THESIS
2022
1 online resource (xi, 115 pages) : illustrations (chiefly color)
Abstract
The use of lanthanum for phosphate removal has gained increasing attention due to its
strong affinity toward phosphate over a wide pH range. In this regard, although lanthanum
hydroxide exhibits promising phosphate removal ability, its practical application remains
limited due to certain technical issues including its structural instability and leaching. To
circumvent these issues, a lanthanum carbonate-based adsorbent was developed in this study.
Lanthanum carbonate@anion exchange resin (LC@AER) and lanthanum hydroxide@anion
exchange resin (LH@AER) beads were first prepared through in-situ precipitation using
identical bead-to-precursor mass ratios. LC@AER beads were chosen for further study as they
displayed better adsorption capacity and stability, and the bead-to-precursor mass rati...[
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The use of lanthanum for phosphate removal has gained increasing attention due to its
strong affinity toward phosphate over a wide pH range. In this regard, although lanthanum
hydroxide exhibits promising phosphate removal ability, its practical application remains
limited due to certain technical issues including its structural instability and leaching. To
circumvent these issues, a lanthanum carbonate-based adsorbent was developed in this study.
Lanthanum carbonate@anion exchange resin (LC@AER) and lanthanum hydroxide@anion
exchange resin (LH@AER) beads were first prepared through in-situ precipitation using
identical bead-to-precursor mass ratios. LC@AER beads were chosen for further study as they
displayed better adsorption capacity and stability, and the bead-to-precursor mass ratio was
further optimized to improve performance and stability. LC@AER (1:2) beads exhibited a
maximum adsorption capacity of 77.43 mg-P/g and excellent selectivity toward phosphate in
the presence of various co-existing anions. Experiments using river water indicated high
phosphate removal efficiency, demonstrating potential for treating river water. Investigations
revealed key differences in phosphate binding mechanisms for batch and column experiments. In batch setting, phosphate is primarily captured through ligand exchange and inner-sphere
complexation. However, in continuous flow operation, surface precipitation and electrostatic
attraction (between phosphate and quaternary ammonium) become increasingly important for
binding phosphate, which may affect phosphate recovery efficiency and must be accounted for
in process design. Overall, the findings indicate that LC@AER (1:2) beads are promising for
phosphate removal in real water samples.
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