In this work, a low-cost lignocellulosic adsorbent with high biosorption capacity is proposed, suitable for
the efficient removal of hexavalent chromium from water
and wastewater media. The adsorbent was produced by
autohydrolyzing Scots Pine (
Pinus Sylvestris
) sawdust. The
effect of the autohydrolysis conditions, i.e., pretreatment
time and temperature, on hexavalent chromium biosorption
was investigated using energy-dispersive X-ray spectroscopy (EDS) and UV-visible spectrophotometry. The
Freundlich, Langmuir, Sips, Radke-Prausnitz, Modified
Radke-Prausnitz, Tóth, UNILAN, Temkin and Dubinin-
Radushkevich adsorption capacities and the rate constant
values for pseudo-first- and pseudo-second-order kinetics
indicated that the autohydrolyzed material exhibits significantly enhanced hexavalent chromium adsorption properties
comparing with the untreated sawdust. The Freundlich's
adsorption capacity
K
F increased from 2.276 to 8.928 (mg g
-1)(L mg
-1)
1/n, and the amount of hexavalent chromium
adsorbed at saturation (Langmuir constant
qm
) increased
from 87.4 to 345.9 mg g
-1
, indicating that autohydrolysis
treatment at 240°C for 50 min optimizes the adsorption
behavior of the lignocellulosic material.