Uptake of crystal violet from water by modified Khalas dates residues
Removal of crystal violet dye (CV) from polluted water was studied by adsorption techniques.
Adsorbents were prepared from waste residue available from syrup date industrial residue (SDIR).
The SDIR from Khalas dates residue (KR) were modified by chemical treatment with formaldehyde
to give KF, and with calcium chloride to give KC adsorbents. The characteristic of adsorbents was
determined by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy and
thermogravimetric analysis. The optimum conditions were determined in batch experiments for the
best uptake of crystal violet CV by adsorbents. The results showed that the adsorption data was well
described by both Langmuir and Freundlich more than Temkin and followed the pseudo-secondorder
equation. Langmuir maximum capacity q (mg g–1) for KF was found 144.49 mg g–1, while it
was 108.25 and 89.31 mg g–1 for KC and KR respectively. Thermodynamic and activated thermodynamic
parameters were determined for the uptake of crystal violet and this study shows that the
adsorption process is exothermic and spontaneous. The column breakthrough curve capacity was
determined for the uptake of crystal violet by modified SDIR. It was found that Thomas and Yoon-
Nelson column kinetics models describe best the experimental kinetic data, and the obtained capacity
was 136.58 mg g–1 for KF and 89.11 mg g–1 for KC. The results prove that the SDIR (raw and treated)
could be used as an effective and economical adsorbent for dye removal from wastewater.