Supplementary Data for

One-pot synthesis of in-situ sulfur doped activated carbon as a

superior metal-free catalyst for adsorption and catalytic oxidation of

aqueous organics

Yaoping Guoa, b, Zequan Zenga*, Yongjin Liua, b, Zhanggen Huanga**, Yan Cuia, and Jieyang Yanga

aState Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P.R. China

bUniversity of Chinese Academy of Sciences, Beijing 100049, P.R. China

*Corresponding author. Tel.: +86 351 4048310; E-mail: zengzequan@sxicc.ac.cn (Z. Zeng)**Corresponding author. Tel.: +86 351 4043727; E-mail: zghuang@sxicc.ac.cn (Z. Huang)

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.This journal is © The Royal Society of Chemistry 2018

Scheme S1 Preparation of in-situ sulfur doped activated carbon (S-AC).

Fig. S1 XRD patterns of the S-AC samples.

Fig. S2 TG profiles of S-AC-600, -700, -800, and -900 samples.

Thermogravimetric analysis (TGA) was conducted in a Netzsch thermal analyzer

with a heating rate of 5 °C min−1 in air. Fig. S2 shows that a minor mass loss below

200 °C was observed due to moisture desorption and then a moderate weight loss was

observed due to the removal of oxygen/sulfur-containing functional groups from 200

up to ~ 430 - ~ 490 °C. When the temperature was further raised, a sharp loss

occurred due to combustion in air, indicating the break down of carbon skeletons.

However, it is worthy noting that the S-AC-x samples completely burned out until the

temperature was raised to 560-590 °C, suggesting that the carbon samples exhibit

high thermal stability. In addition, it can be seen from Fig. S2 that there almost no

residue was remained after the combustion of carbon samples, demonstrating the high

purity of S-AC-x.

Fig. S3 SEM images of (a) S-AC-600, (b) S-AC-700, (c) S-AC-800, and (d) S-AC-900.

Fig. S4 (a) SEM image of S-AC-800, (b) O-, (c) C-, and (d) S-elemental mapping of the image.

Fig. S5 TGA curves of the precursors heated under an argon atmosphere.

The chemical transitions of sulfur-containing precursors to carbonaceous materials

is a complex issue, which undergo a series of carbonization/graphitization processes.

To shed light on the formation mechanism of activated carbon during pyrolysis,

thermogravimetric analysis (TGA) was conducted by heating the precursors of PPS

and PPS/KOH (the weight ratio of PPS versus KOH is 1:2) under an argon

atmosphere. As illustrated by the curve of pure PPS (Fig. S5), almost no weight loss

can be observed below 410 °C due to the high thermal stability of PPS. After that,

there was a sharp weight loss between 410 to 570 °C, during which pyrolysis products

were formed. Further increased the pyrolysis temperature, the curve was slight decline

and then flat to 800 °C.

However, in the presence of KOH, the pyrolysis process of PPS was greatly

changed. As depicted, the dehydrogenation started at a lower temperature, and a

significant weight loss can be observed from ~120 up to 680 °C. It was suggested that

the addition of alkali metal compounds could facilitate the charring as well as

aromatization of the carbon and restricted the formation of tar.1 During this stage,

volatile species such as H2S, SO2, CO2, and CO were released, and hence porous

structure was generated. Besides, in the recomposition process, sulfur atom might be

incorporated into the carbon matrix for generating of thiophene sulfur (–C–S–C–), or

probably be oxidized for generating of oxidized S (–C–SOx–C–, x=2, 3, 4). After that,

persistent weight loss can be also observed at higher temperature (800 °C), which

may be attributed to the activation reaction between char and KOH.1-3 Firstly, KOH

was reduced by the carbon for producing metal potassium and simultaneously

releasing CO2 via reaction (1). Then the generated CO2 could react with the remaining

KOH to produce K2CO3 (Eq 2). In addition, KOH can also reacts with carbon though

Eq 3 to form metal potassium and K2CO3. Similarly, the formed K2CO3 was further

reduced by carbon via reaction (4). In the activation process, large quantities of

volatile species were further expulsed, which lead to the increase degree of

graphitization structure and the increase of surface area as well as pore volume.

However, excess activation would give rise to the collapse of the carbon skeleton

structure and then enlarge the pore size of the material.

(1)4𝐾𝑂𝐻+ 𝐶↔4𝐾+ 𝐶𝑂2 + 2𝐻2𝑂

(2)4𝐾𝑂𝐻+ 2𝐶𝑂2↔2𝐾2𝐶𝑂3 + 2𝐻2𝑂

(3)6𝐾𝑂𝐻+ 𝐶↔2𝐾+ 3𝐻2 + 2𝐾2𝐶𝑂3

(4)𝐾2𝐶𝑂3 + 2𝐶→2𝐾+ 3𝐶𝑂

Fig. S6 FTIR spectra of S-AC-600, -700, -800, and -900, respectively.

Fig. S6 displays FTIR spectra of the S-AC samples. It can be seen that several

characteristic peaks can be observed on the spectra. The peaks at 1720 cm−1, 1573

cm−1 and 1400 cm−1 can be assigned to C=O, C=C, and –COOH groups,

respectively.4 The bands located around 1130 cm−1 and 830 cm−1 indicate the presence

of oxidized sulfur, which can be assigned to O=S=O and C-S-O, respectively. In

addition, the weak peak at 620 cm−1 is characteristic of C–S stretching vibration in

thiophene sulfur. 5

Table S1. Elemental compositions and pHPZC of the carbon samples

Elemental composition (wt. %)Sample C H O S N pHPZC

S-AC-600 66.62 2.61 19.39 10.85 0.53 1.3

S-AC-700 78.54 1.52 11.81 7.57 0.56 1.5

S-AC-800 88.60 1.35 5.42 4.05 0.58 4.6

S-AC-900 86.63 1.09 6.37 5.31 0.60 2.0

Fig. S7 The high resolution XPS C 1s spectra of (a) S-AC-600, (b) S-AC-700, (c) S-AC-800, and

(d) S-AC-900.

Fig. S8 Adsorption of PCP on the reference carbon samples. Reaction conditions: [PCP]0 = 80 mg L−1, catalyst = 0.1 g L−1, and temperature = 25 °C.

Fig. S9 N2 sorption isotherms, and SBET of the reference samples.

Fig. S10 Fitting of pseudo-second order kinetic model for PCP adsorption on S-AC at different

PCP concentration. Reaction conditions: [PCP]0 = 20, 30, 40, 50, 60 mg L−1, catalyst = 0.05 g L−1,

and temperature = 25 °C.

Fig. S11 Fitting of (a) Langmuir, (b) Freundlich, and (c) Temkin adsorption isotherms of PCP on

S-AC at 25 °C. Reaction conditions: [PCP]0 = 20, 30, 40, 50, 60 mg L−1, catalyst = 0.05 g L−1, and

temperature = 25 °C.

Table S2. Isotherm constants for the adsorption of PCP on different carbon samples at 25 °C.

Langmuir𝐶𝑒𝑞𝑒=𝐶𝑒𝑞𝑚

+1

𝑞𝑚𝐾𝐿

Freundlich

𝑙𝑛𝑞𝑒= 𝑙𝑛𝐾𝐹+1𝑛𝑙𝑛𝐶𝑒

Temkin

𝑞𝑒=𝑅𝑇𝑏𝑇𝑙𝑛𝐾𝑇𝐶𝑒

Sample

qm

mg g-1

KL

L mg-1

rL2 n KF

L g-1

rF2 bT

kJ mol-1

KT

L g-1

rT2

S-AC-600 292 0.08 0.9893 2.91 61.57 0.9750 39.05 0.78 0.9763

S-AC-700 385 0.05 0.9875 2.27 51.39 0.9813 27.11 0.43 0.9777

S-AC-800 526 0.08 0.9975 2.65 99.72 0.9927 21.75 0.80 0.9992

S-AC-900 417 0.06 0.9837 2.25 56.74 0.9319 24.99 0.46 0.9581

AC 88 0.67 0.9986 14.56 69.23 0.7975 89.59 0.87 0.7322

ACS-800 481 0.06 0.9841 2.36 73.63 0.9687 21.96 0.54 0.9693

SDAC-800 394 0.14 0.9973 3.92 93.81 0.9050 26.77 0.62 0.9322

Fig. S12 The kinetic data for PCP adsorption on (a) AC, (b) ACS-800, and (c) SDAC-800 at

different PCP concentration. Reaction conditions: [PCP]0 = 20, 30, 40, 50, 60 mg L−1, catalyst =

0.05 g L−1, and temperature = 25 °C.

Fig. S13 Fitting of pseudo-second order kinetic model for PCP adsorption on (a) AC, (b) ACS-

800, and (c) SDAC-800 at different PCP concentration. Reaction conditions: [PCP]0 = 20, 30, 40,

50, 60 mg L−1, catalyst = 0.05 g L−1, and temperature = 25 °C.

Fig. S14 Fitting of (a) Langmuir, (b) Freundlich, and (c) Temkin adsorption isotherms of PCP on

AC, ACS-800, and SDAC-800 at 25 °C. Reaction conditions: [PCP]0 = 20, 30, 40, 50, 60 mg L−1,

catalyst = 0.05 g L−1, and temperature = 25 °C.

Fig. S15 The kinetic data for (a) PE adsorption, and (b) DCP adsorption on S-AC-800 at different

initial concentration; and fitting of pseudo-second order kinetic model for (c) PE adsorption, and

(d) DCP adsorption on S-AC-800 under different initial concentration. Reaction conditions: [PE]0,

and [DCP]0 = 20, 30, 40, 50, 60 mg L−1, catalyst = 0.05 g L−1, and temperature = 25 °C.

Fig. S16 Fitting of (a) Langmuir, (b) Freundlich, and (c) Temkin adsorption isotherms of PE and

DCP on S-AC-800 at 25 °C. Reaction conditions: [PE]0 and [DCP]0 = 20, 30, 40, 50, 60 mg L−1,

catalyst = 0.05 g L−1, and temperature = 25 °C.

Table S3. Isotherm constants for the adsorption of PE and DCP on S-AC-800 at 25 °C.

Langmuir𝐶𝑒𝑞𝑒=𝐶𝑒𝑞𝑚

+1

𝑞𝑚𝐾𝐿

Freundlich

𝑙𝑛𝑞𝑒= 𝑙𝑛𝐾𝐹+1𝑛𝑙𝑛𝐶𝑒

Temkin

𝑞𝑒=𝑅𝑇𝑏𝑇𝑙𝑛𝐾𝑇𝐶𝑒

Phenol

qm

mg g-1

KL

L mg-1

rL2 n KF

L g-1

rF2 bT

kJ mol-1

KT

L g-1

rT2

PE 295 0.03 0.9967 2.91 25.39 0.9870 34.56 0.27 0.9763

DCP 813 0.24 0.9992 2.65 278.99 0.9827 16.83 4.45 0.9772

Fig. S17 (a) Identification of aromatic intermediates produced in S-AC-800 with PS after a (a) 20

min, and (b) 170 min reaction, and standard intermediates tests of (c) benzoquinone, (d) 4-

chlororesorcinol, (e) 4-chlorocatechol and (f) p-chlorophenol.

Fig. S18 Removal of PCP on the reference carbon samples. Reaction conditions: [PCP]0 = 80 mg L−1, catalyst = 0.1 g L−1, [PS] = 15 mM, and temperature = 25 °C.

Table S4. Surface chemistry information of the carbons.

Sample S levelat.%

–C–S–C–at.%

–C–SOx–C–at.%

sp2at.%

C=Oat.%

O=C–O at.%

ID/IG

S-AC-600 3.04 1.12 1.92 45.36 6.64 5.57 1.01

S-AC-700 1.93 0.82 1.11 48.51 8.51 5.45 1.09

S-AC-800 1.18 0.77 0.41 52.41 12.10 6.52 1.12

S-AC-900 1.57 0.85 0.72 51.74 10.47 6.06 1.21

Fig. S19 Effects of ethanol on PCP degradation in ZVI/PS system. Reaction conditions: [PCP]0 =

80 mg L−1, catalyst = 0.1 g L−1, [PS] = 15 mM, and temperature = 25 °C.

Fig. S20 Effect of S-AC-800 dosage on PCP removal. Reaction conditions: [PCP]0 = 80 mg L−1,

catalyst = 0.01, 0.05, 0.075, 0.1 and 0.125 g L−1, [PS] = 15 mM, and temperature = 25 °C.

Fig. S21 Effect of initial PCP concentration on PCP removal in the S-AC-800/PS system.

Reaction conditions: [PCP]0 = 60, 80, and 100 mg L−1, catalyst = 0.1 g L−1, [PS] = 15 mM, and

temperature = 25 °C.

Fig. S20 and Fig. S21 show the effects of catalyst dosage and initial PCP

concentration on PCP adsorption and oxidation in the S-AC-800 system. Results

show that PCP removal significantly increased with the increase of catalyst dosage,

while a reverse trend was observed at an elevated initial PCP concentration due to the

limited active sites and the insufficient PS concentration.

Fig. S22 Effect of reaction temperature on PCP removal and estimation of activation energy (inset)

in S-AC-800/PS system. Reaction conditions: [PCP]0 = 80 mg L−1, catalyst = 0.1 g L−1, [PS] = 15

mM, and temperature = 25, 45, and 55 °C.

Fig. S23 Effects of reaction temperature on PCP removal and estimation of activation energy

(inset) with (a) rGO/PS, (b) AC/PS, (c) ACS-800/PS, and (d) SDAC-800/PS. Reaction conditions:

[PCP]0 = 80 mg L−1, catalyst = 0.1 g L−1, [PS] = 15 mM, and temperature = 25, 45, and 55 °C.

Fig. S24 Stability and reusability of S-AC-800. Reaction conditions: [PCP]0 = 80 mg L−1, catalyst

= 0.1 g L−1, [PS] = 15 mM, and temperature = 25 °C.

Table S5. Textural properties of S-AC-800 before and after use.

SampleSBET

m2 g-1

Smicro

m2 g-1

Vp

cm3 g-1

Vmicro

cm3 g-1

Average pore size

nm

S-AC-800 2777 1816 1.45 0.76 2.09

S-AC-800 after 1st run 1332 779 0.81 0.33 2.44

Regenerated S-AC-800 after 1st run 1825 1203 1.08 0.50 2.36

Fig. S25 (a) N2 sorption isotherms, and (b) pore size distributions of S-AC-800 before and after

use.

Fig. S26 The high resolution XPS S 2p spectra of S-AC-800 before and after use.

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