Adsorption of lead(II) on the goethite surface : voltammetric evaluation of surface complexation parameters

摘要: The adsorption of Pb(II) to the goethite surface was investigated in dilute solutions pH range 6.6–8.2. Increments suspension were added (2.41 × 10−7M) at constant a titration procedure. Differential pulse anodic stripping voltammetry (DPASV) used determine concentration free, nonadsorbed suspensions without prior separation solution and solid phases. This procedure permits achievement high density relatively low total metal concentrations correction for losses reaction vessel. Surface parameters obtained using different methods interpretation experimental data. complex formation constants monodentate bidentate complexes are FeOOH + Pb+2 ⇄ FeOOPb++H+, log KS1= -0.52, 2 FeOOH ⇄(FeOO)2Pb+2H+, βS2= -6.27 kgdm3 Intrinsic acidity from acid-base titrations are, respectively, Kal5 = −6.7, Ka25 −9.0; exchangeable H+ determined as 0.135 mole/kg. capacity is 5.6 10−2 mole/kg (3.8 10−6 mole/m2). average ligand number found be 1.25 throughout adsorption. describe effect changes composition on binding give consistent comprehensive thermodynamic description process within variations particles by factors 3000 1000, respectively. developed here can readily applied determination natural particulate matter.