Potentionmetric Determination of Sulfide Ions and the Behavior of Silver Electrodes at Extreme Dilution

Potentiometric titration behavior of sodium sulfide, methyl mercaptan, dimethyl sulfide, dimethyl disulfide and polysulfides in mixed alkaline solutions and sulfate pulping black liquors

“…The secondary reaction with methyl mercaptan may be considered to occur as follows (28): Figure 3. Effect of methyl mercaptan addition on potentiometric titration curves of elemental sulfur containing sulfate white (WL, 1-3) and black liquors (BL, 1-2) CH3S-+ S°--» CH3SS- (11) S2" + Sn_!0 -> S"2- (12) The effect of the polysulfide formed on determination of sulfide by silver nitrate potentiometric titration is proposed as (6):…”

“…The widespread popularity of the silver nitrate method is due to the insolubility and easy flocculation of silver sulfide in ammoniacal alkaline solution and the accuracy by which changes in drops of the particular potentials can be followed. For classical titrations, the analysis is carried out in sodium acetate-buffered solutions using a potential calibrated, sulfide coated silver-silver (Ag/Ag2S) electrode (12). To date, difficulties were reported in locating the proper end points in sulfide ion titrations by the classical methods.…”

“…RT, Equation 2 also indicates that the potential difference (Ei) is dependent on the sulfide ion activity (052-). Tamele et al (12), studying the behavior of silver electrode in the potentiometric titration of sulfide ions in cases of extreme dilution indicated that, if the solution contains hydrosulfide ion (HS-) concentrations below 10-5iV, the high negative potential drops abruptly on further dilution and approaches a low constant value. Thus, the limiting concentration for normal sulfide ion response in potentiometric titration becomes 10""5JV, or greater, if spurious behavior is to be avoided.…”

Chemical Sensor Based on Silver/Silver Sulfide Microelectrode

“…Recently, Gray and Unwin (2) have reported a simple method for the preparation of Ag/AgCl microelectrode. Electrochemical preparation and behavior of silver modified with silver sulfide have also been extensively studied which usually have been used for the preparation of ion-selective electrodes for silver and sulfide ions (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Ag/Ag 2 S electrodes have prepared by various methods including anodic polarization of silver rod in sodium sulfide solution, by dipping the platinum spiral, coated with porous silver, into a solution of hydrogen sulfide, by sulfidizing the silver wire with sulfur vapor in nitrogenous atmosphere, by sulfidizing with copper-alloyed silver wire in a saturated alkaline solution of sodium sulfide, etc.…”

Argentometric Titration of Sulfide in Alkaline Solutions.

“…Formation of silver bisulfide or the occlusion of sulfide interferes with the stoichiometry of the reaction. Tamele et al performed argentometric titrations of bisulfide in a sodium acetate medium (11,12). The experimental details of the potential measurements and the behavior of the silver sulfide-silver indicator electrode were not reported.…”