Photocatalytic Processes for the Removal of Dye - Green Chemistry for Dyes Removal from Wastewater - page 161

Table 5.9 Comparison of adsorption capacities of bamboo-based materials.

Modification Surface

Area
( m 2 g -1 )

Dye Type pH Adsorption

Capacity
( mg.g -1 )

Ref.

H 3 PO 4 - Carbonization
- Activation

2517 Acid Blue 25 … 785.3 [73]

Acid Yellow 117 111.2

Reactive Black 441.7 [76]

Carbonization 327 Acid Blue 25 … 16.9 [72]

Acid Yellow 117 35.3

Methylene Blue 319.2

H 2 SO 4 - Carbonization 518.6 Methylene Blue … 113.0 [79]

H 3 PO 4 - Carbonization 747 Disperse Red 167 1 3.0 [78]

effect. The adsorption capacities of various bamboo-based adsorbents have
been tabulated in Table 5.9.

5.2.5 Date Pits

Date pits are the seeds of the fruit of the date palm tree. Pit, which consti-
tutes around 10 wt% of the whole date, is considered a byproduct of the date
fruit processing industry. Considering the large production amount of date
pits, which was equivalent to 750 thousand tons in 2011, a more systematic
approach is required to utilize this large volume of waste. Currently, the
major fraction of this waste is used as feed for various livestock or as a soil
organic additive [80]. However, date pits can be considered as a valuable
source of functional carbon for various applications.
The adsorption of methylene blue by unmodified date pits has been
studied by two research groups. Belala et al. [81] characterized the surface
functional groups of date pits and found that this waste material consists of
various functional groups, such as hydroxyl, carboxylic and carbonyl, and
may be a potential adsorbent for the removal of dyes from wastewater.
They found an adsorption capacity of 43.5 mg.g -1 for date pit as adsorbent
(particle size of 0.5-1 mm) and methylene blue as adsorbate. In order to
measure the adsorption capacity, the pH of the dye solution and the adsor-
bent dosage were fixed at 6.3 and 10 g.L -1 , respectively. Al-Ghouti et al. [82]
succeeded in enhancing the adsorption capacity of unmodified waste date
pit by altering the experimental conditions. They found that as the adsor-
bent particle size increased, the adsorption capacity of the date pits for
methylene blue decreased. Also, it has already been mentioned that as the