Magnetic zeolite from fly ash as a cost-effective adsorbent for Cu²⁺, Pb²⁺, Zn²⁺, and Cd²⁺ removal from aqueous media: a comprehensive study

ABSTRACT

In this work, we report the synthesis of magnetic zeolite A using fly ash as the main sources of SiO₂ and Al₂O₃, by hydrothermal use in the adsorption of Pb², Cd², Zn²⁺ and Cu². The composite synthesis was successful, and the obtained material was characterised by using different techniques, such as X-ray diffraction (XRD), X-ray fluorescence (XRF), Infrared vibrational spectroscopy (FTIR), Electron Microscopy (SEM), and pH point of zero charge (pHpzc). XRD measurements confirm zeolites A as the main crystalline phases (98.5%), with the presence of a small amount of sodalite (1.5%). In the SEM of magnetic composite, the characteristic morphology for zeolite A was noted, with magnetite nanoparticles dispersed on its surface, resulting in a composite with magnetic properties. In the adsorption study, the magnetic composite showed a fast rate of adsorption, in which the pseudo second order model was the one that best described the experimental data of the metal ions under study. The Redlich-Peterson isotherm model best represented the experimental data of Pb²⁺ and Cd²⁺, while the Langmuir and Sips models fitted Zn²⁺ and Cu²⁺, respectively. Thus, the results showed that the magnetic composite presented high magnetic quality, facilitating its separation from the aqueous medium, as well as being a promising adsorbent in the adsorption of metal ions in aqueous medium.

GRAPHICAL ABSTRACT

KEYWORDS:

• Zeolite A
• fly ash
• Magnetic Zeolites
• adsorption

Acknowledgments

The authors also would like to thank to Laboratório de Raios-X and Professor José Marcos Sasaki for XRD analyses and Central Analítica- UFC for the SEM analysis (UFC/CT-INFRA/MCTI-SISNANO/Pró-equipamentos-CAPES).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/03067319.2022.2098020

Additional information

Funding

This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001 (No. Proc.: PROEX 23038.000509/2020-82) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), No. Proc.: 305074/2018-0.