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
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
TiO2/Al-PILC catalysts synthesized from a non-conventional aluminum source of aluminum and applied in the photodegradation of organic compounds
(Springer, 2024-07-17) Cardona Rodríguez, Yaneth; Gil Bravo, Antonio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This study explores the transformative potential of Pillared InterLayered Clays (PILC) derived from non-conventional aluminum sources as catalytic supports in the synthesis of TiO2/catalysts for the efficient photodegradation of organic pollutants in water. Montmorillonite (Mt) and three alumina-pillared montmorillonite (PILC) synthesized using various aluminum sources, were impregnated with titanium to synthesize TiO2/catalysts. The successful synthesis of these materials was confirmed through several characterization techniques such as X-ray diffraction (XRD), N2 adsorption-desorption at -196 ºC, morphological analysis using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and Energy-Dispersive X-ray Spectrometry (EDX). The photolysis, adsorption, and catalytic behavior of the TiO2/catalysts were studied for the degradation of triclosan (TCS), 2,6-dichlorophenol (2,6-DCP), and bisphenol A (BPA). All synthesized catalysts surpassed the efficacy of commercial anatase, with TiO2/Al-PILC exhibiting superior performance in comparison to TiO2/Mt. Photodegradation was most effective under UV radiation, with TCS demonstrating the highest degradation (approximately 70%). Notably, Al-PILC samples, particularly those synthesized from saline slags, displayed enhanced properties. Among them, TiO2/Al-PILCAE exhibited the highest degradation rates under both UV and visible light, underlining the remarkable potential of saline slags as precursors for Al-PILC synthesis. This study provides valuable insights into the design and development of efficient catalysts for water treatment applications, paving the way for sustainable and effective solutions in the realm of environmental remediation.
Open Access
Understanding the formation of Al13 and Al30 polycations to the development of microporous materials based on Al13-and Al30-PILC montmorillonites: a review
(Elsevier, 2021) Cardona Rodríguez, Yaneth; Gil Bravo, Antonio; Korili, Sophia A.; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Hydrolysis of aluminum cations (Al3+), the third most abundant metal in the Earth’s crust, is considered relevant in many academic fields, including materials science and chemical engineering. AlIII -polycations and their different uses have also been widely studied, as reflected in the extensive literature in that field. This review summarizes some of those studies, from Al3+ hydrolysis to form Al13 ([Al13O4(OH)24(H2O)12]7+) and Al30 ([(Al30O8(OH)56(H2O)24)]18+) polycations and their specific use as pillaring agents for montmorillonite, which is the most commonly used clay mineral in Aluminum Pillared Interlayered Clays (Al-PILC) synthesis. The experimental conditions published over the years regarding the synthesis of both these AlIII-polycations, as well as the conditions employed to synthesize Al-PILC montmorillonite using Al13 and Al30 polycation solutions, are also summarized. This review highlights some of the findings that have made it possible to explain the formation of Al13- and Al30-PILC montmorillonites, and allow us to clearly understand their differences. Finally, the new tendencies in the development of these materials based on Al-PILC and the applications are also highlighted.
Embargo
Removal of emerging pollutants in water through adsorption and catalytic processes using pillared clays synthesized from aluminum saline slags
(2022) Cardona Rodríguez, Yaneth; Gil Bravo, Antonio; Korili, Sophia A.; Ciencias; Zientziak; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In this work, the aluminum was extracted from the saline slags using both ways the alkaline and the acidic one. Those extracts were used as precursors in the synthesis of Pillared Clays (PILC) obtaining pillared structures from the acidic extract (Al-PILCAE) and from the alkaline one (Al-PILCBE). The parameters in the synthesis of those PILC were studied characterizing the solids obtained with the purpose to optimize the synthesis process and choose the solids with the better characteristics. The solids chosen were studied as adsorbents and catalytic supports for the removal of three emerging pollutants from water: 2,6-dichlorophenol (2,6-DCP), triclosan (TCS), and bisphenol A (BPA). The adsorptive and catalytic behavior was compared with both the raw clay used in their synthesis (montmorillonite – Mt) and with a PILC synthesized by the conventional method using an aluminum commercial salt as the precursor (Al-PILCCM). The first two sections of this thesis focus on the theory related to the subject. First Chapter (I) refers to PILC, their synthesis, the parameters involved in this, and their importance and impact on the properties of the solid obtained. This chapter collected the studies related to this field, trying to understand the formation of the polycations that make possible the synthesis of PILC. The Second Chapter (II) is related to water pollution and the techniques used to eliminate pollutants from the aquatic environment. This chapter focused on the use of the adsorption process, and the use of PILC as adsorbents for organic pollutants, collecting the studies which have used them for this purpose. The next four chapters (Chapter III to Chapter VI) are related to the results and analysis of the results of the experimental part developed in this work. The first two of them (Chapter III and Chapter IV) are related to the synthesis of the porous clay-based materials and their use as adsorbents, and the next two (Chapter V and Chapter VI) to their use in photocatalysis. Chapter Three (III) corresponds to the synthesis of PILC from the saline slag and their evaluation as adsorbents in batch mode. The parameters involved in the synthesis process were evaluated, characterizing every time the synthesized solids to confirm that the pillaring process was successful. The synthesis process which resulted in solids with better characteristics was chosen for every one of both extracts: alkaline (Al-PILCBE) and acidic (Al-PILCAE). Those PILC were evaluated as adsorbents to remove 2,6-DCP, BPA, and TCS from water, in batch mode. The resulting adsorption capacities were compared with Mt and Al-PILCCM. Additionally, the reuse of the intercalating agent sequentially to synthesize Al-PILC as the reuse of the initial Al-PILC synthesized as adsorbent also was studied. It is necessary to highlight that this is the first time that a porous material is synthesized from saline slag using both extracts, alkaline, and acid. The annex in this document is related to this part of the study. The results obtained in the optimization of the synthesis of PILC using saline slag gave, as a result, a methodology that synthesized PILC with improved textural characteristics compared with those prepared through the conventional method. This methodology was evaluated using a commercial salt as the precursor and the results confirmed that the solids obtained using this had improved textural properties than using the conventional methodology. For this reason, due to the novelty of the methodology found, the technical information about the invention was disclosed in a patent application (202130047) as can be seen in the annex section. Chapter Four (IV) corresponds to the study of the three Al-PILC (Al-PILCAE, Al-PILCBE, and Al-PILCCM) as adsorbents in fixed bed column systems for the removal of TCS. In addition to the breakthrough curves, the adsorption of TCS adsorption in this system was optimized for its use in Solid Phase Extraction (SPE) by Response Surface Methodology using a Box–Behnken Design (RSM-BBD). Fixed-bed column studies are usually carried out to consider the possible application of the adsorbents in water purification processes, however, those studies can be made on a small scale to propose new materials to improve methodologies and routinary techniques used in the laboratory, including the sample preparation methodologies such as SPE. This study, for the first time, used chemometric tools to optimize the adsorption of TCS in fixed bed column by Al-PILC to use it in SPE. This is another way to support the research related to water pollution with EP. The low concentrations of EP in water sources can be lower than the Limit of Detection (LOD) and Limit of Quantitation (LOQ) of the analytical techniques necessary to evaluate those. It makes necessary a pre-concentration step prior to their determination and quantification. For this reason, the study and proposal of new sorbents that can be used in preparation techniques such as SPE for the determination and quantification of EP in water are relevant. Chapter Five (V) corresponds to the use and comparison of Mt and the three Al-PILC as catalytic supports for the removal of 2,6-DCP, TCS, and BPA from water through photocatalytic degradation using both VIS and UV light irradiation. TiO2/catalysts were synthesized by wet impregnation through stirring followed by calcination. Different loads of titanium were studied, and the characterization of the solids was carried out by several techniques. Finally, the photoproducts present in the solutions at the end of the process were evaluated by High-Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS). Additionally, since this chapter is the first related to catalysis, it complements the theoretical information shown in chapter two, listing those studies which have used clays and PILC in catalytic photodegradation processes. The novelty of this work lies in the use of Al-PILC synthesized from aluminum saline slags as catalytic supports and the evaluation of visible light irradiation for this process. Finally, Chapter Six (VI) corresponds to the use and comparison of Mt and the three Al-PILC as catalytic supports for the removal of 2,6-DCP, TCS, and BPA from water by Fenton and Photo-Fenton like processes. Fe(III)/TiO2/ catalysts with different titanium and iron loads were evaluated in single-component solutions and in an equimolar mixture. All catalysts were characterized by several techniques and the by-products for every pollutant were identified during the reactions by HPLC-MS. A degradation pathway was suggested for every pollutant based on the by-products identified during the reactions. The originality of this work is related to the fact of analyzing the process in both single and mixture components systems, using Al-PILC synthesized from aluminum saline slags as catalytic supports.
Open Access
Progress and perspectives for the use of pillared clays as adsorbents for organic compounds in aqueous solution
(De Gruyter, 2022-09-14) Cardona Rodríguez, Yaneth; Vicente, Miguel Ángel; Korili, Sophia A.; Gil Bravo, Antonio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
The world is faced with several problems as regards water pollution. This is due to several factors, including the discharge of effluents into the environment with no prior treatment. This wastewater, therefore, contains significant levels of pollutants, including numerous toxic organic contaminants and others that are similarly undesirable. Several studies have attempted to find ways of removing wastewater contaminants using pillared interlayered clays (PILC) as adsorbents. In this work, we present a summary of those studies that have used PILC as adsorbents for the removal of organic compounds from aqueous solutions while simultaneously illustrating their potential for this purpose. A general overview is provided so that the reader can acquire a basic understanding of the PILC and their modified counterparts that have been used, and some of the characteristics that can directly affect their adsorption behavior, especially their textural and surface properties.
Open Access
Catalytic photodegradation of organic compounds using TiO2/pillared clays synthesized using a nonconventional aluminum source
(Elsevier, 2022-10-15) 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
This study evaluates the photocatalytic degradation of 2,6-dichlorophenol (2,6-DCP), triclosan (TCS) and bisphenol A (BPA) by ultraviolet (UV) and visible (VIS) light in the presence of TiO2/catalysts synthesized by wet impregnation followed by calcination. The catalyst supports used were three alumina pillared clays (Al-PILC) synthesized using various aluminum sources and montmorillonite (Mt) as raw material. One of the Al-PILC was prepared following the conventional method (Al-PILCCM), using a commercial aluminum salt, and the other two were synthesized using a saline slag, with the aluminum used being extracted with the alkaline (Al-PILCBE) or the acid (Al-PILCAE) method. Mt was impregnated with various amounts of titanium (1, 5, 10, and 20 wt% Ti) and evaluated for the photodegradation of the aforementioned pollutants, comparing the results with those obtained using commercial anatase. Due to the higher conversion rates, 10 and 20 wt% Ti were chosen to impregnate the Al-PILC and to evaluate the photocatalytic performance. All materials were characterized by several techniques, which confirmed the successful formation of TiO2 in the anatase phase. In all cases, photodegradation was higher when using UV light and the most photodegraded pollutant was TCS (85.15 ± 0.49%), followed by 2,6-DCP (65.43 ± 0.79%) and, to a lesser degree, BPA (36.15 ± 0.65%). Al-PILC showed higher photodegradation percentages, with Al-PILCAE exhibiting the highest values for both types of light. An analysis of the photoproducts by HPLC-MS suggested that the preferred pathway for TCS and 2,6-DCP photodegradation depends on the type of light used.
Open Access
A nonconventional aluminum source in the production of alumina-pillared clays for the removal of organic pollutants by adsorption
(Elsevier, 2021-12-01) Cardona Rodríguez, Yaneth; Korili, Sophia A.; Gil Bravo, Antonio; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This study is the first to propose the use of aluminum saline slag as aluminum source in the synthesis of alumina pillared clays (Al-PILC). Aluminum was extracted from this waste using both alkaline and acid solutions and both were compared for preparation of the intercalation solutions used for the synthesis of Al-PILC. Variations in parameters such as [OH–]/[Al3+], Al/clay (mmol/g), clay/volume solution ratios and temperature were studied in the synthesis processes. The solids obtained were characterized by X-ray diffraction (XRD), N2 adsorption–desorption at −196 °C, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX), which confirmed that the pillaring process was successful. PILC obtained from both acid (Al-PILCAE) and alkaline (Al-PILCBE) extracts were evaluated as adsorbents for three organic pollutants, namely bisphenol A (BPA), 2,6-dichlorophenol (2,6DCP) and triclosan (TCS), in batch mode. The resulting adsorption capacities were compared with montmorillonite (Mt) and an Al-PILC prepared by the conventional method, namely, dropwise addition of an NaOH solution into an aluminum chloride solution (Al-PILCCM). In all cases, the effect of factors such as pH, initial concentration of pollutant, adsorbent dosages and contact time was studied. The kinetic and equilibrium results obtained were evaluated using both pseudo-first- and pseudo-second-order kinetics, and Langmuir, Freundlich and Sips equation isotherms for the equilibrium. The kinetic study showed that the time needed to reach equilibrium was 30, 900 and 510 min for BPA, 2,6DCP and TCS, respectively. Moreover, adsorption data showed that the Al-PILCAE and Al-PILCBE synthesized have excellent potential as adsorbents for 2,6DCP and TCS, removing 98.46% and 98.47% of these compounds, respectively.
Open Access
Use of clays and pillared clays in the catalytic photodegradation of organic compounds in aqueous solutions
(Taylor & Francis, 2024-02-23) Cardona Rodríguez, Yaneth; Korili, Sophia A.; Gil Bravo, Antonio; Ciencias; Zientziak
Conventional wastewater treatment plants do not currently remove all organic compounds, including some emerging pollutants. This has prompted several efforts to develop new methods and materials —or to improve existing ones— to remove such pollutants. The technologies studied to remove contaminants from water include photochemical processes in which the photons activate a material to produce radicals, which go on to initiate a series of reactions that result in oxidation of the pollutant. Several photocatalysts and catalyst supports have been used; these include clays and pillared interlayered clays (PILC), which have shown interesting results in the photodegradation of several organic contaminants. In this review, we describe the studies that have used both clays and PILC for the photodegradation of organic compounds in aqueous solutions. The results reported are summarized and compared, thus confirming that the findings support the use of these systems as photocatalysts and that they are successful and promising materials for the removal of several organic compounds. In this aspect, new synthesis procedures for PILC materials can be proposed from Heterostructures and MOF based on clays.