Open Access
Use of response surface methodology to optimize triclosan adsorption on alumina pillared clays in a fixed-bed column for applications in solid-phase extraction
(Elsevier, 2023-04-01) Cardona Rodríguez, Yaneth; Korili, Sophia A.; Gil Bravo, Antonio; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Fixed-bed column studies are generally conducted to consider possible applications in water-purification processes. In this work, three synthetic alumina pillared interlayered clays (Al-PILC) were analyzed in fixed-bed column studies for use as sorbents for solid-phase extraction (SPE) for the first time. Adsorption processes were studied for triclosan (TCS), which is an emerging pollutant (EP) that has been shown to have several health effects. Breakthrough curves were investigated by varying process parameters such as bed height (0.25–0.75 cm), inlet TCS concentration (20–60 mg/cm3 ), and flow rate (0.5–3 cm3 /min). Bohart-Adams, Bed Depth Service Time (BDST), and Thomas models were satisfactory applied to the results obtained for fixed-bed columns. The adsorption of TCS was successfully optimized for use in SPE for the three adsorbents studied using response surface methodology with a Box–Behnken design (RSM-BBD). The models developed were adequate for the experimental data (95% significance level), with high regression parameters (98.9–99.1). The optimum values for TCS adsorption on the fixed-bed column were 378.04, 367.78, and 378.93 mg (amount of adsorbent packed into the column), 0.5 cm3 /min (flow rate), 4.24, 3.96, and 3.85 (pH), and 2.56, 1.93, and 1.13 mg/dm3 (inlet TCS concentration) for Al-PILCAE, Al-PILCBE, and Al-PILCCM, respectively. From these results synthetic Al-PILC are effective and promising sorbents that can be used for analytical purposes in SPE, and that RSM-BDD is an effective and reliable tool for evaluating and optimizing the adsorption conditions for emerging contaminants in a fixed-bed column system.
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
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
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
Heterogeneous Fenton- and photo-Fenton-like catalytic degradation of emerging pollutants using Fe2O3/TiO2/pillared clays synthesized from aluminum industrial wastes
(Elsevier, 2023-04-01) Cardona Rodríguez, Yaneth; Wegrzyn, Agnieszka; Miskowiec, Pawel; Korili, Sophia A.; Gil Bravo, Antonio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The presence of emerging pollutants (EPs) in water is a major environmental concern. This study evaluates for the first time the removal of three EPs, namely triclosan (TCS), 2,6-dichlorophenol (2,6-DCP), and bisphenol A (BPA), 90 μmol/dm3, from water through both Fenton- and photo-Fenton-like reactions using montmorillonite (Mt) and aluminum interlayered pillared clays (Al-PILC) as catalytic supports. The catalysts (Fe2O3/TiO2/Mt and Fe2O3/TiO2/Al-PILC) were evaluated in single-component solutions and in an equimolar mixture. Two Al-PILC were synthesized from a hazardous waste, namely aluminum saline slag, using either the acid (Al-PILCAE) or the alkaline (Al-PILCBE) aluminum extract as precursors. The third Al-PILC was obtained by the conventional method using a commercial aluminum salt (Al-PILCCM). Catalytic supports were impregnated at 10 and 20 wt% titanium. Iron loadings from 1 to 20 wt% were tested for Mt, while only 20 wt% iron was tested for Al-PILC. All catalysts were characterized using several techniques and the results confirmed the formation of TiO2 and Fe2O3. Almost 100 % of TCS and 2,6-DCP were removed by both Fenton-like (240 and 420 min, respectively) and photo-Fenton-like reactions (30 and 90–120 min, respectively) using the Al-PILC based catalyst. The maximum removal for BPA was 80.14 ± 1.93 % after 120 min under photo-Fenton-like conditions using Al-PILCBE. The catalysts synthesized using the four catalytic supports showed good results for the removal of TCS by both processes, while for 2,6-DCP and BPA the best results were obtained using Al-PILCAE and Al-PILCBE as catalytic supports. Finally, a degradation pathway was suggested for every pollutant based on the by-products identified during the reactions by HPLC-MS. The results revealed that the materials used in this work are suitable catalysts for removing emerging pollutants from water by both Fenton- and photo-Fenton-like reactions.
Open Access
Development of ceramic-MOF filters from aluminum saline slags for capturing CO2
(Elsevier, 2023) Torrez Herrera, Jonathan Josué; Korili, Sophia A.; Gil Bravo, Antonio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This study describes the procedures followed to synthesize ceramic-MOF filters using aluminum saline slag wastes. Briefly, the raw aluminum saline slags were washed at 80 ◦C to significantly reduce the saline content and eliminate gases. The pretreated material was mixed with glucose (G/S ratios between 0.2 and 1.6) and acetone by stirring for 4 h. After this time, the resulting solid was dried at 60 ◦C and then at 190 ◦C. During the glucose caramelization step, PegMn400 was also added and the temperature increased to 1200 ◦C. The obtained solid was impregnated with precursor solutions to achieve a supported ZIF-8 MOF. The ceramic-MOF filters were characterized by X-ray diffraction (XRD), N2 adsorption at 77 K, X-ray fluorescence (XRF), scanning electron microscopy (SEM) and transmission electron microscopy (HR-TEM), thereby confirming the presence of a structure that allows dispersion of the synthesized and supported ZIF-8. Finally, the performance of these ceramic-MOF filters as CO2 adsorbents was evaluated in the temperature range 50–300 ◦C, with isosteric heats of 19 kJ/mol being obtained using the Clausius-Clapeyron equation.
Open Access
Synthesis strategies of alumina from aluminum saline slags
(Elsevier, 2023) Grande López, Lucía; Vicente, Miguel Ángel; Korili, Sophia A.; Gil Bravo, Antonio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Aluminum saline slags is a waste of the metallurgical industry that presents serious environmental problems since it needs very extensive areas for its disposal, the toxicity it causes in the atmosphere and groundwater, in addition to high transportation costs. The valorization of this residue by the synthesis of alumina, a compound widely used in the chemical industry, generates a high impact and great interest. In this work, the strategies for synthesizing alumina from aluminum saline slags are reviewed in a context of growing demand for this metal and environmental crisis. The first sections present the aluminum production processes, both from natural bauxite (primary process) and from the recycling of materials with a high aluminum content (secondary process); paying attention to the waste generated and what environmental problems they produce. The main investigations that have allowed to address the recovery of the waste generated are described below, focusing on the processes of recovery/extraction of the aluminum present in its composition. The aluminum in these residues can be found as a metal or forming other compounds such as simple or mixed oxides. Chemical processes are the most relevant, especially those that deal with the acid and alkaline extraction of the metal. The most important section of the work reports on the methods of synthesis of Al2O3, highlighting the methods of precipitation, sol-gel, hydrothermal synthesis, and combustion, among others. The work ends with a summary and conclusions section.
Open Access
Analysis by temperature-programmed reduction of the catalytic system Ni-Mo-Pd/Al2O3
(Elsevier, 2023) Pedroarena Apezteguía, Iván; Grande López, Lucía; Torrez Herrera, Jonathan Josué; Korili, Sophia A.; Gil Bravo, Antonio; Institute for Advanced Materials and Mathematics - INAMAT2; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Alumina-supported nickel catalysts are used to facilitate many reactions at various scales. However, the deactivation of these catalysts is an important problem that has prompted the search for solutions such as the addition of other metals that act as promoters. In this research, the interactions that form between the support and the metals have been studied, a fundamental property that directly affects the performance of the catalyst. With this idea, several Ni-Pd and Ni-Mo bimetallic and various Ni-Mo-Pd trimetallic samples have been prepared, and the reduction capacity of the oxide phases by temperatura-programmed reduction has been analyzed and studied. It has been found that in bimetallic catalysts, Pd favors the appearance of NiO species that are more easily reducible than Mo. In the same way, the data obtained from the trimetallic simples suggest that the impregnation order of Mo and Pd is not a determining factor in these catalysts. In addition, it has been found that the co-impregnation of Ni with Pd gives better results than the sequential impregnation of these metals. The results obtained have also shown that the order of nickel impregnation is decisive. In the case of Ni-Mo catalysts, by impregnating the molybdenum first, catalysts with better reducing properties can be obtained.