ORCID

https://orcid.org/0009-0001-8135-3371

Date of Award

2025

Document Type

Thesis

Degree Name

MS in Chemistry

Department

Chemistry

First Advisor

Enju Wang

Second Advisor

Victor Cesare

Third Advisor

Anne Vazquez

Abstract

The use of low-cost biowaste adsorbents for the removal of toxic metal ions from aqueous solutions offers significant environmental benefits and demonstrates strong potential. This study evaluated luffa peels and chamomile flowers as low-cost biosorbents for the adsorption and recovery of Cd2+ and Pb2+ ions in both batch and column modes. To enhance adsorption capacity, the biosorbents were treated with 0.4 M HNO3 or 0.4 M NaOH. Fourier transform infrared spectroscopy (FTIR) characterization showed that surface OH, C=O, CO and COO groups played a role in the adsorption process. Batch adsorption studies indicated an order of adsorption capacity as follows: base-treated chamomile flowers > acid-treated chamomile flowers > base-treated luffa peels > acid-treated luffa peels. L-type isotherms were obtained for Pb2+, fitting both the Langmuir and Freundlich models, with maximum adsorption capacities (Qomax) of 34.0 mg/g for luffa peels and 49.5 mg/g for chamomile flowers, while Cd(II) showed the highest adsorption affinity at pH 8.0. The kinetic study demonstrated that adsorption followed a second-order model, reaching equilibrium within 60 minutes. Fixed-bed column adsorption results showed that luffa peels had a Thomas dynamic adsorption capacity (Q0) of 32.9 mg/g for Pb2+ and 25.8 mg/g for Cd2+. The recovery efficiency (R%) remained above 87% over three adsorption-regeneration cycles, indicating high stability of the luffa peels. This study demonstrates that biosorbents like luffa peels and chamomile flowers have substantial potential as low-cost, reusable sorbents for recovering metal ions from aqueous solutions.

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