Center for Environment and Energy Research and Studies (CEERS)
Abstract
The adsorption and desorption behaviors of 17α-Ethinylestradiol on
various sludge derived from different treatment units of a sewage
treatment plant were investigated using batch equilibration
experiments. The results showed that adsorption process could be well
described by pseudo-second-order kinetic model and fast adsorption
played a main role. Adsorption ability varied as the order of aerobic
sludge ≈ anoxic sludge ≈ primary sludge> sludge cake>
anaerobic sludge. Adsorption/desorption isotherms were well fitted by
the modified Freundlich model, and K'f values increased with the
organic matter content. Thermodynamic analysis indicated that
17α-Ethinylestradiol adsorption/desorption was exothermic and
conducted spontaneously. After heat-treatment for removing the organic
carbon, K'f values reduced by more than 78 %, but organic carbon
normalized adsorption constant was 7.76-29.51 mg/g. The
17α-Ethinylestradiol adsorption capacity was found to decrease
from 0.95-1.39 mg/g to 0.44-0.49 mg/g with sludge concentration
increasing from 500 to 4000 mg/L, keep almost unchanged at pH 3-10 and
sharply decrease when pH >10. The adsorption capacity was also found
being fluctuated in the range of 2.0-3.0 mg/g when Ca2+
concentration< 0.5 mol/L and increased rapidly above 0.5 mol/L.
Addition of methanol and acetonitrile could improve 17-Ethinylestradiol
desorption effect, which increased with the organic solvents content,
and desorption degree of acetonitrile was higher than methanol