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Sustainable biomass-derived activated biochar/polyaniline/alginate composite beads for enhanced methylene blue adsorption: experimental and theoretical investigations
(Elsevier, 2025-05-01) Benamraoui, Faouzia; Kecir, Imene; Hechaichi, Chaima; Bourzami, Riahd; Boulahbal, Aziza Imene; Gil Bravo, Antonio; Boutahala, Mokhtar; Bounoukta, Charf Eddine; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
This study investigates biomass-derived adsorbents in powder and bead forms for the efficient removal of methylene blue MB from wastewater. Activated biochar powders (ABC and ABCZ) were synthesized using H3PO4 and ZnCl2 as activators for the chemical treatment of Crataegus azarolus CAS seed waste, while polyaniline (PA) and sodium alginate (SG) were integrated to form two bead-shaped composites. Compared to ZnCl2, H3PO4 activation produced similar acidic site concentrations but resulted in improved mesoporosity and larger pore diameters. Untreated lignin-like ABC and PA-functionalized ABC were successfully encapsulated into uniform composite beads (ABC-SG and ABC-PA-SG) with negatively charged surfaces at neutral pH of solution as confirmed by FTIR, TGA, and pHpzc analyses. Adsorption efficiency depended on material composition, form, and texture. Encapsulation significantly enhanced MB adsorption capacity, with ABC-PA-SG beads achieving 821 mg/g, compared to 261 mg/g for ABC powder. While greater surface area improved MB adsorption in powders, PA incorporation in composite beads contributed to higher adsorption performance. Kinetic modeling showed that MB adsorption on ABC powder was governed by chemisorption and pores filling, while composite beads followed a physical interaction-driven process. Thermodynamic analysis confirmed that adsorption was spontaneous and endothermic. Statistical modeling and DFT calculations provided deeper insights into the adsorption mechanisms. π-π interactions dominated MB adsorption, with a horizontal molecular arrangement. ABC powders exhibited multilayer pore filling on a heterogeneous surface, whereas adsorption on ABC-PA-SG beads followed a double-energy double-layer mechanism. This study provides integrated insights into biomass-derived composite beads adsorbents, highlighting their potential for sustainable wastewater treatment applications.
Open Access
Synthesis of Cu-Al layered double hydroxides from aluminum saline slags
(Elsevier, 2023) Boulahbal, Aziza Imene; Santamaría Arana, Leticia; Azizi, A.; Boutahala, Mokhtar; Korili, Sophia A.; Gil Bravo, Antonio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The use of saline slag, a hazardous waste generated during the recycling of aluminum, as aluminum source for the synthesis CuAl layered double hydroxides (LDH) is for the first time reported in this study. Due to the JahnTeller effect, divalent copper–aluminum LDH come usually with impurities and a pure CuAl LDH is not easy to obtain. The effect of synthesis pH has been examined by comparing LDH synthesized at various pH, ranging from 6 to 12 via a co-precipitation method using aluminum obtained from an alkaline extraction of the slag. For comparison purposes, a sample was synthesized at pH = 9 using commercial aluminum Al(NO3)3⋅9H2O instead of extracted aluminum. The effects of the aging time and calcination temperature are also discussed. The LDH and their calcined metal mixed oxide (layered double oxide, LDO) have been analyzed with several characterization techniques: powder X-ray diffraction (PXRD), N2 adsorption at − 196 ◦C, thermogravimetric analysis (TGA), temperature programmed reduction (TPR), scanning electron microscopy (SEM), transmission electron microscopy and energy-dispersive X-ray spectroscopy (TEM and EDS). Synthesis pH has been proved not only to have a significant effect on the nature of secondary phases but also on the structure and morphology of the samples.
Open Access
Enhancing adsorptive performance of Cu-Al layered double hydroxides from aluminum saline slags: Insights from response surface methodology and molecular dynamic simulation
(Elsevier, 2024-12-01) Boulahbal, Aziza Imene; Santamaría Arana, Leticia; Bourzami, Riahd; Bendrihem, Aymene Salah; Boutahala, Mokhtar; Korili, Sophia A.; Gil Bravo, Antonio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
This study aims to optimize the adsorption process of gallic acid (GA) on Cu-Al layered double hydroxides (LDHs) synthesized via a co-precipitation method at various pH levels. The procedure is based on the adsorption of organic pollutants from aqueous solutions, with evaluations carried out based on operational parameters such as pH, initial concentration, and adsorbent quantity. Two series of LDHs were compared: one using aluminum extracted from saline slags and the other using a commercial aluminum salt as source of aluminum. Saline slags, a by-product of aluminum recycling, are particularly hazardous due to their high toxicity and potential for environmental contamination. Extracting aluminum from these slags and using it in the synthesis of LDHs not only helps in eliminating a dangerous waste but also creates materials with beneficial environmental applications. The adsorption process was optimized using response surface methodology (RSM) coupled with Box- Behnken design (BBD) to assess the effects of key operational parameters. Besides gallic acid, other organic pollutants such as diclofenac and salicylic acid were also evaluated for removal from aqueous solution. The LDH /LDO were characterized by X-ray diffraction (XRD), ATR infrared spectroscopy (ATR-IR), scanning and transmission electron microscopy (SEM/TEM), thermogravimetric analysis (TGA), and nitrogen adsorption at -196ºC. The merit data indicate that the material synthesized at pH = 9 with extracted aluminum exhibits superior adsorption capacity for gallic acid, demonstrating the highest removal rate, nearly reaching 100 %, and achieving equilibrium more quickly than other samples. This superior adsorption performance is also notable for salicylic acid and diclofenac. After four regeneration cycles, the adsorption rate of the adsorbent remains stable, indicating that CCA9 maintains a consistent and efficient adsorption performance. This highlights the robustness of the material and its high reusability in prolonged adsorption applications. Molecular dynamics simulations (MDS) revealed that the adsorption process occurs spontaneously, driven by weak interactions: van der Waals, intermolecular, hydrogen bonding, π-interactions and short contacts.

Gil Bravo, Antonio

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