Mineral carbonation process for CO2 sequestration

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Analysis of the effect of temperature, pH, CO2 pressure and salinity on the olivine dissolution kinetics

AbstractThe dissolution kinetics of olivine has been extensively studied under several temperatures, CO2 pressures, and solution compositions. Dissolution is an important mechanism in the aqueous mineral carbonation process. The overall carbonation reaction consists of dissolution of mineral silicate, e.g. olivine, serpentine and wollastonite, followed by carbonate precipitation, thus fixing CO2 into naturally occurring stable solids, such as magnesite and calcite. The slowness of the dissolution kinetics hinders the overall carbonation reaction and in order to make the process technically and economically feasible, such a reaction should be sped up by finding the optimum operating conditions. Experiments were performed in a flow-through reactor at 90–120–150 ∘C. The pH was adjusted by adding either acids (e.g., HCl, citric acid) or LiOH, and by changing PCO2. The salinity was changed by adding NaCl and NaNO3. From the experimental data, the dissolution rate was estimated by using the population balance equation (PBE) model coupled with a mass balance, and the obtained values were regressed with a linear model log(r)=−npH−B, where r is the specific dissolution rate (mol s−1 cm−2)

A Score Index System for a Semi-Quantitative Assessment of Inhalation Risks at Contaminated Sites

Risk assessment of contaminated sites is typically applied following a tiered approach with increasing levels of complexity. In the standard risk-based corrective action (RBCA) procedure issued by the American Society for Testing and Materials (ASTM), the site-specific evaluation is carried out using fate and transport models that require a relatively large amount of input data. In this work, we introduce a site-specific score index system for a preliminary assessment of the inhalation risks related to contaminants in soil or groundwater that resembles the modeling approaches typically adopted for chemical risk assessment in the field of industrial hygiene. In the developed system, a risk index for the outdoor and indoor volatilization pathways is calculated as the ratio between the calculated concentration at the point of exposure for the contaminant of concern and the corresponding acceptable concentration in air. The concentration at the point of exposure for each contaminant of concern is estimated through simple algorithms that involve a limited number of indexes that depend on the parameters that affect the exposure scenario. This qualitative assessment is then converted into a semi-quantitative approach by introducing scaling factors that were calibrated using the ASTM RBCA fate and transport models. The procedure was validated against the standard RBCA procedure by performing a simple Monte Carlo analysis with 10,000 simulations with randomly varying site-specific parameters. The developed score index system resulted in a conservative estimate of the risks, with percentages of false negatives lower than 1% and false positives lower than 15%. This means that the developed system allows one to screen out sites from further evaluations in more than 80% of cases, while ensuring a conservative estimate of the expected risks. The application to a real case study of a contaminated site confirmed the suitability of the developed approach

Granulation–carbonation treatment of alkali activated steel slag for secondary aggregates production

In view of the EU’s circular economy strategy, there is a need to develop treatments that may allow to improve the management of industrial residues such as steel manufacturing slag, for example by producing secondary products that may be used for different applications. This work evaluates the performance of a combined carbonation and granulation treatment applied to basic oxygen furnace (BOF) steel slag with the aim of producing secondary aggregates and of storing CO2 in a solid and stable form. In order to improve the mechanical properties of the product, a solution of sodium silicate and sodium hydroxide was tested as binder instead of water in both the granulation and combined granulation–carbonation tests. The results showed that the granules produced using the alkali activator with or without CO2 addition, presented a mean size ranging from 1 to 5 mm and adequate mechanical properties for use in civil engineering applications. The maximum CO2 uptake attained was of 4% wt. for the alkali activated and carbonated granules after 60 min of treatment and 7 days curing. As for the leaching behaviour of the produced granules, an increase in the release of Cr and V was found for the product of the granulation–carbonation treatment with alkali activation. Instead, granulation with alkali activation or granulation with carbonation showed to decrease the release of Ba and Cr with regard to the untreated residues

Les reliques des catacombes sous le regard du juge : l'authenticité comme configuration sociale (Milan, XVIIe siècle)

Issu d’une enquête collective du Centre d’anthropologie religieuse européenne (CARE, désormais CéSor), Reliques romaines est la première vue d’ensemble d’un phénomène massif : la diffusion des « corps saints » extraits des catacombes de Rome, de leur « invention » moderne en 1578 au XIXe siècle. L’ouvrage présente une triple originalité. Tout d’abord, il combine un socle documentaire commun (les archives romaines de la distribution) avec des études de cas portant sur de multiples terrains de la réception (du Mexique à la Pologne, des Pays-Bas à la péninsule Ibérique, de l’Allemagne à la France en passant par la Suisse et l’Italie), mettant ainsi en relation des sources et des historiographies jusqu’alors restées disjointes. L’ouvrage peut donc mener de front – et c’est sa seconde originalité – l’histoire institutionnelle, l’histoire sociale et l’histoire religieuse des reliques, explorant toute l’épaisseur du processus de diffusion sans dissocier sa matérialité de sa dimension spirituelle, ses traits communs des parcours individuels qui l’animent. Cette double conjonction permet enfin une réflexion sur les échelles et les temporalités du phénomène : entre universalisme romain et appropriation locale, des rythmes multiples (ceux de la distinction sociale ou des clientèles romaines, ceux de l’acclimatation de la relique ou des conjonctures pèlerines) et des configurations spatiales emboîtées (des grands fronts de catholicité aux querelles de clocher, du réseau des cours princières à celui des implantations jésuites) font des « corps saints des catacombes » un passionnant laboratoire pour une histoire connectant l’ensemble de la catholicité au plus humble sanctuaire

Long-range potential fluctuations and 1/f noise in hydrogenated amorphous silicon

We present a microscopic theory of the low-frequency voltage noise (known as "1/f" noise) in micrometer-thick films of hydrogenated amorphous silicon. This theory traces the noise back to the long-range fluctuations of the Coulomb potential produced by deep defects, thereby predicting the absolute noise intensity as a function of the distribution of defect activation energies. The predictions of this theory are in very good agreement with our own experiments in terms of both the absolute intensity and the temperature dependence of the noise spectra.Comment: 8 pages, 3 figures, several new parts and one new figure are added, but no conceptual revision

Reactivity of neonicotinoid insecticides with carbonate radicals

“NOTICE: this is the author’s version of a work that was accepted for publication in Water Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in WATER RESEARCH, [VOL46, ISSUE11, jul 2012] DOI10.1016/j.watres.2012.03.051¨ ©IWA Publishing 2012. The definitive peer-reviewed and edited version of this article is published in Water Research 46 11 3476-3489 2012 10.1016/j.watres.2012.03.051 and is available at www.iwapublishing.comThe reaction of three chloronicotinoid insecticides, namely Imidacloprid (IMD), Thiacloprid (THIA) and Acetamiprid (ACT), with carbonate radicals (CO3 center dot-) was investigated. The second order rate constants (4 +/- 1) x 10(6), (2.8 +/- 0.5) x 10(5), and (1.5 +/- 1) x 10(5) M-1 s(-1) were determined for IMD, THIA and ACT, respectively. The absorption spectra of the organic intermediates formed after CO3 center dot- is approximately equal to attack to IMD is in line with those reported for alpha-aminoalkyl radicals. A reaction mechanism involving an initial charge transfer from the amidine nitrogen of the insecticides to CO3 center dot- is proposed and further supported by the identified reaction products. The pyridine moiety of the insecticides remains unaffected until nicotinic acid is formed. CO3 center dot- radical reactivity towards IMD, ACT, and THIA is low compared to that of HO center dot radicals, excited triplet states, and O-1(2), and is therefore little effective in depleting neonicotinoid insecticides. (C) 2012 Elsevier Ltd. All rights reserved.This research was financially supported by Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Agencia Nacional de Promocion Cientifica y Tecnologica (Argentina, project PICT 2007 number 00308), and Agencia Espanola de Cooperacion Internacional (project A/8199/07). M.L.D. thanks CONICET for a graduate studentship. M.C.G. is a research member of CONICET. D.O.M. is a research member of Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CIC), Argentina. L.S.J. acknowledges Ministerio de Ciencia e Innovacion for his Juan de la Cierva scholarship.Dell'arciprete, ML.; Soler Escoda, JM.; Santos-Juanes Jordá, L.; Arques Sanz, A.; Martire, DO.; Furlong, JP.; González, MC. (2012). Reactivity of neonicotinoid insecticides with carbonate radicals. Water Research. 46(11):3476-3489. https://doi.org/10.1016/j.watres.2012.03.051S34763489461

The photochemistry of N-p-toluenesulfonyl peptides: the peptide bond as an electron donor

The scope of photobiological processes that involve absorbers within a protein matrix may be limited by the vulnerability of the peptide group to attack by highly reactive redox centers consequent upon electronic excitation. We have explored the nature of this vulnerability by undertaking comprehensive product analyses of aqueous photolysates of 12 N-p-toluene-sulfonyl peptides with systematically selected structures. The results indicate that degradation includes a major pathway that is initiated by intramolecular electron transfer in which the peptide bond serves as electron donor, and the data support the likelihood of a relay process in dipeptide derivatives