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1 Electronic Supplementary Information

2 for

3 Molecular fractionation and sub-nano scale distribution of

4 dissolved organic matter on allophane †

5

6 Yang Ding, a ,b Yang Lu, a ,b Peng Liao, a ,b, c Shimeng Peng, a ,b Yuzhen Liang, a ,b Zhang Lin, a ,b Zhi 7 Dang, a ,b Zhenqing Shi a ,b,*89 a School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong

10 510006, People’s Republic of China11 b The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of 12 Education, South China University of Technology, Guangzhou, Guangdong 510006, People’s Republic 13 of China14 c Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control, School of 15 Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 16 518055, People’s Republic of China1718 † Electronic supplementary information (ESI) available. 1920 * Corresponding author at: School of environment and energy, South China University of Technology, 21 Guangzhou, China, 51000622 Tel: +86 20 3938050323 Email address: zqshi@scut.edu.cn 24252627 Number of pages: 728 Number of tables: 229 Number of figures: 530

Electronic Supplementary Material (ESI) for Environmental Science: Nano.This journal is © The Royal Society of Chemistry 2019

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31 S1. Additional Experimental Details

32 All reagents used for FT-ICR-MS experiments are either ultrapure or MS grade. Each Bond Elut-

33 PPL cartridge was preconditioned with 18 mL methanol, and then with 18 mL 0.01 M HCl. Before FT-

34 ICR-MS analysis, samples were acidified to pH 2 using 1 M HCl. Then 10-60 mL DOM samples

35 (depending on the DOC concentrations) were passed through a 1 g per 6 mL Bond Elut-PPL cartridge

36 (Agilent Technologies, U.S.A) by gravity, and then rinsed with 12 mL 0.01 M HCl to remove salts. The

37 adsorbed DOM in cartridges was extracted by eluting with 18 mL methanol and the eluted samples

38 were concentrated under a N2 condition. The concentrated samples were kept in the dark at -20 oC.

39 We calculated AI, DBE, and Kendrick mass defect as:1-3

40 (1)1 + C 0.5O S 0.5HAI =

C 0.5O S N P- - -

- - - -

41 (2)1DBE = 1 + (2C H + N + P)2

-

42 Kendrick mass = exact m/z of peak × [(nominal mass (F)) / (exact mass (F))] (3)

43 Kendrick mass defect = observed nominal mass - Kendrick mass (4)

44 where C, H, N, O, S and P refer to the number of carbon, hydrogen, nitrogen, oxygen, sulfur and

45 phosphorus, respectively. F represents a certain functional group (i.e. COO).

46 The relative intensity (RI) of molecules and the relative frequency (RF) were calculated as

47 following:

48 RI (i) = Ii/Imax (5)

49 RF (U) = ∑IU/(IU)max (6)

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50 where Ii and Imax represent the intensity of a molecule i and the highest intensity of the molecule in

51 DOM sample, respectively. IU represents the sum of the intensities of molecules in a certain range (U)

52 of molecular properties (i.e. MW, AI, O number, and DBE).

53

54 S2. Additional tables

55 Table S1. Parameters of UV-vis absorption spectra for original DOM samples and supernatant 56 samples.

Sample numbera

1 2 3 4 5 6 7 89

Reaction pH 4.5 4.5 4.5 4.5 4.5 5.0 5.0 5.0

R 1:25 1:12.5 1:8.3 1:6.3 1:5 1:25 1:12.5 1:8.3

S275-295 (nm-1) 0.011 0.022 0.021 0.021 0.019 0.018 0.020 0.017 0.016

Sample numbera

10 11 12 13 14 15 16 1718

Reaction pH 5.0 5.0 5.5 5.5 5.5 5.5 5.5 6.5 6.5

R 1:6.3 1:5 1:25 1:12.5 1:8.3 1:6.3 1:5 1:25 1:12.5

S275-295 (nm-1) 0.016 0.016 0.019 0.018 0.017 0.015 0.015 0.018 0.016

Sample numbera

19 20 21 22 23 24 25 26

Reaction pH 6.5 6.5 6.5 7.5 7.5 7.5 7.5 7.5

R 1:8.3 1:6.3 1:5 1:25 1:12.5 1:8.3 1:6.3 1:5

S275-295 (nm-1) 0.015 0.015 0.014 0.015 0.015 0.014 0.013 0.012

57 aSample 1 represents original DOM (pH 5.0). Samples 2-6, 7-11, 12-16, 17-21, and 22-26 58 represent the supernatant after adsorption with different R values (1:25, 1:12.5, 1:8.3, 1:6.3, 59 and 1:5) at pH 4.5，5, 5.5, 6.5, and 7.5, respectively. The pH of all samples for UV-vis 60 detection were adjusted at 5.0-5.5.61

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62 Table S2. Special surface area and pore volume of allophane samples before and after DOM 63 adsorption.

samples Special surface area (m2 g-1) Pore volume (cm3 g-1)

Pristine allophane 144 0.223Allophane-100a 111 0.169

64 aAllophane sample after DOM adsorption (100 mg L-1) at pH 5.0.6566

67 S3. Additional figures

68

69 Figure S1. The relative fluorescence intensity of each component in each sample. The relative 70 fluorescence intensity of each component was expressed as a percentage (Ci%) of the sum of all four 71 component intensities (ΣCi) using, Ci%=Ci/ΣCi×100%. Sample 1 represents original DOM. Samples 72 2-6, 7-11, 12-16, 17-21, and 22-26 represent the supernatant after adsorption with different R values 73 (1:25, 1:12.5, 1:8.3, 1:6.3, and 1:5) at pH 4.5，5, 5.5, 6.5, and 7.5, respectively.74

75

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7677 Figure S2. High-resolution TEM images of allophane after synthesis before DOM adsorption.

7879 Figure S3. ESI-FT-ICR-MS spectra for the original DOM and supernatant samples (marked in Figure 80 1a) with different R values after adsorption by allophane at pH 5.0. R: initial DOC:allophane mass 81 ratios.

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82

8384 Figure S4. The relative frequency of molecular compounds of different AI in original DOM and the 85 supernatant samples after adsorption on allophane at pH 5.0. (a) Compounds containing C, H and O, (b 86 and c) compounds containing C, H, O and one or two N atoms, respectively, and (d) compounds 87 containing C, H, O and one or two S atoms. R: initial DOC:allophane mass ratios.

88

89 Figure S5. X-ray photoelectron spectroscopy (XPS) C1s region for the DOM adsorbed allophane with

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90 R values from 1:25 to 1:5 at pH 5.0. R: initial DOC:allophane mass ratios.

91 Reference

92 1 S. Kim, R. W. Kramer and P. G. Hatcher, Graphical method for analysis of ultrahigh-93 resolution broadband mass spectra of natural organic matter, the van Krevelen diagram, 94 Anal. Chem., 2003, 75, 5336-5344.95 2 B. P. Koch and T. Dittmar, From mass to structure: an aromaticity index for high-resolution 96 mass data of natural organic matter, Rapid Commun. Mass Sp., 2006, 20, 926-932.97 3 A. M. Kellerman, D. N. Kothawala, T. Dittmar and L. J. Tranvik, Persistence of dissolved 98 organic matter in lakes related to its molecular characteristics, Nat. Geosci., 2015, 8, 454.99