that the removal efficiency of adsorbents generally improved with increasing amount of
JNZ. This is expected because the higher dose of adsorbent in the solution, the greater
availability of exchangeable sites for the ions, i.e. more active sites are available for binding
of Fe3+ ions. Moreover, our recent studies using olive cake, natural quartz and natural
bentonite and tripoli [19-22] are qualitatively in a good agreement with each other and with
those found in the literatures [