Open Access
Adsorption recovery of Ag(I) and Au(III) from an electronics industry wastewater on a clay mineral composite
(University of Science and Technology Beijing, 2019) Rakhila, Youness; Elmchaouri, Abdellah; Mestari, Allal; Korili, Sophia A.; Abouri, Meriem; Gil Bravo, Antonio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
The aim of this work is to investigate the ability of an adsorbent of a clay mineral composite to remove and recover gold and silver ions from wastewater. The composite was prepared by mixing phosphogypsum (PG), obtained from an industrial waste, and a natural clay mineral. The materials were characterized before and after use in adsorption by several techniques. Batch adsorption experiments were carried out, and the effects of the contact time and the pH and temperature of solution on the removal processes were investigated. The optimum pH for the adsorption was found to be 4. The adsorption of these metal ions reached equilibrium after 2 h of contact. The pseudo-first- and the pseudo-second-order kinetic models, as well as the Freundlich and the Langmuir isotherm equations, were considered to describe the adsorption results. The maximum adsorbed amount of 85 mg·g−1 Ag(I) and 108.3 mg·g−1 Au(III) was found. The recovery of the adsorbed gold and silver ions from the adsorbent was also analyzed. Strong acids appeared to be the best desorption agents to recover gold and silver ions. The use of aqua regia gave regeneration rates close to 95.3% and 94.3% for Ag(I) and Au(III), respectively. Finally, the removal of gold and silver ions from an industrial wastewater was tested in batch experiments, and percentage recoveries of 76.5% and 79.9% for Ag(I) and Au(III), respectively, were obtained. To carry out the industrial application of the proposed methodology, an economic viability study is required.
Open Access
Optimizing the removal of nitrate by adsorption onto activated carbon using response surface methodology based on the central composite design
(Taylor & Francis, 2020) Taoufik, Nawal; Elmchaouri, Abdellah; Korili, Sophia A.; Gil Bravo, Antonio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
This study sheds light on the adsorption process for the removal of nitrate ions from synthetic aqueous solutions. This contaminant pose a potential risk to the environment and can cause health effects including cancers and methemoglobinemia in infants. When the adsorption process is carried out, the effect by the several operating parameters such as initial nitrate concentration, pH, mass of activated carbon, and contact time becomes apparent. The essential process variables are optimized using response surface methodology (RSM) based on the central composite design (CCD) experiments. For this purpose 31 experimental results are required to determine the optimum conditions. The optimum conditions for the removal of nitrates is found to be: initial nitrate concentration = 15 mg/L; initial pH 4.0; mass of activated carbon = 25 mg, and contact time = 70 min. At these optimized conditions, the maximum removal of nitrates is found to be 96.59%.
Open Access
Progress in the removal of pharmaceutical compounds from aqueous solution using layered double hydroxides as adsorbents: a review
(Elsevier, 2020) Santamaría Aquilué, Rafael; Vicente, Miguel Ángel; Korili, Sophia A.; Gil Bravo, Antonio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Emerging contaminants and, among them, pharmaceutical compounds, have a significant impact on water ecosystems. Layered Double Hydroxides (LDH), being easy to synthesize and cheap materials, have recently gained attention as adsorbents in aqueous solutions. This work describes the latest research performed in the adsorption capacity of LDH towards both antibiotics and Non-Steroidal Anti-Inflammatory Drugs (NSAID) describing and analyzing the synthesis conditions (Me2+:Me3+ molar ratio, calcination temperature, choice of metals for the memory effect), kinetics and isotherm models used, use of support (more practical in a 3D over a 2D form), temperature effect and several techniques for the recovery of the adsorbents. LDH exhibited great performance and potential as clean adsorbents for these emerging contaminants.
Open Access
Optimization of the pentachlorophenol adsorption by organo-clays based on response surface methodology
(MDPI, 2022) El Mahmoudi, Soufiane; Elmchaouri, Abdellah; El Kaimech, Assya; Gil Bravo, Antonio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
The aim of this study is to optimize the adsorption of pentachlorophenol (PCP) using an organo-clay under the response surface methodology. The adsorbent was selected from a montmorillonite exchanged by various cations, such as Fe3+, Al3+, Zn2+, Mg2+, Na+ , and modified by bromide cetyltrimethylammonium (CTAB) as surfactant. The obtained organo-montmorillonite was characterized using several techniques, such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and nitrogen adsorption, performed at −196 ◦C. The results showed an increase in basal space from 1.65 to 1.88 nm and a decrease in the specific surface and pore volume, with an increase in pore diameter, including the presence of characteristic bands of -CH2 - and -CH3 - groups at 2926 and 2854 cm−1 in the FTIR spectrum after the modification. The optimization of PCP removal by clay adsorbents is achieved using the response surface methodology (RSM) with a four-factor central composite model, including pH of solution, mass of adsorbent, contact time, and initial concentration. The results proved the validity of the regression model, wherein the adsorption capacity reaches its maximum value of 38 mg/g at a lower adsorbent mass of 20 mg, pH of 6, contact time (tc) of 5 h, and initial concentration of 8 mg/L.
Embargo
Improvement of the adsorption properties of an activated carbon coated by titanium dioxide for the removal of emerging contaminants
(Elsevier, 2019) Taoufik, Nawal; Elmchaouri, Abdellah; Anouar, Fatna; Korili, Sophia A.; Gil Bravo, Antonio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
Three activated carbon coated titanium dioxide composites are evaluated as adsorbents for the removal of three pharmaceutical compounds: clofibric, gallic and salicylic acids from aqueous solutions. These composite materials are characterized by several techniques as SEM, FT-IR, TGA and point of zero charge determination. The adsorption mechanism of acids was investigated and compared to the adsorption on the virgin carbon. The analysis of adsorption isotherms and kinetic properties reveals that the addition of TiO2 increased the adsorption capacities of the initial material. The adsorption kinetics has been studied in terms of pseudo-first and pseudo-second order kinetic models, and the Freundlich, Langmuir, Temkin, Tôth and Sips isotherms models have also been applied to the equilibrium adsorption data. The analysis of results indicated that the adsorption of acids on the activated carbon-titanium dioxide composites is well described by the pseudo-first order kinetic model and the Sips isotherm equation fitted the sorption experimental results better than other models.
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
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
Saline slag waste as an aluminum source for the synthesis of Zn–Al–Fe–Ti layered double-hydroxides as catalysts for the photodegradation of emerging contaminants
(Elsevier, 2020) Santamaría Arana, Leticia; Vicente, Miguel Ángel; Korili, Sophia A.; Gil Bravo, Antonio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua, PI017-PI039 CORRAL
In this work, aluminum extracted from saline slag waste is valorized to create a layered double-hydroxide series containing zinc and various proportions of aluminum/titanium. Materials were synthesized by the co-precipitation method with an Me2+/Me3+ molar ratio of 3:1 and tested for the removal of diclofenac and salicylic acid from water under UV radiation. The incorporation of 5 wt% iron by wet impregnation is evaluated. In addition, another series of zinc, aluminum/iron materials with and without 5 wt% impregnated titanium are tested as catalysts for comparison. Structural characterization and comparison of the two series was performed by powder X-ray diffraction (PXRD), nitrogen adsorption at 77 K, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction (TPR) measurements. The uncalcinated samples had a typical hydrotalcite structure with a high crystallinity; the presence of ZnO, ZnFe2O4 or Fe3O4 was found after calcination. The specific surface areas of the dried samples ranged from 78 to 199 m2/g, being highest for Zn6Al0.5Ti1.5. Overall, the results showed that the ZnAlTi series were more effective catalysts than ZnAlFe for photodegradation of the emerging contaminants diclofenac and salicylic acid, under UV light at 298 K, considering two concentrations of the organic molecules (5 and 50 μmol/dm3).
Open Access
Comparative removal of emerging contaminants from aqueous solution by adsorption on an activated carbon
(Taylor & Francis, 2019) Gil Bravo, Antonio; Taoufik, Nawal; García Mora, Ana María; Korili, Sophia A.; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
Batch sorption experiments were performed to study the adsorption of six emerging pollutants from aqueous solutions using a commercial granular activated carbon as adsorbent. Caffeine, clofibric acid, diclofenac, gallic acid, ibuprofen and salicylic acid were selected as representative contaminants. The activated carbon was characterized by nitrogen adsorption at 77 K, and through the determination of point of zero charge. The effects of several operational parameters, such as pH, initial concentration of organic molecules, mass of adsorbent and contact time, on the sorption behaviour were evaluated. The contact time to attain equilibrium for maximum adsorption was found to be 40 min. The kinetic data were correlated to several adsorption models, and the adsorption mechanism found to follow pseudo-second-order and intraparticle-diffusion models with external mass transfer predominating in the first 15 min of the experiment. The equilibrium adsorption data were analysed using the Freundlich, Langmuir and Toth isotherm equation models. The similar chemical structure and molecular weight of the organic pollutants studied to make the adsorption capacity of the activated carbon used very similar for all the molecules.
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.