Embargo
Photodegradation of paracetamol on CaAlGa and ZnAlTi mixed metal oxides (MMO) synthesized via LDH from Al-saline slags
(Elsevier, 2025-04-01) Jiménez, Alejandro; Guerra, Miguel; Pascual, Dana; Trujillano, Raquel; Rives, Vicente; Vicente, Miguel Ángel; Gil Bravo, Antonio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Preparation of CaAlGa and ZnAlTi mixed metal oxides (MMO) synthesized via CaAlGa–hydrocalumites and ZnAl–hydrotalcite impregnated with TiO2 using saline slags as aluminum source, is reported for the first time. The solids obtained by calcination at 750 ºC are highly crystalline and the photocatalytically active crystalline phases Ca12Al14-xGaxO33, ZnO, ZnAl2O4 and Zn2TiO4 have been identified. The MMO were used for the catalytic degradation of paracetamol under UV irradiation, obtaining good results for the removal of this emerging pollutant, reaching a removal above 90 % for the sample containing 25 % Ga3 +, under the optimum photodegradation conditions ([Paracetamol]0 = 40 mg/L and catalyst dose = 1 g/L), showing better results than the commercial photocatalyst TiO2–P25 from Degussa and other more complex catalysts based on MMO. In addition, this photocatalyst was submitted to a cyclic process study, finding that it maintained its performance after at least two cycles.
Open Access
Modification of the Thomas model for predicting unsymmetrical breakthrough curves using an adaptive neural-based fuzzy inference system
(IWA Publishing, 2019) Amiri, Mohammad Javad; Khozaei, Maryam; Gil Bravo, Antonio; Ciencias; Zientziak
The Thomas equation is a popular model that has been widely used to predict breakthrough curves (BTCs) when describing the dynamic adsorption of different pollutants in a fixed-bed column system. However, BTCs commonly exhibit unsymmetrical patterns that cannot be predicted using empirical equations such as the Thomas model. Fortunately, adaptive neural-based fuzzy inference systems (ANFISs) can be used to model complex patterns found in adsorption processes in a fixed-bed column system. Consequently, a new hybrid model merging Thomas and an ANFIS was introduced to estimate the performance of BTCs, which were obtained for Cd(II) ion adsorption on ostrich bone ash-supported nanoscale zero-valent iron (nZVI). The results obtained showed that the fair performance of the Thomas model (NRMSE = 27.6% and E-f = 64.6%) improved to excellent (NRMSE= 3.8% and E-f = 93.8%) due to the unique strength of ANFISs in nonlinear modeling. The sensitivity analysis indicated that the initial solution pH was a more significant input variable influencing the hybrid model than the other operational factors. This approach proves the potential of this hybrid method to predict BTCs for the dynamic adsorption of Cd(II) ions by ostrich bone ash-supported nZVI particles.
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
Inorganic–organic hybrids based on sepiolite as efficient adsorbents of caffeine and glyphosate pollutants
(Elsevier, 2020) Baldan Junior, Hugo; Silva Grazziano, Eliane da; Saltarelli, Michelle; Crispim, Denise; Nassar, Eduardo José; Trujillano, Raquel; Rives, Vicente; Vicente, Miguel Ángel; Gil Bravo, Antonio; Korili, Sophia A.; Faria, Emerson H. de; Ciuffi, Katia J.; Institute for Advanced Materials and Mathematics - INAMAT2
Sepiolite clay mineral was functionalized with (3-chloropropyl)triethoxysilane (ClPTES) or 3-[tri(ethoxy/methoxy)silyl] propylurea (TEMSPU) alkoxides and tested as adsorbent for herbicide glyphosate and also of caffeine, two pollutants with very different chemical composition. The materials obtained were characterized by X-ray diffractometry, infrared spectroscopy, thermal analysis, scanning electron microscopy and nitrogen adsorption at −196 °C, and submitted to toxicity and desorption tests. Silane functional groups blocked sepiolite active positions, and adsorption occurred within the zeolitic channels and on the surface of the functionalized solids. Caffeine and glyphosate effectively interacted with urea groups from grafted alkoxide, which could lower the mobility of the adsorbed contaminants. Glyphosate adsorbed on functionalized sepiolite derivatives showed low toxicity.
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.
Open Access
A comparative study of acid and alkaline aluminum extraction valorization procedure for aluminum saline slags
(Elsevier, 2022) Jiménez, Alejandro; Rives, Vicente; Vicente, Miguel Ángel; Gil Bravo, Antonio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
A management process for saline slags, one of the wastes from Secondary Aluminum Production, is proposed. The process begins with a grinding step, followed by washing with water, which removed the fluxing salts but provoking the hydrolysis of AlN, yielding Al(OH)3 and ammonia. Sieving of the solid generated an intermediate and a fine fraction. The first one was rich in metallic aluminum, and can also be returned to the Secondary Aluminum Production. The fine fraction was submitted to a extraction process in acid (HCl or HNO3) or alkaline (NaOH, KOH or CsOH) conditions, under reflux at 90 ºC, obtaining an Al(III) solution that can be used in the synthesis of aluminum-based solids. HCl (1-8 mol/L) and NaOH (1-4 mol/L) were used as reference solutions, HNO3, NaOH and KOH were used under specific conditions; the slag fraction:extraction solution solid:liquid ratio was also varied. The optimum extraction conditions were: extraction time 2 h, solid:liquid ratio 3:10, concentration 3 mol/L for the NaOH medium and 4 mol/L for the HCl medium. More than 30% of the aluminum present in the fraction smaller than 0.4 mm was recovered (the remaining aluminum was present as insoluble phases, corundum and spinel). Acid or basic media can be selected depending on the final use of Al(III) solutions, the basic medium leading to an Al(III) solution with a lower amount of impurities. The hazardousness of the solid obtained after the extraction process was greatly decreased, making possible the use of this solid residue in sectors such as construction.
Open Access
Ni-Mo2C/y-Al2O3 catalysts for syngas production in pyrolysis-dry reforming of plastics - the effect of amine nature on catalyst performance
(Elsevier, 2025-05-29) Pawelczyk, Ewelina; Frackiewicz, Izabela; Gil Bravo, Antonio; Karczewski, Jakub; Maciejewski, Michał E.; Dymerski, Tomasz; Gebicki, Jacek; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Pyrolysis combined with dry reforming (PCDR) is eco-friendly technology for plastic waste management, allowing for sustainable production of syngas. Design of suitable catalysts with high performance and stability is crucial for its industrialization. In this work, Ni-Mo2C/γ-Al2O3 catalysts were synthesized using organic–inorganic precursors. Three types of amines (hexylamine – aliphatic linear, cyclohexylamine – aliphatic cyclic, aniline – aromatic) were used as carbon source in the precursor preparation to investigate their effect on catalyst physicochemical properties and its catalytic performance. Catalytic performance of the obtained catalysts was examined in PCDR of model waste plastic mixture. It was revealed that catalytic activity of catalysts prepared with aliphatic amines was higher compared to aromatic aniline, amine commonly used for carbide synthesis. The differences in catalyst properties, which affected their catalytic activity were characterized using N2-adsorption at −196 °C, XRD, H2-TPR, SEM, TG/DTG and CO2-adsorption methods. A correlation was observed between amine molecule complexity and Mo2C crystallite size, significantly affecting hydrogen generation. The less complex the amine, the smaller the crystallite and the increased hydrogen production. Moreover, the use of aliphatic amines resulted in the stronger Ni-support interactions, the increased number of more favorable, larger mesopores as well as the presence of the metallic Mo phase and the lack of unbound carbon in contrast to the catalyst obtained using aniline. The catalyst synthesized using hexylamine increased H2 yield by more than tenfold, syngas yield by more than threefold, and the H2/CO ratio by fivefold, which offers an opportunity for future industrialization of PCDR.
Open Access
Photocatalytic degradation of trimethoprim on doped Ti-pillared montmorillonite
(Elsevier, 2019) González, Beatriz; Trujillano, Raquel; Vicente, Miguel Ángel; Rives, Vicente; Korili, Sophia A.; Gil Bravo, Antonio; Institute for Advanced Materials and Mathematics - INAMAT2
Montmorillonite pillared with titanium and doped with Cr3+ or Fe3+ has been tested for the photo-degradation of the antibiotic trimethoprim (trimethoxybenzyl-2,4-pyrimidinediamine) under different conditions, namely, in the dark or in UV light, with or without catalyst, finding excellent catalytic performance under photocatalytic conditions. The degradation by-products were preliminary analysed by mass spectrometry. The results suggested that the molecule broke in two halves, corresponding to its two existing rings. The process continued with the breakage of new fragments from the trimethoxybenzene half, these fragments later reacted with the methoxy groups in this part of the molecule, giving species with m/z values higher than that for the starting molecule, and with the breakage of new fragments.
Open Access
Feasibility to producing second generation bioethanol in Bolivia
(Universidad Nacional del Sur (Argentina), 2021) Beltrán Siñani, Magaly Inés; Gil Bravo, Antonio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
Bioethanol produced worldwide is mostly obtained from agricultural crops such as sugarcane and corn. However, it has negative environmental effects, so opportunity for producing bioethanol from agricultural waste arises. This study evaluates the feasibility to produce second generation bioethanol from orange waste (peel and bagasse) generated in the province of Chapare, Bolivia. Bioethanol production yield estimation is carried out by theoretical and experimental ways, DNS and HPLC methods are used for the quantification of reducing sugars, produced by acidic and enzymatic hydrolysis of the waste. Regarding the results obtained, the best alternative in terms of bioethanol production is the enzymatic hydrolysis. An economic and environmental impact evaluation are also included considering the production of bioethanol from real orange residues. The determined price of bioethanol production is USD 0.78 per liter.
Open Access
Preparation of Al/Fe-PILC clay catalysts from concentrated precursors: enhanced hydrolysis of pillaring metals and intercalation
(Royal Society of Chemistry, 2020) Vallejo, Carlos Andrés; Galeano, Luis Alejandro; Trujillano, Raquel; Vicente, Miguel Ángel; Gil Bravo, Antonio; Institute for Advanced Materials and Mathematics - INAMAT2
The modification of bentonite with Al-Fe species from different concentrated precursors at both stages: (i) the preparation of the (Al/Fe)-mixed pillaring solution and (ii) intercalation itself, was studied at lab scale. The final solids were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Cationic Exchange Capacity (CEC), textural analyses by nitrogen adsorption-desorption at 77 K, and hydrogen-temperature programmed reduction (H2-TPR). Finally, the modified clays were assessed as active materials in the Catalytic Wet Peroxide Oxidation (CWPO) of phenol under very mild conditions through 1.0 h of reaction: T = 25.0 °C ± 0.1 °C, pH = 3.7, ambient pressure (76 kPa), and 0.5 g catalyst per dm3. Metal hydrolysis by the dissolution of elemental aluminium (final Total Metal Concentration TMC = 4.62 mol dm-3) achieved the best results, decreasing the volume of solution per mass unit of clay required to successfully expand the layered starting mineral by a factor of close to 75, in comparison with the widespread conventional preparation using highly diluted Al-based pillaring solutions. Even in the absence of any solvent for the clay dispersion, the intercalating/pillaring method was shown to be favourable, as a novel strategy promoting the process intensification and subsequent preparation of Al/Fe- and other Al-based pillared clays at larger scales. The best catalyst prepared from concentrated precursors exhibited 79.1% phenol conversion, 19.3% TOC mineralization, and pretty low iron leaching (0.037 mg Fe dm-3; ∼0.12% w/w) in such a short catalytic assessment; all these results were quite comparable or even exceeded those exhibited by the catalyst prepared from dilute precursors. © 2020 The Royal Society of Chemistry.