چكيده لاتين :
The large amounts of the dyestuffs used in industries are toxic and
whenever are released into wastewaters can lead to environmental and health problems. One
of the most commonly used dyes in industries is Rhodamine B. It is widely used in printing,
leather, paper and textile industries and is harmful to both human beings and animals. Thus,
it is necessary to treat contaminated wastewater prior to discharging into water streams.
Among all conventional physical, chemical and biological methods, adsorption is a very
simple and effective method for removing dyes from wastewater even at low concentration.
Activated carbons (ACs) are among the most widely used efficient absorbents which can
remove these pollutants from aqueous phase and cause to prevent damages to the
environments. Specific surface area, pore volume, pore-size distribution and the nature of
surface are the main factors that influence AC performance. The surface modifications result
in the change in the surface reactivity, chemical, physical and structural properties. Based on
the type and chemical nature of the dyes, the surface of AC can be modified to enhance the
affinity toward the desired contaminants. Depending on the application, there are different
methods to modify AC, which can be classified as chemical, physical and biological
modification. Plasma treatment is an environmental friendly method, which can introduce
functional groups onto material surfaces without changing the bulk properties of the
substrate.
Methods: Modification of AC surfaces by means of plasma is a well-known method to
enhance its adsorption capacity. Hence, in this research AC was prepared using chemical
activation method from sound (SBAC) and rotted (RBAC) beech wood (Fagus orientalis) as
precursors. The impregnation was carried out by ZnCl2 with the ratio of 75 percent to
precursor mass and carbonization was performed at activating temperature of 400 ºC. The
potential of AC treatment by plasma was then examined to introduce oxygen-containing
groups onto AC surfaces and to enhance its efficiency to remove a basic dye, Rhodamine B,
from aqueous solution. After carbonization step, surface modification of activated carbons
was then conducted by dielectric barrier discharge (DBD) plasma in a parallel- plate reactor
under different conditions of voltages (2, 4, and 6 kv) and treatment time(20, 30, and 40
min). Specific surface area, average pore diameter and pore volume of ACs were
characterized from the results obtained by N2 adsorption at 77 K. In order to evaluate
structure changes in plasma modified-ACs the FT-IR spectroscopy and scanning electron
microscopy (SEM) were also used. Then, the capability of modified-ACs in removing of
Rhodamine B was assessed and was compared with untreated ones. The batch adsorption
tests have been carried out in the laboratory by contacting a 100 ml of dye aqueous solution
with 0.15g of AC. The adsorption capacity of Rhodamine B in aqueous solution was
measured using UV-Vis spectrometer at 555 nm.
Results: The results indicated that the iodine number of ACs prepared from sound wood
(SBAC) was less than RBAC that indicate more development of micropores in RBAC.
Activated carbons from sound wood exhibited more specific surface area (1538 m2g
-1
), total
pore volume (0.649 cm3g
-1
) and less average diameter (1.69 nm) in comparison with RBAC.
As it was expected, chemical activation of precursors by ZnCl2 could successfully develop
micropores through dehydrating reactions. It was found that adsorption capacity of untreated
ACs prepared from rotted beech wood was higher in comparison with sound wood ACs. This
may be attributed to differences in chemical compositions of precursors, which results inThe large amounts of the dyestuffs used in industries are toxic and
whenever are released into wastewaters can lead to environmental and health problems. One
of the most commonly used dyes in industries is Rhodamine B. It is widely used in printing,
leather, paper and textile industries and is harmful to both human beings and animals. Thus,
it is necessary to treat contaminated wastewater prior to discharging into water streams.
Among all conventional physical, chemical and biological methods, adsorption is a very
simple and effective method for removing dyes from wastewater even at low concentration.
Activated carbons (ACs) are among the most widely used efficient absorbents which can
remove these pollutants from aqueous phase and cause to prevent damages to the
environments. Specific surface area, pore volume, pore-size distribution and the nature of
surface are the main factors that influence AC performance. The surface modifications result
in the change in the surface reactivity, chemical, physical and structural properties. Based on
the type and chemical nature of the dyes, the surface of AC can be modified to enhance the
affinity toward the desired contaminants. Depending on the application, there are different
methods to modify AC, which can be classified as chemical, physical and biological
modification. Plasma treatment is an environmental friendly method, which can introduce
functional groups onto material surfaces without changing the bulk properties of the
substrate.
Methods: Modification of AC surfaces by means of plasma is a well-known method to
enhance its adsorption capacity. Hence, in this research AC was prepared using chemical
activation method from sound (SBAC) and rotted (RBAC) beech wood (Fagus orientalis) as
precursors. The impregnation was carried out by ZnCl2 with the ratio of 75 percent to
precursor mass and carbonization was performed at activating temperature of 400 ºC. The
potential of AC treatment by plasma was then examined to introduce oxygen-containing
groups onto AC surfaces and to enhance its efficiency to remove a basic dye, Rhodamine B,
from aqueous solution. After carbonization step, surface modification of activated carbons
was then conducted by dielectric barrier discharge (DBD) plasma in a parallel- plate reactor
under different conditions of voltages (2, 4, and 6 kv) and treatment time(20, 30, and 40
min). Specific surface area, average pore diameter and pore volume of ACs were
characterized from the results obtained by N2 adsorption at 77 K. In order to evaluate
structure changes in plasma modified-ACs the FT-IR spectroscopy and scanning electron
microscopy (SEM) were also used. Then, the capability of modified-ACs in removing of
Rhodamine B was assessed and was compared with untreated ones. The batch adsorption
tests have been carried out in the laboratory by contacting a 100 ml of dye aqueous solution
with 0.15g of AC. The adsorption capacity of Rhodamine B in aqueous solution was
measured using UV-Vis spectrometer at 555 nm.
Results: The results indicated that the iodine number of ACs prepared from sound wood
(SBAC) was less than RBAC that indicate more development of micropores in RBAC.
Activated carbons from sound wood exhibited more specific surface area (1538 m2g
-1 ), total pore volume (0.649 cm3g
-1 ) and less average diameter (1.69 nm) in comparison with RBAC.
As it was expected, chemical activation of precursors by ZnCl2 could successfully develop
micropores through dehydrating reactions. It was found that adsorption capacity of untreated
ACs prepared from rotted beech wood was higher in comparison with sound wood ACs. This
may be attributed to differences in chemical compositions of precursors, which results in
