Cooperative and Competitive Adsorption of Amino Acids with Ca2+ on

The interactions of biomolecules such as amino acids with mineral surfaces in the near-surface environment are an important part of the short and long...
1 downloads 0 Views 1MB Size
Subscriber access provided by UNIV WAIKATO

Article

Cooperative and competitive adsorption of amino acids with Ca2+ on rutile (#-TiO2) Namhey Lee, Dimitri A. Sverjensky, and Robert M Hazen Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/es501980y • Publication Date (Web): 10 Jul 2014 Downloaded from http://pubs.acs.org on July 13, 2014

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Environmental Science & Technology is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 24

Environmental Science & Technology

1 2 3 4

Cooperative and competitive adsorption of amino acids with Ca2+ on rutile (α-TiO2)

5

Namhey Leea,b*, Dimitri A. Sverjenskya,b, and Robert M. Hazenb a

6 7

Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, USA.

8 9

b

10 11 12 13 14

Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, 20015, USA. *Correspondence to: [email protected] Abstract The interactions of biomolecules such as amino acids with mineral surfaces in the near-

15

surface environment are an important part of the short and long-term carbon cycles.

16

Amino acid-mineral surface interactions also play an important role in biomineralization,

17

biomedicine, and in assembling the building blocks of life in the prebiotic era. Although

18

the pH effects during adsorption of amino acids onto mineral surfaces have been studied,

19

little is known about the effects of environmentally important divalent cations. In this

20

study, we investigated the adsorption of the oppositely charged amino acids glutamate

21

and lysine with and without the addition of divalent calcium. Without calcium, glutamate

22

shows a maximum in adsorption at a pH of ~4 and lysine shows a maximum in

23

adsorption at a pH of ~9.4. In comparison, with calcium present, glutamate showed

24

maxima in adsorption at both low and high pH, whereas lysine showed no adsorption at

25

all. These dramatic effects can be described as cooperative adsorption between glutamate

26

and Ca2+ and as competitive adsorption between lysine and Ca2+. The origin of these

27

effects can be attributed to electrostatic phenomena. Adsorption of Ca2+ at high pH makes

28

the rutile surface more positive, which attracts glutamate and repels lysine. Our results

1

ACS Paragon Plus Environment

Environmental Science & Technology

29

indicate that the interactions of biomolecules with mineral surfaces in the environment

30

will be strongly affected by the major dissolved species in natural waters.

31 32 33 34 35 36 37

Keyword: glutamate, lysine, cation, rutile, cooperative/competitive adsorption

1. Introduction The interactions between mineral surfaces and organic molecules are ubiquitous,

38

ranging from the fate of organic matter during weathering and transport to the oceans, the

39

transport of nutrients in soil, and the fate of contaminants, to medical issues including

40

biotechnology, pharmaceuticals and the viability of metal implants in the human body1-9.

41

Recent dramatic increases of interest in nanoparticles have also brought our attention to

42

how organic molecules alter mineral growth at surfaces10-12. Furthermore, mineral

43

surfaces and organic molecule interactions can provide vital clues for the evolution of

44

abiotically-formed organic molecules in prebiotic times.

45

By definition, all amino acids have both positive and negatively charged -NH3+, -COOH

-COO-). As a result, the net

46

functional groups on them (-NH2

47

charge of the molecules varies with pH, leading to a variety of interesting adsorption

48

behavior. Previous studies of amino acid adsorption have been restricted to simple

49

systems typically containing one amino acid and one mineral in a 1:1 background

50

electrolyte13-16. However, near-surface natural waters are more complex: they are most

51

commonly Ca2+-Na+-HCO3--SiO2 waters. As a first step to begin addressing this

52

complexity, we investigated the potential competitive or cooperative adsorption of amino

53

acids and Ca2+ on the rutile surface. We compared how the addition of Ca2+ changes the

54

adsorption characteristics of glutamate and lysine on rutile. The results illustrate the

2

ACS Paragon Plus Environment

Page 2 of 24

Page 3 of 24

Environmental Science & Technology

55

responses of two very different amino acids to the presence of Ca2+ under a range of

56

environmental conditions. While it is known that cations can form bridging complexes

57

with organics by forming tertiary complexes17, few studies have been done involving

58

cations and amino acids18. Studies involving metal-humic acid interactions show that in

59

the presence of divalent cations, the adsorption of organics is enhanced at high pH

60

values19, 20. However due to the complex structure of NOM and its massive size, it is not

61

easy to pinpoint what is causing this enhanced adsorption. In the present study, we built

62

on our previous studies of glutamate adsorption on rutile13, 21 together with our surface

63

complexation modeling studies of calcium on rutile22, to enable an experimental and

64

surface complexation modeling study of the adsorption of amino acids on rutile in the

65

presence of calcium.

66 67

2. Materials and Methods

68

All solutions were made from milli-Q water (Millipore resistance 18.2 Mega

69

ohm).

L-glutamic acid (Acros Organics, 99%), L-lysine monohydrochloride (Acros

70

Organics, 99%) and calcium chloride standard solution of 0.5 M (Fluka analytical) were

71

used without any further purification. The solutions were sonicated for more than 15

72

minutes and visually checked prior to use to ensure complete dissolution. The pH was

73

adjusted by adding precise volumes of standardized NaOH and HCl. Measurement of pH

74

was carried out using a combination electrode (Thermo-Electron, Orion 8103 BNUWP)

75

that was previously calibrated with standardized pH buffers.

76

The rutile powder used in this study was obtained from Oak Ridge National

77

Laboratory (courtesy of J. Rosenqvist, D. Wesolowski, and M. Machesky). At Oak Ridge

78

National Laboratory, rutile powder from Tioxide Specialties Ltd. (Cleveland, UK) was 3

ACS Paragon Plus Environment

Environmental Science & Technology

79

pretreated using the procedure developed by Machesky et al.23 that includes numerous

80

washing-boiling-decanting cycles in Milli-Q water until the supernatant had a pH>4. The

81

suspension was then thermally treated at 200 °C for two weeks in a Teflon-lined

82

autoclave. The acid released during the thermal treatment was removed by repeated

83

washing-decanting cycles, until the pH of the supernatant was above 5. Then the powder

84

was dried in a vacuum oven at 60 °C. The BET surface area was determined to be 18.1 ±

85

0.1 m2.g-1 by N2 adsorption. X-ray powder diffraction (XRD) confirmed that the particles

86

were rutile. SEM images showed needled-shaped particles that are approximately 400-

87

500 nm long and 50-100 nm wide. The predominant face is (110). Additional (101) and

88

(111) faces were present near both ends of the particles as well as on (110) face in the

89

form of steps and kinks

90

(pHpzc) for this rutile is 5.413.

24

. Previous titration data showed that the point of zero charge

91 92

2.1 Batch adsorption experiments

93

Batch adsorption experiments were conducted with a solid concentration of 3.0

94

g.L-1 and amino acid concentration of 10 µM. Precise volume of calcium chloride

95

standard solution was added to amino acid solutions to give desired concentrations. In a

96

50 mL falcon tube, 0.09 g of rutile powder was mixed with 30 mL of each amino acid

97

solution. The pH was adjusted ranging from 3 to 11 while constantly purged with argon

98

gas to avoid contamination by CO2. Then the suspensions were sealed, put on the rotator

99

for about 18 hours and allowed to reach steady state. After that, the pH was measured, the

100

suspensions were centrifuged for 15 min at a relative centrifugal force of 1073×g (Fisher

101

Scientific accuSpin 400), and the supernatant was collected by filtering through 0.2 mM

4

ACS Paragon Plus Environment

Page 4 of 24

Page 5 of 24

Environmental Science & Technology

102

filter syringes (Waters). The supernatants were then analyzed using ion chromatography

103

to determine the amino acids remaining in the solution. For the detection and

104

measurement of amino acids a Dionex ICS-5000 AAA-Direct ion chromatograph was

105

used. The chromatograph was equipped with a 2-250 AminoPac PA10 analytical column

106

and an integrated pulsed amperometry (IPAD) electrochemical detector25. Unlike other

107

traditional methods for analyzing amino acids, the AminoPac column allows the accurate

108

detection of amino acids in water without the complications of pre- or post-column

109

derivitization. The method consists of high-pH anion exchange separation of the analyte

110

solution in the AminoPAC column followed by integrated pulsed amperometry

111

electrochemical detection. Compounds containing aliphatic amine functional groups are

112

oxidized at the gold electrode in high pH solutions and are therefore amenable to

113

electrochemical detection. Direct analysis of the amino acid used in this method not only

114

minimizes the uncertainties of incomplete derivitization of conventional amino acid

115

detection methods, but also allows monitoring for any additional amine-bearing

116

molecules in the system. In this study, the amino acids did not show any sign of

117

degradation after being exposed to the rutile.

118 119

2.2 Surface complexation modeling We applied the extended triple-layer model (ETLM) of surface complexation22, 26,

120 121

27

122

glutamate adsorption in the presence of calcium, the model used was completely

123

predictive, without fitting parameters. Amongst other features, the ETLM specifically

124

accounts for the electrical work associated with desorption of chemisorbed water

125

molecules during inner-sphere surface complexation of ligands. As a consequence, it

to our adsorption data. We wish to emphasize that for the calculations modeling

5

ACS Paragon Plus Environment

Environmental Science & Technology

126

indicates the number of inner-sphere linkages (e.g. >Ti–O–C) for an adsorbate ligand, as

127

well as the number of Ti surface sites involved in the reaction stoichiometry. These

128

results can significantly constrain the likely mode of surface attachment. The calculations

129

reported below were carried out with the computer code GEOSURF described

130

previously28. We used the same surface protonation and electrolyte adsorption parameters

131

established in our previous study of the rutile–NaCl system13 (Table 1). The glutamate

132

adsorption reactions and equilibrium constants used in the present study were also

133

consistent with those established in our previous study. For calcium adsorption we used

134

the previously published ETLM for calcium adsorption on rutile22. For both the glutamate

135

and the calcium surface reactions, the log K values previously published were adjusted

136

for the tetranuclear complexes to account for the lower solid concentrations in the present

137

study following the standard state theory previously published29. In this way, the surface

138

complexation model for glutamate with calcium used in the present study was completely

139

predictive. For lysine on rutile, we carried out iterative application of the surface

140

complexation modeling to our experimental adsorption data over a wide range of pH

141

values. Attachments of lysine were adopted based on surface species suggested in the

142

previous ATR–FTIR studies to establish the most appropriate reaction stoichiometries for

143

lysine on rutile5, 30-32. The detailed attachment mode of lysine is discussed below.

144 145

3. Results and discussion

146

3.1 Glutamate adsorption with and without calcium present

147

The previous glutamate adsorption study on rutile established the adsorption as a

148

function of salt concentration and surface coverage over a wide range of pH with a rutile

149

concentration of 20 g/L13. The results indicate that glutamate has its maximum adsorption 6

ACS Paragon Plus Environment

Page 6 of 24

Page 7 of 24

Environmental Science & Technology

150

near a pH of about 4 where the rutile surface is positively charged and the glutamate is

151

negatively-charged (HGlu-). However, at high pH values in the range of 7 to about 10,

152

there is essentially no adsorption as the rutile surface is negatively charged which

153

repulses the negatively-charged glutamate. Detailed studies of the adsorption mechanism

154

of glutamate on rutile using the ETLM and ATR-FTIR spectroscopy combined with

155

quantum chemical calculations revealed that there are at least two surface species present

156

for glutamate attachment on rutile surfaces13,

157

species where glutamate attaches "lying-down" on the surface and binding occurs through

158

inner-sphere coordination of both α-and γ-carboxyl groups. The other species is a

159

chelating-monodentate species in which glutamate binds through inner-sphere

160

coordination with the γ-carboxyl group in a "standing-up" configuration (with or without

161

protonation of the α-carboxyl). This binding conformation is illustrated in Fig. 1 from

162

Jonsson et al. (2009)13. The predicted surface speciation shows that the bridging-

163

bidentate species is dominant at low pH values and low glutamate concentrations13. The

164

chelating species becomes dominant at high pH values and high glutamate

165

concentrations.

21

. One species is a bridging-bidentate

166

In the present study, batch adsorption experiments were carried out in the same

167

manner, but with a much lower solid concentration of 3.0 g.L-1, no added NaCl and with

168

about two orders of magnitude lower glutamate concentrations (10 µM). These conditions

169

were chosen to amplify the percent adsorption of amino acids and to increase the surface

170

coverage by calcium. The adsorption data for glutamate alone are depicted in Fig. 2a.

171

Overall, the results showed comparable pH-dependent adsorption behavior to that

172

previously observed, with a maximum at a pH value of about 4 (Fig. 2a). The maximum

7

ACS Paragon Plus Environment

Environmental Science & Technology

173

adsorption density was about 0.13 µM.m-2.

174

In Figs. 2c and d, the adsorption of glutamate is shown in the presence of calcium.

175

With 1 and 3 mM of calcium ion present, the glutamate adsorption properties changed

176

substantially. Glutamate still has a maximum in its adsorption near a pH of 4 (about 0.1

177

µM/m2), albeit slightly lower than when only glutamate is present. However, an

178

additional adsorption maximum is now also observed at high pH values, from about 8 to

179

11. With 1 mM of calcium present, glutamate was adsorbed up to 0.05 µM/m2 and with 3

180

mM of Ca2+ the adsorption density increased up to 0.075 µM.m-2 at a pH of about 9.6.

181

Glutamate adsorption at a pH of about 4 did not vary significantly with the calcium

182

concentration. However, near a pH of about 9.6, the glutamate adsorption shows a strong

183

dependence on the Ca2+ concentrations. This suggests that the adsorption near a pH of 4

184

originates solely from the rutile and glutamate interactions whereas near a pH of 9.6, the

185

adsorption is clearly facilitated by Ca2+.

186

It has long been known that strong adsorption of Ca2+, and other divalent cations,

187

at high pH converts the surface charge on rutile from negative to positive33. Therefore, it

188

can be expected that the positively charged rutile surface at high pH values will

189

electrostatically attract the negatively-charged glutamate. Effectively, this should result in

190

a cooperative adsorption of calcium and glutamate at high pH values. Although in

191

principle the cooperative adsorption of calcium and glutamate could result from the

192

adsorption of an aqueous Ca-glutamate complex, aqueous speciation calculations indicate

193

that this is a very weak complex in the aqueous phase, present at low concentrations

194

(TiOH functional group, the other attachment point occurs

291

through the ε-NH3+ group. This outer-sphere species is predicted to predominate at pH

292

values greater than about 9.

293

Application of the same surface complexation model to the data shown in Fig. 4c

294

was made in a predictive mode. With Ca2+ present, the model predicted no significant

295

amount of lysine adsorption, in agreement with the experimental data. These results are

296

well explained by the change in surface charge of the rutile with added calcium (Fig. 3).

297

The more positive surface charge of the rutile in the presence of calcium repels the

298

positively-charged lysine, resulting in no adsorption

299

These observations can be generalized to other amino acids as well as other

300

simple organic acids. Acidic amino acids that are largely in negatively-charged forms

301

will probably show cooperative adsorption with all divalent cations at high pH values

302

given that the substrate becomes positively charged at those pH values. On the other

303

hand, basic amino acids that are mainly in a positively charged form will be outcompeted

304

by divalent cations at high pH conditions where the surface is deprotonated. This is a

305

simple yet very interesting observation. It may have wide application because Ca2+ is a

306

major ion in near-surface natural waters. Our study illustrates that the interactions of

307

amino acids with mineral surfaces in 2:1 electrolytes can differ greatly from the results of

308

laboratory experiments in 1:1 electrolytes. The cooperative or competitive adsorption of

309

divalent cations and amino acids shows that biomolecules could participate in complex

310

adsorption behavior in natural systems. Further experiments are needed to generate a

13

ACS Paragon Plus Environment

Environmental Science & Technology

311

better understanding of and provide potential for prediction in natural systems.

312

Furthermore, it can be expected that a better understanding of cooperative or competitive

313

adsorption could provide insights into such diverse areas as the chemical evolution of

314

biomolecules in the origin of life, and the design of biosensors and biodetection methods.

315 316 317 318 319 320 321

Acknowledgements

322

The authors are extremely grateful for the specially cleaned rutile powder sample

323

provided to them by J. Rosenqvist and D. Wesolowski of Oak Ridge National

324

Laboratory, as well as M. Machesky.

325

assistance in the laboratory from C. M. Jonsson, C. L. Jonsson, C. F. Estrada and C.

326

Feuillie. N. Lee and D. A. Sverjensky greatly appreciate the support of R. J. Hemley

327

during their stay as visiting researchers at the Geophysical Laboratory. This research was

328

conducted with support from the NSF EAR-1023865 (DAS), DOE DE-FG02-96ER-

329

14616 (DAS), NSF EAR-1023889 (RMH), NASA Astrobiology Institute, and the

330

Carnegie Institution of Washington.

We greatly appreciate discussion with and

331 332 333

14

ACS Paragon Plus Environment

Page 14 of 24

Page 15 of 24

334 335 336 337 338 339 340 341

Environmental Science & Technology

Figure 1. Previously proposed diagrammatic representation of surface species of glutamate: at left is the “lying-down” species, bridging-bidentate species with four points of attachements involving one inner-sphere Ti-O-C bond and one Ti-OH…O=C hydrogen bond for each carboxylate , on the right is the “standing-up” species, chelating with two points of attachment involving one inner-sphere Ti-O-C bond and one TiOH2+…O=C to a single titanium (Jonsson et al., 2009)13).

342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 15

ACS Paragon Plus Environment

Environmental Science & Technology

370 371 372 373 374 375

Figure 2. Adsorption of glutamate on rutile as a function of pH: (a) Glutamate adsorption without Ca2+; (c) Glutamate adsorption with 1 mM Ca2+; (e) Glutamate adsorption with 3 mM Ca2+. The solid curves were predicted using previously published, separate glutamate and Ca+2+ adsorption models (Table 1); (b), (d), (f) Predicted glutamate surface speciation. Blue dotted line indicates the sum of species. (a) (b)

376 377

(c)

378 379

(e)

(d)

(f)

380 16

ACS Paragon Plus Environment

Page 16 of 24

Page 17 of 24

381 382 383 384 385

Environmental Science & Technology

Figure 3. Predicted ζ potential vs. pH. Without any ligands on the surface, the particle charge continues to decrease with increasing pH. Glutamate adsorption does not make a noticeable difference. In contrast, with1 and 3 mM Ca2+ present, the surface charge is converted from negative to positive at high pH values.

386 387 388 389

17

ACS Paragon Plus Environment

Environmental Science & Technology

390 391 392 393 394 395

396 397 398 399

Figure 4. Adsorption of lysine on rutile as a function of pH. (a) Percent adsorbed lysine without added Ca2+. The solid curve was calculated using the lysine adsorption model with parameters in Table 1 in order to fit the data shown; (b) Predicted surface speciation of lysine on rutile; (c) Percent adsorbed lysine with 3 mM added Ca2+. (a)

(b)

(c)

400 401

18

ACS Paragon Plus Environment

Page 18 of 24

Page 19 of 24

402 403 404 405 406 407 408 409

Environmental Science & Technology

Figure 5. Diagrammatic representation of surface species of lysine based on surface complexation modeling and published ATR-FTIR studies (see text): at left is the “lyingdown” species where lysine attaches via the ε- NH3+ group and the α-carboxylic group forming an hydrogen bond. On the right is the “standing-up” species where lysine is adsorbed to the surface via the ε- NH3+ only. Both species are weakly bound outer-sphere species.

410 411 412

19

ACS Paragon Plus Environment

Environmental Science & Technology

413 414 415 416 417 418 419 420 421 422

Table 1. Aqueous glutamate, lysine properties, rutile characteristics, and Extended Triple Layer Model (ETLM) parameters for proton, electrolyte and glutamate, lysine and calcium adsorption on rutile. All the rutile surface protonation and electrolyte adsorption equilibrium constants, and the glutamate adsorption equilibrium constants with a superscript of theta refer to the site-occupancy standard state29. The numerical values of these were taken from previous studies on the same rutile sample13. The equilibrium constants with a superscript of zero refer to the hypothetical 1.0 M standard state and have numerical values consistent with the site densities, the BET surface area, and the solid concentration used in the present study29 Similar considerations apply to the calcium adsorption equilibrium constants which were derived in a previous study22.

423 424 425 426 427

Protonation constants from Smith and Martell (2004)34, electrolyte ion pair constants given by De Stefano et al (2000) 35 3535. Rutile properties are Ns= 3.0. sites/nm2 and 12.5 sites/nm2, As = 18.1 m2g-1, C1= 120 µFcm-2, C2= 120 µFcm-2, pHppzc= 5.4, ∆pKnθ= 6.3, log θ K1θ= 5.25, log K2θ= 8.50, log K θNa+ = 2.68, log KCl − = 2.48.

428 429 430 20

ACS Paragon Plus Environment

Page 20 of 24

Page 21 of 24

431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476

Environmental Science & Technology

References: 1. Scheidegger, A. M.; Sparks, D. L., A Critical Assessment of Sorption-Desorption Mechanisms At the Soil Mineral/Water Interface. Soil Science 1996, 161, (12), 813-831. 2. Ghio, A. J.; Kennedy, T. P.; Whorton, A. R.; Crumbliss, A. L.; E., H. G.; Hoidal, J. R., Role of surface complexed iron in oxidant generation and lung inflammation induced by silicates. Am J Physiol Lung Cell Mol Physiol 1992, 263, (5), 511-518. 3. Shen, H.; Tan J.; W.M., S., Surface-mediated gene transfer from nanocomposites of controlled texture. Nature Materials 2004, 3, 569-574. 4. Weber, W. J., McGinleya P. M., and Katz, L. E. , Sorption phenomena in subsurface systems: Concepts, models and effects on contaminant fate and transport. Water research 1991, 25, (5), 499-528. 5. Roddick-Lanzilotta, A. D.; McQuillan, A. J., An in situ infrared spectroscopic investigation of lysine peptide and polylysine adsorption to TiO2 from aqueous solutions. J. Colloid Interface Sci. 1999, 217, (1), 194-202. 6. Roddick-Lanzilotta, A. D.; McQuillan, A. J., An in situ infrared spectroscopic study of glutamic acid and of aspartic acid adsorbed on TiO2: Implications for the biocompatibility of titanium. J. Colloid Interface Sci. 2000, 227, (1), 48-54. 7. Tsortos, A.; Nancollas, G. H., The adsorption of polyelectrolytes on hydroxyapatite crystals. J. Colloid Interface Sci. 1999, 209, (1), 109-115. 8. Vasudevan, D.; Stone, A. T., Adsorption of Catechols, 2-Aminophenols, and 1,2Phenylenediamines at the Metal (Hydr)Oxide/Water Interface: Effect of Ring Substituents on the Adsorption onto TiO2. Environ. Sci. Technol. 1996, 30, (5), 16041613. 9. Vasudevan, D.; Stone, A. T., Adsorption of 4-Nitrocatechol, 4-Nitro-2Aminophenol, and 4-Nitro-1,2-Phenylenediamine at the Metal (Hydr)Oxide/Water Interface: Effect of Metal (Hydr)Oxide Properties. J. Colloid Interface Sci. 1998, 202, (1), 1-19. 10. Chen, C.; Qi, J.; Zuckermann, R.; DeYoreo, J., Engineered Biomimetic Polymers as Tunable Agents for Controlling CaCO3 Mineralization. J. Am. Chem. Soc. 2011, 133, (14), 5214-5217. 11. Wang, D.; Wallace, A.; De Yoreo, J.; Dove, P., Carboxylated molecules regulate magnesium content of amorphous calcium carbonates during calcification. PNAS 2009, 106, (51), 21511-21516. 12. Nielsen, M.; Lee, J.; Hu, Q.; Han, T.; De Yoreo, J., Structural evolution, formation pathways and energetic controls during template-directed nucleation of CaCO3. Faraday Discuss. 2012, 159, 105-121. 13. Jonsson, C. M.; Jonsson, C. L.; Sverjensky, D. A.; Cleaves II, H. J.; Hazen, R. M., Attachment of l-Glutamate to Rutile (α-TiO2): A Potentiometric, Adsorption, and Surface Complexation Study. Langmuir 2009, 25, (20), 12127-12135. 14. Jonsson, C. M.; Jonsson, C. L.; Estrada, C.; Sverjensky, D. A.; Cleaves II, H. J.; Hazen, R. M., Adsorption of L-aspartate to rutile (a-TiO2): Experimental and theoretical surface complexation studies. Geochim. Cosmochim. Acta 2010, 74, 2356-2367. 15. Bahri, S.; Jonsson, C. M.; Jonsson, C. L.; Azzolini, D.; Sverjensky, D. A.; Hazen, R. M., Adsorption and Surface Complexation Study of L-DOPA on Rutile

21

ACS Paragon Plus Environment

Environmental Science & Technology

477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520

(α-TiO2) in NaCl Solutions. Environ. Sci. Technol. 2011, 45, 3959-3966. 16. Vlasova, N. N.; Golovkova, L. P., The adsorption of amino acids on the surface of highly dispersed silica. Colloid J. 2004, 66, (6), 657-662. 17. Schindler, P. W., Co-adsorption of metal ions and organic ligands; formation of ternary surface complexes. Rev. Mineral. Geochem. 1990, 23, 281-307. 18. Fitts, J.; Persson, P.; Brown Jr., G. E.; Parks, G. A., Structure and Bonding of Cu(II)–Glutamate Complexes at the γ-Al2O3–Water Interface. J. Colloid Interface Sci. 1999, 220, (1), 133-147. 19. Weng, L.; Riemsdijk, W. H.; Hiemstra, T., Cu2+ and Ca2+adsorption to goethite in the presence of fulvic acids. Geochim. Cosmochim. Acta 2008, 72, 5857-5870. 20. Zhao, Y.; Geng, J.; Wang, X.; Gu, X.; Gao, S., Adsorption of tetracycline onto goethite in the presence of metal cations and humic substances. J. Colloid Interface Sci. 2011, 361, 247-251. 21. Parikh, S. J.; Kubicki, J. D.; Jonsson, C. M.; Jonsson, C. L.; Hazen, R. M.; Sverjensky, D. A.; Sparks, D. L., Evaluating Glutamate and Aspartate Binding Mechanisms to Rutile (α-TiO2) via ATR-FTIR Spectroscopy and Quantum Chemical Calculations. Langmuir 2011, 27, (5), 1778-1787. 22. Sverjensky, D. A., Prediction of the speciation of alkaline earths adsorbed on mineral surfaces in salt solutions. Geochim. Cosmochim. Acta 2006, 70, (10), 2427-2453. 23. Machesky, M. L.; Wesolowski, D. J.; Palmer, D. A.; Ichiro-Hiyashi, K., Potentiometric titrations of rutile suspensions to 250 C. J. Colloid Interface Sci. 1998, 200, (2), 298-309. 24. Livi, K. S., B; Azzolini, D; Seabourne, CR;Hardcastle, TP; Scott, AJ; Scott, AJ; Erlebacher, JD ;Brydson, R;Sverjensky, DA, Atomic-Scale Surface Roughness of Rutile and Implications for Organic Molecule Adsorption. Langmuir 2013, 29, (23), 6876-6883. 25. Clarke, A. P.; Jandik, P.; Rocklin, R. D.; Liu, Y.; Avdalovic, N., An integrated amperometry waveform for the direct, sensitive detection of amino acids and amino sugars following anion-exchange chromatography. Anal. Chem. 1999, 71, (14), 27742781. 26. Sverjensky, D. A., Prediction of surface charge on oxides in salt solutions: Revisions for 1 : 1 (M+L-) electrolytes. Geochim. Cosmochim. Acta 2005, 69, (2), 225257. 27. Sverjensky, D. A.; Fukushi, K., Anion adsorption on oxide surfaces: Inclusion of the water dipole in modeling the electrostatics of ligand exchange. Environ. Sci. Technol. 2006, 40, (1), 263-271. 28. Sahai, N.; Sverjensky, D. A., GEOSURF: A computer program for modeling adsorption on mineral surfaces from aqueous solution. Comput. Geosci. 1998, 24, (9), 853-873. 29. Sverjensky, D. A., Standard states for the activities of mineral surface sites and species. Geochim. Cosmochim. Acta 2003, 67, (1), 17-28. 30. Kitadai, N.; Yokoyama, T.; Nakashima, S., ATR-IR spectroscopic study of Llysine adsorption on amorphous silica. J. Colloid Interface Sci. 2009, 329, (1), 31-37. 31. Kitadai, N.; Yokoyama, T.; Nakashima, S., In situ ATR-IR investigation of Llysine adsorption on montmorillonite. J. Colloid Interface Sci. 2009, 338, (2), 395-401.

22

ACS Paragon Plus Environment

Page 22 of 24

Page 23 of 24

521 522 523 524 525 526 527 528 529 530 531 532 533 534

Environmental Science & Technology

32. Roddick-Lanzilotta, A. D.; Connor, P. A.; McQuillan, A. J., An In Situ Infrared Spectroscopic Study of the Adsorption of Lysine to TiO2 from an Aqueous Solution. Langmuir 1998, 14, (22), 6479-6484. 33. Jang, H. F., DW, The specific adsorption of alkaline-earth cations at the rutile/water interfae. Colloids surfaces 1986, 21, 235-257. 34. Smith, R. M.; Martell, A. E., NIST Critically Selected Stability Constants of Metal Complexes Database. In Administration, T., Ed. U. S. Department of Commerce: Washington, DC, 2004. 35. De Stefano, C.; Foti, C.; Gianguzza, A.; Sammartano, S., The interaction of amino acids with the major constituents of natural waters at different ionic strengths. Marine Chemistry 2000, 72, (1), 61-76.

23

ACS Paragon Plus Environment

Environmental Science & Technology

No  Ca2+  

With  Ca2+  

ACS Paragon Plus Environment

Page 24 of 24