Soil washing is a kind of physical method to remove organic matters from contaminated soil. However, its eluate after washing may result in secondary pollution to the environment. In this study, activated coke (AC) was used to remove organic pollutants from contaminated soil eluate. The effect of temperature, initial chemical oxygen demand (COD) and AC dosage on COD removal efficiency was investigated. The results showed that the organic matter can be removed in the eluate because the COD dropped a lot. When the AC dosage was 20 g·L−1, 88.92% of COD decreased after 480 min of adsorption at 50 °C. The process of adsorption can be described by the Redlich–Peterson isotherm. The adsorption was spontaneous and endothermic. The pseudo-second-order model can be used to describe the adsorption process. After adsorption, the acute toxicity of the eluate was reduced by 76%, and the water qualities were in agreement with Chinese discharge standard GB 14470.1-2002, which means the eluate could be discharged to the environment.

INTRODUCTION

2,4,6-Trinitrotoluene (TNT) is a kind of nitro aromatic compound, which can be used as a high explosive in many fields (Seok-Young Oh 2015). During its production and usage, large amounts of wastewater containing TNT and its transformation products are produced, which may infiltrate and contaminate the soils near the military sites (Via et al. 2014). The contaminated soils are toxic to plants and crops, and do harm to local residents (Lamichhane et al. 2012; Ungradova et al. 2013). Hence, it is important to remediate the contaminated soils effectively.

Soil washing is a kind of physical method that can remove heavy metals (Ye et al. 2015) and organic matters (Dadrasnia & Agamuthu 2013) effectively and conveniently from contaminated soil. However, the eluate remaining after washing results in secondary pollution to the environment and so should be further treated before its discharge. Adsorption is an efficient method to remove pollutants from wastewater, where activated carbon (Wie Ner et al. 1998; Marinović et al. 2005; Boddu et al. 2009), resin (Sklari et al. 2012; Cegłowski & Schroeder 2015; Du et al. 2015; Zagklis et al. 2015) and alumina (Glorias-Garcia et al. 2014; Saadi et al. 2014; Wiśniewska et al. 2014) have often been used as adsorbents. However, the high cost of adsorbents hinders the application of the adsorption method. A cheap and effective adsorbent is a prerequisite for its practical application.

Activated coke (AC) is a kind of substitute material for activated carbon, which is produced from naturally occurring carbonaceous materials like wood, lignite and petroleum coke (Tong et al. 2014) and is often used to treat gas purification because of its low cost and high adsorption capacity (Li et al. 2008; Wang et al. 2009; Ogriseck & Galindo Vanegas 2010; Sun et al. 2011; Jastrząb 2012; Schmauss & Keppler 2014; Wang et al. 2014). In our previous study, it was used to treat coking wastewater (Zhang et al. 2010) and red water (Zhang et al. 2011). To our knowledge, there are still few reports focused on treatment of contaminated soil eluate by AC. The objective of the present work was to investigate the feasibility of AC to remove organic pollutants from contaminated soil containing nitro aromatic compounds. The effect of temperature, initial chemical oxygen demand (COD), and AC dosage on COD removal efficiency was studied. In addition, the adsorption kinetics and thermodynamics were investigated.

MATERIALS AND METHODS

Materials

The soil contaminated with explosives was provided by Gansu Yinguang Chemical Industry Group Co., Ltd. The soil eluate was obtained under the conditions of1:1 water/soil ratio. It has an intense red color with a density of 0.99 g·mL−1. Since its composition is complex with a high amount of COD, it was diluted 10 times with de-ionized water before treatment. The COD removal efficiency (R%) was used to evaluate the adsorption efficiency, which can be calculated by the equation: 
formula
1
where CODt represents COD of eluate at contact time t and COD0 represents the initial COD of eluate.

AC was obtained from Datang Yima coke plant (Yima Coal Industry Group, Henan, China). The particle range was 0.45–0.90 mm, with a specific surface area of 408 m2·g−1. The luminescent bacterium Vibrio qinghaiensis sp. nov. was provided by Beijing Hamamatsu Photon Techniques Inc., China.

Static adsorption test

The static adsorption test was used to study the effect of AC dosage, initial COD, and temperature on COD removal efficiency. The following equation was used to calculate the adsorption capacity of AC: 
formula
2
where qe (mg·g−1) is the adsorption capacity of AC at adsorption equilibrium, and COD0 (mg·L−1) and CODe (mg·L−1) are the initial and equilibrium COD of eluate, respectively. W (g) is the mass of AC and V (L) is the volume of eluate solution.

In the study of the effect of AC dosage on COD removal efficiency, weighed amounts of AC (0.5, 1, 2, 4, 6, 8, 10 g) were placed in a 100 mL flask containing 50 mL eluate samples with an initial COD of 424.65 mg·L−1. The flasks were sealed and shaken at 50 °C and 200 rpm in a constant temperature oscillator (Taicang Laboratory Equipment Factory, Jiangsu Province, China). After the adsorption system reached equilibrium, 2.5 mL of the solution was withdrawn, and passed through a 0.45 μm membrane filter to test COD.

In the study of the effect of initial COD on COD removal efficiency, a weighed amount of AC (1 g) was placed in six 100 mL flasks containing 50 mL eluate samples in different dilutions. The initial COD was 111.72, 206.98, 293.44, 335.10, 378.75, and 424.65 mg·L−1, respectively. The flasks were sealed and shaken at 50 °C and 200 rpm in a constant temperature oscillator. After the adsorption system reached equilibrium, 2.5 mL of the solution was withdrawn, and passed through a 0.45 μm membrane filter to test COD.

In the study of the effect of temperature on COD removal efficiency, a weighed amount of AC (1 g) was placed in ten 100 mL flasks containing 50 mL eluate samples with an initial COD of 424.65 mg·L−1. The flasks were sealed and shaken at different temperatures (15, 20, 30, 40, 50 °C) in a constant temperature oscillator at 200 rpm. Take out one by one at 5, 10, 15, 30, 45, 60, 120, 180, 300, and 480 min, 2.5 mL of the solution was withdrawn, and passed through a 0.45 μm membrane filter to test COD.

Water quality detection

The water quality was detected according to different national standards. COD was determined by fast digestion of potassium dichromate (Hach heating system, Hach Corporation, USA) under Chinese standard GB 11914-89. The chrominance was determined by dilution method until the water sample became colorless, according to Chinese standard GB 11903-89. The nitro compound content was detected by spectrophotometry (Shimadzu, UV-1800) according to Chinese standard GB 4819-1985. The acute toxicity of the eluate was determined by luminescent bacteria test (Zhao et al. 2013).

RESULTS AND DISCUSSION

Effect of contact time on COD removal efficiency

Figure 1 shows the effect of contact time on COD removal efficiency. The COD removal efficiency increased quickly from 0 to 76.65% in the first 60 min, and then leveled off afterwards. After 480 min, the COD removal remained almost unchanged, meaning that the adsorption process reached equilibrium. The equilibrium adsorption capacity of AC was 16.41 mg·g−1. In the present study, a total contact time of 480 min was chosen to ensure the adsorption process reached equilibrium.
Figure 1

Effect of contact time on COD removal efficiency.

Figure 1

Effect of contact time on COD removal efficiency.

Effect of AC dosage on COD removal efficiency

Figure 2 presents the effect of AC dosage on COD removal efficiency. When AC dosage increased from 10 to 20 g·L−1, COD removal efficiency increased rapidly from 68.91 to 88.92%; then it gradually increased to 95.22% up to an AC dosage of 200 g·L−1. This is because the number of active sites and surface area increase with increasing AC dosage. It can also be noted that the adsorption capacity decreased from 29.3 to 2.0 mg·g−1 when the AC dosage increased from 10 to 200 g·L−1, suggesting that the higher the AC dosage, the lower the amount of AC taking part in the adsorption.
Figure 2

Effect of AC dosage on COD removal efficiency.

Figure 2

Effect of AC dosage on COD removal efficiency.

Effect of initial COD and temperature on COD removal efficiency

Figure 3 illustrates the effect of initial COD and temperature on COD removal efficiency. It can be observed that COD removal efficiency decreased with increasing initial COD. When the initial COD increased from 111.8 to 424.6 mg·L−1 at 15 °C, COD removal efficiency dropped from 94.07 to 77.32%. It can also be noted that COD removal efficiency increased with increasing temperature. At the initial COD of 424.6 mg·L−1, when the temperature rose from 15 to 50 °C, the COD removal efficiency increased from 77.3 to 89.4%, suggesting that the adsorption process may be endothermic.
Figure 3

Effect of initial COD and temperature on COD removal efficiency.

Figure 3

Effect of initial COD and temperature on COD removal efficiency.

The adsorption kinetics

The pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Bangham models were used to fit the experimental data at different temperatures. The pseudo-first-order model (Bertoni et al. 2015) is expressed as: 
formula
3
Its integrated form is: 
formula
4
where qe1 (mg·g−1) is adsorption capacity of AC at equilibrium, qt (mg·g−1) is the amount adsorbed at time t (min), and k1 (min −1) is the rate constant. The parameters k1 and qe1 can be obtained from the slope and the intercept of the linear plots.
The pseudo-second-order model (Kuśmierek et al. 2015) is expressed as: 
formula
5
Its integrated form is: 
formula
6
where qe2 (mg·g−1) is the adsorption capacity at equilibrium, and k2 (g·mg−1·min−1) is the pseudo-second-order constant. The parameters qe2 and k2 can be obtained from the slope and intercept of the linear plots of t/qt versus t.
The intraparticle diffusion model (Arshadi et al. 2015) is expressed as: 
formula
7
where k3 (mg·g−1·min−0.5) is the particle internal diffusion rate constant. C (mg·g−1) is the intercept of the equation, and is related to the thickness of the boundary layer. The higher the value, the bigger the boundary effects.
The linear equation of Bangham (Kaur et al. 2015) is expressed as: 
formula
8
where C0 (mg·L−1) is the initial COD of the soil eluate, m (mg·L−1) is AC dose, V (mL) is the volume of the solution, qt (mg·g−1) is the amount adsorbed at time t, and a (<1) and kb are constants.

Table 1 lists the fitting results of the above-mentioned models at different temperatures. It can be seen that the correlation coefficient R2 for the pseudo-second-order kinetic model is much higher than that for the other three kinetic models in the temperature range of 15–50 °C, and is higher than 0.995, indicating that the second-order kinetic model was more suitable to describe the adsorption process than the other three models. The adsorption capacity at calculated equilibrium (qe2) shows propinquity with the experimental data (qexp).

Table 1

Fitting results of kinetics parameters for the adsorption of COD onto AC

  Pseudo-first-order model
 
Pseudo-second-order model
 
Intraparticle diffusion
 
Bangham
 
T (°C) qe (EXP) (mg·g−1qe1 (mg·g−1k1 (min−1R2 q e2 (mg·g−1k2 (g·mg−1·min−1ha (mg·g−1·min−1R2 k3 (mg·g−1·min−0.5C (mg·g−1R2 kb a R2 
15 16.680 1.709 6.452 × 10−3 0.291 16.529 2.001 × 10−2 5.362 1.000 0.187 13.257 0.676 1.901 × 10−3 0.121 0.867 
20 16.615 0.845 1.272 × 10−2 0.693 16.639 5.502 × 10−2 15.111 1.000 0.066 15.466 0.581 2.982 × 10−3 0.043 0.716 
30 17.629 1.190 4.601 × 10−3 0.085 16.863 1.700 × 10−1 47.623 0.999 0.145 14.625 0.550 2.351 × 10−3 0.102 0.758 
35 17.910 5.037 1.223 × 10−2 0.823 17.857 1.102 × 10−2 3.381 0.999 0.168 14.486 0.698 2.302 × 10−3 0.109 0.819 
40 18.417 5.044 1.501 × 10−2 0.792 18.348 1.121 × 10−2 3.364 0.999 0.141 15.353 0.904 2.701 × 10−3 0.090 0.898 
50 19.553 4.860 5.102 × 10−3 0.951 19.157 7.000 × 10−3 2.572 0.999 0.277 13.720 0.910 1.804 × 10−3 0.179 0.965 
  Pseudo-first-order model
 
Pseudo-second-order model
 
Intraparticle diffusion
 
Bangham
 
T (°C) qe (EXP) (mg·g−1qe1 (mg·g−1k1 (min−1R2 q e2 (mg·g−1k2 (g·mg−1·min−1ha (mg·g−1·min−1R2 k3 (mg·g−1·min−0.5C (mg·g−1R2 kb a R2 
15 16.680 1.709 6.452 × 10−3 0.291 16.529 2.001 × 10−2 5.362 1.000 0.187 13.257 0.676 1.901 × 10−3 0.121 0.867 
20 16.615 0.845 1.272 × 10−2 0.693 16.639 5.502 × 10−2 15.111 1.000 0.066 15.466 0.581 2.982 × 10−3 0.043 0.716 
30 17.629 1.190 4.601 × 10−3 0.085 16.863 1.700 × 10−1 47.623 0.999 0.145 14.625 0.550 2.351 × 10−3 0.102 0.758 
35 17.910 5.037 1.223 × 10−2 0.823 17.857 1.102 × 10−2 3.381 0.999 0.168 14.486 0.698 2.302 × 10−3 0.109 0.819 
40 18.417 5.044 1.501 × 10−2 0.792 18.348 1.121 × 10−2 3.364 0.999 0.141 15.353 0.904 2.701 × 10−3 0.090 0.898 
50 19.553 4.860 5.102 × 10−3 0.951 19.157 7.000 × 10−3 2.572 0.999 0.277 13.720 0.910 1.804 × 10−3 0.179 0.965 

ah: initial release rate. For temperatures up to 30 °C, the reaction is endothermic and h is higher than for temperatures above 30 °C, when the desorption rate is also high.

Equilibrium isotherms

An adsorption isotherm refers to the relationship of concentration between the two phases at adsorption equilibrium. The Langmuir equation is often used to describe the saturated monomolecular layer adsorption, which can be expressed as (Anisuzzaman et al. 2015): 
formula
9
Its linear form is: 
formula
10
where Ka (L·mg−1) is the adsorption equilibrium constant, Ce is the COD of eluate at reaction equilibrium and qm (mg·g−1) is the maximum amount of COD adsorbed per unit mass by the AC.
The Freundlich equation (Li et al. 2015) is an empirical formula based on the adsorption between the different surfaces, which can be expressed as: 
formula
11
Its linear form is: 
formula
12
where KF is Freundlich constant and n is adsorption intensity.
The Redlich–Peterson isotherm (Foo & Hameed 2010) combines the features of Langmuir and Freundlich and can be applied either in homogeneous or heterogeneous systems due to its versatility. It approaches the Freundlich isotherm model at high concentration limit (as the exponent g tends to zero) and is in accordance with the low concentration limit of the ideal Langmuir condition (as the g values are all close to one). The specific form is: 
formula
13
The parameters KR (L·g−1) and aR (L·mg−1) are constants and g (0 < g < 1) is the exponent. Its linear form is: 
formula
14
where KR, aR, and g can obtained using the tool of origin.

Table 2 lists the fitting results of the three isotherms. It can be observed that the correlation coefficients of the three isotherms are mostly higher than 0.990. The best belong to the Redlich–Peterson isotherm. To compare the difference between theory and experiment, we calculate the qe in theory in Table 2 as qcal1, qcal2, qcal3 and present the qe in the experiment as qexp. Obviously, the qecal3 in the Redlich–Peterson isotherm is very near to qexp, meaning that the best fit is the Redlich–Peterson isotherm. It can also be noted that qm increased with increasing temperature, indicating that the adsorption process may be endothermic.

Table 2

Isotherm parameters for the adsorption of COD onto AC

  Langmuir
 
Freundlich
 
Redlich–Peterson
 
T (°C) qexp qcal1 (mg·g−1qm (mg·g−1Ka (L·mg−1R2 qcal2 (mg·g−1KF n R2 qcal3 (mg·g−1KR (L·mg−1)g aR (L·g−1g R2 
15 15.967 15.709 83.333 0.012 0.876 35.466 0.542 1.114 0.997 15.805 0.194 7.900 × 10−3 0.776 0.996 
20 16.303 16.264 50.000 0.020 0.988 16.672 1.281 1.789 0.995 16.249 0.289 4.480 × 10−2 0.615 1.000 
30 16.771 12.533 19.608 0.051 0.991 18.177 0.968 1.531 0.993 16.772 0.481 3.540 × 10−2 0.843 0.999 
40 17.417 17.109 23.256 0.043 0.992 12.299 1.346 1.959 0.989 17.372 1.319 1.844 × 10−1 0.752 0.999 
50 18.443 17.917 26.316 0.038 0.991 12.540 1.379 1.821 0.993 18.428 1.667 2.310 × 10−1 0.712 1.000 
  Langmuir
 
Freundlich
 
Redlich–Peterson
 
T (°C) qexp qcal1 (mg·g−1qm (mg·g−1Ka (L·mg−1R2 qcal2 (mg·g−1KF n R2 qcal3 (mg·g−1KR (L·mg−1)g aR (L·g−1g R2 
15 15.967 15.709 83.333 0.012 0.876 35.466 0.542 1.114 0.997 15.805 0.194 7.900 × 10−3 0.776 0.996 
20 16.303 16.264 50.000 0.020 0.988 16.672 1.281 1.789 0.995 16.249 0.289 4.480 × 10−2 0.615 1.000 
30 16.771 12.533 19.608 0.051 0.991 18.177 0.968 1.531 0.993 16.772 0.481 3.540 × 10−2 0.843 0.999 
40 17.417 17.109 23.256 0.043 0.992 12.299 1.346 1.959 0.989 17.372 1.319 1.844 × 10−1 0.752 0.999 
50 18.443 17.917 26.316 0.038 0.991 12.540 1.379 1.821 0.993 18.428 1.667 2.310 × 10−1 0.712 1.000 

Adsorption thermodynamics

In order to have a better understanding of the effect of temperature on the adsorption process, we calculated the thermodynamics parameters including changes of Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) according to the following equations (Ghiloufi et al. 2015): 
formula
15
 
formula
16
where R is a constant with value of 8.314 J mol−1; T is temperature and K0 is the thermodynamic equilibrium constant, which can be obtained from the intercept of the plots of ln(qe/Ce) versus qe (Zhao et al. 2013). ΔH and ΔS can be calculated from the slope and intercept of the linear plots of ΔG versus T.

The Gibbs free energy varies at −12.02, −12.44, −13.19, −14.13 and −15.58 kJ·mol−1, while the temperature varies at 15, 20, 30, 40 and 50 °C respectively, indicating that the adsorption process is spontaneous. The higher the temperature, the bigger the ΔG absolute value and the easier the reaction (Basu & Suresh Kumar 2015). In general, ΔH < 40 kJ·mol−1 suggests absorption behaviour belongs to the physical function, and the value is 16.45 kJ·mol−1 in our study, indicating that the adsorption is physical. A positive value means the process is endothermic. ΔS is 98.40 J·mol−1, illustrating the addition of the randomness of the system.

Water quality analysis

The change of eluate quality before and after adsorption was evaluated by determining pH, chrominance, COD, and suspended solids (SS). After the eluate had been adsorbed for 480 min at AC dosage of 20 g·L−1, the pH value changed from 9 to 8. The chrominance decreased from 50 to 1°. The COD removal was 89.45%, reducing from 424.6 to 44.8 mg·L−1. The SS decreased from 75 to 3 mg·L−1. The total nitro compounds’ concentration decreased from 85.03 to 8.83 mg·L−1. The parameters of the eluate are in agreement with Chinese discharge standard GB 14470.1-2002.

The acute toxicity of the eluate before and after adsorption was also evaluated by luminescence bacteria test. Before and after adsorption, the dilution ratio at 50% luminescence inhibition ratio was 5.00 and 1.20 times, respectively, indicating that the acute toxicity of eluate after adsorption was reduced by 76% after adsorption.

Figure 4 shows the photographs of eluate sample before and after adsorption (50 °C, 480 min, 20 g·L−1 AC dosage). It can be clearly seen that the soil eluate turned from being dark-colored and opaque to colorless and transparent after adsorption.
Figure 4

Photographs of eluate sample before and after adsorption.

Figure 4

Photographs of eluate sample before and after adsorption.

CONCLUSIONS

AC can be used to reduce COD from soil eluate. When the AC dosage was 20 g·L−1, 89.45% COD could be removed after 480 min of adsorption at 50 °C. The adsorption of COD on AC can be described by the Redlich–Peterson isotherm. The adsorption was spontaneous and endothermic. The pseudo-second-order model can be used to describe the adsorption process. After adsorption, the acute toxicity of the eluate was reduced by 76%, and the water qualities were in agreement with Chinese discharge standard GB 14470.1-2002.

ACKNOWLEDGEMENTS

The authors are grateful to the reviewers for their comments, which significantly improved the quality of the manuscript.

REFERENCES

REFERENCES
Arshadi
M.
Faraji
A. R.
Amiri
M. J.
Mehravar
M.
Gil
A.
2015
Removal of methyl orange on modified ostrich bone waste – a novel organic–inorganic biocomposite
.
J. Colloid Interf. Sci.
446
,
11
23
.
Bertoni
F. A.
Medeot
A. C.
González
J. C.
Sala
L. F.
Bellú
S. E.
2015
Application of green seaweed biomass for MoVI sorption from contaminated waters. Kinetic, thermodynamic and continuous sorption studies
.
J. Colloid Interf. Sci.
446
,
122
132
.
Dadrasnia
A.
Agamuthu
P.
2013
Organic wastes to enhance phyto-treatment of diesel-contaminated soil
.
Waste Manage. Res.
31
,
1133
1139
.
Ghiloufi
I.
Al-Hobaib
A. S.
El Mir
L.
2015
Partial carbonized nanoporous resin for uptake of lead from aqueous solution
.
Water Sci. Technol.
72
(
6
),
974
982
.
Glorias-Garcia
F.
Arriaga-Merced
J. M.
Roa-Morales
G.
Varela-Guerrero
V.
Barrera-Díaz
C. E.
Bilyeu
B.
2014
Fast reduction of Cr(VI) from aqueous solutions using alumina
.
J. Ind. Eng. Chem.
20
,
2477
2483
.
Lamichhane
K. M.
Babcock
R. W.
Turnbull
S. J.
Schenck
S.
2012
Molasses enhanced phyto and bioremediation treatability study of explosives contaminated Hawaiian soils
.
J. Hazard. Mater.
243
,
334
339
.
Marinović
V.
Ristić
M.
Dostanić
M.
2005
Dynamic adsorption of trinitrotoluene on granular activated carbon
.
J. Hazard. Mater.
117
,
121
128
.
Schmauss
D.
Keppler
H.
2014
Adsorption of sulfur dioxide on volcanic ashes
.
Amer. Mineral.
99
,
1085
1094
.
Sklari
S. D.
Samaras
P.
Zouboulis
A. I.
Kungolos
A.
2012
Guest editorial
.
Desal. Water Treat.
39
,
190
191
.
Sun
F.
Gao
J.
Zhu
Y.
Qin
Y.
2011
Mechanism of SO2 adsorption and desorption on commercial activated coke
.
Korean J. Chem. Eng.
28
,
2218
2225
.
Tong
K.
Zhang
Y.
Fu
D.
Meng
X.
An
Q.
Chu
P. K.
2014
Removal of organic pollutants from super heavy oil wastewater by lignite activated coke
.
Colloids Surf. A: Physicochem. Eng. Aspects
447
,
120
130
.
Ungradova
I.
Simek
Z.
Vavrova
M.
Stoupalova
M.
Mravcova
L.
2013
Comparison of extraction techniques for the isolation of explosives and their degradation products from soil
.
Int. J. Environ. Anal. Chem.
93
,
984
998
.
Wang
L.
Li
C.
Yin
H.
Feng
L.
Yu
Y.
Hou
Y.
2009
Sulfur removal of FCC gasoline by selective adsorption over activated semi-coke
.
Chem. Technol. Fuels Oils
45
(
2
),
85
91
.
Wie Ner
A.
Remmler
M.
Kuschk
P.
Stottmeister
U.
1998
The treatment of a deposited lignite pyrolysis wastewater by adsorption using activated carbon and activated coke
.
Colloids Surf. A: Physicochem. Eng. Aspects
139
,
91
97
.
Wiśniewska
M.
Terpiłowski
K.
Chibowski
S.
Urban
T.
Zarko
V. I.
Gun'Ko
V. M.
2014
Investigation of stabilization and destabilization possibilities of water alumina suspension in polyelectrolyte presence
.
Int. J. Miner. Process.
132
,
34
42
.
Zagklis
D. P.
Vavouraki
A. I.
Kornaros
M. E.
Paraskeva
C. A.
2015
Purification of olive mill wastewater phenols through membrane filtration and resin adsorption/desorption
.
J. Hazard. Mater.
285
,
69
76
.
Zhang
M. H.
Zhao
Q. L.
Bai
X.
Ye
Z. F.
2010
Adsorption of organic pollutants from coking wastewater by activated coke
.
Colloids Surf. A: Physicochem. Eng. Aspects
362
,
140
146
.