Open Access
Layered double hydroxides from aluminum saline slags applied in adsorption and photocatalysis processes for the removal of emerging pollutants
(2020) Santamaría Arana, Leticia; Gil Bravo, Antonio; Korili, Sophia A.; Ciencias; Zientziak; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
The objective of the work studied here was to synthesize Layered Double Hydroxides (LDH) with aluminum extracted from saline slags and test their function once calcined into adsorbents/catalysts for use in the removal of emerging contaminants (pharmaceutical compounds) from aqueous media.Two different techniques for the removal of contaminants were tested, adsorption and photocatalysis. In the present work, a new procedure for the recovery of aluminum present in saline slags generated during the secondary recycling processes of aluminum as adsorbent/photocatalyst of diclofenac and salicylic acid, as examples of emerging contaminants, has been reported. Results obtained have been extensively analyzed throughout the present study.
Open Access
Multifunctional nanocomposites based on kaolinite/titania/iron applied to hydrogen peroxide production and bisphenol-A removal
(Elsevier, 2024-11-06) Do Prado, Marcus Vinicius; Lima, Vinicius; Oliveira, Larissa; Nassar, Eduardo José; Marçal, Liziane; Faria, Emerson H. de; Vicente, Miguel Ángel; Trujillano, Raquel; Santamaría Arana, Leticia; Gil Bravo, Antonio; Korili, Sophia A.; Ciuffi, Katia J.; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The rising global demand for hydrogen peroxide, recognized for its eco-friendly properties, underscores the need for greener synthesis methods. Traditional production processes pose environmental risks, while direct synthesis faces challenges like water formation, explosion hazards, and stability issues, limiting industrial application. On the other hand, Bisphenol A (BPA), an endocrine disruptor widely used in plastics, presents significant environmental and health concerns due to its potential leaching into food and water. The present work introduces efficient and selective photocatalysts aimed at sustainable hydrogen peroxide synthesis and BPA degradation. Both processes were enhanced by the synergistic properties of Fe2O3–TiO2 nanoparticles dispersed within a kaolinite matrix. The Fe2O3-TiO2 photocatalysts, characterized by photoluminescence spectroscopy and X-ray diffraction, showed reduced emission upon iron incorporation and anatase presence on the kaolinite surface. The photocatalytic activity was evaluated through hydroxylation of terephthalic acid, revealing a 127 umol/L min hydroxylation rate for the KaFeTi400 sample. BPA degradation studies indicated optimal performance in acidic conditions, achieving 96 % removal in 2 h and 98 % in 4 h, with the addition of H2O2 enhancing efficiency. Further, the photocatalyst facilitated benzyl alcohol oxidation to benzaldehyde, demonstrating a H2O2 production rate of 120 umol. These findings highlight the multifunctional capabilities and environmental benefits of the photocatalyst, underscoring its potential for sustainable hydrogen peroxide synthesis and broader applications in environmental remediation. The catalysts address the pressing challenges associated with hydrogen peroxide synthesis and pollutant removal, particularly in the context of sustainability and environmental impact.
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
Synthesis of high-surface-area C3N4 deposited on halloysite-derived silica nanotubes: enhanced visible light degradation of norfloxacin
(Elsevier, 2024) Santamaría Arana, Leticia; Korili, Sophia A.; Gil Bravo, Antonio; López de Luzuriaga Fernández, José Manuel; Monge Oroz, Miguel; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Silica nanotubes, obtained from halloysite clay nanotubes that were calcined and acid-activated, were used as support for graphitic carbon nitride (g-C3N4) via a simple deposition method. They were chosen in order to avoid any agglomeration issues, as there was an increase of the specific surface area with respect to pristine halloysite. The composite was tested for the degradation of a persistent emerging pollutant in water, namely, antibiotic norfloxacin. Experiments were performed in darkness (until adsorption-desorption equilibrium was attained) and, subsequently under visible light. Comparison of the performance between the photocatalysts shows that the composite was 49% faster than g-C3N4. The introduction of persulfate in the lumen of the nanotubes via vacuum negative-pressure suction and injection was also tested for the generation of .OH radicals that fasten the degradation rate, obtaining a further 47% increase in the degradation rate of norfloxacin thanks to the release of this anion during the photodegradation process. The degradation mechanism of SiO2/g-C3N4 sample was studied with trapping experiments by the use of scavengers that were introduced to quench the photodegradation: triethanolamine for photoexcited holes (h+), tert-butanol for hydroxyl radicals (.OH) and a N2 atmosphere for superoxide radicals (.O2.).
Open Access
Layered double hydroxides for CO2 adsorption at moderate temperatures: synthesis and amelioration strategies
(Elsevier, 2023) Santamaría Arana, Leticia; Korili, Sophia A.; Gil Bravo, Antonio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Curving the CO2 atmospheric levels is one of the challenges of this century, given its direct impact on climate change. Of the several strategies of CO2 capture and storage, sorption-enhanced water–gas shift (SEWGS) process, a combination of CO2 adsorption and the water–gas shift reaction, has been appointed as one of the most promising techniques due to is low energy consumption and high efficiency. SEWGS operating settings at both moderate temperature (200–450 ◦C) and high pressure (more than 10 bar) bring the need to find an adsorbent capable of working at these conditions. Calcined layered double hydroxides (LDH) have been proven to give the best results in this range of pressure/temperatures even though its performance can be greatly improved. Herein, a state-of-art of the research accomplished up until now is presented. Several strategies can be followed to improve the adsorbents performance: the synthesis method, LDH composition, modifications employed to promote their adsorption capacity or how the adsorption conditions can affect their efficiency
Open Access
Metal-Al layered double hydroxides synthesized from aluminum slags as efficient CO2 adsorbents at pre- and post-combustion temperature
(Elsevier, 2023) Santamaría Arana, Leticia; Korili, Sophia A.; Gil Bravo, Antonio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Layered double hydroxides (LDH) have been proposed as the materials that offer the best performance in the moderate-temperature range, between 200 and 450 °C, for CO2 adsorption, so the effect of some synthesis parameters and surface modification on their adsorption capacities is herein investigated. This work reports the use of M2+ (Co, Mg, Ni and Zn)/Al layered double hydroxides synthesized with a 3:1 molar ratio by the co-precipitation method and using aluminum extracted from saline slags as source of this metal as CO2 adsorbents. The synthesis and use of Zn/TiAl is also reported considering several proportions of Al-Ti. Structural characterization and comparison of the series has been achieved using powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), nitrogen physisorption at single bond196 °C and thermogravimetry measurements (TGA). The performance of calcined LDH as CO2 adsorbents was evaluated in the 50 – 400 °C temperature range and 80 kPa and results show that Ni6Al2 and Mg6Al2 samples present a significant adsorption capacity at low temperature (0.382 and 0.292 mmolCO2/g, respectively). At 400 °C only Mg6Al2 maintains its high adsorption capacity (0.275 mmolCO2/g) compared to the other calcined LDH. Its adsorption capacity at moderate-temperature range was proven to be better than that of a commercial Mg6Al2 sample. In all materials the CO2 adsorption capacity at 200–450 °C increased by incorporating potassium (K2CO3 and KOH as sources) up to 0.58 mmolCO2/g for Mg6Al2 +K2CO3. The addition of the amine TEPA in the low-temperature range worked for Co6Al2 and Mg6Al2 (increment > 40 %). In the case of Zn6Al2, the partial substitution of Al by Ti also increased the CO2 adsorption capacity from 0.177 to 0.244 mmolCO2/g, finding isosteric heats between 17.07 and 23.30 kJ/mol using the Clausius-Clapeyron equation.
Open Access
Multifunctional heterogeneous catalysts: Tetrakis (pentafluorophenyl)porphinato]iron(III) immobilized on amine-functionalized Diatomaceous Earth for catalytic and adsorption applications
(Elsevier, 2023) Do Prado, Marcus Vinicius; González, Beatriz; Vicente, Miguel Ángel; Trujillano, Raquel; Nassar, Eduardo José; Gil Bravo, Antonio; Santamaría Arana, Leticia; Korili, Sophia A.; Marçal, Liziane; Faria, Emerson H. de; Ciuffi, Katia J.; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The use of Diatomaceous Earth (DE) as a promising support of a synthetic metalloporphyrin is reported, trying to heterogenize metalloporphyrin catalysts to mimicking enzyme site isolation and improving reaction selectivity. New multifunctional hybrid materials consisting of DE amino–functionalized with aminopropyltriethoxysilane (DE–APTES), followed by grafting with [meso–tetrakis(pentafluorophenyl)porphinato]iron(III) (DE–APTES–FeTFPP), were prepared and fully characterized. FeTFPP was grafted into DE–APTES via the amine groups (band at 1570 cm–1 ). The brown color of the materials indicated that FeTFPP was immobilized in the matrix; a Soret band characteristic of ironporphyrin located in a confined space, was found at 416 nm. Leaching studies confirmed that the ironporphyrin was entrapped and not just adsorbed on the silica surface. DE was composed of typical quartz and cristobalite crystalline phases and amorphous silica. The intensity of its characteristic reflection at 22◦ (2θ) decreased in the presence of FeTFPP, evidencing that the ironporphyrin influenced the organization of the material. Catalytic tests using DE–APTES–FeTFPP in cyclooctene epoxidation to cyclooctene oxide (56 % yield, with complete selectivity for the epoxide) and cyclohexane oxidation (4 % yield of oxidized products, with ketone/alcohol selectivity ~ 3:1), evidenced the versatility of the catalyst and the multifunctionality of the resulting hybrid materials and the ability of DE as a promising natural support for ironporphyrin catalysts. Finally, the capacity of the materials as CO2 adsorbents was evaluated in the temperature range 100–200 ◦C. DE–APTES showed a maximum adsorption capacity of 1.26 mmol/g at 100 ◦C, 18 times higher than the value found under the same conditions for the non–functionalized support.
Open Access
M(II)-Al-Fe layered double hydroxides synthesized from aluminum saline slag wastes and catalytic performance on cyclooctene oxidation
(Elsevier, 2022) Santamaría Arana, Leticia; Oliveira-Garcia, L.; Faria, Emerson H. de; Ciuffi, Katia J.; Vicente, Miguel Ángel; Korili, Sophia A.; Gil Bravo, Antonio; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Aluminum was extracted from saline slags via an alkaline method and employed in the synthesis of Layered Double Hydroxides (LDH) with various M2+ cations (Co, Mg, Ni and Zn), while Al and Fe were the M3+ cations, using the co-precipitation method and a M2+/M3+ 2:1 ratio. The structural characterization of the samples was performed with powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), nitrogen physisorption at 77 K, thermogravimetric analysis (TGA), temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). Their catalytic performance was tested for the oxidation of olefins (cyclooctene) and their biomimetic potential was analyzed. Results show a great selectivity towards epoxides with no other products obtained. Reaction yields followed the descending order Co4AlFe, Zn4AlFe, Ni4AlFe, and Mg4AlFe, the sample with cobalt as M2+ converting up to 85% of cyclooctene.
Open Access
Zn-Ti-Al layered double hydroxides synthesized from aluminum saline slag wastes as efficient drug adsorbents
(Elsevier, 2020) Santamaría Arana, Leticia; López Aizpún, María; García Padial, Marcos; Vicente, Miguel Ángel; Korili, Sophia A.; Gil Bravo, Antonio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua, PI017-PI039 CORRAL; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This work reports the synthesis of Zinc-Titanium-Aluminum (ZnTiAl) layered double hydroxides (LDH) with various proportions of Al[sbnd]Ti and a Zn/(Al[sbnd]Ti) molar ratio of 3:1 by the co-precipitation method. Two series, made with commercial aluminum (Al) and aluminum extracted from saline slags (Al*), have been considered. Structural characterization and comparison of the two series has been made using powder X-ray diffraction (PXRD), Nitrogen physisorption at 77 K, Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Thermogravimetry measurements. The adsorption capacity of diclofenac and salicylic acid, as examples of emergent pollutants, by the different LDH on batch and fixed-bed column experiments has been analyzed. The effect of various parameters, such as the pH, the initial concentration of pollutant, the mass of adsorbent and the contact time, on the sorption behavior were studied and compared. The contact time to attain equilibrium for maximum adsorption was found to be between 100 and 400 min. The kinetic and equilibrium results were correlated to several adsorption and isotherm equation models. The synthesized materials were more effective in removing diclofenac than salicylic acid, being Zn6Al*2 the hydrotalcite that showed the highest adsorption capacity. The results showed a new application of a material obtained from the valorization of an industrial waste such as aluminum saline slags.
Open Access
Effect of gold nanoparticles on SiO2@g-C3N4 catalyst for the degradation of amoxicillin
(Elsevier, 2024-08-05) Santamaría Arana, Leticia; Korili, Sophia A.; Gil Bravo, Antonio; López de Luzuriaga Fernández, José Manuel; Monge Oroz, Miguel; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Gold nanoparticles in different proportions (0.5 and 1 %) have been grafted at the surface of a SiO2@g-C3N4 nanotube-based composite (SiO2 nanotubes obtained from halloysite clay) and also g-C3N4 (for comparison purposes) to test their degradation capacity over the antibiotic amoxicillin proving that the introduction of these nanoparticles on the catalyst modifies the degradation mechanism followed by the pollutant. Results obtained show that the introduction of the appropriate percentage of gold NPs in the composite improves amoxicillin degradation efficiency and establish a direct correlation between the presence of gold NPs and the production of ∙O2.