. The increase of waste liquid decreases the phase ratio

increases the concentration and extraction rate of theanine in the bottom phase

since the protein and the saccha

ride enter the bottom phase with theanine.