Porous Geopolymers Derived from Tunisian Clay and Mineral Wastes for Efficient Methylene Blue Removal
Abstract
The valorization of phosphogypsum (PG), a byproduct of phosphoric acid production, along with waste glass (WG) and silica fume (SF) into value-added materials has attracted growing attention in recent years. The present study aims to synthesize three types of porous geopolymers (GD, GDP, and GDG) using Tunisian clay and locally available mineral wastes, and to investigate their potential as low-cost adsorbents for the removal of methylene blue (MB) dye from aqueous solutions. The physicochemical characteristics of the raw precursors and the resulting porous geopolymers were analyzed using various techniques, including FTIR, XRD, BET, and SEM. Variations in Si/Al, Na/Al, and Ca/Al ratios play a critical role in the geopolymer structure. The high Ca/Al ratio in GDP (porous geopolymer from calcined clay and phosphogypsum) promotes the formation of C-A-S-H, leading to increased macroporosity, which favors adsorption capacity despite the presence of a more heterogeneous morphology. The results indicated that the maximum adsorption capacity (Qmax) for MB dye was obtained for the GDP sample, reaching 68 mg/g. Adsorption experiments revealed the successful removal of MB dye by geopolymers, with the Langmuir isotherm and pseudo-second-order kinetic models adequately describing the adsorption process. The MB uptake by geopolymers was facilitated by weak physicochemical interactions, including electrostatic attraction, hydrogen bonding, and pi-pi interactions. This study proposes a simple and effective alkali activation strategy that combines different industrial wastes within a single geopolymer system, resulting in improved porosity and adsorption efficiency. Overall, the findings highlight the potential of these waste-derived geopolymers as promising and sustainable adsorbents for wastewater treatment applications.
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BibTeX
@article{amor2026porous,
title = {{Porous Geopolymers Derived from Tunisian Clay and Mineral Wastes for Efficient Methylene Blue Removal}},
author = {Assia Ben Amor and Hadj-Otmane Chahinez and Abdelkader Ouakouak and Mohamed Mezni and Khaled Mahmoudi and Emad N. El Qada and Farid Fadhillah and Amine Aymen Assadi and Anouar Hajjaji and Noureddine Hamdi and Hichem Tahraoui and Abdeltif Amrane},
journal = {Minerals},
year = {2026},
month = jun,
doi = {10.3390/min16060652},
url = {https://hal.science/hal-05683603v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Porous Geopolymers Derived from Tunisian Clay and Mineral Wastes for Efficient Methylene Blue Removal
AU - Assia Ben Amor
AU - Hadj-Otmane Chahinez
AU - Abdelkader Ouakouak
AU - Mohamed Mezni
AU - Khaled Mahmoudi
AU - Emad N. El Qada
AU - Farid Fadhillah
AU - Amine Aymen Assadi
AU - Anouar Hajjaji
AU - Noureddine Hamdi
AU - Hichem Tahraoui
AU - Abdeltif Amrane
PY - 2026
DA - 2026/06/26
JO - Minerals
DO - 10.3390/min16060652
UR - https://hal.science/hal-05683603v1
AB - The valorization of phosphogypsum (PG), a byproduct of phosphoric acid production, along with waste glass (WG) and silica fume (SF) into value-added materials has attracted growing attention in recent years. The present study aims to synthesize three types of porous geopolymers (GD, GDP, and GDG) using Tunisian clay and locally available mineral wastes, and to investigate their potential as low-cost adsorbents for the removal of methylene blue (MB) dye from aqueous solutions. The physicochemical characteristics of the raw precursors and the resulting porous geopolymers were analyzed using various techniques, including FTIR, XRD, BET, and SEM. Variations in Si/Al, Na/Al, and Ca/Al ratios play a critical role in the geopolymer structure. The high Ca/Al ratio in GDP (porous geopolymer from calcined clay and phosphogypsum) promotes the formation of C-A-S-H, leading to increased macroporosity, which favors adsorption capacity despite the presence of a more heterogeneous morphology. The results indicated that the maximum adsorption capacity (Qmax) for MB dye was obtained for the GDP sample, reaching 68 mg/g. Adsorption experiments revealed the successful removal of MB dye by geopolymers, with the Langmuir isotherm and pseudo-second-order kinetic models adequately describing the adsorption process. The MB uptake by geopolymers was facilitated by weak physicochemical interactions, including electrostatic attraction, hydrogen bonding, and pi-pi interactions. This study proposes a simple and effective alkali activation strategy that combines different industrial wastes within a single geopolymer system, resulting in improved porosity and adsorption efficiency. Overall, the findings highlight the potential of these waste-derived geopolymers as promising and sustainable adsorbents for wastewater treatment applications.
SN - 2075-163X
ER -