supporting information...mid-infrared spectra were acquired by diffuse reflectance infra- red...
TRANSCRIPT
S1
Supporting Information
Sorption of hydrophobic organic compounds to a diverse suite of
carbonaceous materials with emphasis on biochar
Darya Kupryianchyk, Sarah Hale, Andrew R. Zimmerman, Omar Harvey, David Rutherford, Samuel Abiven,
Heike Knicker, Hans-Peter Schmidt, Cornelia Rumpel, Gerard Cornelissen*
Pages: 22
Tables: 5
Figures: 13
S2
Chemicals and materials
Polyoxymethylene passive samplers (POM, 76µm, CS Hyde Company, Illinois, USA) were
precleaned with heptane (1 day), methanol (1 day), Millipore water (1 day), stored in Millipore
water and rinsed with Millipore water prior to use. Standards phenanthrene and deuterated
phenantrene-d10 (d-PHE) both in methanol (≥99.5% purity) were purchased from (Sigmad
Aldrich, Norway), 2,2',5,5'-tetrachlorobiphenyl in isooctane (≥99.5% purity,), C13-labeled
2,2',5,5'-tetrachlorobiphenyl (C13-CB52) in nonane were acquired from Chiron AS, Norway
with a declared purity of >99%. C13-CB52 and d-PHE were used as internal standards. Other
chemicals used in the study included acetone (ACS standards, ≥99.9% purity), heptane (HPLC
grade, ≥99.3% purity), hexanes (HPLC grade, ≥99.9% purity), methanol (SupraSolv, ≥99.8
purity), sodium azide (≥99% purity), silica gel (particle size: 0.063-0.200), and sodium sulphate
(pro analysi, ≥90% purity) were purchased from Merck, Germany.
Sorbent characterization
The CM samples were characterized for total C, H ,N, and O, moisture and ash content, surface
area, pore volume, thermal and chemical stability, and aromaticity.
Elemental composition
Total C, H and N were determined by using a Carlo Erba 1110 CHN Elemental Analyzer. O
content was calculated assuming C+H+N+O is equal to 100%.
Moisture content was determined gravimetrically as the weight loss at 200oC. Ash content was
determined by heating under air at 750oC until a constant weight was obtained.
Surface area and pore size distribution
The surface areas (SA) and pore size distributions of the CM samples were measured by both
N2 and CO2 sorption on a Quantachrome Autosorb I, at 77 K and CO2 at 273 K, respectively.
CM samples of 0.2-0.5 g were de-gassed under vacuum at least 24 h at 180oC prior to analysis.
SA-N2 was calculated using sorption data from the 0.01-0.3 P/Po linear segment of the N2
adsorption isotherms and BET theory (Brunauer et al. 1938), while SA-CO2 used the <0.02 P/Po
data range and were interpreted using canonical Monte Carlo simulations of the non-local
density functional theory (DFT). Because N2 is kinetically impeded from entering micropores
(<1 mn) (De Jonge et al. 2000), SA-N2 represents only nanopore-enclosed surfaces only
mesopores (2 nm – 50 nm). SA-CO2 includes micropores because CO2 diffusion is less
kinetically limited and CM is more flexible at 273 K (De Jonge et al. 2000, Pignatello et al.
2006). Pore size distributions were interpreted using the N2 desorption isotherms using Barrett-
Joyner-Halenda (BJH) theory. The pore size distribution in the range 3.5–15 Å was calculated
using the Grand-Canonical-Monte-Carlo (GCMC) method and assumes slit-shaped pores and
an equilibrium model.
Thermal stability
Thermogravimetric analysis. Thermogravimetric analysis was used to estimate degree of
aromatic condensation (degree of charring) of the CM. This measure is assumed to largely
determine persistence of charred material in the environment.
The degree of charring has been studied by measuring the weight loss of a char sample as it
undergoes additional pyrolysis under a nitrogen atmosphere in a thermogravimetric analyzer
(TGA). Each sample was heated sequentially to 8 increasing temperatures, varying by 100-
S3
degree increments, between 200 and 900°C, with a hold time of one hour at each temperature.
The weight loss occurring at 200°C was taken as the moisture content of the sample. The weight
loss at each temperature increment above 200°C, after correction for moisture and ash content,
was used to determine the cumulative weight loss (total weight loss), as well as incremental
loss profiles at each temperature step.
Thermogravimetry and recalcitrance index, R50. To quantify CM recalcitrance, i.e. stability,
and sequestration potential the recently developed recalcitrance index (the R50) by Harvey et al.
(2012) was used. The index uses the energy required for thermal oxidation of the CM (as
estimated with TGA), relative to that required for a graphite reference, as a measure of thermal
stability/ recalcitrance. Extensive details on the method and data processing are provide
elsewhere (Harvey et al. 2012). Briefly, weight loss associated with the thermal oxidation of
the CM (10-15 mg) were studied in air (at flow rate 10 mL/min) using a thermogravimetric
analyzer with capabilities for measuring heat induced weight loss at temperatures up to 1000oC
(Q500; TA Instruments, New Castle, DE). Thermal analysis started at an oven-temperature of
30°C and increased at a ramp rate of 10°C/min until no further weight loss was recorded. Cut-
off temperatures were between 800 and 1000°C. After correction for moisture and ash content,
values of R50 was calculated using the equation: R50 = T50, sample/T50, graphite, where T50, sample is the
temperature corresponding to 50% thermal oxidation/volatilization of CM material and
T50,graphite is the temperature corresponding to 50% thermal oxidation of the graphite reference
under the experimental conditions.
Aromaticity
DRIFT spectroscopy. Functional groups of the CMs were analyzed by diffuse reflectance
infrared Fourier trans- form spectroscopy (DRIFT) (Wiedemeier et al. 2014). Mid-infrared
spectra were acquired by diffuse reflectance infra- red Fourier transform spectroscopy (DRIFT).
Spectra were recorded using a Bruker TENSOR 27 spectrophotometer (Fällanden, Switzerland)
from 4000–400 1/cm (average of 64 scans per sample at 4 1/cm resolution) on a powder
containing 3% of ground sample KBr. The samples were homogenized in an Eppendof tube at
a frequency of 25 1/cm for 3 min. Prior to measurement, the samples were dried in an oven at
70°C. Assignments of the infrared absorption bands were based on a literature compilation
(Table S1). The aromaticity was evaluated by computing the integrated peak areas below 4
main peaks of interest (1510, 1420, 1320 and 821 cm-1) and calculated as: Aromaticity =
(1420+821)/(1510+1320) (Wiedemeier et al. 2014). 13C-NMR. Solid-state NMR spectra were obtained on a Bruker Avance III 600 using zirconium
rotors of 4 mm OD with KEL-F-caps. The cross polarization magic angle spinning (CPMAS)
technique was applied during magic-angle spinning of the rotor at 15 kHz (13C). A ramped 1H-
pulse was applied during a contact time of 1 ms in order to circumvent spin modulation of
Hartmann-Hahn conditions. The 13C-chemical shifts were referenced to tetramethylsilane (=0
ppm) and were calibrated with glycine (176.04 ppm). For some samples the condensation
degree was too high and the 1H content too low for efficient cross polarization. In this case, the
spectra were obtained by direct excitation of the 13C spins (Bloch Decay). For quantification,
the spectra were divided into different chemical shift regions as it was described previously
(Table S2) (Knicker 2011). The relative carbon distribution was determined by integrating the
signal intensities of those chemical shift regions.
S4
Sorption isotherms
Sorption isotherm experiments were conducted using a state-of-the-art passive sampler batch
setup similar to that first described in Jonker and Koelmans (Jonker and Koelmans 2001).
Briefly, CM (0.05 g), deionised water (40 mL) with sodium azide (100 mg/L), and a POM-76
passive sampler (0.1 g) were added to 50 mL E-flasks. Flasks were spiked with various
concentration of CB52, 0.0005 to 50 µg, and phenanthrene, 0.05 to 250 µg. The amount of
spiked co-solvent was <0.65% of the water volume and therefore the co-solvent effect can be
considered negligible in this system (Schwarzenbach et al. 2002). The sorbent-sorbate mixtures
were shaken end-over-end (6 rpm) for 28 d in the dark, which has been shown to be enough to
reach equilibrium (Hawthorne et al. 2009, Hawthorne et al. 2011). The kinetic equilibrium
development was explicitly tested for sediment-activated carbon (AC) mixtures for time periods
up to 78 d and also higher-temperature equilibration (Cornelissen et al. 2006).
After the sorption experiments the POM-76 strips were wiped clean with paper tissues and
extracted with 20 mL heptane/acetone (80:20 v/v) for 48 h. Prior to extraction, recovery
standards C13-CB52 and d-PHE were spiked to the solvent to monitor process recovery of CB52
and phenanthrene, respectively. Extraction recovery was within an acceptable 86-104% range
for CB52 and from 79-98% for PHE. The extract was reduced to 1 mL and then eluted with 10
mL of heptane through a precleaned (with 5 mL heptane) silica gel column topped with sodium
sulfate. The solvent was collected and concentrated to 0.5 mL, internal standard (CB77) was
added and samples were analyzed on GCMS. LOD were 0.1 pg/L for both CB52 and PHE.
Experimental and analytical blanks were included in the experiment. The level of solute in the
blanks was <5 times lower than those in the samples with lowest spike concentration. All data
were corrected for blanks. Mass balances for the exactly same experimental system (flasks,
shaking, procedure) were earlier found to be 80–100% (Cornelissen et al. 2006).
CB52 and PHE were analyzed on an Agilent 6850 Gas Chromatograph (DB-XLB column,
length 30 m, id 0.25 mm and 0.1 lm film thickness) coupled to an Agilent 5973 mass
spectrometer in electron impact mode (EI+, 70 eV) and single ion monitoring data acquisition,
using He as carrier gas. A temperature program was run from 50oC (1 min) to 300oC (25 min),
ramping from 50oC to 300oC at a rate of 10oC/min.
Data analysis
CB52 and PHE isotherms were fitted with the Freundlich sorption model: nF
WFCM CKC (1)
where CCM is the HOC concentration on the sorbent (µg/kg) calculated from a mass balance of
the system, KF is the Freundlich coefficient (µg/kg)/( µg/L)nF and nF the Freundlich exponent.
CB52 and PHE aqueous concentrations (CW, µg/L) were calculated from equilibrium
concentrations measured in POM (CPOM, µg/kg) according to:
CW = KPOM/CPOM (2)
using previously published POM-water partitioning coefficients (KPOM, L/kg) (Hawthorne et al.
2009, Hawthorne et al. 2011). To obtain CCM, mass balance of the system was used according
to:
POMPOMWWCMCMtot mCVCmCM (3)
S5
where Mtot is the initial spiked HOC (µg), mCM is the mass of CM added (kg), VW is the volume
of water used (L), CPOM concentrations measured in POM (µg/kg), and mPOM is the mass of
POM added (kg).
Finally, KF and nF can be estimated from experimental data by a linear regression of LogCCM
against LogCW:
WFFCM CnLogKLogC (4)
Linear regression analyses (n=17) was used to study the effect of, H/C, O/C, SA, sorbent
feedstock, temperature of production, and aromaticity on sorption affinity constants. The
analyses were performed in Microsoft Excel 2013 (Microsoft Corporation, Redmond, WA,
USA).
Results and Discussion
C13-NMR
Fig. S7 shows the 13C NMR spectra and their intensity distribution after the removal of the
interference of side bands. Due to the high amount of graphene groups in PW700, SG700,
cocoAC and activated biochar, tuning of the NMR probe was not possible for these materials
and no 13C NMR spectrum could be acquired.
Aromaticity increased from 61.5 to 94.3% with increasing pyrolysis temperature from 250 to
500°C for the series of pinewood biochars. Whilst the spectrum of PW250 still exhibited signals
assignable to C in carbohydrates, PW300 and PW500 showed a higher degree of aromatization
and no carbohydrates.
DDM500 had the lowest concentration of aromatic carbon (58.8%). Signals in the O-alkyl
region of the NMR spectrum of DDM500 (e.g. 75 ppm, 104 ppm) indicated that this sample
was only slightly charred (Fig. S7). The high aromaticity of the fast pyrolysis biochar (83.1%)
suggested that the fast pyrolysis method was very efficient, and the short residence time of 15
min was enough to result in creation of a highly aromatic structure.
A small shoulder in the phenol C region (160-140 ppm) was observed in the wildfire char
spectrum, what is quite typical for natural chars and can be best explained by the formation of
furans and benzofurans from cellulose (Knicker et al., 2008).
S6
Table S1. Major IR adsorption bands and assignments (Guo and Bustin 1998, Moore and Owen
2001, Baldock and Smernik 2002, Weiland and Guyonnet 2003, Nuopponen et al. 2006).
Wavelength,
1/cm
Description
(trend during charring)
3050-3020 C-H aromatic stretch (increase)
3000-2800 C-H aliphatic stretch (decrease)
2850-2820 Aliphatic C-H (difference between samples)
1730-1680 Aromatic carbonyl/carboxyl C=O stretch (increase)
1610-1570 C=C stretch (increase)
1510-1500 Lignin, aromatic C=C stretch (decrease)
1430-1380 Aromatic C=C stretch (increase)
1260-1210 Cellulose (decrease)
1060-1020 Aliphatic C-O- and alcohol C-O stretch (decrease)
880, 805, 745 C-H aromatic bending deformation (increase)
Table S2. Tentative chemical shift assignment of various peaks in a 13C NMR spectrum
(Knicker 2011).
ppm Assignment
0-45 Alkyl-C
45-110 O- and N-alkyl
45-60 aliphatic C-N, methoxyl
60-90 alkyl-O (carbohydrates, alcohols)
90-110 acetal and ketal carbon (carbohydrates)
110-160 Sp2-hybridized C
110-140 aryl-H and aryl-C carbons, olefinic-C
140-160 aryl-O and aryl-N carbons
160-185 Carbonylic-C/carboxylic-C/amide-C
160-185 carboxyl and amide-C
S7
Table S3. Parameters and statistics of regression analyses used to study the effect of sorbent material surface area (SA), pore volume (Vp), H/C,
O/C, (O+N)/C rations, thermal stability (R50), temperature of production, and aromaticity (as measured with DRIFT) on sorption affinity constant
(LogKF) of CB52 and PHE.
Table S4. Relationship between sorption affinity constant LogKF values and surface area (SA), pore volume (Vp), H/C, O/C, (O+N)/C rations,
thermal stability (R50), temperature of production, and aromaticity (as measured by DRIFT).
CB52 PHE
SA Vp H/C O/C R50 T Arom
index SA Vpore H/C O/C R50 T
Arom
index
AN
OV
A
R2 0.45 0.44 0.60 0.71 0.44 0.70 0.11 0.57 0.59 0.47 0.59 0.56 0.61 0.26
n 17 17 15 14 17 17 17 17 17 15 14 17 17 17
df 1. 15 1. 15 1. 13 1. 12 1. 15 1. 15 1. 15 1. 15 1. 15 1. 14 1. 13 1. 15 1. 15 1. 15
F 12.2 11.7 19.5 28.8 11.7 35.1 1.89 20.0 21.7 11.7 17.4 18.8 23.5 5.18
p 3.3·10-3 3.8·10-3 7.0·10-4 1.7·10-4 3.8·10-3 2.8·10-5 0.118 4.5·10-3 3.1·10-4 4.9·10-2 1.3·10-3 5.9·10-4 2.1·10-4 3.8·10-2
Inte
rcep
t value 5.59 5.66 7.88 5.14 1.72 4.05 6.22 5.10 5.14 6.78 6.78 1.93 4.21 5.50
SE 0.35 0.33 0.31 0.33 1.45 0.46 0.38 0.22 0.21 0.25 0.21 0.94 0.38 0.25
t 16.1 17.0 25.8 15.7 1.18 8.90 16.52 23.0 24.8 27.5 32.5 2.06 11.2 22.0
p 7.0·10-11 3.3·10-11 6.3·10-3 2.4·10-9 2.6·10-1 2.3·10-7 4.9·10-11 4.2·10-13 1.3·10-13 6.7·10-13 4.6·10-15 5.7·10-2 1.2·10-8 8.1·10-13
Slo
pe
value 0.002 7.413 -33.41 -2.164 9.007 0.005 0.096 0.002 6.258 -20.93 -2.866 7.389 0.004 0.106
SE 0.001 2.164 7.575 0.404 2.635 0.001 0.070 0.000 1.345 6.122 0.687 1.704 0.001 0.046
t 3.49 3.43 -4.41 -5.36 3.42 5.92 1.38 4.47 4.65 -3.42 -4.17 4.34 4.85 2.28
p 3.3·10-3 3.8·10-3 6.1·10-6 1.5·10-3 1.7·10-4 2.8·10-5 0.118 4.5·10-3 3.1·10-4 4.9·10-2 1.3·10-3 5.9·10-4 2.1·10-4 3.8·10-2
CB52 PHE
SA LogKF=0.0022 SA+5.59 LogKF=0.0018 SA+5.11
Vp LogKF=7.41 Vp+5.66 LogKF=6.26 Vp+5.14
H/C LogKF=-33.41 H/C+7.87 LogKF=-20.93 H/C+6.78
O/C LogKF=-4.19 O/C+7.77 LogKF=-2.87 O/C+6.79
(O+N)/C LogKF=-4.19 (O+N)/C+7.80 LogKF=-2.88 (O+N)/C+6.81
R50 LogKF=9.01 R50+1.72 LogKF=7.39 R50+1.93
T LogKF=0.0052 T+4.05 LogKF=0.0035 T+4.21
Aromaticity LogKF=0.14 Arom+6.12 LogKF=0.14 Arom+5.44
S8
Table S5. Individual data points (i.e. the concentration of HOCs on the sorbent materials (LogCCM, µg/kg), and the freely dissolved aqueous concentration measured
by passive samplers (LogCW, µg/L)) of sorption isotherms for CB52 and PHE.
Biochar CB52 Biochar PHE
HW500 LogCw -3.55 -2.97 -1.62 -0.40 -5.98 -5.73 -5.04 -4.64 HW500 LogCw -1.00 -0.50 -1.29 1.33 0.30 -3.13 -2.90 -2.36 -1.81
LogCCM 3.24 4.29 5.25 5.81 1.68 2.00 2.69 2.98 LogCCM 5.80 5.90 5.70 6.90 6.50 4.00 4.30 5.00 5.29
DDM500 LogCw -2.34 -1.15 -0.42 -5.96 -5.86 -5.03 -4.84 -4.14 -3.74 DDM500 LogCw -2.34 -1.48 0.40 1.22 -2.47 -2.38 -1.79 -1.45 -0.63 -0.16
LogCCM 4.20 5.13 5.82 0.60 0.94 1.61 1.93 2.63 2.91 LogCCM 3.70 4.70 5.67 6.63 2.94 3.28 3.97 4.28 4.97 5.25
FW500 LogCw -4.09 -3.19 -2.21 -0.95 -0.30 -5.49 -4.66 -3.94 -3.93 FW500 LogCw -2.04 -1.30 0.13 1.46 -2.57 -2.15 -1.69 -1.17 -0.27 0.19
LogCCM 2.12 3.13 4.15 5.00 5.73 0.86 1.89 2.60 2.95 LogCCM 3.69 4.68 5.65 6.62 2.94 3.26 3.97 4.25 4.90 5.19
PMV500 LogCw -4.65 -3.67 -3.89 -2.24 -0.58 -6.07 -5.93 -5.04 -4.65 PMV500 LogCw -3.40 -2.39 -0.15 1.30 0.30 -2.83 -2.65 -1.90 -0.99
LogCCM 2.25 3.25 4.30 5.29 5.89 1.70 2.00 2.68 2.99 LogCCM 3.70 4.70 5.68 6.54 6.00 4.00 4.29 4.99 5.29
PW250 LogCw -3.92 -4.21 -2.24 -1.07 -0.27 -5.93 -5.10 -4.85 PW250 LogCw -1.72 -1.59 0.70 1.61 -1.10 -2.33 -1.85 -1.54 -0.57
LogCCM 1.96 3.16 4.17 5.08 5.72 0.60 1.62 1.94 LogCCM 4.00 4.69 5.67 6.59 4.40 3.26 3.98 4.27 4.96
PW350 LogCw -4.02 -3.54 -3.13 -1.46 -0.32 PW350 LogCw -3.20 -2.40 -0.20 1.20 -0.80 -2.79 -2.37 -1.68 -1.26
LogCCM 2.06 3.23 4.29 5.21 5.73 LogCCM 3.69 4.71 5.70 6.64 5.50 3.99 4.29 5.00 5.30
PW500 LogCw -4.43 -4.18 -3.94 -2.65 -1.16 PW500 LogCw -1.21 -2.27 0.20 1.28 -3.30 -2.88 -2.66 -0.50 -1.76
LogCCM 2.22 3.28 4.31 5.28 5.97 LogCCM 5.50 4.70 6.20 6.90 3.80 4.00 4.30 5.90 5.29
PW700 LogCw -4.83 -4.87 -4.32 -3.57 -2.16 PW700 LogCw -3.20 -2.26 -1.20 -0.44 -3.46 0.70 -2.67 -2.05 -1.70
LogCCM 2.27 3.31 4.30 5.30 5.99 LogCCM 3.80 4.70 5.72 6.70 3.50 7.50 4.29 4.99 5.30
SG700 LogCw -4.53 -4.29 -3.88 -2.68 -1.39 SG700 LogCw -2.37 -1.99 -0.50 0.87 -3.09 -2.88 -1.97 -2.24 -1.85 -1.43
LogCCM 2.23 3.28 4.30 5.30 6.00 LogCCM 3.68 4.69 5.70 6.68 2.99 3.29 3.99 4.29 4.99 5.29
CocoAC LogCw -5.19 -4.27 -3.58 -2.93 -2.00 -6.22 -5.51 -5.20 CocoAC LogCw -2.69 -2.15 -1.77 -1.15 -3.02 -3.02 -1.34
LogCCM 2.20 3.29 4.29 5.30 5.99 1.99 2.69 2.99 LogCCM 3.70 4.70 5.70 6.70 2.99 3.29 3.92
Activated BC LogCw -4.50 -3.70 -2.89 -2.11 -1.46 -6.15 -5.43 -5.59 Activated BC LogCw -1.31 -1.96 -1.40 -1.50 -3.13 -3.02 -2.39 -2.21 -1.81 -1.53
LogCCM 3.70 4.50 4.98 6.04 6.71 2.00 2.69 2.99 LogCCM 3.52 4.69 5.70 6.70 2.99 3.29 4.00 4.30 4.99 5.30
Non-activated BC LogCw -4.20 -3.18 -2.77 -2.22 -1.12 -6.10 -5.28 Non-activated BC LogCw -2.45 -1.61 -2.41 -2.07 0.67 -3.39 -3.09
LogCCM 3.50 4.05 4.96 6.04 6.70 2.00 3.00 LogCCM 2.60 3.69 4.70 5.71 6.69 4.00 4.29
Aged 150 years LogCw -3.85 -2.88 -1.89 -0.69 -0.08 -6.48 -5.39 -4.68 -5.10 -3.50 -2.96 Aged 150 years LogCw -2.37 -2.00 -1.37 -0.82 0.56 0.89
LogCCM 1.84 2.91 3.88 4.06 5.41 1.30 1.41 2.17 2.62 3.24 3.60 LogCCM 3.69 3.80 4.51 4.93 5.52 5.56
Aged 2000 years LogCw -3.84 -3.04 -2.19 -0.93 -0.14 -5.30 -4.71 -4.57 -3.62 -3.22 Aged 2000 years LogCw -2.14 -1.91 -1.14 -0.86 0.13 0.70
LogCCM 1.80 3.06 4.15 5.00 5.55 1.58 2.30 2.39 3.32 3.52 LogCCM 3.65 3.85 4.60 4.83 5.55 5.91
Fast pyrolysis LogCw -3.98 -3.16 -2.36 -1.11 -0.28 Fast pyrolysis LogCw -1.78 -1.94 0.08 1.65 -4.55 -4.45
LogCCM 2.02 3.14 4.19 5.11 5.70 LogCCM 3.66 4.71 5.68 6.56 2.99 3.30
Wildfire LogCw -3.38 -2.70 -2.64 -1.29 -0.30 Wildfire LogCw -2.07 -1.64 -1.27 1.72 -4.36
LogCCM 2.80 3.92 4.25 5.19 5.73 LogCCM 3.67 4.70 5.71 6.67 3.00
Tropical Zambian LogCw -3.87 -3.20 -3.10 -1.34 -0.22 Tropical Zambian LogCw -2.50 -2.70 -0.52 1.79 -2.94 -3.01 -2.20 -2.04 -1.25
LogCCM 1.90 3.17 4.28 5.20 5.65 LogCCM 3.70 4.69 5.69 6.47 3.29 4.00 4.29 4.99 5.30
S9
0,000
0,002
0,004
0,006
0,008
0,010
4 5 7 9 11 13 61 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Hardwood 500
0,000
0,002
0,004
0,006
0,008
0,010
4 5 7 9 11 13 61 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Digestive dairy manure 500
0,000
0,001
0,002
0,003
0,004
0,005
4 5 7 9 11 13 61 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Food waste 500
0,00
0,02
0,04
0,06
0,08
0,0000
0,0002
0,0004
0,0006
0,0008
0,0010
0,0012
0,0014
4 5 7 9 11 13 61 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Paper mill waste 500
0,000
0,001
0,002
0,003
0,004
0,005
0,006
4 5 7 9 11 13 61 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Pinewood 250
0,000
0,002
0,004
0,006
0,008
0,010
0,012
0,014
4 5 7 9 11 13 61 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Pinewood 350
0,000
0,005
0,010
0,015
4 5 7 9 11 13 61 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Pinewood 500
0,000
0,005
0,010
0,015
0,020
0,025
4 5 7 9 11 13 61 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Pinewood 700
0,000
0,005
0,010
0,015
0,020
4 5 7 9 11 13 61 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Switchgrass 700
0,000
0,020
0,040
0,060
0,080
0,100
0,120
4 5 6 7 9 10 12 15 88 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
CocoAC
S10
Figure S1. Pore volume distribution related to the pore width for sorbent materials as measured
using CO2 (open bars) and N2 (black) as sorbates.
0,000
0,020
0,040
0,060
0,080
0,100
4 5 7 9 11 13 61 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Activated biochar
0,000
0,005
0,010
0,015
0,020
4 5 7 9 11 13 61 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Non-activated biochar
0,000
0,002
0,004
0,006
0,008
0,010
0,012
0,014
4 5 7 9 11 13 61 3 000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Aged 150 years
0,000
0,002
0,004
0,006
0,008
0,010
0,012
4 5 7 9 11 13 61 3500
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Aged 2000 years
0,000
0,002
0,004
0,006
0,008
0,010
0,012
4 5 7 9 11 13 61 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Fast pyrolysis
0,000
0,002
0,004
0,006
0,008
0,010
0,012
0,014
4 5 7 9 11 13 61 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Wildfire
0,000
0,002
0,004
0,006
0,008
0,010
0,012
4 5 7 9 11 13 61 3000
Po
re v
olu
me,
cm
3/g
Pore diameter, Å
Tropical Zambian
S11
Figure S2. Surface area of the CM used in the study vs. pore volume as measured with CO2
method.
0,0
0,1
0,2
0,3
0,4
0 200 400 600 800 1000 1200
CO
2p
ore
volu
me,
cm
3/g
CO2 surface area, m2/g
S12
Figure S3. Total dry weight loss of sorbent materials measured with thermogravimetric
analysis.
Figure S4. Dry weight loss for each step in the stepwise analysis of sorbent materials as
measured with thermogravimetric analysis.
0
20
40
60
80
100T
ota
l w
eigh
t lo
ss, %
TGA. Total weight loss
S13
Figure S5. Recalcitrance index (R50) as measured with thermogravimetric analysis.
Figure S6. Diffuse reflectance infrared Fourier transform (DRIFT) spectra of sorbent materials
used in the study. Wavelength allocation based on literature (Table S1).
0
0,2
0,4
0,6
0,8
1R
50
R50
S14
Figure S7. Solid-state 13C NMR spectra of sorbent materials used in the study.
Aged 150 years
S15
Figure S8. Sorption isotherms for CB52 and PHE on sorbent material. Data are plotted as the
concentration of HOCs on the sorbent materials (LogCCM), against the freely dissolved aqueous
concentration measured by passive samplers (LogCW).
0
1
2
3
4
5
6
7
8
-7 -6 -5 -4 -3 -2 -1 0
LogC
CM
, µ
g/k
g
LogCW, µg/L
CB52 Hardwood 500
Digestive dairy manure 500
Food waste 500
Paper mill waste 500
Pinewood 250
Pinewood 350
Pinewood 500
Pinewood 700
Switchgrass 700
CocoAC
Activated BC
Non-activated BC
Aged 150 years
Aged 2000 years
Fast pyrolysis
Wildfire
Tropical Zambian
2
3
4
5
6
7
8
-5 -4 -3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE Hardwood 500
Digestive dairy manure 500
Food waste 500
Paper mill waste 500
Pinewood 250
Pinewood 350
Pinewood 500
Pinewood 700
Switchgrass 700
CocoAC
Activated BC
Non-activated BC
Aged 150 years
Aged 2000 years
Fast pyrolysis
Wildfire
Tropical Zambian
S16
y = 0,74x + 6,26
R² = 0,98
0
2
4
6
8
-7 -6 -5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Hardwood 500
y = 0,91x + 6,27
R² = 1,00
0
2
4
6
8
-7 -6 -5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Digestive dairy manure 500
y = 0,89x + 6,02
R² = 0,98
0
2
4
6
8
-6 -5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Food waste 500
y = 0,80x + 6,64
R² = 0,91
0
2
4
6
8
-7 -6 -5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Paper mill waste 500
y = 0,87x + 6,03
R² = 0,95
0
2
4
6
8
-7 -6 -5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Pinewood 250
y = 0,90x + 6,34
R² = 0,87
0
2
4
6
8
-5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Pinewood 350
y = 1,00x + 7,48
R² = 0,82
0
2
4
6
8
-5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Pinewood 500
y = 1,20x + 8,95
R² = 0,81
0
2
4
6
8
-6 -5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Pinewood 700
y = 1,08x + 7,84
R² = 0,87
0
2
4
6
8
-5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Switchgrass 700
y = 0,99x + 7,93
R² = 0,95
0
2
4
6
8
-7 -6 -5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. CocoAC
S17
Figure S9. Sorption isotherms for CB52 on sorbent materials. Data are plotted as the
concentration of CB52 on the sorbent materials (LogCCM), against the freely dissolved aqueous
concentration measured by passive samplers (LogCW).
y = 0,96x + 8,01
R² = 0,99
0
2
4
6
8
-7 -6 -5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Activated biochar
y = 0,94x + 7,66
R² = 0,96
0
2
4
6
8
-7 -6 -5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Non-activated biochar
y = 0,58x + 4,94
R² = 0,86
0
2
4
6
-7 -6 -5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Aged 150 years
y = 0,77x + 5,68
R² = 0,91
0
2
4
6
-6 -5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Aged 2000 years
y = 0,98x + 6,16
R² = 0,98
0
2
4
6
8
-5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Fast pyrolysis
y = 0,88x + 6,20
R² = 0,93
0
2
4
6
8
-4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Wildfire
y = 0,92x + 6,20
R² = 0,83
0
2
4
6
8
-5 -4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
CB52. Tropical Zambian
S18
y = 0,63x + 6,28
R² = 0,96
2
4
6
8
-4 -3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Hardwood 500
y = 0,88x + 5,51
R² = 0,95
2
4
6
8
-3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Digestive dairy manure 500
y = 0,86x + 5,33
R² = 0,96
2
4
6
8
-3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Food waste 500
y = 0,58x + 5,84
R² = 0,97
2
4
6
8
-4 -3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Paper mill waste 500
y = 0,74x + 5,34
R² = 0,94
2
4
6
8
-3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Pinewood 250
y = 0,65x + 5,95
R² = 0,96
2
4
6
8
-4 -3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Pinewood 350
y = 0,68x + 6,17
R² = 0,97
2
4
6
8
-4 -3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Pinewood 500
y = 0,98x + 6,94
R² = 1,00
2
4
6
8
-4 -3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Pinewood 700
y = 0,93x + 6,18
R² = 0,91
2
4
6
8
-4 -3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Switchgrass 700
y = 1,38x + 7,42
R² = 0,63
2
4
6
8
-4 -3 -2 -1 0
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. CocoAC
S19
Figure S10. Sorption isotherms for phenanthrene (PHE) on sorbent materials used in the study.
Data are plotted as the concentration of PHE on the sorbent materials (LogCCM), against the
freely dissolved aqueous concentration measured by passive samplers (LogCW).
y = 1,25x + 7,08
R² = 0,49
2
4
6
8
-4 -3 -2 -1
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Activated biochar
y = 0,67x + 5,89
R² = 0,44
2
4
6
8
-4 -3 -2 -1 0 1
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Non-activated biochar
y = 0,60x + 5,18
R² = 0,96
2
4
6
8
-3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Aged 150 years
y = 0,80x + 5,43
R² = 0,99
2
4
6
8
-3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Aged 2000 years
y = 0,55x + 5,50
R² = 0,91
2
4
6
8
-5 -4 -3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Fast pyrolysis
y = 0,63x + 5,71
R² = 0,86
2
4
6
8
-5 -4 -3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Wildfire
y = 0,59x + 5,72
R² = 0,80
2
4
6
8
-4 -3 -2 -1 0 1 2
Lo
gC
CM
, µ
g/k
g
LogCW, µg/L
PHE. Tropical Zambian
S20
Figure S11. CB52 and PHE sorption coefficients KF, to sorbent materials as a function of
(O+N)/C ratio (a), thermal stability index (R50), surface area (c) and pore volume (d) as
measured N2 method.
a b
c d
S21
Figure S12. Van Krevelen diagram.
Figure S13. Relationship between geosorbent pyrolysis temperature (a) and aromaticity (b) and
recalcitrance index (R50).
y = 0,11x + 0,01
R² = 0,79
0,00
0,02
0,04
0,06
0,08
0,10
0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7
H/C
O/C
a b
S22
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