Ingeniería Química

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Abatement of 2,4-D by H2O2 solar photolysis and solar photo-Fenton-like process with minute Fe(III) concentrations
(2018-11) Serra-Clusellas, Anna; De Angelis, Laura; Lin, Chung-Ho; Vo, Phuc; Bayati, Mohamed; Sumner, Lloyd; Lei, Zhentian; Amaral, Nathalia B.; Bertini, Liliana María; Mazza, José; Pizzio, Luis R.; Stripeikis, Jorge; Rengifo-Herrera, Julian A.; Fidalgo de Cortalezzi, María Marta
"The Photo-Fenton-like (PF-like) process with minute Fe(III) concentrations and the Hydrogen Peroxide Photolysis (HPP), using Xe-lamp or solar light as sources of irradiation, were efficiently applied to eliminate the herbicide 2,4-D from water. PF-like experiments concerning ferric and H2O2 concentrations of 0.6 mg L 1 and 20 mg L 1 respectively, using Xenon lamps (Xe-lamps) as a source of irradiation and 2,4-D concentrations of 10 mg L 1 at pH 3.6, exhibited complete 2,4-D egradation and 77% dissolved organic carbon (DOC) removal after 30 min and 6 h of irradiation respectively whereas HPP (in absence of ferric ions) experiments showed a 2,4-D reduction and DOC removal of 90% and 7% respectively after 6 h of irradiation. At pH 7.0, HPP process achieved a 2,4-D abatement of approximately 75% and a DOC removal of 4% after 6 h. PF-like exhibited slightly improved 2,4-D and DOC removals (80% and 12% respectively) after the same irradiation time probably due to the low pH reduction (from 7.0 to 5.6). Several chlorinated-aromatic intermediates were identified by HPLC-MS. These by-products were efficiently removed by PF at pH 3.6, whereas at neutral PF-like and acid or neutral HPP, they were not efficiently degraded. With natural solar light irradiation, 10 and 1 mg L 1 of 2,4-D were abated using minor H2O2 concentrations (3, 6, 10 and 20 mg L 1 ) and iron at 0.6 mg L 1 in Milli-Q water. Similar results to Xe-lamp experiments were obtained, where solar UV-B þ A light H2O2 photolysis (HPSP) and solar photo-Fenton-like (SPF-like) played an important role and even at low H2O2 and ferric concentrations of 3 and 0.6 mg L 1 respectively, 2,4-D was efficiently removed at pH 3.6. Simulated surface water at pH 3.6 containing 1 mg L 1 2,4-D, 20 mg L 1 H2O2 and 0.6 mg L 1 Fe(III) under natural sunlight irradiation efficiently removed the herbicide and its main metabolite 2,4-DCP after 30 min of treatment while at neutral pH, 40% of herbicide degradation was achieved. In the case of very low iron concentrations (0.05 mg L 1) at acid pH, 150 min of solar treatment was required to remove 2,4-D."
Absorption of siderite within a chemically modified poly(lactic acid) based composite material for agricultural applications
(2018-05) García, Nancy L.; Fascio, Mirta; Errea, María Inés; Dufresne, Alain; Goyanes, Silvia Nair; D'Accorso, Norma Beatriz
"Iron is an essential micronutrient for higher plants. Although abundant in most soils, Fe3+ is not available for plant uptake, because of its poor solubility. Ferrous sulfate is a fertilizer used for crops but, Fe2+ is readily oxidized to the plant-unavailable ferric form. It is therefore important to provide Fe2+ to plants, minimizing the loss of this nutrient by oxidation in Fe3+. This paper reports the development of a composite material consisting of a matrix (PLARAM), obtained by the chemical modification of poly(lactic acid), capable of retaining ferrous carbonate (siderite) within PLARAM (PLARAMFe). From the matrix, Fe2+ is released into the soil, enhancing its bioavailability. PLARAM and PLARAMFe films were obtained and their water wettability was studied. One side of the films was more hydrophilic than the other, turning this material attractive as a protective film when it is necessary to avoid loss of humidity."
Adsorption with catalytic oxidation in a recirculating bed reactor for contaminated groundwater
(2018-06) Russo, Analia; De Angelis, Laura; Jacobo, Silvia E.
"A novel nanoremediation concept, which is based on in situ trapping of organic contaminants by adsorption and catalytic oxidation in combination with oxidants such as hydrogen peroxide is presented. In earlier works we explored the porous structure of a modified natural clinoptilolite loaded with iron as a supported catalyst (NZ -AFe). The supported catalyst prevents iron release during all the process. This paper presents novel results for BTX (Benzene, Toluene and Xylene) removal from aqueous solution considering that adsorption and oxidation processes are taking place simultaneously. The experiment was achieved by fluxing an aqueous solution of BTX 3.3 mM and hydrogen peroxide, at neutral pH, using the same reservoir. After 870 min, C/C0 reaches near 10% for each pollutant. The system removed 65 mg BTX in the present conditions (13 mg/g NZ-A-Fe). The results indicate that the recirculation bed reactor is an excellent system to remove by adsorption and oxidation processes BTX from water due to high mass transfer coefficients and other advantages when compare to batch reactor experiments."
Already used and candidate polymeric membranes for CO2 separation plants
(2018) Gutiérrez, Juan Pablo; Ale Ruiz, Elisa Liliana; Erdmann, Eleonora
"This chapter presents the already used polymeric membranes and the potential candidates for the CO2 acid gas separation. Mainly, this work describes the characteristics of each membrane and the differences according to transport properties, conditions, and quality of the products. In addition to this, the types of membranes according to their capacity to separate CO2 from sources such as CO2/CH4 mixture, natural gas, and flue gases are also described. Also, the energy requirement to accomplish a certain product specification is introduced, this last used for the transport of natural gas. Finally, the characteristics of the potential candidate membranes and challenges for industrial applications are summarized."
Applying the monitoring breakdown structure model to trace metal content in edible biomonitors: an eight-year survey in the Beagle Channel (southern Patagonia)
(2020-02) Conti, Marcelo Enrique; Tudino, Mabel Beatriz; Finoia, Maria Grazia; Simone, Cristina; Stripeikis, Jorge
"The purpose of this paper is to investigate the trace metal content in edible biomonitors (i.e., mollusks) in the Beagle Channel (southern Patagonia) and to assess the human health risks associated with their consumption. Rationale: The monitoring breakdown structure (MBS) conceptual model was applied to four sampling campaigns (2005 → 2012) that collected 729 samples of Mytilus chilensis and Nacella magellanica. The composition of trace elements (Cd, Cr, Cu, Ni, Pb and Zn) in the mollusks was determined using graphite furnace (GFAAS) or flame atomic absorption spectrometry (FAAS). We compared the mean obtained values with the maximum levels (MLs) of each element established by international organizations. Then, based on semi-structured interviews, we calculated the estimated daily intake (EDI) of local residents and compared it with safety reference doses, i.e., the provisional tolerable daily intake (PTDI), provisional maximum tolerable daily intake (PMTDI), and tolerable daily intake (TDI), as well as the benchmark dose level lower confidence limit for Pb (BMDL01, a reference point (RP)/point of departure (POD). Moreover, to obtain information about the potential health risks of ingesting heavy metals (HMs) through mollusk consumption, we evaluated the target hazard quotient (THQ) and the hazard index (HI). Findings: For Cd and Pb, 65% and 40% of bivalves exceeded the MLs established by the Mercado Común del Sur (Mercosur), respectively. Except for Cd in N. magellanica (i.e., 1.20 μg/kg/bw/day), EDI values were clearly lower than the safety reference doses. For Cr, Cu, Ni, Pb and Zn, mussels were safe for consumption and did not raise concerns for public health. Likewise, THQ values were well below one for most of the studied metals, indicating that the exposed human population is assumed to be safe. Occasional high consumers of mollusks from the most contaminated sites may be at some health risk. Originality: The food production system and the environment are complex systems; this is crucial to understand when we consider ecosystems as a food source (i.e., marine ecosystems). Here we consider edible biomonitors, that are organisms that can have a dual function. They are food, and at the same time, if properly calibrated, they can act as indicators of environmental quality. This study is the first to investigate relevant essential and non-essential trace metal content in two edible mollusks from the Beagle Channel in a long-term survey (2005 → 2012). The information variety was high; approximately thirteen thousand determinations were conducted to support the risk assessment for mollusk consumption. Other aspects connected with the health risks and the uncertainty factors related to the presence of essential and non-essential minerals in edible mollusks as well as the use of the MBS are also discussed."
Arapey sweet potato peel waste as renewable source of antioxidant: extraction, nanoencapsulation and nanoadditive potential in films
(2021-01) Guerrero-León, Beatriz; Corbino, Graciela; Dufresne, Alain; Errea, María Inés; D'Accorso, Norma Beatriz; García, Nancy L.
"In this work, the peel of Arapey Sweet Potato (Ipomoea batatas), a vegetable waste, was used as a source of phenolic compounds which are widely recognized as beneficial antioxidants for human health. The extract obtained from Ipomoea batatas exhibited an antioxidant activity significantly higher than many antioxidant agents reported in literature (476.96 mg of TROLOX mL-1), as well as good thermal stability. Nanocapsules of the extract coated with low molecular weight polylactic acid were prepared by the emulsification-solvent evaporation method and the nanoparticles obtained were characterized physical; thermal; and morphologically. An analysis of the variables that were investigated to increase the encapsulation efficiency is presented here. Besides, PLA films prepared via the solution-casting method exhibited good compatibility with the nanoparticles loaded with the antioxidant extract, as was evidenced by the uniform and stable dispersion of these particles in the films. Furthermore, an improvement of the mechanical properties of the PLA films due to the presence of the nanoparticles were clearly observed. Results reported here are encourage enough to propose the nanocapsules described in this work as additives or to be used immersed in films for controlled release of antioxidants, putting in value a vegetable waste."
Barrier properties and structural study of nanocomposite of HDPE/Montmorillonite modified with polyvinylalcohol
(2013-02) Carrera, María C.; Erdmann, Eleonora; Destéfanis, Hugo A.
"In this work was studied the permeation of CO2 in films of high-density polyethylene (HDPE) and organoclay modified with polyvinylalcohol () obtained from melt blending. Permeation study showed that the incorporation of the modified organoclay generates a significant effect on the barrier properties of HDPE. When a load of 2 wt% of was incorporated in the polymer matrix, the flow of CO2 decreased 43.7% compared to pure polyethylene. The results of TEM showed that clay layers were dispersed in the polymeric matrix, obtaining an exfoliated-structure nanocomposite. The thermal stability of nanocomposite was significantly enhanced with respect to the pristine HDPE. DSC results showed that the crystallinity was maintained as the pure polymeric matrix. Consequently, the decrease of permeability was attributable only to the effect of tortuosity generated by the dispersion of . Notably the mechanical properties remain equal to those of pure polyethylene, but with an increase in barrier properties to CO2. This procedure allows obtaining nanocomposites of HDPE with a good barrier property to CO2 which would make it competitive in the use of packaging."
Bulk polymerization of styrene using multifunctional initiators in a batch reactor: A comprehensive mathematical model
(2016-02) Berkenwald, Emilio; Laganá, María Laura; Acuña, Pablo; Morales Balado, Graciela Elizabeth; Estenoz, Diana
"A detailed, comprehensive mathematical model for bulk polymerization of styrene using multifunctional initiators - both linear and cyclic - in a batch reactor was developed. The model is based on a kinetic mechanism that considers thermal initiation and chemical initiation by sequential decomposition of labile groups, propagation, transfer to monomer, termination by combination and re-initiation reactions due to undecomposed labile groups. The model predicts the evolution of global reaction variables (e.g, concentration of reagents, products, radical species and labile groups) as well as the evolution of the detailed complete polymer molecular weight distributions, with polymer species characterized by chain length and number of undecomposed labile groups. The mathematical model was adjusted and validated using experimental data for various peroxide-type multifunctional initiators: diethyl ketone triperoxide (DEKTP, cyclic trifunctional), pinacolone diperoxide (PDP, cyclic bifunctional) and 1,1-bis(tert-butylperoxy)cyclohexane (L331, linear bifunctional). The model very adequately predicts polymerization rates and complete molecular weight distributions. The model is used to theoretically evaluate the influence of initiator structure and functionality as well as reaction conditions."
Carbohydrate-derived polytriazole nanoparticles enhance the antiInflammatory activity of cilostazol
(2022-11-30) Rivas, M. Verónica; Musikant, Daniel; Díaz Peña, Rocío; Álvarez, Daniela; Pelazzo, Luciana; Rossi, Ezequiel; Martínez, Karina D.; Errea, María Inés; Pérez, Óscar E.; Varela, Óscar; Kolender, Adriana K.
"Poly(amide-triazole) and poly(ester-triazole) synthesized from d-galactose as a renewable resource were applied for the synthesis of nanoparticles (NPs) by the emulsification/solvent evaporation method. The NPs were characterized as stable, spherical particles, and none of their components, including the stabilizer poly(vinyl alcohol), were cytotoxic for normal rat kidney cells. These NPs proved to be useful for the efficient encapsulation of cilostazol (CLZ), an antiplatelet and vasodilator drug currently used for the treatment of intermittent claudication, which is associated with undesired side-effects. In this context, the nanoencapsulation of CLZ was expected to improve its therapeutic administration. The carbohydrate-derived polymeric NPs were designed taking into account that the triazole rings of the polymer backbone could have attractive interactions with the tetrazole ring of CLZ. The activity of the nanoencapsulated CLZ was measured using a matrix metalloproteinase model in a lipopolysaccharide-induced inflammation system. Interestingly, the encapsulated drug exhibited enhanced anti-inflammatory activity in comparison with the free drug. The results are very promising since the stable, noncytotoxic NP systems efficiently reduced the inflammation response at low CLZ doses. In summary, the NPs were obtained through an innovative methodology that combines a carbohydrate-derived synthetic polymer, designed to interact with the drug, ease of preparation, adequate biological performance, and environmentally friendly production."
Carboxymethylated bacterial cellulose: an environmentally friendly adsorbent for lead removal from water
(2018-12) Rossi, Ezequiel; Montoya Rojo, Úrsula; Cerrutti, Patricia; Foresti, María Laura; Errea, María Inés
"Carboxymethylated bacterial cellulose (CMBC) was synthesized under controlled reaction condition to provide a material with a degree of substitution (DS) that guarantees that the characteristic water insolubility of cellulose is retained (DS = 0.17). The CMBC synthesized was fully characterized by conductometric titration, infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis and solubility assays. The suitability of the produced CMBC for lead removal from water was evaluated. Experimental isotherm data were fitted to different models of sorption isotherms: Langmuir, Freundlich, Dubinin-Radushkevich, and Frumkin, with Langmuir equation resulting in the best fit. Kinetic data were also adjusted to pseudo-first-order and pseudo-second-order models and results undoubtedly showed that the pseudosecond-order kinetic equation was the one that most appropriately described the lead adsorption of CMBC, indicating that lead is adsorbed on CMBC predominantly by chemical interaction. The breakthrough curve was fitted to different models: Bohart-Adams, Clark and Modified Dose-Response, being the Bohart-Adams equation the one that gave the best fit. Desorption studies were carried out in order to know the technical feasibility of the reuse of CMBC. Almost 96% of the retained lead was eluted in just 20 mL, and the CMBC lifetime was over 50 adsorption/desorption cycles. Overall, results obtained suggest that the CMBC herein synthesized may result in an alternative economic and environmentally friendly lead adsorbent for water treatment."
Chitosan: from organic pollutants to high-value polymeric materials
(2017) Errea, María Inés; Rossi, Ezequiel; Goyanes, Silvia Nair; D'Accorso, Norma Beatriz
"...chitosan has proved to be versatile for so many industrial applications and its versatility is the main value of this polymer. However, the lability at acidic pH of chitosan is a limiting factor that affects mainly its industrial implementation for the removal of metallic anions from water. In addition, the physical and mechanical properties may vary between two manufacturing batches due to the characteristic polydispersity of chitosan with respect to molecular weight and degree of acetylation. This variation could affect the industrial process and in some cases, when strict specifications are requested (e.g., drug delivery), increase the final cost of the product because a purification step prior to use is required. Briefly, despite of the disadvantages mentioned before, due to its great versatility, its nontoxicity, its biodegradability, and the fact that it has a renewable resource, the industrial interest in chitosan and its application has been increasing remarkably in the last years."
Comparative assessment of oxygen uptake rate of activated sludge and Escherichia coli exposed to nanomaterials
(2022-08) Aude Luppi, Vergenie E.; Oppezzo, Oscar J.; Fidalgo de Cortalezzi, María Marta
"The adverse effects of engineered nanomaterials (ENMs) on bacterial populations found in wastewater treatment plants (WWTPs) or natural systems have been studied for more than a decade, but conflicting evidence on the matter still makes it a subject of considerable concern. In this paper, the short-term exposure impact of titanium dioxide nanoparticles (nTiO2), carboxyl-functionalized multiwall carbon nanotubes (f-MWCNT), and zero-valent iron nanoparticles (nZVI) toward activated sludge and Escherichia coli (E. coli) was investigated through respiration inhibition experiments. Microorganisms were exposed to nanoparticle concentrations of 50, 100 and 200 mg/L (nTiO2, f-MWCNT) and 20, 50 and 100 mg/L (nZVI). The experiments showed that nTiO2 produced no inhibition in activated sludge or E. coli; up to 100 mg/L of nZVI did not inhibit the activated sludge respiration but 50 mg/L inhibited 24 ± 3% the respiration of E. coli and damaged its cell membrane. Activated sludge respiration was inhibited 17 ± 3% with 200 mg/L of f-MWCNT while for E. coli the inhibition was 36 ± 15% and the cell membrane was damaged with a 100 mg/L dose. Transmission electron microscopy (TEM) showed nTiO2-bacteria and nZVI-bacteria surface interaction while bacteria appeared punctured by f-MWCNT. E. coli was more susceptible than activated sludge to the nanomaterials and nZVI was more toxic than f-MWCNT for E. coli. These results demonstrated the absence of acute toxicity effects of the studied nanomaterials at those concentrations expected to occur in activated sludge facilities, and it would only be a concern in case of extremely high inputs, underscoring the resilience of WWTPs biological treatment."
Composite materials based on hybrid mesoporous solids for flow through determination of ultratrace levels of Cd(II)
(2018-07) Minaberry, Yanina Susana; Stripeikis, Jorge; Tudino, Mabel Beatriz
"In this work we present a solid phase extraction (SPE) flow through system coupled to graphite furnace atomic absorption spectrometry (GFAAS) for the determination of Cd(II) at ultratrace levels. The flow system holds a minicolumn which was filled, one in turn, with three different lab made materials: a) mesoporous silica functionalized with 3-aminopropyl groups from 3-aminopropyl triethoxysilane (HMS); b) HMS with a resin, Amberlite IR120; c) HMS-Amberlite IR120 and polyvinyl alcohol (PVA). All the solids were characterized by FTIR and SEM. Batch experiments were performed in order to study the optimum adsorption pH, the adsorption kinetics and the maximum adsorption capacity.The materials were compared in terms of their aptitude for the pre-concentration of the analyte under dynamic conditions. Microvolumes of HCl were employed for the release of cadmium and its introduction into the electrothermal atomizer. The operational variables of the flow system were also tested and optimized. The comparison of the figures of merit revealed HMS-A-PVA as the best option from an analytical point of view: limit of detection= 4.7 ng L-1, limit of quantification= 16 ng L-1, RSD %= 4 (n =6, 100 ng L-1), linear range: from LOQ up to 200 ng L-1 and a lifetime over 600 cycles with no obstructions to the free movement of fluids, material bleeding or changes on the analytical sensitivity. The proposed method was shown to be tolerable to several ions typically present in natural waters and was successfully applied to determination of trace of Cd(II) in real samples. A full discussion of the main findings with emphasis on the interaction metal ion/fillings will be provided."
Compressive behavior of rigid polyurethane foams nanostructured with bacterial nanocellulose at low and intermediate strain rates
(2019-05) Chiacchiarelli, Leonel Matías; Cerrutti, Patricia; Flores-Johnson, Emmanuel A.
"Nanocellulose reinforced foams are lightweight with improved mechanical properties; however, the strain-rate effect on their mechanical response is not yet fully understood. In this work, rigid polyurethane foams (PUFs) nanostructured with bacterial nanocellulose at 0.2 wt % (BNCF) and without it (PUF) are synthesized and subjected to compression tests at different strain rates. The BNC acts as a nucleation agent, reducing the cell size but maintaining a similar apparent density of 40.4 3.3 kg m −3 Both BNCF and PUF exhibit strain-rate effect on yield stress and densification strain. The BNCF exhibits localized progressive crushing and reduced friability, causing a remarkable recovery in the transverse direction. Numerical simulations show that functionally graded foams subjected to impact could be designed using different layers of PUF and BNCF to vary energy absorption and acceleration rate. The results presented herein warrant further research of the mechanical properties of nanostructured foams for impact applications."
Curing process of benzoxazine systems. An experimental and theoretical study
(2019-09) Gilbert, E.; Forchetti, A.; Pesoa, Juan I.; Berkenwald, Emilio; Spontón, Marisa E.; Estenoz, Diana
"A mathematical model that simulates the curing process of benzoxazine (Bz) systems is presented. The model predicts the conversion, gel point and Tg along the curing process, and considers the diffusional limitations to mass transfer due to the increase in the system viscosity along the process. This model can be used to select an appropriate combination of time and temperature in order to obtain a material with pre-specified properties. The theoretical parameters were adjusted with experimental data: conversion, weight-average molecular weight, weight fraction of solubles and Tg. The Bz based on bisphenol A and aniline (BzBA) was used to adjust the model. The curing kinetic of this Bz was followed by FTIR, SEC and DSC, considering five different curing conditions. A very good agreement between experimental and simulated values was observed, even when curing is carried out under different temperatures profiles."
Decontamination of water: adsorption of heavy metals to hematite particles, derived from ferroxane, and a comparison of different filtration process designs
(2014-09) Bühler, Frank; Fidalgo de Cortalezzi, María Marta; Bertini, Liliana María; Wessling, Matthias
"The presence of heavy metal ions in water poses a major environmental health risk to local residents.Industrial waste water often contains heavy metal ions, e.g., chromium, lead and nickel. If the waste water is not properly treated prior to discharge, these highly toxic metal ions may leak into the ground water. A warning example is the highly contaminated river called Matanza-Riachuelo in Argentina. Environmental factors such as diarrheal diseases, respiratory diseases, and cancer are significant public health problems associated with the multiple industries in the basin which are responsible for the high level of heavy metal contamination. This issue is aggravated by inadequate infrastructure in the nearby informal settlements, where residents are left with few options for drinking water. To address this problem, a user-friendly, low energy demanding and low cost treatment technology shall be developed for households, schools or other small-scale application at Instituto Technologico de Buenos Aires (ITBA), Argentina."
Detection of chlorantraniliprole residues in tomato using field-deployable MIP photonic sensors
(2021-02) Rossi, Ezequiel; Salahshoor, Zahra; Ho, Khanh-Van; Lin, Chung-Ho; Errea, María Inés; Fidalgo de Cortalezzi, María Marta
"A photonic sensor based on inversed opal molecular imprinted polymer (MIP) film to detect the presence of chlorantraniliprole (CHL) residue in tomatoes was developed. Acrylic acid was polymerized in the presence of CHL inside the structure of a colloidal crystal, followed by etching of the colloids and CHL elution. Colloidal crystals and MIP films were characterized by scanning electron microscopy and FT-IR, confirming the inner structure and chemical structure of the material. MIP films supported on polymethylmethacrylate (PMMA) slides were incubated in aqueous solutions of the pesticide and in blended tomato samples. The MIP sensor displayed shifts of the peak wavelength of the reflection spectra in the visible range when incubated in CHL concentrations between 0.5 and 10 μg L−1, while almost no peak displacement was observed for non-imprinted (NIP) films. Whole tomatoes were blended into a liquid and spiked with CHL; the sensor was able to detect CHL residues down to 0.5 μg kg−1, significantly below the tolerance level established by the US Environmental Protection Agency of 1.4 mg kg−1. Stable values were reached after about 30-min incubation in test samples. Control samples (unspiked processed tomatoes) produced peak shifts both in MIP and NIP films; however, this matrix effect did not affect the detection of CHL in the spiked samples. These promising results support the application of photonic MIP sensors as an economical and field-deployable screening tool for the detection of CHL in crops."
Detection of progesterone in aqueous samples by molecularly imprinted photonic polymers
(2022-04) Qasim, Sally; Hsu, Shu-Yu; Rossi, Ezequiel; Lin, Chung-Ho; Polo Parada, Luis; Fidalgo de Cortalezzi, María Marta; Salahshoor, Zahra
"A label-free molecular imprinted polymer (MIP) sensor was fabricated for the detection of progesterone in aqueous solutions, by polymerization inside the void spaces of colloidal crystals, which gave them photonic properties. The prepolymerization mixture was prepared from acrylic acid as the functional monomer, ethylene glycol as the cross-linker agent, ethanol as solvent, and progesterone as the imprinted template. After polymerization, the colloidal crystal was removed by acid etching and the target eluted with a solvent. Material characterization included as follows: attenuated total reflectance-Fourier-transform infrared spectroscopy, dynamic light scattering, swelling experiments, and environmental scanning electron microscopy. MIPs were investigated by equilibrium binding, kinetics experiments, and UV–visible spectra to investigate Bragg diffraction peak shift that occurs with the rebinding at different progesterone concentrations in deionized water and 150-mM NaCl solutions. The MIP response was investigated with progesterone concentration in the 1–100 μg L−1 range, with LOD of 0.5 μg L−1, reaching the detected range of hormone in natural waters. Furthermore, hydrogel MIP films were successfully tested in various real water matrices with satisfactory results. Moreover, the MIP film exhibited good selectivity toward the progesterone hormone evidenced by a larger response than when exposed to structurally similar molecules. Computational studies suggested that size along with surface potential influenced the binding of analog compounds. Due to their ease of use and low cost, the sensors are promising as screening tools for the presence of progesterone in aqueous samples."
Development of poly(lactic acid) nanocomposites reinforced with hydrophobized bacterial cellulose
(2020-01) Ávila Ramírez, Jhon Alejandro; Bovi, Jimena; Bernal, Celina; Foresti, María Laura; Errea, María Inés
"Poly(lactic acid)/bacterial cellulose nanocomposites were prepared by solvent casting. Aiming to reduce the incompatibility between polar bacterial cellulose (BC) and the nonpolar poly(lactic acid) (PLA) matrix which induces filler aggregation and poor reinforcement dispersion, BC was acetylated by the use of a non-conventional route catalyzed by citric acid. The derivatized BC (AcBC) was incorporated into de PLA matrix at varying filler loadings, and optical, morphological, structural, thermal, tensile and barrier (water vapor) properties of PLA/AcBC in comparison with PLA/BC were evaluated. Noticeable changes in the nanocomposite properties were ascribed to the success of the route proposed to surface hydrophobize BC, which significantly improved its dispersibility within the PLA matrix and the matrix-filler interaction. By the way, the variation of filler loading allowed attaining remarkable increases in the nanocomposite films stiffness without significant reductions in tensile strength and water vapor permeability."
Electrostatic interactions in virus removal by ultrafiltration membranes
(2017) Gentile, Guillermina José; Cruz, Mercedes Cecilia; Rajal, Verónica Beatriz; Fidalgo de Cortalezzi, María Marta
Ultrafiltration membranes are increasingly used in potabilization to remove viral particles. This removal is controlled by electrostatic repulsion, attatchment and size exclusion. The effect of electrostatic interaction in virus filtration was investigated. Our work included characterization of bacteriophage PP7 and polyethersulfone membrane with respect to size and surface charge; the removal of this bacteriophage at laboratory scale by ultrafiltration membrane process and the mechanism and limitations were analyzed and discussed under DLVO and XDLVO theories. A partial removal of the bacteriophage was achieved; however, enhanced separation may be achieved considering that the process is affected by the aqueous matrix. The presence of divalent cations diminished the effectiveness of the procedure as opposed to monovalent cations and species with amphoteric behavior such as bicarbonate. DLVO and XDLVO predicted the interactions studied between bacteriophae PP7 and polyethersulfone membrane.

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