Camellia cakes are the waste product from processing industry of Camellia fruits

which are formed in the extraction process of its oil by a squeezer.The cakes contain a lot of valuable bioactive components such as tea saponin.In order to utilize Camellia cake resources

five kinds of bioadsorbents were prepared after the extraction of tea saponin by using alcohol extraction

ultrasound-assisted alcohol extraction

water extraction and ultrasound-assisted water extraction methods.The potential and mechanism of the five bioadsorbents for the removal of heavy metals from wastewater were investigated using Ni2+ ions.The bioadsorbent prepared by alcohol extraction process is superior to that by water extraction process.Ultrasound-assisted alcohol extraction improves the adsorptive performance of the sample obviously

with the maximum Langmuir adsorption ability of 17.57 mg·g-1

and increases the extraction efficiency of tea saponin to 19.63%

probably due to the cavitation and mechanistic effects of ultrasound waves.The FTIR analysis of the bioadsorbents indicated that the —OH，—NH，C=O，C—OH and —CN groups on the surface of the bioadsorbents may be the adsorptive sites to Ni2+ ions.The alcohol extraction process of tea saponin can retain these functional groups

while the water extraction process may cause the dissolution of the water soluble components from the biomaterials

reducing the amount of the functional groups and the adsorptive ability of the water extracted bioadsorbents.