ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

From solid wastes to an effective geopolymer adsorbent: characterization, experiments, and statistical physics formalism for Cr(VI) remediation

Ahmed S. Elshimy, Ali Q. Selim, Areej Al Bahir, M. Al-Dossari, N. S. Abd EL-Gawaad, Mohamed A. Ali, Hazem I. Bendary, and Moaaz K. Seliem

Faculty of Earth Science, Beni–Suef University, Beni Suef, Egypt

E-mail: debakyms@yahoo.com

Received: 2 December 2024  Accepted: 16 February 2025

Abstract:

The present study outlines a facile and cost-effective method to prepare a geopolymer adsorbent by activating alumina flakes (AF) and carbonates-rich ornamental stone wastes (OSW) with sodium silicate (7.5 wt.% of Na₂O). The as-synthesized AF/OSW-G geopolymer was employed to remove Cr(VI) after being characterized using a variety of analytical FTIR, FESEM, EDX, XRD, zeta potential, and mapping analysis techniques. Several conventional and statistical adsorption models were applied to outline the adsorption data at a solution pH of 2.0 and a temperature range of 25–55 °C. With maximum adsorption capacities ranging from 86.07 to 107.56 mg/g, the Langmuir model effectively described the experimental data. Additionally, the steric and energetic parameters of the statistical monolayer adsorption model were used to clarify the number of Cr(VI) removed per a functional group, the density of AF/OSW-G active sites, the uptake capacities at saturation, and the interaction energies. The hydroxyl functional group of AF/OSW-G primarily controlled the multi-docking adsorption mechanism that was provided by various chromium states, such as Cr(VI) and Cr(III), according to the theoretical remediation. The adsorption of Cr(VI) ions was endothermic and governed by the adsorption–reduction coupled mechanism. The AF/OSW-G was considered to be significantly stable and suitable for recycling in wastewater treatment based on the recovery results. Overall, the results indicated that alumina flakes and ornamental stone wastes could be utilized in the fabrication of powerful binders for water decontamination.

Keywords: Building Materials; Calcium-based cement; Geochemistry; Inorganic Chemistry; Zeolites; Geotechnical Engineering and Applied Earth Sciences; Ornamental stone waste; Cr(VI) adsorption; Statistical models; Geopolymers; Reusability study

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-025-04087-4

Chemical Papers 79 (7) 4647–4659 (2025)