Photocatalytic Processes for the Removal of Dye - Green Chemistry for Dyes Removal from Wastewater - page 170

Figure 5.15 Effect of pH on methylene blue adsorption from solution onto palm kernel
fiber [96].

Table 5.15 Relationship between methylene blue amount adsorbed (q e ) and
changes in hydrogen ion concentration [96].

Initial Dye
Concentration
( g.L -1 )

Initial
Solution pH

Final
Solution pH

ΔpH
( mol.L -1 )

q e ( mg.g -1 ),
MB

500 7.01 5.02 671.78

9.45 10-3

400 7.01 5.14 546.27

7.15 10-3

300 7.01 5.31 4.80 10-3 418.57

200 7.01 5.56 2.66 10-3 283.77

dye concentration. The adsorption of an anionic dye by palm kernel fiber
has also been reported by Ofomaja and Ho [97]. The maximum mono-
layer adsorption capacity of the fiber for this anionic dye (38.6 mg.g -1 ) was
much lower than that observed for methylene blue as the cationic dye. As
the mass of the adsorbent was increased, the number of the unsaturated
adsorption sites was believed to increase, resulting in the reduction in the
adsorbent capacity, as seen in Figure 5.16. They also postulated that this
reduction in capacity could be due to the aggregation of the particles and
a decrease in the surface area of the adsorbent. Furthermore, they showed
that temperature increase had a reverse effect on the uptake capacity of
the fiber, which was ascribed to the weakening of the interaction between