Abstract:
Adsorption of fluoride (F) on the raw and modified local cement clay was investigated by
batch method. Modified clays were prepared through calcination, using the Na and Mg
saturated (C-Na, C-Mg) clay at 500 and 850°C (C-500, C-850) and calcination of Mg
incorporated clay at 500°C (C-Mg-500). The equilibration time was attained in 5 h.
Adsorption of F increased with increasing adsorbent dose. Decrease of the initial F
concentration resulted in an increasing amount of F adsorption. F adsorption isotherms
fitted well with both Freundlich and Langmuir models. Low F adsorption was obtained
on the raw, incorporated or calcined clays. However maximum F adsorption was found
for C-Mg-500, with Kf and Q0 values of 0.27 and 1.69, respectively. This work indicated
that the calcination of incorporated clay with Mg increased the F adsorption
significantly, due to increased and stabilized positive sites.
