چكيده لاتين :
The possibility of using volcanic ash soils (VAS) or Andisols as a low-eost and natural adsorbent
is investigated in this study for the removal of Cr (VI) from synthetic wastewater. Andisols can be used as adsorbent
because they are characterized by the presence of non-crystalline secondary minerals such as allophane and imogolite
that show variable charge characteristics and have the ability to retain cations and anions. The adsorption of Cr on
to two VAS from Mt. Isarog and Mandalagan (B-Horizon), Philippines, was carried out at ambient temperature
using batch adsorption studies. The effects of different parameters such as amount of adsorbent, contact time, initial
Cr concentration and pH of the solution were investigated. The results showed that the VAS from Isarog is more
effective in the removal of Cr than in Mandalagan. The maximum removal efficiency of the Isarog soil for a Cr
concentration of 10 mg/L reached 89% with a dose of 20 giL at a moderately acidic pH of3. The Mandalagan soil on
the other hand could remove only 65% at the same pH conditions and parameters. The difference in the removal of
the two soils may be attributed to their physico-chemical properties in which the Isarog soil has higher clay content,
porosity and lower bulk density. Isarog soil has fine particles with higher surface area and more active noncrystalline
minerals and thus has higher removal efficiency than Mandalagan soil. Based on the results, the use of
VAS from Isarog appears to be economical and an alternative to commercially available adsorbents for the removal
of Cr from contaminated wastewater.
