10.1071/EN19017_AC CSIRO 2019 Environmental Chemistry 2019, 16(4), 289-295 Supplementary Material The aqueous chemistry of tellurium: critically-selected equilibrium constants for the low-molecular-weight inorganic species Montserrat FilellaA,C and Peter M. MayB ADepartment F.-A. Forel, University of Geneva, Boulevard Carl-Vogt 66, CH-1205 Geneva, Switzerland BChemistry, School of Engineering and Information Technology, Murdoch University, Murdoch, WA 6150, Australia CCorresponding author. Email: [email protected] 1 Table S1. Published tellurium redox potentials. Reactiona E / V T / oC Conditions Technique Reference Comments – 2– 2– 2– 2 Te(s) + 2 e = Te2 –0.845 ? I unknown Polarography Panson 1964 Value for Te2 = Te(s) + Te (Te electrode) in Lingane (1952) wrong; pH = 13 Panson (1963) right + – H2Te = Te(s) + 2 H + 2 e 0.51 ? I unknown Polarography Panson 1963 First reaction: value similar to 2– – Awad (1962) but differs from Te = Te(s) + 2 e 0.95 Lingane (1952) 2– 2– –4 Te2 = Te(s) + Te K = 2x10 Second reaction: differs from Awad (1962) and Latimer (1952) + – Te(s) + 2 H + 2 e = H2Te –0.50 30 I unknown Polarography Awad 1962 (overpotential 2 Te(s) + 2 H+ + 2 e– = H Te –0.365 0.003–0.02 M 2 2 measurements) – 2– HCl 2 Te(s) + 2 e = Te2 –0.74 2 Te(s) + 4 e– = 2 Te2– –1.1 + – TeO2(s) + 4H2O = H6TeO6(s) + 2H + 2 e –1.02 25 none, 0 Estimation Latimer 1953 Error in the sign of H2Te = + – - 2– 2– – Te(s) + 2H + 2e in the 2 OH + TeO3 = TeO4 + H2O + 2 e –0.4 original publication – 2– – Te(s) + 6 OH = TeO3 + 3 H2O + 4 e 0.57 + – H2Te = Te(s) + 2 H + 2 e 0.72 Te2– = Te(s) + 2 e– 1.14 2– 2– –12 Te2 = Te(s) + Te K = 5.5x10 2 Reactiona E / V T / oC Conditions Technique Reference Comments + – TeO2(s) + 4 H2O = H6TeO6(s) + 2 H + 2 e –1.02 25 Estimation Latimer 1938 - 2– 2– – 2 OH + TeO3 = TeO4 + H2O + 2 e –0.4 – 2– – Te(s) + 6 OH = TeO3 + 3 H2O + 4 e 0.02 + – H2Te = Te(s) + 2H + 2 e 0.69 Te2– = Te(s) + 2 e– 0.92 + – 2 H2O + Te(s) = TeO2(s) + 4 H + 4 e –0.5286 25 Variable HCl Direct Schuhmann 1925 measurement –0.5213 45 + + – 2 H2O + Te(s) = TeOOH + 3 H + 4 e –0.5590 – 2– 2 Te(s) + 2 e = Te2 –0.818 19–20 2.5 M HCl Direct cell Kasarnowsky 1923 measurements Te(s) = Te4+ + 4 e– 0.549 3 Table S2. Published Te(-II) acid-base equilibrium constants. Reactiona K logKa T / oC I electrolyte Te concentration Technique Reference Comments pH range Te2– + H+ = HTe– (1.28 ± 0.02)x10–12 –11.9 25 extrapolated to I dilute NaOH and Spectrophotometry Myers 2007 = 0 (DHC) buffers pH 12 Te2– + H+ = HTe– 6.9x10–13 abstract –12.2 25 1 M NaOH 0.1 mM range Polarography Panson 1963 Includes also Lingane’s data in the calculations 5x10–13 conclusions –12.3 above pH 14 Different value given in the abstract and in the conclusions Te2– + H+ = HTe– –11 Unknown 0–14 Polarography Lingane and Value needed to fit their Niedrach 1948 polarographic curves; not a ‘real’ determination – + –3 H2Te = HTe + H 2.27x10 –2.64 18 Unknown Conductimetry de Hlasko 1922 No details about H2Te preparation – – + H2Te = HTe + H –2 Unknown Solubility Bruner-Krakau 1913 aValue in italics calculated from original K value. If not in italics, logK value is as published. bValues of pH in italics. 4 Table S3. Published Te(IV) acid-base and TeO2(s) solubility constants. Reaction K logKa T / oC I electrolyte Te concentrationb Technique Reference Comments pH range TeO2(s) + H2O = H2TeO3 –4.64 ± 0.15 25 0 -0.30–13.6 Solubility and Grundler et al. Coarse TeO2 powder 99+% potentiometry for 2013 adquired from Aldrich. No –3.79 ± 0.04 80 pK3 only further characterisation –2.72 ± 0.05 200 + + H3TeO3 = H2TeO3 + H –2.81 ± 0.20 25 –2.22 ± 0.09 80 –1.08 ± 0.18 200 – + H2TeO3 = HTeO3 + H –5.18 ± 0.19 25 –5.95 ± 0.06 80 –6.63 ± 0.11 200 – 2– + HTeO3 = TeO3 + H –10.02 ± Other T 0.01 + + TeO2(s) + H2O + H = H3TeO3 –2.20 25 0 0–8 Estimation from McPhail 1995 No experimental details given solubility data + TeO2(s) + H2O = H2TeO3 –5.03 25 data from other Values calculated at other T – + (0.01 to 350 C) TeO2(s) + H2O = HTeO3 + H –11.41 25 sources + + Origin of solubility data: the H3TeO3 = H2TeO3 + H –2.83 25 author refers to a manuscript – + HTeO3 + H = H2TeO3 6.38 25 in preparation, apparently never published 2– + TeO3 + 2 H = H2TeO3 15.94 25 values at other T 5 Reaction K logKa T / oC I electrolyte Te concentrationb Technique Reference Comments pH range 4+ – 3+ –12 Te + OH = Te(OH) 0.909x10 11.96 28 0.1 M KNO3 0 to 4? Spectrophotometry Nazarenko et 4+ – 2+ –24 with competing al. 1977 Te + 2 OH = Te(OH)2 0.336x10 23.53 Values also at ligand 4+ – + –35 0.3, 0.5, 0.7 Te + 3 OH = Te(OH)3 0.683x10 34.83 and 1.0 M 4+ – –46 Te + 4 OH = Te(OH)4 0.709x10 45.85 – 2– + HTeO3 = TeO3 + H –9.56 ± 0.02 20 0 Potentiometry + Masson 1976 TeO2 Koch-Light electronic MINIQUAD (pK1) grade, 99.998% pure, no – + –6.08 ± 0.06 H2TeO3 = HTeO3 + H and solubility (the further characterization + + –2.8 ± 0.2 other two) H3TeO3 = H2TeO3 + H Table with most previous values; comments on many studies Solubility values found dependent on equilibration time; different values when starting with TeO2(s) or H2TeO3(s) 4+ – 2+ 28 –4 Te + 2 OH = Te(OH)2 6.3x10 28.8 20 2.5 M HClO4 2.5x10 –0.1 M Comparative Nabivanets et Polymerisation when –3 –1 2+ – + 14 electrodialysis + al. 1974 [Te(IV)] > 5x10 g-atom L Te(OH)2 + OH = Te(OH)3 1.0x10 14.0 1.0 M HClO4 Bjerrum method Masson (1976): Te(IV) Te(OH) + + OH– = Te(OH) 1.7x1012 12.2 0.5 M NaClO 3 4 4 solubility exceeded 6 Reaction K logKa T / oC I electrolyte Te concentrationb Technique Reference Comments pH range – + H2TeO3 = HTeO3 + H –6.92 ± 0.05 20 0 3–10 Potentiometry with Nazarenko et Masson (1976): Te(IV) competing ligand+ al. 1973 solubility exceeded; Bjerrum –6.50 ± 0.05 0.1 M NaClO4 Bjerrum method not applicable –6.56 ± 0.05 0.5 –6.36 ± 0.05 1.0 –6.18 ± 0.05 1.5 – 2– + HTeO3 = TeO3 + H –9.43 ± 0.06 0 –9.36 ± 0.06 0.1 M NaClO4 –9.00 ± 0.06 0.5 –8.60 ± 0.06 1.0 –8.48 ± 0.06 1.5 – + –2 H2TeO3 = HTeO3 + H –6.27 ± 0.02 25 1.5 M NaCl 2x10 M Potentiometry and Ganelina and Masson (1976): Te(IV) – 2– + Na2TeO3 solubility+ Bjerrum Borgoyakov solubility exceeded; Bjerrum HTeO3 = TeO3 + H –8.43 ± 0.02 method 1971 not applicable 3.5–10.5 + + –2 TeO(OH) + H2O = TeO(OH)2 + H (2.1 ± 0.7)x10 –1.68 18 0.5 M NaClO4 0.5–2 Solubility Nabivanets and “Freshly prepared tellurium Kapantsyan hydroxide TeO(OH)2” but 1968 reactions are between dissolved species – + H2TeO3 = HTeO3 + H –2.46 25 0.1 M NaClO4 Solvent extraction Sekine et al. These values do not make 1968 sense –3.07 3.0 M NaClO4 + + H3TeO3 = H2TeO3 + H –3.16 0.1 M NaClO4 –4.17 3.0 M NaClO4 7 Reaction K logKa T / oC I electrolyte Te concentrationb Technique Reference Comments pH range –11 Kbasic Kb’(TeO2 plus acid) 3.1x10 –10.5 25 0.1–2.5 Solubility + Rossotti Issa and Awad TeO2 prepared as in –6 and Rossotti method 1954 Schuhmann (1925) but not Kacid Ka’ (TeO2 plus base) 2.51x10 –5.6 7–8 characterised Paper difficult to interpret: equations never written + + TeO2(s) + H = TeO(OH) –2.1 25 Various HClO4 This value does not Schuhmann TeO2 not characterised but appear in the 1925 proved to be anhydrous publication. It corresponds to the log of the mean value of tree Te/[H+] ratios + TeO2(s) + 4 H 300 2.5 18 Various HCl The first two Kasarnowsky H2TeO3(s) and TeO2(s) have + constants 1924 different solubilities H2TeO3(s) + 4 H 0.021 –1.7 correspond to 4+ – 2– –64 4+ + 4 Te + 6 OH = TeO3 + 3 H2O 1.3x10 –63.9 [Te ]/[H ] ratios H2TeO3(s) = Te(O2(s) + H2O 5550 ± 500 cal Tellurite + acid 2.7x10–3 –2.6 0.0075 M Conductimetry Blanc 1920 These values quoted as –6 Na2TeO3 ‘recommended values’ by Tellurite + base 1.8x10 –7.7 Dutton (1966) aValue in italics calculated from original K value. If not in italics, logK value is as published. bValues in italics are pH. 8 Table S4. Published Te(VI) acid-base constants. Reactiona K logK a T / oC I electrolyte Te concentration Technique Reference Comments pH range – + Te(OH)6 = TeO(OH)5 + H –7.166 ± 0.004 25 1.0 m NaClO4 0.005-0.100 Glass electrode Marhold et al. -1 – 2– + mol kg 1988 TeO(OH)5 = TeO2(OH)4 + H –10.090 ± 0.005 – + 5-11 2 Te(OH)6 = Te2O(OH)11 + H –6.222 ± 0.036 – 2– + Te2O(OH)11 = Te2O2(OH)10 + H –7.050 ± 0.020 – + Te(OH)6 = TeO(OH)5 + H –7.586 ± 0.008 25 0.1 M KCl 0.001-0.005 M Glass electrode Purokoski et al.