Ingeniería Química

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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."
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."
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."
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."
Preparation of an environmentally friendly lead adsorbent. A contribution to the rational design of heavy metal adsorbents
(2020-10) Rossi, Ezequiel; Ávila Ramírez, Jhon Alejandro; Errea, María Inés
"This work described the preparation and characterization of water insoluble chitosan derivatives as lead adsorbents. In highly regioselective reactions, N-substituted crosslinked chitosan derivatives were obtained by crosslinking native chitosan with mucic and adipic acid (a polyhydroxylated and a non-functionalized diacid of the same length chains). The crosslinking degree of the chitosan modified with adipic acid was significantly higher than that crosslinked with mucic acid (0.446 and 0.316, respectively), while the degree of substitution was almost the same (approximately 80 %). Lead adsorption isotherms were constructed at different temperatures and adjusted to well-known models, obtaining the best fit to the experimental data with Langmuir model. The lead adsorption capacity of new materials was greater than many of the adsorbents described in literature (76.3 and 69.7 mg g−1 for chitosan modified with mucic and adipic acid, respectively). Moreover, thermodynamic parameters were calculated, and results showed that the lead adsorption on the derivatives was spontaneous, exothermic, and governed by chemical interaction. Besides, kinetic studies were performed and adjusted to well-known models. The pseudo-second order kinetic equation was the one that most appropriately described the lead adsorption on the new materials. Results were consistent with the strong electrostatic attraction established between the lead cations and the free carboxylate groups of the derivatives."
Preparation of water insoluble carboxymethylated bacterial cellulose with maximum lead retention capacity
(2021-06) Montoya Rojo, Úrsula; Rossi, Ezequiel; Cerrutti, Patricia; Errea, María Inés; Foresti, María Laura
"Chemical modification of bacterial cellulose (BC) through carboxymethylation was carried out to prepare a low-cost highly stable lead adsorbent material (CMBC). Aiming to maximize its adsorption capacity, the effect of the carboxymethylation extent conferred to BC on the lead retention ability of the insoluble CMBC products obtained was studied. Results evidenced a strong linear correlation between the lead retention capacity of CMBC samples and their degree of substitution, highlight-ing a key role on the biobased adsorbents performance of the amount of negatively charged carboxylate groups available for an ion-exchange-governed lead adsorption process. Proper tuning of the carboxymethylation extent conferred to BC thus allowed maximizing its lead adsorption capacity, reaching values (i.e.127.2 mg g−1) that doubled those previously reported."

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