Shell biomass material supported nano-zero valent iron to remove Pb2+ and Cd2+ in water

Nanoscale zero-valent iron (NZVI) has a high adsorption capacity for heavy
metals, but easily forms aggregates. Herein, preprocessed undulating venus
shell (UVS) is used as support material to prevent NZVI from reuniting.
The SEM and TEM results show that UVS had a porous layered structure and
NZVI particles were evenly distributed on the UVS surface. A large number
of adsorption sites on the surface of UVS-NZVI are confirmed by IR and XRD.
UVS-NZVI is utilized for adsorption of Pb2+ and Cd2+ at pH=6 in aqueous
solution, and the experimental adsorption capacities are 29.91 mg•g-1 and
38.99 mg•g-1 at optimal pH, respectively. Thermodynamic studies indicate
that the adsorption of ions by UVS-NZVI is more in line with the Langmuir
model when Pb2+ or Cd2+ existed alone. For the mixed solution of Pb2+ and
Cd2+, only the adsorption of Pb2+ by UVS-NZVI conforms to the Langmuir
model. In addition, the maximum adsorption capacities of UVS-NZVI for Pb2+
and Cd2+ are 93.01 mg•g-1 and 46.07 mg•g-1.Kinetic studies demonstrate
that the determination coefficients (R2) of the pseudo first-order kinetic
model for UVS-NZVI adsorption of Cd2+ and Pb2+ are higher than those of
the pseudo second-order kinetic model and Elovich kinetic model. Highly
efficient performance for metal removal makes UVS-NZVI show potential
application to heavy metal ion adsorption.