Complexation of Lead(II) Ions with Hydroxide Ions in Nitrate-Chloride Solutions

Abstract

Complexation of lead(II) ions with hydroxide ions in nitrate-chloride solutions at 298 K was studied using potentiometric titration.The search for the optimal composition of the alkaline electrolyte is an important technological task in processing of scrap lead accumulators with an active paste containing lead(II) oxide [1].The high solubility of PbO in alkaline solutions is known to be due to formation of strong lead(II) hydroxide complexes [2,3]. The presence of both organic and inorganic admixtures and, in particular, chlorides in alkaline solutions strongly affects the complexation of lead(II) ions [135]. For example, it was found in [4] that mixed lead(II) hydroxidechloride complexes are formed at low alkali concentrations (<0.4 M) in a solution containing a mixture of sodium chloride and hydroxide.Proceeding with the studies [4, 5], we examined the complexation of Pb(II) in mixed nitrate-chloride solutions containing sodium hydroxide as an additive in order to analyze the effect of the concentration of chloride ions on the formation of lead hydroxide complexes and, if possible, to determine the composition of mixed chloride-hydroxide complexes. EXPERIMENTALThe complexation of lead(II) ions was studied by potentiometric titration at 298 K. The experimental technique and the electrochemical cell have been described earlier [4,5].We used as a supporting electrolyte aqueous solutions containing a mixture of sodium nitrate (0.3 3 1.0 M) and sodium chloride (0 3 0.7 M) with concentrations that allowed us to obtain a solution with an ionic strength equal to unity (in the limiting case, no sodium chloride was present, and the nitrate concentration was 1.0 M).The potentiometric titration was carried out with a sodium hydroxide solution containing sodium chloride, the concentrations of NaOH and NaCl being equal to the concentrations of NaNO 3 and NaCl, respectively, in the supporting electrolyte. This allowed us to maintain a constant ionic strength in a solution under study during all the experiments.The half-cell of the electrochemical cell under study can be represented as:ÄPb(Hg)³Pb(NO 3 ) 2 , NaNO 3 , NaOH, NaCl, (1) where Pb(Hg) is a lead amalgam electrode.A typical dependence of the potential of the amalgam electrode on the logarithm of the alkali concentration in solutions containing sodium chloride is shown in Fig. 1. It can be seen that the E3ln c OH ! Fig. 1. Potential of the indicator electrode, E, vs. the logarithm of the total concentration of hydroxide ions ln c OH ! in solution. Supporting electrolyte (M): 0.7 NaNO 3 + 0.3NaC1 + 1 10 !3 Pb(NO 3 ) 2 . (c OH !) Total concentration of hydroxide ions.

Oriented Attachment: A Path to Columnar Morphology in Chemical Bath Deposited PbSe Thin Films

“…As has already been stated, at low [OH – ]/[Pb 2+ ] ratios solid oxide clusters are formed due to Pb­(OH) 2 precipitation which are then converted to PbSe clusters by reaction with free selenide anions. Increasing this ratio leads to the formation of Pb­(OH) 3 – complexes. , If cation solution concentration is high enough for saturation, direct precipitation of nanocubic PbSe occurs which are subsequently deposited through OA. During growth, the cation concentrations are continuously depleted and once a critical point is reached where precipitation is no longer favorable, the PbSe particles may redissolve, giving rise to pure IBI mechanism.…”

Lead Hydroxide Nanowires Obtained from Lead Nitrate Solution by Adding Chloride Ions

“…Although it is doubtful if the simple hydroxide Pb(OH)2 is stable in the solid state,4 some research has studied the crystal structure of lead hydroxide [4][5][6]. Previous studies have shown that the Pb(OH) 2 precipitates can form in solution at low sodium hydroxide concentrations [7,8]. However, the morphology of Pb(OH) 2 precipitates has rarely been reported.…”

Shape-Controlled Synthesis and Related Growth Mechanism of Pb(OH) 2 Nanorods by Solution-Phase Reaction

“…[31]. The content of lead hydroxide in precipitates may be attributed to the relative low concentration of alkali (0.03 M), [28,29] compared to 0.2M sodium hydroxide in Ref. [31].…”

“…[27] Previous studies have shown that Pb(OH) 2 precipitates can form in solutions at low sodium hydroxide concentrations. [28,29] However, the morphology of Pb(OH) 2 precipitates has rarely been reported. The previous morphology of lead hydroxide crystal is plate-like in the work by Sole and Yoffe.…”