Accepted Manuscript

Record-high adsorption capacities of polyaniline-derived porous carbons for the

removal of personal care products from water

Dong Kyu Yoo, Hyung Jun An, Nazmul Abedin Khan, Gil Tae Hwang, Sung
Hwa Jhung

PII: S1385-8947(18)31182-3
DOI: https://doi.org/10.1016/j.cej.2018.06.144
Reference: CEJ 19355

To appear in: Chemical Engineering Journal

Received Date: 11 May 2018

Revised Date: 20 June 2018
Accepted Date: 21 June 2018

Please cite this article as: D.K. Yoo, H.J. An, N.A. Khan, G.T. Hwang, S.H. Jhung, Record-high adsorption capacities
of polyaniline-derived porous carbons for the removal of personal care products from water, Chemical Engineering
Journal (2018), doi: https://doi.org/10.1016/j.cej.2018.06.144

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 Record-high adsorption capacities of polyaniline-
derived porous carbons for the removal of personal
care products from water

Dong Kyu Yoo, Hyung Jun An, Nazmul Abedin Khan,* Gil Tae Hwang, and Sung Hwa
Jhung*

Department of Chemistry and Green-Nano Materials Research Center, Kyungpook National

University, Daegu 41566, Korea

*Corresponding Authors: Dr. Nazmul Abedin Khan, Prof. Sung Hwa Jhung

Fax: 82-53-950-6330

E-mail: sung@knu.ac.kr; nazmulkhan.du@gmail.com

Abstract

Contamination of water resources with organics such as personal care products (PCPs) is

severe because of the increasing living standards, huge production/consumption of PCPs, and

increasing population. In this study, the removal of three typical PCPs, triclosan, oxybenzone,

and p-chloro-m-xylenol, from water was carried out via adsorption over highly porous carbon,

prepared from the pyrolysis of polyaniline (pANI) under suitable conditions. The carbons

(named PDCs or pANI-derived carbons) showed record-high adsorption for the three PCPs,

partly because of the large porosity of the PDC. Moreover, the adsorption mechanism,

excluding van der Waals interactions, could be explained by the adsorption over a wide range

of pH conditions. H-bonding (PCPs as H-donor), together with hydrophobic interaction

(especially at high pH), might be the plausible mechanism for the remarkable adsorption.

Additionally, the used PDC could be recycled by simple solvent washing. Therefore, the

PDCs could be potential adsorbents to purify water contaminated with PCPs.

Keywords: adsorption; polyaniline-derived carbon; personal care products; water purification

1. Introduction

With increasing living standards and population worldwide, the production and

consumption of pharmaceuticals and personal care products (PPCPs) are increasing day by

day [1-8]. Consequently, the contamination of water resources (including surface water and

even groundwater) with such organics is a severe problem [1-8]. Water contaminated with

organics such as PPCPs has been purified by various methods such as electrochemical

processes [9], oxidation (including advanced oxidation processes) [10, 11], and

biotransformation [12]. However, further work is required for developing effective ways to

purify contaminated water, and adsorption might be one such strategy considering the low

cost (especially cheap investment), mild operation conditions, and wide range of applications

[2,13,14]. For efficient adsorptive removal, however, effective adsorbents (with high capacity,

high selectivity, and ready reusability) are essential in commercial applications.

So far, various materials such as carbons (including activated carbon (AC) [15, 16],

carbon nanotubes [17, 18], and carbon composites [19]), TiO2 [20], zeolites [21], metal-

organic frameworks (MOFs such as MIL-101-(OH)3 [22], MAF-6 as carbon precursors [23],

and functionalized MOFs [24]), and natural sediments [25] have been utilized in the

adsorptive removal of PCPs (especially triclosan (TCS), oxybenzone (OXB), and p-chloro-m-

xylenol (PCMX)). Among the mentioned adsorbents, carbonaceous materials are attractive

for the adsorptive purification of water because of their high hydrophobicity [26], high

porosity, and ready availability with affordable cost.

Recently, various organic polymers have been converted into porous carbons for

diverse applications including adsorption [27-32]. Polyaniline (pANI) [33, 34] is an

especially interesting precursor for carbons because nitrogen (which can be maintained in the

produced carbon), together with carbon, is one of major components of the polymer. Very

recently, we have shown that pANI-derived carbon (PDC), prepared under suitable conditions
(pyrolyzed at 500 oC and re-pyrolyzed or activated (after adding KOH) at 700 oC for 1 h) was

very effective in the liquid-phase adsorption of various organics such as diethylphthalate

(DEP), phthalic acid (PA), Janus Green B dye, dibenzothiophene, and 4,6-

dimethyldibenzothiophene from water or fuels [35].

Inspired by our previous study [35], we prepared PDCs via the pyrolysis of pANI at a

wide range of temperatures (up to 900 oC) and applied them in the adsorptive purification of

water containing three typical PCPs, TCS, OXB, and PCMX. The molecular structures and

physical properties (and major applications) [23, 36-38] are shown in Scheme 1 and Table 1,

respectively. The PDC obtained at 800 oC (in the second pyrolysis or activation) showed

record-high adsorption for the three PDCs and could be easily recycled by solvent washing.

Therefore, PDCs might be very useful in adsorptive purification of water contaminated with

organics. Moreover, the plausible adsorption mechanisms (H-bond (PCPs as H-donor) and

hydrophobic interactions) could be suggested.

2. Materials and Methods

2.1. Chemicals and preparation of PDCs

All the used chemicals were obtained from commercial venders and applied in this

study without further purification. The PDCs were obtained by the pyrolysis of pANI and

further activated after adding KOH (the weight of KOH was 2 times the weight of the product

obtained from the first pyrolysis) at 600-900 oC for 1 h, similar to our previous work [35].

The range of pyrolysis temperature was selected based on the fact that yield and porosity of

PDC decreased and increased, respectively, with increasing the temperature [35]. The

obtained products were named as PDC-x, where x indicates the pyrolysis (second step) or

activation temperature (in oC, from 600 to 900 oC). Detailed information on the chemicals

and preparation procedure can be referred to a previous report [35].

2.2. Characterization

The porosities (such as BET surface area and total pore volume) of the PDCs and AC

were obtained by N2 adsorption at 77 K after activation for 12 h at 150 oC. The

concentrations of acid sites of PDCs were measured by Boehm titration [39]. The carbon,

nitrogen and oxygen contents of the PDCs were measured with an elemental analyzer

(Thermo Fisher, Flash-2000, equipped with a TCD detector). The hydrophobicity of some

selected adsorbents was evaluated by measuring the adsorbed quantities of water and n-

octane at 30 oC by using a thermogravimetric analysis system (a Perkin Elmer TGA 4000),

similar to a previous work [40]. The Raman and XPS spectra of some selected samples were

obtained with a Raman spectrometer (Renishaw, in Via reflex) and a Quantera SXM X-ray

photoelectron spectrometer (ULVAC-PHI, with a dual-beam charge neutralizer), respectively.

2.3. Adsorption of PCPs from water

Stock solutions of the three PCPs (100 ppm) were prepared by dissolving them in a mixed

solvent of deionized water and methanol (8:2, vol/vol). The stock solutions were further

diluted with deionized water to get the desired PCPs solutions. The pH of the PCPs solutions

was increased up to 7.0 ± 0.2 by adding a few drops of NaOH solution (0.1 M), considering

the general pH of stream water and rainwater [41]. PCP solutions with a wide range of pH

values were obtained by adding a small amount of NaOH or HCl aqueous solution (0.1 M).

The PDCs and AC were evacuated in a vacuum oven overnight at 100 oC and stored in a

desiccator. The desired amount (3 mg) of adsorbent was added to the adsorbate solutions (25

mL) with fixed concentrations, and the slurry composed of the adsorbents and PCPs was

mixed well at 25 oC by using a magnetic stirrer for a designed time (1-12 h). After adsorption

was carried out for a fixed time, the solution was separated from the carbons using a syringe

filter (polytetrafluoroethylene, hydrophobic, 0.5 μm). A UV spectrometer (UV-1800,

Shimadzu Japan) was applied to measure the remaining adsorbate concentration in the
separated solution. The absorbance at 260, 320, and 279 nm was used to measure the

concentration of TCS, OXB, and PCMX, respectively. The reusability of PDC-800 was

evaluated up to five cycles in TCS adsorption after washing it with ethanol, drying, and

evacuation, similar to the process for the fresh adsorbent. Detailed methods including

calculations can be referred to a previous document [42].

3. Results and Discussion

3.1. Adsorption of PCPs

Fig. 1 compares the adsorbed quantities (q12h) of TCS and OXB over various PDCs

and AC after 12 h of adsorption. The q12h (based on the unit weight of the adsorbent, shown

in Figs. 1a and 1c) for both TCS and OXB decreases in the order PDC-800>PDC-900~PDC-

750>PDC-700>>PDC-600~AC. PDC-800 shows the most effective adsorption in the removal

of TCS and OXB, which is quite different from our previous study that shows the best

performance for PDC-700 [35]. This remarkable adsorption over PDC-800 might be because

of the very high porosity of PDC-800 compared with the other adsorbents (Table 2). However,

there is another contribution since PDC-800, which has the highest q12h (based on the unit

weight), also shows the highest q12h (based on the BET surface area, shown in Figs. 1b and

1d), even though the differences between PDC-800 and other PDCs (such as PDC-700, PDC-

750, and PDC-900) are quite small. In other words, PDC-800 should have the same q12h

(based on the unit BET surface area) as the other PDCs if van der Waals interaction or

porosity is the only important parameter in the adsorption of TCS and OXB. The reason or

mechanism for this phenomenon (the highest q12h with PDC-800) will be explained in the

next section. Similar to the results for TCS and OXB, PDC-800 shows the highest q12h for

PCMX (as shown in Fig. 2), again confirming that PDC-800 is the best adsorbent among

those studied so far for PCMX adsorption or removal.

 Subsequent research was performed mainly with PDC-800 and AC as the

representative materials for the best PDC for the three PCPs and the most common adsorbent,

respectively. Fig. 3 shows the adsorbed quantities (qt) of TCS over PDC-800 and AC over a

wide range of adsorption times. TCS was selected as a representative PCP since the qt(PDC-

800)/qt(AC) ratio was the highest for TCS (among the studied PCSs). Irrespective of the

adsorption time, PDC-800 showed much higher qt compared with AC. The kinetic constants

(k2 values, calculated by using a pseudo-second-order non-linear model [42]) shown in Table

3 also illustrate that PDC-800 adsorbs TCS much more rapidly than AC, reconfirming the

very favorable interaction between PDC-800 and TCS. The adsorption isotherms of TCS over

PDC-800 and AC were obtained from adsorption for a sufficiently long time of 12 h over a

wide range of TCS concentrations. The Langmuir isotherm [42] was applied to interpret the

adsorption, including the maximum adsorption capacity (Q0). The isotherms and Langmuir

plots are shown in Figs. 4a and 4b, respectively. The calculated Q0 values shown in Table 3

reconfirm that PDC-800 is much more effective compared with the conventional adsorbent

AC. Moreover, another Langmuir parameter, b values [42], showed that PDC-800 is more

effective in TCS adsorption than AC.

As described, various adsorbents including AC and multi-walled carbon nanotube

(MWCNT) have been used in the adsorptive purification of water containing the PCPs TCS,

OXB, and PCMX. Table 4 compares the summarized results (Q0 or qt) on the adsorption of

the three PCPs over various adsorbents [15, 17, 19-23, 43-45] including PDC-800. As shown

in the table, to the best of our knowledge, PDC-800 shows the maximum adsorption capacity

or Q0 for TCS. Moreover, PDC-800 has much higher qt for OXB and PCMX than the Q0 or qt

observed earlier. Since Q0 is usually higher than qt, these results also confirm that PDC-800 is

the best adsorbent to remove OXB and PCMX from contaminated water.

3.2. Adsorption mechanism

 Understanding the adsorption mechanism is very important not only for finding

competitive adsorbents but also for developing the basic science of adsorption. Various

adsorption mechanisms [46-49] such as electrostatic interaction, acid-base interaction, H-

bonding, π-π interaction, hydrophobic interaction, and van der Waals interaction have been

suggested to explain adsorption from both water and fuels.

In this study, the most effective adsorbent was PDC-800 rather than PDC-700, which

in an earlier study [35] showed the highest adsorptive performance to remove organics such

as DEP, Janus Green B, and 4,6-dimethyldibenzothiophene. Therefore, the adsorption

mechanisms might be different in the two studies. Considering the importance of the porosity

(BET surface area and total pore volume) in this study (as shown in Fig. 1), the contribution

of van der Waals interaction [50] will be considerable. Excluding this traditional or

conventional interaction, other mechanisms are essential to explain the observation.

Since the pH of the aqueous solution has a profound influence on the adsorbed

amounts [46, 49], the q12h values were obtained over a wide range of pH values. As shown in

Fig. 5, q12h increased with increasing pH up to a certain value (~8) and decreased with a

further increase in pH. First, electrostatic interaction [46] can be considered since this has

been used quite often; however, this mechanism cannot be applied to interpret the observation

considering the generally neutral species below the pH corresponding to the pKa values

shown in Table 1. Acid-base interaction might not be useful either to interpret the observation

since PDC-800 is generally acidic (as shown in Table 2) and the three PCPs are also weakly

acidic because of the presence of phenolic species.

Considering the ample H-donor or acceptor sites on both PCPs and PDC-800, H-

bonding [47] might be a suitable mechanism to explain the adsorption. First, PDC-800 may

be considered as a H-donor similar to the DEP/PA and thiophenics adsorption over PDC-700

[35]. If this is the direction of H-bonding, q12h should decrease monotonously with increasing
pH considering the steady deprotonation of carboxylic and phenolic acids with the increase in

pH. However, the results in Fig. 5 do not agree with this expectation. Therefore, another

direction of H-bonding (or PCPs as H-donor) is considered. As shown in Fig. 5, q12h

decreases sharply as the pH becomes higher than the pKa values (highlighted with dotted

lines). This is easily understood since the three PCPs cannot contribute as a H-donor at such

high pH because of deprotonation. The relatively low q12h at very low pH (for example, ~ 3)

than the value at medium pH (for example, ~ 6) might be explained by the –COOH and –

COO- groups present on PDC-800 at those pH values. Carboxylate is a better H-acceptor than

the carboxylic group; therefore, q12h at very low pH should be lower than the value where –

COO- can be observed. This expectation is well harmonized with the experimental results

shown in Fig. 5.

The direction of H-bonding in this study is opposite to the direction observed in our

previous study [35] even though the adsorbents (PDC-700 and PDC-800) are quite similar to

each other. This very different direction of H-bonding might be explained by the content of

the H-donor/acceptor sites of the PDC-700 and PDC-800 adsorbents. The concentration of

the possible H-donor sites (carboxylic and phenolic) in PDC-800 is lower than that in PDC-

700 (as shown in Table 2). However, the concentration of H-acceptor sites (carboxylic,

phenolic, and lactonic) in PDC-800 is higher than that in PDC-700 since the concentration of

lactonic groups increases notably with increasing pyrolysis temperature [35, 51]. In other

words, PDC-700 and PDC-800 have high concentrations of H-donor and H-acceptor sites,

respectively; therefore, it can be assumed that the directions of H-bond formation with the

two adsorbents are opposite to each other.

If the described H-bond (H-donor from PCPs) is the main mechanism, q12h should be

very low at pH higher than 7.7-9.7, considering the pKa values (Table 1). Even though q12h

decreased sharply with increasing pH, there is considerable adsorption at pH 11, for example.
This q12h might be explained by a few mechanisms such as hydrophobic [52-54] and π-π [54-

58] interactions. As shown in Fig. 6, the hydrophobicity of PDC-800 is higher compared with

that of AC because PDC-800 and AC preferentially adsorb n-octane and water, respectively

(even though AC is regarded as one of the typical hydrophobic materials [26]). Moreover, the

three adsorbates are hydrophobic based on the high logKOW values shown in Table 1.

Therefore, hydrophobic interaction can be one of the important mechanisms for the

adsorption of PCPs over PDC-800. Π-π interaction cannot be ruled out since all the

adsorbates have a benzene ring and the adsorbent has a graphitic layer, which is confirmed by

Raman analysis (shown in Fig. 7a). Finally, H-bonding in the opposite direction (PCPs as H-

acceptor) can also contribute to the adsorption at very high pH considering the pyrrole group

on PDC-800, which is observed most noticeably (among the nitrogen species) by XPS

(shown in Fig. 7b).

3.3. Reusability of adsorbent

Reusability of an adsorbent is very important, especially for commercial applications,

considering the cost of the adsorbent. As shown in Fig. 8, PDC-800 can be used up to five

cycles after simple solvent (ethanol) washing, without any noticeable decrease in the

adsorbed quantity of TCS. Importantly, PDC-800 recycled for four times shows around 5.6

times higher q12h, compared with that of fresh AC. Moreover, the nitrogen adsorption

isotherm of the recycled PDC-800 does not show any noticeable difference from that of fresh

PDC-800. Therefore, PDC-800 is a readily reusable adsorbent for TCS adsorption and

removal. Considering the existence of similar functional group, phenolics, on the three PCPs,

the PDC-800 might be also reusable in adsorption of OXB and PCMX from water.

4. Conclusions
 Porous carbons, derived from the pyrolysis of pANI under wide conditions, were

applied in the adsorptive purification of water containing three typical PCPs (TCS, OXB, and

PCMX), and the following conclusions could be derived. First, PDC, especially that obtained

at 800 oC, showed record-high adsorption capacities (compared with any adsorbent reported

so far) for the three adsorbates. Moreover, the used PDC could be easily recycled, at least up

to for five cycles, via simple solvent washing. Second, the activation temperature (under

KOH) was very important not only for porosity but also for the produced functional groups of

the PDCs. Activation at 800 oC was very effective to have highly porous carbon with high

concentration of H-acceptor sites (carboxylic, phenolic, and lactonic). Third, the remarkable

adsorptive performance of PDC could be explained with not only the large porosity but also a

few adsorption mechanisms such as H-bonding and hydrophobic interactions. The direction

of H-bonding for the PCPs adsorption over PDC could be also defined (PCPs and PDC as H-

donor and H-acceptor, respectively). Forth, PDC can be suggested as a potential adsorbent to

purify water contaminated with organics, considering the record-high adsorption capacities,

ready reusability, and facile synthesis.

Acknowledgment: This work was supported by the National Research Foundation of Korea

(NRF) grant funded by the Korea government (Ministry of Education) (grant number:

2017R1D1A3B03033345).
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Table Legends:

1. Table 1. Physical properties and applications of PCPs.

2. Table 2. Textural properties, compositions and concentrations of functional groups

of adsorbents.

3. Table 3. Adsorption kinetic constants and Langmuir parameters for the adsorption of
TCS over AC and PDC-800.

4. Table 4. Maximum adsorption capacities (Q0) or adsorbed quantities (q12h) of some

reported adsorbents for the removal of TCS, OXB and PCMX from water.

Scheme Legend:

1. Scheme 1. Molecular structures of (a) triclosan, (b) oxybenzone and (c) p-chloro-m-
xylenol.

Figure Legends:

1. Fig. 1. Adsorbed amounts (q12h) of (a, b) triclosan and (c, d) oxybenzone over the
studied adsorbents after adsorption for 12 h. The q12h based on unit weight and BET surface
area are shown on left (Figures a and c) and right (Figures b and d) side, respectively, of the
figure.

2. Fig. 2. Adsorbed amounts (q12h) of p-chloro-m-xylenol over the studied adsorbents

after adsorption for 12 h.

3. Fig. 3. Effect of contact time on the adsorbed quantity of triclosan over AC and
PDC-800.

4. Fig. 4. (a) Adsorption isotherms (b) Langmuir plots for the adsorption of triclosan
from water over AC and PDC-800.

5. Fig. 5. Effect of pH on the adsorbed amounts of (a) triclosan, (b) oxybenzone and (c)
chloroxylenol over PDC-800. The dotted lines show the pKa values of each adsorbate.
6. Fig. 6. Amount of adsorbed (a) H2O and (b) n-octane over AC and PDC-800. (c)
Ratios of adsorbed amounts (mmol/mmol) of n-octane and water over AC and PDC-800. The
adsorptions were done up to 60 min from vapor phase (P/P0=0.5) at 30 oC.

7. Fig. 7. (a) Raman and (b) XPS (in nitrogen region) spectra of PDC-800.

8. Fig. 8. (a) Reusability of PDC-800 for the adsorption of triclosan after washing with
ethanol. The red line shows the adsorbed amount of triclosan over fresh AC. (b) Nitrogen
adsorption isotherms of the fresh and regenerated (after the first recycle) PDC-800s.
Table 1. Physical properties and applications of PCPs.

MW Water solubility Dimension

Adsorbates pKa logKow
(g/mol) (g/L) (Å)*

Triclosan [36] 289.53 0.005 7.9 4.2-4.8 10.8 x 5.4

Oxybenzone [23] 228.25 0.007 7.6 3.79 11.7 x 5.7

p-chloro-m-xylenol [37, 156.61 0.33 9.7 3.27 6.7 x 6.4

38]

* Calculated by Gaussian software

Table 2. Textural properties, compositions and concentrations of functional groups of
adsorbents.

SABET PVtot C N O Conc. of functional group (mmol/g)

Material
(m2/g) (cm3/g) (wt%) (wt%) (wt%) Carboxylic Lactonic Phenolic Total

AC 1016 0.56 ND ND ND - - - -
PDC-600 597 0.40 73.4 8.6 7.7 2.07 0.23 0.82 2.88
PDC-700 2261 1.17 67.2 5.3 7.3 2.03 0.16 0.75 2.94
PDC-750 2488 1.20 81.5 2.8 5.0 1.98 0.35 0.65 2.98
PDC-800 2752 1.76 80.4 3.0 2.4 1.87 0.65 0.55 3.07
PDC-900 2549 1.51 90.1 2.8 2.5 1.68 0.93 0.48 3.09
Table 3. Adsorption kinetic constants and Langmuir parameters for the adsorption of TCS
over AC and PDC-800.

k2 Qo b
-1 -1
R2 -1 -1
R2
(g mg h ) (mg·g ) (L·mg )

AC 0.006 0.999 174 0.089 0.998

PDC-800 2.30 0.998 1318 0.184 0.998

Table 4. Maximum adsorption capacities (Q0) or adsorbed quantities (q12h) of some reported
adsorbents for the removal of TCS, OXB and PCMX from water.
SABET Solution Q0 Reference
Adsorbates Adsorbents
(m2·g-1) pH (mg·g-1)
triclosan TiO2 - 7.0 39.7 [20]
MWCNT 235 6.0 160.66 [17]
Activated carbon 738.8 6.0 70.42 [15]
Modified organo-zeolites - 7.0 46.95 [21]
Magnetic activated carbon 674 7.0 303 [43]
Magnetic carbon composites 1311 2.0 892.9 [19]
Activated carbon 1016 7.0 173.6 This work
PDC-800 2752 7.0 1318 This work
oxybenzone MAF-6 1339 7.0 71 [23]
CDM-6 1642 7.0 440 [23]
Activated carbon 1016 7.2 153* This work
PDC-800 2752 7.2 906* This work
p-chloro Powder activated carbon - - 1.3 [44]
-m-xylenol Hyacinth stem 20 - <1.0 [45]
MIL-101-(OH)3 1838 7.0 79* [22]
Activated carbon 1016 7.2 340* This work
PDC-800 2752 7.2 840* This work

* adsorbed quantities (q12h) rather than maximum adsorption capacities (Q0)

Scheme 1. Molecular structures of (a) triclosan, (b) oxybenzone and (c) p-chloro-m-xylenol.
 0.4
1000
(a) (b)

q12h /SBET(mg/m )
2
800
0.3
q12h (mg/g)

600
0.2
400

200 0.1

0
AC PDC-600 PDC-700 PDC-750 PDC-800 PDC-900 0.0
AC PDC-600 PDC-700 PDC-750 PDC-800 PDC-900
Adsorbents
Adsorbents
0.4
1000
(d)

q12h /SBET(mg/m )
(c)
2
800
0.3
q12h (mg/g)

600

0.2
400

200 0.1

0
AC PDC-600 PDC-700 PDC-750 PDC-800 PDC-900
0.0
Adsorbents AC PDC-600 PDC-700 PDC-750 PDC-800 PDC-900

Adsorbents
Figure 1. Adsorbed amounts (q12h) of (a, b) triclosan and (c, d) oxybenzone over the studied
adsorbents after adsorption for 12 h. The q12h based on unit weight and BET surface area are
shown on left (Figures a and c) and right (Figures b and d) side, respectively, of the figure.
 1000

800
q12h (mg/g)

600

400

200

0
AC PDC-600 PDC-700 PDC-750 PDC-800 PDC-900

Adsorbents

Figure 2. Adsorbed amounts (q12h) of p-chloro-m-xylenol over the studied adsorbents after
adsorption for 12 h.
 1000

AC
800 PDC-800
qt (mg/g)

600

400

200

0
0 2 4 6 8 10 12
Time (h)
Figure 3. Effect of contact time on the adsorbed quantity of triclosan over AC and PDC-800.
 1.2
1200 (a) AC (b)
PDC-800

Ce/qe (g/L)
900 0.8
qe (mg/g)

600

0.4

300
AC
PDC-800

0 0.0
0 40 80 120 160 200 0 50 100 150 200

Ce (ppm) Ce (ppm)

Figure 4. (a) Adsorption isotherms (b) Langmuir plots for the adsorption of triclosan from
water over AC and PDC-800.
 1000
1000 (a) (b)
800
800

q12h (mg/g)
q12h (mg/g)

600
600

400
400

200 200

0 0
0 2 4 6 8 10 12 0 2 4 6 8 10 12
pH of solutions pH of solutions

1000
(c)
800
q12h (mg/g)

600

400

200

0
0 2 4 6 8 10 12
pH of solutions

Figure 5. Effect of pH on the adsorbed amounts of (a) triclosan, (b) oxybenzone and (c)
chloroxylenol over PDC-800. The dotted lines show the pKa values of each adsorbate.
 2.0 8
(a) (b)

Amount adsorbed (mmol/g)

AC
Amount adsorbed (mmol/g)

AC PDC-800

1.5 PDC-800 6

1.0 4

0.5 2

0.0 0
0 10 20 30 40 50 60 0 10 20 30 40 50 60
Time (min) Time (min)

6
(c) AC
PDC-800
n-octane/H2O

0
0 10 20 30 40 50 60

Time (min)

Figure 6. Amount of adsorbed (a) H2O and (b) n-octane over AC and PDC-800. (c) Ratios of
adsorbed amounts (mmol/mmol) of n-octane and water over AC and PDC-800. The
adsorptions were done up to 60 min from vapor phase (P/P0=0.5) at 30 oC.
 G D Original data N1s
(a) 1594 1338
PDC-800 (b) Fitted curve
398.7 (pyridinic N)
399.8 (pyrrolic N)
400.7 (graphitic N)
Intensity (a.u.)

Intensity, a.u.
404.3 (C-N-O)

IG/ID = 1.02

2500 2000 1500 1000 500 410 408 406 404 402 400 398 396
-1
Wave number (cm ) B.E.(eV)

Figure 7. (a) Raman and (b) XPS (in nitrogen region) spectra of PDC-800.
 1000 (a) 1200 (b) PDC-800

Adsorbed amount (cm /g)

Regenerated PDC-800

3
1000
800
q12h (mg/g)

800
600
600
400
400

200 200

0 0
1 2 3 4 5 0.0 0.2 0.4 0.6 0.8 1.0
Number of Cycles Relative pressure (P/Po)

Figure 8. (a) Reusability of PDC-800 for the adsorption of triclosan after washing with
ethanol. The red line shows the adsorbed amount of triclosan over fresh AC. (b) Nitrogen
adsorption isotherms of the fresh and regenerated (after the first recycle) PDC-800s.
Graphical Abstract
 Research Highlight

- Polyaniline-derived porous carbons (PDCs) were applied in removal of three

PCPs.

- Record-high adsorption for triclosan, oxybenzone and p-chloro-m-xylenol.

- Adsorption explained with van der Waals, H-bonding and hydrophobic

interactions.

- The direction of H-bonding could also be defined (PCPs as H-donor).

- The PDCs showed perfect reusability for successive adsorptions in water.