  The Jiangmen Underground Neutrino Observatory (JUNO) uses 20k tons of liquid
scintillator (LS)to detect neutrinos. The content of radioactive substances in
the liquid scintillator will affect theexperimental results. JUNO will use
counter current water extraction to reduce the radioactive metalions inside the
LS. In this article, The factors that affect the final water extraction like
the partitioncoefficient and the factors that affect it, the optimal mass
transfer droplet size, the flow rate ratio,theoretical stage and different
working mode (LS as continuous phase or dispersed phase) have beenstudied. We
built counter current extraction prototype in the laboratory and a pilot plant
in Daya Bay.We not only study the factors above, but also get a lot of
engineering experience that worth sharing.
