This study explored the removal of contaminants from
surrogate
solutions using magnetite particles. Commercially available magnetite
was used for the removal of copper, lead, nitrate, and phosphate from
surrogate solutions. Single-stage experiments with copper, lead, and
phosphate surrogate solutions achieved over 98% removal, while nitrate
removal experiments only achieved 7.47%, in 24 h at high (20 g/L)
magnetite doses and initial concentrations of 100 mg contaminant/L.
Two-stage experiments with copper showed over 99.9% cumulative removal
after the second stage. Adsorption kinetics experiments for copper,
lead, and phosphate demonstrate rapid uptake of contaminants with
high doses of magnetite, removing over 90% of contaminants in 4 min
or less and follow a pseudo-second-order model. Ultimately, this study
aims to establish the minimum magnetite dose and/or minimum number
of stages required to remove contaminants below water quality standards
for human and/or aquatic life. Water pollution is a serious global
issue, and this study poses a potential solution that can be modified
for a variety of applications, including environmental contamination
and industrial wastewater treatment.
Bone waste is a problematic slaughterhouse waste typically disposed of in landfills. The pyrolyzed product of this waste shows strong potential in mine and industrial waste water remediation and work is needed to identify chemical and structural parameters which drive performance. Diffuse Reflectance Fourier Transform Spectroscopy (DRIFTS) was used to probe carbonate (CO32−), phosphate (PO43−) and hydroxyl (OH−) environments of mineral phases and functional group chemistry in carbonaceous phase, revealing a potentially synergistic functionality between the two in bone char. CO32− and water substitutions in the mineral lattice were found to persist after pyrolysis to 750 °C, and more soluble non-apatite calcium phosphate phases were observed using second derivative analysis of the v3 PO43− band. Nitrogen-rich functional groups were found in the carbonaceous phase which are associated with complexation of aqueous metals, and ordered aromatic clusters identified by Raman spectroscopy indicate a porous carbon skeletal structure to promote metals adsorption and complexation. These results point to unique chemical and structural features of bone char which are not easily replicated by synthetic carbonated apatite or activated carbon and which contribute to the excellent aqueous metals removal power of bone char.
Graphical Abstract
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