Abstract:
The retention of nitrite ions in
solutions of different concentrations by three
cornhusks-based powders was analyzed.
Natural cornhusk powder (NCHP), as waste
obtained from local market, the alkalized
cornhusk powder (ACHP) and the biochar
from the original material (CHBC) have
been characterized through scanning electron
microscopy (SEM) and elemental
composition EDAX - TEAM analysis
(Energy dispersive analysis X-ray - Texture
and ele-mental analytical microscopy) and
tested for the removal of nitrite ions. The
influence of initial nitrite concentration and
contact time was studied under slow stirring
rate conditions (150 rpm). For all three
adsorbents both Freundlich and Langmuir
isotherm equations described the process
with R2 > 0.95, denoting physical adsorption
and chemisorption on the surface. The
estimated retained quantities (mg·g-1)
determined from isotherms were 4.4783
(NCHP), 8.3542 (ACHP) and 8.7413
(CHBC). The Ho&McKay model was better
adjusted to the adsorption data with R2 >
0.985, while the Lagergren model produced
regression factors between 0.61 and 0.88.
Considering the biggest concentration of
nitrite solution of 50 mg·L-1 and the longest
contact time of 150 minutes, the equilibrium
capacity qe (mg·g-1) predicted by the
Ho&McKay model for the considered
adsorbents were: 4.5065 (NCHP), 8.5179
(ACHP) and 8.9445 (CHBC) compared to
the obtained qt (mg·g-1) of 4.4384 (NCHP),
8.0685 (ACHP) and 8.5753 (CHBC). The
nitrite uptake in the experiments reached a
maximum of 2.2192 mg·g-1 on NCHP, 4.0342 mg·g-1 on ACHP and 4.2877 mg·g-1
on CHBC. Considering the cost-effective
treatment steps, there is the possibility of
valorising an important amount of waste as
adsorbent materials.
