TITLE:
Simultaneous Removal of Chromium and Lead from Water by Sorption on Iraqi Montmorillonite
AUTHORS:
Mahmood M. Barbooti
KEYWORDS:
Lead, Chromium, Adsorption, Water Heavy Metals Removal, Montmorillonite
JOURNAL NAME:
Journal of Environmental Protection,
Vol.6 No.3,
March
19,
2015
ABSTRACT: A
certified clay mineral from Iraq, montmorillonite, is used for the adsorption
of chromium and lead ions from water. Experimental design is utilized here to
plan for the practical work and analysis of the results. Batch wise experiments
are carried out to equilibrate Cr and Pb solutions (250 mg/L) individually and
simultaneously with montmorillonite (5 - 20 g/L) at various pH ranges (2 - 7.5)
for 10 - 60 minutes. The results indicate perfect fit with the model used.
Chromium adsorption is sensitive to pH changes being high at neutral medium.
Lead is almost independent of the pH of the solution. In nearly neutral medium,
the sorption capacity of Cr is 21.4 and that of lead is 24.3 mg/g. The optimum
conditions for >96% Cr removal are 12 - 15 g clay/L, 40 - 50 minutes and a
pH of 5 - 7. For lead, almost 100% removal can be attained using 12 - 15 g
clay/L, 40 - 50 min. at a pH of 4 - 6. The effects of various operating
parameters are discussed. Simultaneously, the lead shows a greater tendency to
sorption than chromium and a ratio of 5:4 can best represent the occupation of
the active surface of the clay. The most favorable conditions for simultaneous
removing of Cr, 86% and Pb, 100% may be 12.5 g/L clay content and a pH of 7.5
within 30 minutes. The kinetic study of the results indicates the adsorption
follow pseudo-second order kinetics in which chemical interaction is also
involved. The kinetic study confirms the dependence of chromium adsorption on
the pH of the medium being favoured at high pH values.