Cr(VI) adsorption from aqueous solutions on
the microfungus
Ustilago maydis
modified with formaldehyde
(
UmF) was studied as a function of the initial pH,
contact time, chromium concentration and temperature.
The pH results showed that Cr(VI) adsorption on
UmF is
higher at acidic pH values and decreases as the pH
increases to alkaline values. Cr(VI) adsorption also
depends on the chromium concentration and temperature.
The Cr(VI) adsorption data as a function of concentration
obey the Freundlich and Langmuir isotherms at pH values
of 2 and 6.5. The maximum sorption capacity of
UmF for
Cr(VI) at pH 2 was 2.53 × 10
-3 mol/g (131.55 mg/g),
which is significantly higher than that at pH 6.5
(0.33 9 10
-3 mol/g or 17.60 mg/g). The negative value of
ΔH° and the positive values of ΔG° indicate that the
chromium adsorption process is exothermic and nonspontaneous.
The pHpzc value was 5 for UmF and it played
a role in the Cr(VI) adsorption.
