In-situ cost-effective synthesis of zeolite A in Al₂O₃–SiO₂ glass fibers for fixed bed adsorption of Cu²⁺, Cd²⁺ and Pb²⁺

The in-situ coating of zeolite crystals on Al₂O₃–SiO₂ glass fiber was investigated using two commercial fibers (FB1 and FB2). The fibers were submitted to hydrothermal treatment at different temperatures, resulting in the crystallization of zeolite on their surfaces. The materials obtained were characterized by X-ray fluorescence, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. Batch and fixed bed essays were carried out to evaluate the performance of the materials in the adsorption Cu²⁺, Cd²⁺ and Pb²⁺ from aqueous solutions, at 28 ± 2 °C. The syntheses in which the FB1 sample was employed resulted in zeolite A as the only crystalline phase. The exception was the FB1-100 material which sodalite was also formed. When FB2 samples were used, only the FB2-85 material indicated resulted in zeolite A without secondary phases, while the other materials presented a mixture of phases. The materials FB1-95 and FB2-95 presented better performance in batch adsorption experiments than the other samples, with Qe for FB1-95 being 0.049 mmol g⁻¹ for the three metal ions, and Qe for FB2-95 being 0.043, 0.047, and 0.049 mmoL g⁻¹ for Cu²⁺, Cd²⁺ and Pb²⁺, respectively. Therefore, these samples were selected for the study of fixed bed adsorption. The following adsorption order was verified: Pb²⁺  > Cd²⁺  > Cu²⁺. Linear Driving Force (LDF) model proved to be suitable for the adsorption experimental data, confirming the high potential of the FB1-95 and FB2-95 materials for the adsorption of Cu²⁺, Cd²⁺ and Pb²⁺ in aqueous solution.