Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee

Size: px

Start display at page:

Download "Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee"

Tamsin Bishop
5 years ago
Views:

1 Supplementary Information Ion Exchange Thermodynamics at The Rutile-Water Interface: Flow Microcalorimetric Measurements and Surface Complexation Modeling of Na- K-Rb-Cl-NO3 Adsorption Tyler Hawkins 1, Nicholas Allen 1, Michael L. Machesky 2, David J. Wesolowski 3 and Nadine Kabengi 1,4,* 1 Department of Geosciences, Georgia State University, Atlanta, GA U.S.A. 2 Illinois State Water Survey, Prairie Research Institute, Champaign, IL U.S.A. 3 Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee Department of Chemistry, Georgia State University, Atlanta, GA U.S.A. *Corresponding author kabengi@gsu.edu Journal: Langmuir Prepared: April 28 th, Supplementary Data Sections (12 pages) 1. Figure S1 2. Microcalorimetry and basic operational procedure - Figure S2. 3. Figure S3. 4. Table S1. 5. Table S2. 6. Figure S4. 7. Figure S5 8. Figure S6. 9. Figure S Table S Table S References.

1. Results from Scanning Electron Microscopy and Figure S1 A representative scanning

The rutile particles were found to be needle-shaped, approximately 500 nm long and 50

The dominant face, as apparent in comparison with the crystallographic representation,

2 1. Results from Scanning Electron Microscopy and Figure S1 A representative scanning electron micrographs for rutile is shown in Fig SI.1. The rutile particles were found to be needle-shaped, approximately 500 nm long and 50 nm wide. The dominant face, as apparent in comparison with the crystallographic representation, is the 110 surface. Figure S1: Representative Scanning Electron Micrographs of the Tioxide rutile sample, showing the dominance of the 110 face; crystallographic representation from Zhang et al. 1

3 2. Instrumentation and basic operational procedure for the flow microcalorimeter. The flow microcalorimeter consists of a microcolumn assembly containing the sample holder in which a known amount of solid sample is packed. An electrolyte solution containing the species of interest is allowed to flow through the packed micro column at controlled flow rates (between 0.30 and 0.35 ml min -1 ) until thermal equilibrium and hence a steady baseline is obtained. A pair of thermistors, one upstream and one downstream from the sample holder, form one half of an electronic bridge and sense temperature changes in the solution as it passes through the column. As the input solution is changed to one with a different composition, ph, ionic strength or concentration, any changes in solution temperature resulting from heat evolved or consumed as a result of either physical or chemical interactions between the reacting solute produce a calorimetric signal that is displaced graphically and recorded as a function of time. The return of the calorimetric signal to the pre-experiment baseline is taken to indicate the end of the reaction being studied and thermal equilibrium, although it is always possible that the reaction continues with the heat evolved or consumed having a time scale of several hours and/or falling below the detection limit of the calorimeters (~ 4 J/mg or K). The heats of reaction (Q in mj/mg solid) are calculated, when required, by integrating the calorimetric peaks to obtain flow rate-averaged peak areas and are converted to energy units (Joules) by comparison with peaks of known energy inputs generated from a calibrating resistor located within the flow stream inside the micro-column. Figure S2 below shows a series of heat pulses and the associated calibration curve.

4 Figure S2: (upper) Peaks obtained from a series of heat pulses, and (lower) the associated calibration curve.

5 3. Figure S3. Figure S3. Surface charge data (solid symbols and lines) and SCM fits (open symbols and lines) in 0.03 m and 0.3 m RbCl (upper left), NaCl (upper right), and KCl (lower left).

6 4. Table S1. Reaction stoichiometry s, log K values, and Charge Distribution Factors (CDFs) for the rutile surface protonation and Rb +, K +, and Na + surface complexation reactions at 25C. CDF values represent that fraction of the adsorbing species charge apportioned to the surface. Surface protonation values taken from Machesky et al. 2, and Rb + and Na + values taken from Machesky et al. 3 Values for K + refit from the surface charge data in Ridley et al. 4 Surface Protonation Log K/CDF TiOH H + TiOH /1 Ti2O H + Ti2OH /1 Inner-sphere Rb + 2 TiOH Ti2O Rb H + [( (0.3)TiOH )( 1.7TiOH )( Ti2O )2] Rb + (tetradentate) -1.00/0.48 TiOH Ti2O Rb H + [( (0.15)TiOH )( 0.85TiOH )( Ti2O )] Rb + (BOTO bidentate 1 ) -1.80/0.24 Outer-sphere Rb + TiOH Rb + ( TiOH ) Rb /0 Ti2O Rb + ( Ti2O ) Rb /0 Inner-sphere K + 2 TiOH Ti2O K H + [( (0.3)TiOH )( 1.7TiOH )( Ti2O )2] K /0.57 (tetradentate) TiOH Ti2O K H + [( (0.15)TiOH )( 0.85TiOH )( Ti2O )] K + (BOTO bidentate) -1.30/0.28 Outer-sphere K + TiOH K + ( TiOH ) K /0 Ti2O K + ( Ti2O ) K /0 Inner-sphere Na + 2 TiOH Ti2O Na H + [( (0.7)TiOH )( 1.3TiOH )( Ti2O )2] Na /0.59 (tetradentate) TiOH Ti2O Na H + [( (0.5)TiOH )( 0.5TiOH )( Ti2O )] Na + (BOTO bidentate) 2 TiOH Na H + [( (0.6)TiOH )( 1.4TiOH )] Na + (TOTO 2 bidentate) -0.85/ /0.33 Outer-sphere Na + TiOH Na + ( TiOH ) Na /0 Ti2O Na + ( Ti2O ) Na /0 1 BOTO: bidentate configurations on one bridging oxygen and one terminal oxygen 2 TOTO: bidentate configuration on two terminal oxygens

7 5. Table S2. Cations specific effects Cations Bare Ionic Radius (Å) 1 Hydrated Radius (Å) 2 Primary Hydration Numbers 3 Bulk Hydration Enthalpy ( H hyd ) (kj/mol) 1 Na K Rb Cl NO Marcus, Y. 5 2 Nightingale, E.R., Jr 6. 3 Mähler, J., and Persson, I. 7

8 6. Figure S4. Figure S4. Representative calorimetric responses obtained for nitrate and chloride exchange obtained at ph values of 2.0, 3.25, 58 and An increase in voltage resulting in positive peaks corresponds to a release in energy and hence an exothermic reaction. A decrease in voltage and hence negative peaks indicate an endothermic reaction.

9 7. Figure S5 Figure S5. Representative calorimetric responses obtained for rubidium and potassium exchange obtained at ph value of 5.8. An increase in voltage resulting in a positive peak corresponds to a release in energy and hence an exothermic reaction. A decrease in voltage and hence a negative peak indicates an endothermic reaction.

10 8. Figure S6. Figure S6. Distribution of terminal oxygen (TO) and bridging oxygen (BO) groups in 0.05M NaCl between ph 2 and The inset shows site fractions from 0 to 0.01 in expanded fashion. TOH(-) and BO (-) are negatively charged terminal and bridging oxygens, respectively, and TOH2(+) and BOH(+) the positively charged counterparts. Outer-sphere Na + species to TO and BO groups are in blue, the bidendate BOTO species in dark yellow, the tetradentate (TD) species in dark green, the inner-sphere Cl complex to a BOH group (ClBOH) in orange, and the Na + bidentate TOTO complex in violet.

11 9. Figure S7 Figure S7. Distribution of terminal oxygen (TO) and bridging oxygen (BO) groups in 0.05M KCl between ph 2 and The inset shows site fractions from 0 to 0.01 in expanded fashion. TOH(-) and BO (-) are negatively charged terminal and bridging oxygens, respectively, and TOH2(+) and BOH(+) the positively charged counterparts. Outer-sphere K + species to TO and BO groups are in blue, the bidendate BOTO species in dark yellow, the tetradentate (TD) species in dark green, and the inner-sphere Cl complex to a BOH group (ClBOH) in orange.

12 10. Table S3. Amounts of Rb +, K +, and Na + ions adsorbed (moles/m 2) as Tetradentate (TD), Bidentate (BOTO and TOTO), and Outer-sphere (OS) species, as well the total amounts adsorbed in 0.05M solutions at ph 2, 3.25, 5.8, and 11. TD (moles/m 2 ) BOTO (moles/m 2 ) TOTO (moles/m 2 ) OS (moles/m 2 ) Total Adsorbed (moles/m 2 ) ph K + Na + Rb + K + Na + Rb + K + Na + Rb + K + Na + Rb + K + Na + Rb E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E 06

13 11. Table S4. The average degree of dehydration and waters lost from Na +, K +, and Rb + as obtained from the SCM. ph dehydration degree 1 Na + K + Rb + Average Average dehydration dehydration waters waters lost 2 degree degree lost Average waters lost from the SCM output 2 calculated as follows: dehydration degree * primary hydration number (from table S2)

14 12. References (1) Zhang, Z.; Fenter, P.; Cheng, L.; Sturchio, N. C.; Bedzyk, M. J.; Předota, M.; Bandura, A.; Kubicki, J. D.; Lvov, S. N.; Cummings, P. T.; Chialvo, A. A.; Ridley, M. K.; Bénézeth, P.; Anovitz, L.; Palmer, D. A.; Machesky, M. L.; Wesolowski, D. J. Ion Adsorption at the Rutile Water Interface: Linking Molecular and Macroscopic Properties. Langmuir, 2004, (2) Machesky, M.L.; Předota, M.; Wesolowski, D.J.; Vlcek, L.; Cummings, P.T; Rosenqvist, J; Ridley, M.K.; Kubicki, J.D.; Bandura, V.A.; Kumar, N., Sofo, J.O. Surface Protonation at the Rutile (110) Interface: Explicit Incorporation of Solvation Structure within the Refined MUSIC Model Framework. Langmuir, 2008, 24 (21), pp (3) Machesky, M. L.; Předota, M.; Ridley, M. K.; Wesolowski, D. J. Constrained Surface Complexation Modeling: Rutile in RbCl, NaCl, and NaCF3SO3 Media to 250 C. J Phys. Chem. C, 2015, 119(27), (4) Ridley, M. K.; Hiemstra, T.; van Riemsdijk, W. H.; Machesky, M. L. Inner-sphere complexation of cations at the rutile water interface: A concise surface structural interpretation with the CD and MUSIC model. Geochim. Cosmochim. Acta, 2009, 73(7), (5) Marcus, Y. Ions in solution and their solvation. Wiley:Hoboken NJ, 2015; pp (6) Nightingale, E. R., Phenomenological Theory of Ion Solvation. Effective Radii of Hydrated Ions. J Phys. Chem., 1959, 63 (9), (7) Mähler, J.; Persson, I.; A Study of the Hydration of the Alkali Metal Ions in Aqueous Solution. Inorg. Chem. 2012, 51,

HYDROGEN BONDING AT THE RUTILE (110) SURFACE - AQUEOUS INTERFACE. University of South Bohemia, Jírovcova 24, České Budějovice , Czech Republic

HYDROGEN BONDING AT THE RUTILE (110) SURFACE - AQUEOUS INTERFACE M. PŘEDOTA 1,2, M. L. MACHESKY 3, D. J. WESOLOWSKI 4, and P. T. CUMMINGS 5,4 1 Department of Health Physics and Biophysics, Faculty of Health