Effect of pH on the heavy metal-clay mineral interaction

Conference · Wed Dec 31 04:00:00 EST 1997

OSTI ID:576620

Altyn, O; Oezbelge, H O; Dogu, T; Oezbelge, T A ^[1]

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1. Middle East Technical Univ., Ankara (Turkey)

Adsorption and ion exchange of Pb and Cd on the surface of kaolinite and montmorillonite were studied with a strong emphasis on the pH values of solutions containing heavy metal ions. The pH range studied was 2.5 - 9. For kaolinite at a clay/solution ratio of 1/10 (w/w), Pb removal changes from 20 to 30% for an initial Pb concentration of 1640 ppm, and Cd removal changes from 10 to 20% for an initial Cd concentration of 1809 ppm. Due to its high exchange capacity, montmorillonite can remove more heavy metal than kaolinite. Removal rates for montmorillonite can reach up to 90% for both Pb and Cd. In the pH range of 3-6, there is a plateau for the removal rates. At pH values higher than 6, removal seems to increase artificially due to the precipitation of heavy metals. Under similar conditions for both clays, the rate of removal of Pb is always higher than that of Cd. As the pH value decreases for montmorillonite, there is a strong tendency for decreased surface area and swelling, as indicated by BET surface area measurements, adsorbed layer thickness and pore size distribution data. In the range of pH values studied, X-ray diffraction analysis showed the appearance of a characteristic (001) peak for montmorillonite, indicating that the crystalline structure of the clay was intact during the experiments.

• Research Organization: USDOE, Washington, DC (United States)
• OSTI ID: 576620
• Report Number(s): CONF-970208--Proc.; ON: DE98001967
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
54 ENVIRONMENTAL SCIENCES
CADMIUM
CLAYS
CONTAINMENT
ION EXCHANGE
KAOLINITE
LEAD
METALS
MONTMORILLONITE
PH VALUE
POLLUTION CONTROL
SORPTIVE PROPERTIES
SURFACE AREA
SWELLING
THICKNESS