Biomass material - undulating venus shell - supported nanoscale zero-valent iron for the adsorption of Pb2+ and Cd2+ ions in aqueous solution

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 maximum adsorption capacities are 29.91
mg·g-1 and 38.99 mg·g-1, respectively. Adsorption isotherm results
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. 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.