Abstract: Interaction mechanism of SDBS surfactants and NPSS-10 surfactants with sodium ion and calcium ion is studied
by potential titration method in high temperature.（1）SDBS interactes weakly with sodium ion，since ion-pair is formed by the
interaction of sodium ion and anionic head groups of SDBS in micelle，which shields static electricity of anionic head groups and
decrease the polar of surfactants in certain extent.（2）NPSS-10 interact more strongly with sodium ion when the concentration
is over cmc，because EO groups which hydrated dehydrates in high temperature and ion-pair is formed by the interaction of
sodium ion and anionic head groups of NPSS-10 in micelle，which decreases polar of the surfactant and increases anti-salinity
ability.（3）SDBS has no interaction with calcium ion and does not form chemical precipitation in solution containing low
concentration calcium ion，but in high concentration calcium ion solution. SDBS has strong interact with calcium ion and
brings about chemical precipitation（alkylphenol sulphonate）.（4）NPSS-10 has strong interaction with calcium ion and has no
chemical precipitation in low concentration calcium ion solution，because a complex is formed by interaction of EO groups in
NPSS-10 molecular with calcium ion. NPSS-10 has no interaction with calcium ion and has no chemical precipitation in high
concentration calcium ion solution，because the polar of NPSS-10 not only decreases，but also static effects decrease interaction
of sulfnonate head groups and calcium ion so ion-pair is formed difficultly，and avoids bringing about the chemical precipitation
from interaction of calcium ion and sulfonate head groups. NPSS-10 has stronger ability of resist calcium ion.

Key words: high temperature, NPSS-10, SDBS, Na+, Ca2+, static electricity mechanism