Abstract: The behaviour of triethanolamine(TELA) at electrode/solution interface in alkaline solution with and without Zn²⁺、Cd²⁺、Cu²⁺、Fe³⁺ and Sn⁴⁺ ions has been studied by means of differential capacity,polarography,in-situ surface-enhanced Raman spectroscopy(SERS)and microdisc electrodes.The influence of TELA on the discharging process of above ions and the inhibition of TELAon the electrodeposition of zinc have been studied.The results are summarized as follows:TELAhas a stronger adsorptivity at the Hg(or Ag)/solution interface and adsorbs with·lat" orientation on Ag electrode at the potential of maximum adsorption(～-0. 60 V).TELAadsorption on Hg electrode obeys the Frumkin isotherm and possesses a linear relationship between(E_p-E_m)₂ and lg_CTELA.Mixed ligand coordination compounds of metallic ions(such as Zn²⁺,Cd²⁺,Cu²⁺,Ni²⁺ and Fe³⁺) with TELAand OH^- ions are formed,and these coordination compounds are surface-active. Their adsoption activities on Hg electrode are Ni(Ⅱ)>Fe(Ⅲ),Cu(Ⅱ)>Zn(Ⅱ)>Cd(Ⅱ).TELA affects the electroreduction of t he above metallic ions in different degree.The influences of TELAare the same in the sequence as adsoption activities corresponding to mixed ligand coordination compounds,The free energy of TELAadsorption in the presence of zinc ion has a more negative value than that in the absence of zinc ion.The interaction of adsorbed TELAmolecular changes from weak repellant to weak attraction in the presence of zinc ion.The observed rate constants for zinc electrodepositon(at-1.400 V)reduce according to the increase of TELAconcentration,and its inhibitive mechanism can be expressed by k_s=k₀(1-θ)+k₁θ.

Key words: Triethanolamine, Adsorption, Surface-active coordination compound, Inhibition