48
A. Geethakarthi
was obtained at 400 °C [33]. The surface area, pore volume and pore size distribution
of carbon samples activated at three different temperatures 700, 800 and 900 °C have
been carried out using nitrogen adsorption isotherms at 77 K. The production yield
was observed to decrease with increase in activation temperature. The average pore
size distribution was dependent mainly on the concentration of chemical impregnation and heat treatment temperature. The average pore diameter of 38.8 A° was
obtained at activation temperature 700 °C and later on increased with activation
temperature up to 800 °C but reversed at further higher temperature. The decrease in
the pore diameter was due to the suppression of the pore widening of stable carbon
structures formed during pre-carbonization process and coalescence of pores in the
carbon matrices.
3.2.4 Pore Development and Specific Surface Area
Wang et al. [105] carried adsorption of a basic dye, methylene blue, from aqueous
solutions onto three activated carbons: one derived from coconut shell and the other
two coal-based carbons. The physical and surface chemical properties of the activated carbons are characterized using BET-N 2 adsorption, X-ray photoelectron spectroscopy (XPS) and mass titration. It was found that acid treatment had little effect on
carbon textural characteristics but significantly changed the surface chemical properties, resulting in an adverse effect on dye adsorption. The physical properties of
activated carbon, such as surface area and pore volume, have little effect on dye
adsorption, while the pore size distribution and the surface chemical characteristics
play an important role in dye adsorption. The pH value of the solution also influences
the adsorption capacity significantly. For methylene blue, a higher pH of solution
favoured the adsorption capacity. The kinetic adsorption of methylene blue on all
carbons followed a pseudo-second-order equation.
4 Development of Tannery Sludge-Activated Carbon
4.1 Characterization of Tannery Sludge
The preliminary tannery sludge collected from common effluent treatment plant
throughout different seasons of the year was dried in an oven at 105 °C ± 2 °C
until the mass of the sludge remained constant. The dried sludge was crushed and
sieved in IS sieves. The sludge retained in the sieve sizes 300 µm and 600 µm was
arbitrarily chosen for experimentation. The proximate and ultimate analysis of the
raw sludge was conducted in the laboratory as per the ASTM standards (D3172-07
and 3176-89). Table 13 shows the proximate and ultimate analysis of the raw tannery
sludge in dry basis.
A. Geethakarthi
was obtained at 400 °C [33]. The surface area, pore volume and pore size distribution
of carbon samples activated at three different temperatures 700, 800 and 900 °C have
been carried out using nitrogen adsorption isotherms at 77 K. The production yield
was observed to decrease with increase in activation temperature. The average pore
size distribution was dependent mainly on the concentration of chemical impregnation and heat treatment temperature. The average pore diameter of 38.8 A° was
obtained at activation temperature 700 °C and later on increased with activation
temperature up to 800 °C but reversed at further higher temperature. The decrease in
the pore diameter was due to the suppression of the pore widening of stable carbon
structures formed during pre-carbonization process and coalescence of pores in the
carbon matrices.
3.2.4 Pore Development and Specific Surface Area
Wang et al. [105] carried adsorption of a basic dye, methylene blue, from aqueous
solutions onto three activated carbons: one derived from coconut shell and the other
two coal-based carbons. The physical and surface chemical properties of the activated carbons are characterized using BET-N 2 adsorption, X-ray photoelectron spectroscopy (XPS) and mass titration. It was found that acid treatment had little effect on
carbon textural characteristics but significantly changed the surface chemical properties, resulting in an adverse effect on dye adsorption. The physical properties of
activated carbon, such as surface area and pore volume, have little effect on dye
adsorption, while the pore size distribution and the surface chemical characteristics
play an important role in dye adsorption. The pH value of the solution also influences
the adsorption capacity significantly. For methylene blue, a higher pH of solution
favoured the adsorption capacity. The kinetic adsorption of methylene blue on all
carbons followed a pseudo-second-order equation.
4 Development of Tannery Sludge-Activated Carbon
4.1 Characterization of Tannery Sludge
The preliminary tannery sludge collected from common effluent treatment plant
throughout different seasons of the year was dried in an oven at 105 °C ± 2 °C
until the mass of the sludge remained constant. The dried sludge was crushed and
sieved in IS sieves. The sludge retained in the sieve sizes 300 µm and 600 µm was
arbitrarily chosen for experimentation. The proximate and ultimate analysis of the
raw sludge was conducted in the laboratory as per the ASTM standards (D3172-07
and 3176-89). Table 13 shows the proximate and ultimate analysis of the raw tannery
sludge in dry basis.