Production and characterization of activated carbon from palm shell by using microwave heating method / Roozbeh Hoseinzadeh Hesas
Activated carbon (AC) demonstrated significant adsorption of pollutants in gas and liquid phases due to its high micropore volume, large specific surface area, favorable pore size distribution, thermal stability, capability for rapid adsorption and low acid/base reactivity. Palm shell (agricultur...
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| Format: | Thesis |
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2014
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| Online Access: | http://studentsrepo.um.edu.my/7693/ http://studentsrepo.um.edu.my/7693/4/PhD_Thesis%252C_KHA_100113.pdf |
| Summary: | Activated carbon (AC) demonstrated significant adsorption of pollutants in gas and
liquid phases due to its high micropore volume, large specific surface area, favorable
pore size distribution, thermal stability, capability for rapid adsorption and low
acid/base reactivity. Palm shell (agricultural waste) is used as a raw material in this
study due to its inherent characteristics such as high carbon content, low ash, and almost
negligible sulfur content.
In the present work, microwave heating was applied instead of conventional heating
techniques as a heat source of AC preparation. This method reveals higher sintering
temperatures and shorter processing times which result in higher efficiency and more
energy saving. The effects of significant parameters such as microwave radiation time
and power level, different types of chemical and physical agents, chemical impregnation
ratio and particle size in production of ACs were investigated. Accordingly, the effects
of these variables on the structural and surface chemical properties of the ACs were
explored.
Several methods of characterization were utilized to examine the prepared ACs
including nitrogen adsorption-desorption at -196 °C, proximate and ultimate analysis,
Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy
(SEM). Moreover, CO2 adsorption at different temperatures and methylene blue (MB)
adsorption were carried out. The response surface methodology was used to optimize
the preparation conditions of palm shell based ACs with microwave heating methods by
zinc chloride chemical activation. The influence of variances on MB
adsorption capacity and AC yield was investigated.
Based on the analysis of variance, microwave power and microwave radiation time
were identified as the most influential factors for AC yield and MB adsorption capacity,
respectively.
In this study, effects of different heating methods of microwave and conventional on
textural and surface chemical properties of the ACs were compared. The ZnCl2
chemical activation at different weight ratio of ZnCl2 to precursors were applied. The
results indicated that for both the microwave and conventionally prepared samples, the
BET surface area (SBET) is enhanced to a maximum value at optimum impregnation
ratio and then decreased with further increases in the agent ratio. The total pore volume
in the microwave samples increased continuously with increasing zinc chloride, while
in the conventional samples, the total pore volume increased up to the optimum
impregnation ratio and then decreased.
Oil palm shell based ACs were also prepared using KOH as an activation agent under
the microwave irradiation. The effects of the activation time, chemical impregnation
ratio and microwave power on the AC properties were investigated. To study the effects
of the nature of the physical agent, the impregnated precursors were activated under a
flow of carbon dioxide or nitrogen. The results demonstrates that the CO2 activation
requires a shorter activation time to reach the maximum SBET than the activation under
N2 since CO2 reacts with the carbon to develop the porosity. |
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