Removal of BrO3 from drinking water samples using newly developed agricultural
waste based activated carbon and its determination by ultra-performance liquid
chromatography-mass spectrometry
Mu. Naushad*,1, Mohammad R. Khan1, Zeid A. ALOthman1, Ibrahim AlSohaimi1, Francisco RodriguezReinoso2, Turki M. Turki1, Rahmat Ali1
1
Department of Chemistry, College of Science, Bld#5, King Saud University, Riyadh, Saudi Arabia
2
Laboratorio de Materiales Avanzados, Departamento de Química Inorganica, Universidad de Alicante,
Apartado 99 E-03080, Spain
*Corresponding author address: Tel. 0096614674198; Email: shad81@rediffmail.com
Table of content
Index
Captions
Text S1
Text for adsorption kinetics, isotherm and thermodynamic studies.
Fig. S1
N2 adsorption/desorption isotherms
Fig. S2
Effect of various operating parameters on the adsorption of BrO3 by DAC (a)
contact time, (b) pHi, (c) initial concentration of BrO3 and (d) temperature.
Fig. S3
Regeneration studies for DAC (equilibration time 25 min; adsorbent dosage =
50 mg; volume 50 mL; initial concentration of BrO3 2 mg L-1; agitation speed
150 rpm).
Fig. S4
Plots of kinetic and isotherm models for the adsorption of BrO3 by DAC (a)
pseudo-first-order, (b) pseudo-second-order; (c) Langmuir isotherm and (d)
Freundlich isotherm models (adsorbent dosage = 100 mg; volume 200 mL; pH
4; agitation speed 150 rpm and temperature 25 C).
Fig. S5
Van’t Hoff plot for the adsorption of BrO3 onto DAC (equilibration time 25
min; adsorbent dosage = 50 mg; volume 50 mL; initial concentration of BrO3
was 2 mg L-1; agitation speed 150 rpm).
Text S1.
Adsorption kinetics
The pseudo-first-order and pseudo-second-order equations
are represented as
follows:
Pseudo-first-order:
log qe  qt   log qe 
k1t
2.303
(1)
Pseudo-second-order:
(2)
t
1
t


2
qt k 2 q e
qe
where, qt and qe are the amounts of BrO3 adsorbed at time t, and at
equilibrium, respectively, k1(1/min) and k2 (g/mg.min) are the rate constants for
pseudo-first-order and pseudo-second-order, respectively.
Isotherm studies
Adsorption isotherms describe the adsorption equilibrium between the
adsorbate
and
adsorbent.
The
adsorption
isotherm
data
are
important
for
understanding and practical design of adsorption system. The Langmuir model
is mainly applied to designate the sorption processes where no interaction
between sorbate species takes place on sites, having the same sorption energies
free of surface coverage. Whereas, Freundlich isothermal model is used for
multilayer adsorption analysis in heterogeneous systems where adsorption heat
distribution is non-uniform and adsorption is the summation result of all the
active sites.
The Langmuir isotherm model can be represented as:
1
1
1


qe
qm bqmCe
(3)
Where, Ce is the equilibrium concentration of BrO3 (mg L–1); qm (mg g-1) and b
(L mg-1) are the Langmuir constants associated to maximum monolayer adsorption
capacity and energy of adsorption, respectively.
A dimensionless equilibrium parameter (RL) has been defined to evaluate the
validity of the Langmuir-type adsorption process:
RL 
1
1  bCo
(4)
Where, Co is the lowest initial concentration of BrO3ion. The RL value indicates whether
the adsorption is unfavorable (RL> 1), linear (RL = 1), favorable (0 < RL< 1) or
irreversible (RL = 0).
Freundlich isotherm is expressed by the following equation:
log qe  log K f 
1
log C e
n
(5)
Where, Kf (mg/g(L/mg)1/n) and n (dimensionless) are the Freundlich isotherm
constants which are indicators of adsorption capacity and adsorption intensity,
respectively. The value of n is a sign of the favorability of adsorption. If the values of
n1, it represent the favorable nature of adsorption.
Thermodynamic studies
The values of ΔG° were calculated as:
G 0  H 0  TS 0
(6)
where, R is a universal gas constant (8.314 J mol-1. K-1), T (K) is an absolute temperature.
The values of ∆Ho and ∆So were calculated from the slopes and
intercepts of the plots of lnKc versus 1/T (Figure S5) by using the following
equation.
H 0 S 0
ln K c  

RT
R
(7)
Where Kc (L mg-1) is equilibrium constant defined as:
Kc 
C Ae
Ce
(8)
where, CAe (mg L-1) and Ce (mg L-1) are the equilibrium concentrations of adsorbate on
solid and in solution phase, respectively.
Fig S1.
Fig. S2.
100
% Adsorption/Desorption
% Adsorption
% Recovery
95
90
85
80
75
0
1
2
3
4
Number of cycles
Fig. S3.
5
6
3.5
a
1.4
2 ppm
4 ppm
2.5
4 ppm
6 ppm
2
b
6 ppm
t/qt
1
log (qe-qt)
3
2 ppm
1.2
0.8
0.6
1.5
0.4
1
0.2
0.5
0
0
0
5
10
15
20
0
5
10
15
Time (min)
25
30
Time (min)
0.7
0.7
c
0.6
d
0.6
0.5
1/qe
0.5
1/qe
20
0.4
0.3
0.3
25 °C
45 °C
0.2
45 °C
55 °C
0.1
25 °C
0.2
0.1
0.4
55 °C
0
0
0
5
10
15
1/Ce
Fig. S4.
20
25
0
5
10
15
1/Ce
20
25
3
ln Kc
2.5
2
2 ppm
1.5
4 ppm
6 ppm
1
0.5
0.003
0.0031
0.0032
1/T
Fig. S5.
0.0033
0.0034