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1 Supporting information cover sheet Manuscript title: ADSORPTION AND DESORPTION OF OXYTETRACYCLINE AND CARBAMAZEPINE BY MULTIWALLED CARBON NANOTUBES Authors: Patryk Oleszczuk,2, Bo Pan,3, Baoshan Xing Affiliation: Department of Plant, Soil and Insect Sciences, University of Massachusetts, Amherst, Massachusetts 003, USA; 2 Laboratory of Soil Reclamation and Waste Management, Institute of Soil Science and Environmental Management, University of Life Sciences, Lublin, Poland; 3 College of Environmental Science & Technology, Kunming University of Science & Technology, Kunming, Yunnan, , China. Corresponding author bx@pssci.umass.edu Journal name: Environmental Science and Technology Number of pages: 3 Number of tables: 4 Number of figures: 9 Date of preparation: October 24, S

2 Kinetics sorption and desorption models In order to evaluate the kinetic sorption mechanism, the pseudo-first-order, pseudo-second-order and intraparticle diffusion models were tested. The linear form of the pseudo-first-order equation is given by: () The linear form of the pseudo-second-order model [] is given by: (2) The rate constant for intra-particle diffusion (k ip ) is given by Weber and Morris [2]: (3) where q t are the amounts of compound adsorbed on adsorbent at various time t (mg/g); k is the equilibrium rate constant of pseudo-first order kinetics (min - ) and t is the contact time (min); k 2 is the equilibrium rate constant of the pseudo-second-order kinetics (g/(mg h)); k ip is the intraparticle diffusion rate constant (mg/(g min /2 )) and C (mg/g) is a constant that gives idea about the thickness of the boundary layer. S2

3 Desorption kinetics data were fitted to a two-phase first order equation, which consists of rapid and slow desorption fractions [3], using SigmaPlot.0 (San Jose, CA): were S t and S 0 are the sediment-sorbed amounts at time t and at the start of the experiment, respectively. F rap and F slow are the rapidly and slowly desorbing fractions, respectively. The rate constants of rapid and slow desorption are designated k rap and k slow (h - ), respectively. S3

4 Table S. Calculated pseudo-second-order adsorption rate constants for OTC and CBZ Nanotubes OTC CBZ q e k 2 r 2 t 80 q e k 2 r 2 t 80 MWCNT MWCNT MWCNT MWCNT MWCNT q e is equilibrium solid phase concentration (mg/g). k 2 is the pseudo-second-order rate constant (g/mg h). t 80 is equilibration time required to reach 80% of adsorption capacity Table S2. The monolayer adsorption capacity (Q m ) used in surface coverage calculations Carbon nanotubes OTC CBZ MWCNT MWCNT MWCNT MWCNT MWCNT Q m is the monolayer adsorption capacity (mmol/kg) calculated by A surf /(A m xn)x, where A surf is the MWCNT surface area (m 2 /g); A m is the projecting area of a single adsorbate molecule (cm 2 ) estimated by πx(3mw/(4πxdxn)) 2/3, where N is the Avogadro constant, and MW is the molecular weight (g/mol). S4

5 Table S3. Rate constants for rapid (k rapid ) and slow (k slow ) desorption of OTC and CBZ from multiwalled carbon nanotubes (MWCNT40) along with rapidly (F rapid ) and slowly (F slow ) desorbing fractions depending on ph of desorption solution Compound F rapid k rapid (h - ) F slow k slow (h - ) r 2 OTC ph 5 0.0± E-02±3.7E ± E-05±.0E ph ± E-02±3.2E ± E-04±8.7E ph ±0.05.E-0±6.9E ± E-05±8.2E ph ± E-02±.2E ± E-04±4.E CBZ ph ± E-02±2.0E ± E-03±.3E ph ±0.23.E-0±7.4E ± E-03±.4E ph ±0.24.9E-0±.7E ± E-04±.7E ph ± E-02±.2E ± E-5±2.9E Table S4. Recovery [%] of oxytetracycline (OTC) and carbamazepine (CBZ) from multiwalled carbon nanotubes after methanol extraction. CNTs OTC CBZ MWCNT 98.5± ±3.82 MWCNT20.± ±2.29 MWCNT ±3.46.4±.06 MWCNT ± ±2.44 MWCNT0 0.4± ±4.9 ± solid particles were extracted three times by methanol S5

6 0 40 OTC sorbed concentration (mg/g) MWNT MWNT CBZ sorbed concentration (mg/g) Equilibrium time (h) Equilibrium time (h) Figure S. kinetics of oxytetracycline and carbamazepine depending on outer diameter of carbon nanotubes. Initial concentration of pharmaceuticals was 2.5 mg/l S6

7 Solid phase concentration (mg/g) 00 0 MWNT MWNT0 FM 00 0 MWNT MWNT0 LM 00 0 MWNT MWNT0 PMM Aqueous concentration (mg/l) Figure S2. Adsorption isotherms of oxytetracycline on multiwalled carbon nanotubes. The solid lines are the Freundlich (FM), Langmuir (LM) and Polanyi-Manes (PMM) model fitting results, respectively. Solid phase concentration (mg/g) 00 0 MWNT MWNT0 FM MWNT MWNT0 LM 0. 0 Aqueous concentration (mg/l) 00 0 MWNT MWNT0 PMM 0. 0 Figure S3. Adsorption isotherms of carbamazepine on multiwalled carbon nanotubes. The solid lines are the Freundlich (FM), Langmuir (LM) and Polanyi-Manes (PMM) model fitting results, respectively. S7

8 Solid phase concentration, mg/cm 2 0. MWCNT MWCNT20 MWCNT40 MWCNT60 MWCNT0 OTC Aqueous concentration, mg/l 0. MWCNT MWCNT20 MWCNT40 MWCNT60 MWCNT0 CBZ Aqueous concentration, mg/l Figure S4. Surface area normalized adsorption isotherms of OTC and CBZ on multiwalled carbon nanotubes Surface coverage [%] 0 OTC Equilibrium concentration [mmol/l] Surface coverage [%] CBZ MWNT MWNT Equilibrium concentration [mmol/l] Figure S5. Surface coverage of organic compounds on multi-walled carbon nanotubes with outer diameters. Surface coverage was calculated by dividing the adsorbed amount by monolayer adsorption capacity (Table S4). S8

9 Figure S6. TEM images of MWCNT40 before (A) and after (B) ultrasonic treatment S9

10 Solid phase concetration [mg/g] Solid phase concetration [mg/g] Solid phase concetration [mg/g] MWCNT Desorption 0,0 0, MWCNT40 0,0 0, 0 MWCNT0 Desorption Desorption 0, MWCNT20 Desorption 0,0 0, 0 MWCNT60 Desorption 0,0 0, 0 Figure S7. -desorption hysteresis of OTC on MWCNTs. S

11 Solid phase concetration [mg/g] Solid phase concetration [mg/g] Solid phase concetration [mg/g] MWCNT Desorption 0,0 0, , 0 MWCNT40 MWCNT0 Desorption Desorption 0, MWCNT20 Desorption 0, 0 MWCNT60 Desorption 0, 0 Figure S8. -desorption hysteresis of CBZ on MWCNTs. S

12 .2.0 OTC.2.0 CBZ TII 0.6 TII MWCNT MWCNT20 MWCNT40 MWCNT60 MWCNT MWCNT MWCNT20 MWCNT40 MWCNT60 MWCNT C e [mg/l] C e [mg/l] Figure S9. Thermodynamic index of irreversibility, TII, for sorption of oxytetracycline (OTC), and carbamazepine (CBZ) on multiwalled carbon nanotubes. S2

13 References [] Ho, Y. S.; McKay, G., The kinetics of sorption of basic dyes from aqueous solutions by sphagnum moss peat. The Canadian Journal of Chemical Engineering 998, 76, [2] Weber, W. J.; Morris, J. C. In Proceedings of the International Conference on Water Pollution Symposium, 962; Pergamon Press, Oxford: 962. [3] Cornelissen, G.; Rigterink, H.; Ferdinandy, M. M. A.; van Noort, P. C. M., Rapidly desorbing fractions of PAHs in contaminated sediments as a predictor of the extent of bioremediation. Environmental Science and Technology 998, 32, [4] Hari, A.C.; Paruchuri, R.A.; Sabatini, D.A.; Kibbey, T.C.G. Effect of ph and cationic and nonionic surfactant on the adsorption of pharmaceuticals to a natural aquifer material. Environ. Sci. Technol. 2005, 39, [5] Vuckovic, D.; Shirey, R.; Chen, Y.; Sidisky, L.; Aurand, C.; Stenerson, K.; Pawliszyn, J. In vitro evaluation of new biocompatible coatings for solid-phase microextraction: Implications for drug analysis and in vivo sampling applications Anal. Chim. Acta 2009, 638, [6] Ono, M.; Tozuka, Y.; Oguchi, T.; Yamamura, S.; Yamamoto, K. Effects of dehydration temperature on water vapor adsorption and dissolution behavior of carbamazepine. Int. J. Pharm. 2002, 239, -2. S3

Tannic Acid Sorption and Its Role for Stabilizing Carbon Nanotube Suspensions

Supporting Information Tannic Acid Sorption and Its Role for Stabilizing Carbon Nanotube Suspensions Daohui Lin 1,2 and Baoshan Xing 2, * 1. Department of Environmental Science, Zhejiang University, Hangzhou,