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CHEMICAL ENGINEERING TRANSACTIONS

VOL. 55, 2016

A publication of

The Italian Association

of Chemical Engineering
Online at www.aidic.it/cet

Guest Editors: Tichun Wang, Hongyang Zhang, Lei Tian
Copyright © 2016, AIDIC Servizi S.r.l.,
ISBN 978-88-95608-46-4; ISSN 2283-9216

Ion-exchange Capability for Ammonium Removal using
Zeolite Modified by Potassium Permanganate

Hua Guo, Xiaoyan Zhang, Junliang Liu*
Agricultural University of Hebei Province, Baoding 071000,China.
hb-ljl@163.com

In this study, the ability to remove ammonium aqueous solutions of the natural zeolite particles produced in
Jinzhou, Liaoning and the zeolite particles modified by potassium permanganate were characterized by using
the static adsorption experiments. The results showed that ammonia adsorption capacity of natural zeolite is
preferable, and adsorption capacity of the zeolite particles modified by potassium permanganate is slightly
lower, but still maintain preferential adsorption. In addition, the Freundlich isotherm model proved a better fit in
the description of ammonia adsorption process than Langmuir model both for the natural zeolites and zeolite
particles after potassium permanganate treatment, with R2 ranging from 0.9328 to 0.9893. The adsorption
kinetic data of ammonium onto the zeolite particles modified by potassium permanganate could be well
described by a pseudo-second-order kinetics equation.

1. Introduction
The water environment quality is deteriorating, and ammonia nitrogen pollution has become the major
pollution factors of water plant and sewage treatment plants in China, with the increase in emissions of
pollutants. In water supply works, ammonia under the action of microorganisms can be converted to nitrite
nitrogen, will be combined with the production of carcinogenic nitrosamines with proteins, a great threat to
human health. It’s required to strengthen the traditional water purification process for ammonia removes in
micro-polluted water. In the drainage projects, many of the sewage treatment plant have to mention the
subject of facing the implementation of more stringent standards, because of the more serious water pollution.
It’s also need to enhance the removal of ammonia nitrogen. Effective method for removing ammonia nitrogen
is of great significance.
Conventional ammonia removal methods include physical chemistry, chemical, biological method, all of which
are difficult to remove the solubility of ammonia nitrogen effectively. Traditional biological process requires
strict control of temperature, pH and other factors, which makes it is of low efficiency with high operating costs.
Ion exchange adsorption denitrification by adsorbent such as zeolite is under the spotlight in recent years.
Zeolite has a special ion exchange properties, the exchange may occur in the environment of ammonium ion.
A large number of studies have shown that natural zeolite has good ammonia removal, while some research
about factors such as acid, alkali, salt, temperature, microwave affecting on zeolite adsorption effectiveness of
ammonia were carried out. But rare studies focus on the impact of potassium permanganate, a strong oxidant
commonly used in water treatment, on the ammonium adsorption performance by zeolite.
In this regards, the following objectives were in this study: (1) denitrification properties of natural zeolite; (2)
determination of the effect of potassium permanganate on ammonia removal by natural zeolite; (3)
identification of an empirical model that best describes this ion-exchange process. Water purification
experiments to provide a reference for the combination of process selection. The result provides a reference
for the selection of combination process about water purification.

2. Materials and methods
2.1 Materials and reagents
The natural zeolite used in this study, which was crushed to a particle size of 0.5~1.5mm originated from
Liaoning province, China. The ammonium ion exchange capacity was of 30~50g/kg. The zeolite had the

DOI: 10.3303/CET1655028

Please cite this article as: Guo H., Zhang X.Y., Liu J.L., 2016, Ion-exchange capability for ammonium removal using zeolite modified by
potassium permanganate, Chemical Engineering Transactions, 55, 163-168 DOI:10.3303/CET1655028

163

following main chemical composition(in%): SiO2=73, Al2O3=16. It was washed in deionized water to remove
impurities, and was heated at 105℃ for drying.
A certain amount of natural zeolite particles weighed was immersed in a certain concentration of potassium
permanganate solution for several hours, at solid-liquid ratio of 1:30, and then filtered, washed, dried, to obtain
the zeolite particles after potassium permanganate treatment.
Main chemical reagents: Potassium chloride, sodium tartrate, potassium iodide, mercury, sodium hydroxide
and hydrochloric acid, etc., all of which were of analytical grade.

2.2 Experimental equipment and test method
The main experimental equipment are: electric mixer, SHA-B oscillator, spectrophotometer, electronic balance.
The Nessler's reagent colorimetric method was used for the determination of ammonium.

2.3 Experimental method
This study was directed to provide emergency alternative technologies for excessive ammonia water, and in
the consideration for the reuse possibility of urban sewage treatment plant effluent.
Ammonia in micro-polluted surface water does not exceed 10 mg/L in most instances, and is generally not
more than 20 mg/L in secondary biological treatment effluent of municipal sewage treatment plant. Therefore,
experimental ammonia concentration in solution is 2~20mg/L. The initial experimental ammonia solution was
made of ammonium chloride solved in tap concentration of 1000mg/L, which was diluted to several
concentrations gradient for using.

2.3.1 The effect of potassium permanganate on the ammonia adsorption capacity of zeolite
In this procedure, the ammonia adsorption capacity of natural zeolite and modified zeolite was investigated
with the same dosing quantity in 10mg/L of ammonia solution. The removal procedure, using modified zeolite
as an example, was as follow. Take 10mg/L of ammonia solution per 50ml into five bottles of 250ml
Erlenmeyer flasks. Add 0.10g, 0.20g, 0.3g, 0.4g, 0.5g modified zeolite by potassium permanganate
respectively. Shake them in oscillator at 25±1℃ for 24h to achieve adsorption equilibrium. Then after filtering,
determine the ammonia nitrogen concentration of the solution. The ammonia exchanged on zeolite was
calculated using the equation:

( )0 e
e

V C C
q

m
−

(1)

Where qe is the ammonia exchanged on zeolite (mg/g), C0 and Ce are the initial and equilibrium concentration
of ammonia in solution (mg/L), respectively, m is the clinoptilolite mass, and V is the volume of the solution (L).

2.3.2 Isothermal absorption
Taking modified zeolite for example, the isothermal absorption procedure was as follow. Take 2mg/L, 4mg/L,
6mg/L, 8mg/L, 10mg/L, 15mg/L, 20mg/L of ammonia solution per 50ml into seven bottles of 250ml Erlenmeyer
flasks. Add 0.3g modified zeolite respectively. Shake them in oscillator at 25±1℃ for 24h to achieve
adsorption equilibrium. Then determine the ammonia nitrogen concentration of the solution after filtering.

2.3.3 Ammonia absorption kinetics
Take 10mg/L of ammonia nitrogen concentration solution in 1000ml, and divide into fifteen bottles of 1000ml
beakers, and put 2g modified zeolite respectively. Use rapid magnetic stirring to stir for 5min, 10min, 15min,
20min, 25min, 30min, 40min, 60min, 120min, 180min, 240min, 300min, 360min, 480min, and 560min. Take
supernatant fluid after filtering, and test the static absorption of ammonia nitrogen concentration in the solution
afterwards.

3. Results and discussion
3.1 Effect of potassium permanganate
Under different dosing quantities, natural zeolite and modified zeolite absorption of ammonia nitrogen is
shown in Figure 1.

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Figure 1: Adsorption of NH4
+ by natural zeolite and modified zeolite under different dosing quantities

The ammonia adsorption capacity of modified zeolite is lower than of natural zeolite under different dosing
quantities at the same initial NH4

+ concentrations. Ammonia nitrogen adsorption capacity of modified zeolite
decreased, which may be related to changes in the zeolite surface pore condition. Zeolites are a class of
hydrated aluminum silicate minerals with porous skeletal structure, which ion exchange properties closely
associated with cavities and channel conditions. This may related to pore clogging because of manganese
dioxide reduced from potassium permanganate when the adsorption of ammonia nitrogen produced from
simulated wastewater containing a small amount of reducing material, with modified zeolite particles.
The amounts of ammonium removed by natural and modified zeolite were determined. As the dosage of
zeolite increased, the removal efficiency of ammonia increased, but the amounts of ammonia adsorbed by per
gram of zeolite decreased, adsorbent efficiency declined. This was because before reaching the saturation
concentration, in the same amount and concentration of ammonia nitrogen solutions, the more of zeolite
particles dosage, the more units of zeolite absorption potentially decreased.

3.2 Absorption isotherms of zeolite particles
The ammonia adsorption isotherms of these two kinds of zeolite particles were shown in Figure 2. The
adsorption capacity of ammonia nitrogen of natural zeolite and modified zeolite were both increased with the
equilibrium concentration of ammonia nitrogen increased. This was because with increasing concentration,
adsorption impetus improved.

Figure 2: NH4
+ adsorption isotherms for natural and modified zeolite particles

To characterize the exchange equilibrium of NH4
+ ions by zeolite particles, the Freundlich and Langmuir

absorption models were used as follows:
Freundlich equation:

e e
nq KC= (2)

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Where qe is the NH4
+ exchanged on zeolite (mg/g), Ce is the initial and equilibrium concentrations of NH4

(mg/L), k and n are constants determined by regression of the experimental isotherm data.

Isotherm converts into:

e e
1

lg lg lgq K C
n

= +
(3)

Take lgqe as Y factor and lgCe as X factor to make a plane coordinate system. Then make regression of the

experimental isotherm data.

Langmuir equation:
0

e
e

e1
bq C

q
bC

=
+ (4)

Where 0q is the maximum adsorption amount on zeolite (mg/g), b is a constants determined by regression of
the experimental isotherm data. The rest parameters are the same as above.
Isotherm converts into：

e
e0 0

1 1C
C

q q bq
= +

(5)

Take e
e

C
q

as Y factor and
eC as X factor to make a plane coordinate system. Then make regression of the

experimental isotherm data.

Figure 3: Freundlich adsorption isotherm equation
of linear regression of natural zeolite

Figure 4: Langmuir adsorption isotherm equation
of linear regression of natural zeolite

Figure 5: Freundlich adsorption isotherm equation
of linear regression of modified zeolite

Figure 6: Langmuir adsorption isotherm equation
of linear regression of modified zeolite

Fitting parameters of isotherm equation are shown in Tab.1.

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Table 1: Parameters for ammonia nitrogen of natural and modified zeolites adsorption isotherm

Model Fruendlich Langmuir
K n R2 q0 (mg/g) b R2

natural zeolite 1.5678 1.4255 0.9893 5.8480 0.3919 0.8381
modified zeolite 0.3995 1.2577 0.9328 3.6846 0.1198 0.7091

Ion-exchange isotherms characterize the equilibrium relationship between the amounts of exchanged ion by
zeolite and its equilibrium concentration in the solution. In this study, the ion-change isotherm data obtained
for natural and modified zeolite were fitted to the Fruendlich and Langmuir models. The resulting exchange
isotherms as well as experimental data are shown in Figure 4 to Figure 6. The estimated model parameters,
including R2, for the different models are presented in Tab.1, which indicates that the experimental data of
NH4

+ exchange could be well fitted by both two models. It was also made clear that the Fruendlich model
provided a more consistent fit to the experimental data compared with the Langmuir model. The Fruendlich
model of natural zeolite which correlation coefficient R2 is 0.9893, provided a more consistent fit than modified
zeolite. Freundlich absorption isotherm parameter n in modified zeolite model is still greater than 1, which
means the modified zeolite absorption is also a preferential absorption of ammonia nitrogen. This suggests
that the modified zeolite for the algae and algae toxin maintains the effective of ammonia nitrogen removal.

3.3 Ammonia absorption kinetics
Kinetic models were employed to describe NH4

+ adsorption to the modified zeolite. Adsorption kinetics is the
study of adsorption speed, and it is closely related to contact time. Under different adsorption times, modified
zeolite absorption of ammonia nitrogen is shown in Figure 7.

Figure 7: Kinetic curve of NH4
+ adsorption for modified zeolite

The adsorption capacity of the zeolite to ammonia nitrogen changed significantly with the adsorption time, the
adsorption capacity increased rapidly in the first 40 minutes, then became slower, to 500 minutes reached the
basic balance, which is consistent with the equilibrium time of natural zeolite and modified zeolite in literature
(Ma, 2000; Zhang, 2010). It indicates that the adsorption rate of modified zeolite does not change obviously.
The experimental data were fitted by pseudo-first-order and pseudo-second-order equations to study the
adsorption kinetics.
Pseudo -first-order equation:

( )e t e 1ln = lnq q q K t− − (6)
Pseudo-second-order equation：

2
t 2 e e

1 1t
t

q K q q
= +

(7)
Where qe is the amount of ammonium absorbed at equilibrium, mg/g; qt is the amount of ammonium absorbed
at time t, mg/g; K1 is the pseudo-first-order adsorption rate constant, min

-1; K2 is the pseudo-second-order
adsorption rate constant, g/(mg⋅min). R2 for the different models were determined, and a higher R2 value was
considered to represent goodness of conformity between the measured and estimated NH4

+ absorbed data.
The fitting results are shown in Tab.2. The fitting coefficient of pseudo-second-order equation is higher than
that of pseudo-first-order equation, the former is better than the latter to fit the adsorption kinetic
characteristics of adsorbed NH4

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Table 2: Kinetic models for NH4
+ absorb from modified zeolite

(mg/g)
Pseudo -first-order equation Pseudo-second-order equation

1K (min
-1) e,calq (mg/g) R2 2K (g/(mg•min)) e,calq (mg/g) R2

3.63 0.11 3.5887 0.9136 0.0048 3.9620 0.9947

4. Conclusions
In this study, the NH4

+ ion-exchange capacity of zeolite modified by potassium permanganate decreased
slightly than natural zeolite, but it’s still a preferential adsorption. Ion exchange data was fitted to the
Fruendlich, Langmuir models, and the Fruendlich model provided a more consistent fit to the experimental
data. Kinetic models were employed to describe NH4

+ adsorption to the modified zeolite, and pseudo-second-
order equation is a suitable model.

Acknowledgments

This study was supported by Science and Technology Fund Project of Agricultural University of Hebei
Province (LG201630).

Reference

Davis M.E., Lobo R.F. 1992, Zeolite and molecular sieve synthesis, Chemistry of Materials, 4, 756-768.
Davis M.E., 1991, Zeolites and molecular sieves: not just ordinary catalysts, Industrial and Engineering

Chemistry Research, 30, 1675-1683.
Jiang X., Zhou X.N., Ding M.Y., Jin X.C., Liu K., 2008, Study on low concentration ammonia nitrogen removal

by natural and modified clinoptilolites, Research of Environmental Sciences, 21, 37-42.
Kithome, M., Paul, J.W., Lavkulich, L.M., Bomke, A.A., 1998, Kinetics of ammonium adsorption and desorption

by the natural zeolite clinoptilolite, Soil Sci. Soc. Am. J., 62, 622-629.
Ma J., Shi Y., Chen Z.L., Zhang J., Li G.B., 2000, Comparison of pre-oxidation and pre-chlorination for

permanganate algae removal, Water & Wastewater Engineering, 26, 25-27.
Malekian R., Abedi-Koupai J., Eslamian S.S., et al. 2011, Ion-exchange process for ammonium removal and

release using natural Iranian zeolite, Applied Clay Science, 51, 323-329.
Okoniewska E., Lach J., Kacprzak M., Neczaj E., 2007, The removal of manganese, iron and ammonium

nitrogen on impregnated activated carbon, Desalination, 206, 251-258.
Penn C.J., Warren J.G., Smith S., 2010, Maximizing Ammonium Nitrogen Removal from Solution Using

Different Zeolites. Journal of Environmental Quality. 39, 1478-1485.
Sun Z.M., Qu X.S., Wang G.F., Zheng S.L., Frost R.L., 2015, Removal characteristics of ammonium nitrogen

from wastewater by modified Ca-bentonites. Applied Clay Science, 107, 46-51.
Tang D.Y., Zheng Z., Guo Z.B., Lin Z.R., Dong C., Wang X.L., 2011, Modification of Low Concentration

Ammonia nitrogen wastewater by zeolite adsorption and desorption study. Journal of Environmental
Engineering, 02, 293-296.

Zhang X.Y., Wu Z.W., Wang Z.W., Zhou Q., Yang D.H., 2010, Adsorption characteristics of ammonium ions
by natural clinoptilolite powder. China Environmental Science, 30, 609-614.

Zheng H., Han L.J., Ma H.W., Zhang H.M., Liu D.H., Liang S.P., 2008, Adsorption characteristics of
ammonium ion by zeolite 13X, J. Hazard. Mater., 158, 577-584.

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