HCl Neutralization Research Articles

HCl Neutralization by Alkaline Sorbents in the Gasification of Chloride-Containing Fuel in the Filtration Combustion Mode

In this paper, we have studied the patterns of the HCl absorption by calcium-containing sorbents under countercurrent gasification in the filtration combustion mode. Experiments have been performed in a vertical batch reactor at temperatures of up to 1200°C. The following sorbents have been employed: calcium oxide and calcium carbonate (in the form of chalk and marble). The efficiency of HCl absorption by sorbents has been estimated. The completeness of HCl uptake has been shown to be limited by partial hydrolysis of the calcium chloride formed in the high-temperature zone.

The effect of thermal treatment on the acid neutralizing capacity of newberyite: structural assessment and kinetics of the HCl neutralization reaction

The newberyite MgHPO4·3H2O antacid activity has never been investigated before. Crystalline and heated Newberyite, at 200 °C, was tested as a neutralizing of hydrogen chloride acid (HCl 0.1 M to simulate gastric juice). Results show that the substrate has a basic behavior and may be used as an active ingredient in the antacid formulation. HCl Neutralization 0.1 M depends of newberyite concentration and pH1 was reached when 0.5 M was used. The crystalline and heated newberyite antacid power was compared with that of some commercial antacids. The newberyite heated pushed pH to 4 after 4 min when the crystalline product was brought it to 3 after 15 min. The antacid neutralizing capacity (ANC) was evaluated using direct and reverse titration methods. ANC values increased when particle sizes decreased. The heated product at 200 °C increased strongly the ANC and the maximum value reached was 13 meq/g. The kinetic study of neutralization reaction was carried out by pHmetry. The rate constants are depending of newberyite quantity and the optimal neutralization of HCl 0.1 M was obtained for 0.5 g. The resulting structural transformations have been investigated. XRD showed that the product became amorphous after heating at 200 °C. FT-IR and Raman spectroscopy agree on departure of the three crystallization water molecules, when MgHPO4·3H2O was heated. Surface area measurement was determined by Brunauer, Emmett and Teller and indicates that the product hasn’t an important porosity. Scanning electron microscopy coupled with energy dispersive spectrometry elementary analysis was also carried out and confirmed FT-IR and Raman spectroscopy results.

都市ごみ用ハ゛ク゛フィルタ集塵機におけるHCL除去用消石灰使用量の低減

都市ごみ用ハ゛ク゛フィルタ集塵機におけるHCL除去用消石灰使用量の低減

Supercritical hydrothermal synthesis of titanium dioxide nanostructures with controlled phase and morphology

A novel template- and organic-free synthesis of TiO2 nanostructures with controlled phase and morphology was realized through batch supercritical hydrothermal treatment (400°C) of titanate nanotubes (TNTs) with H2O2 in NaOH aqueous solution. Well-defined 3D titanate hierarchical spheres (THSs), 2D multilayered titanate nanosheets (TNSs), and 1D monodisperse anatase nanorods (ANRs) exposing (010) facets were prepared in 15min by slightly varying the NaOH solution pH. Specifically, the obtained Na/H-THSs (without/with HCl neutralization) exhibited highly porous structures with large specific surface area (109m2g−1 and 196m2g−1, respectively). Temperature-dependent phase and morphology evolutions of products under subcritical condition (200 and 300°C) were investigated. The formation of the TiO2 nanostructures from TNTs was proposed mainly following a dissolution–nucleation-growth mechanism, suggesting that both supercritical temperature and NaOH solution pH were determinant factors governing the nucleation and growth process and thus the phase and morphology.

Morphology modification of TiO2 nanotubes by controlling the starting material crystallite size for chemical synthesis

TiO2 nanotubes (NTs) were prepared by low-temperature chemical synthesis using anatase TiO2 particles with different crystallite sizes in a NaOH solution followed by water washing and HCl neutralization. The synthesized TiO2 NTs showed diverse morphologies depending on the starting materials. The crystallite size of TiO2 raw materials increased with an increase in annealing temperature, and larger TiO2 NTs, around 31 nm in diameter, were obtained from large raw powder with a crystallite size of 117 nm. X-ray diffraction and Raman spectroscopy revealed that the obtained TiO2 NT exhibited lower crystallinity; however, Raman vibration seems to be more likely than a rutile structure.

Effect of activated carbons modification on porosity, surface structure and phenol adsorption

The primary objective of this work was the examination of modified activated carbons with tailored adsorption capacity properties. Production of activated carbons with desired properties was accomplished by modification of surface functional groups and introduction of acidic/basic properties. Modification of an activated carbon was performed using partial oxygen gasification, nitric acid treatment, urea impregnation followed by pyrolysis and pyrolysis in a urea saturated stream. The surface properties of the produced samples were estimated by the multibasic titration method of Boehm and by the CO/CO 2 gas evolution profiles, while pore structure development was measured by the N 2 and CO 2 gas adsorption isotherms. Oxygen gasification resulted in samples with surface area slightly lower that the raw activated carbon; the introduction of surface functional groups depended upon the severity of the treatment: carbonylic and phenolic type groups were introduced in all partially gasified samples, while low temperatures and short reaction times enhanced the basic character of the carbon. However, nitric acid treatment resulted in the introduction of high nitrogen amounts in the samples, the reduction of surface area and the development of a surface containing carboxylic, lactonic, phenolic and carbonylic groups with negligible HCl neutralization capacity. Treatment of activated carbon by urea supported the formation of basic groups and carbonyls. The presence of surface functional groups affected the adsorption capacity of the produced samples for the removal of specific pollutants such as phenols. Urea treated samples with a basic character and high nitrogen content presented the highest phenol uptake capacity; nitric acid treated carbons and oxygen gasified samples presented an acidic surface functionality and a low phenol adsorption capacity. The beneficial role of nitrogen on phenol adsorption was attributed to adsorbate–adsorbent interactions.

Determination of Isoflavones in Ready-to-Feed Soy-Based Infant Formula

An alkaline hydrolysis/liquid chromatography (LC) method was developed for determination of isoflavones in ready-to-feed soy-based infant formula. The method consists of a 15 min methanol extraction, 10 min alkaline hydrolysis, HCl neutralization, gravity filtration, aqueous dilution, and 50 min LC analysis with UV detection at 262 and 250 nm to quantify 6 isoflavone analytes: daidzin, glycitin, genistin, daidzein, glycitein, and genistein. The concentration averages for 10 commercial batches (microg aglycone/g formula) were daidzein, 6.12 +/- 1.23; glycitein, 1.19 +/- 0.16; genistein, 12.8 +/- 2.35; and total, 20.1 +/- 3.61. Validation experiments demonstrated extraction completion and analyte stability to alkaline hydrolysis. Spike recoveries ranged from 97.6 to 104.1%, and a series of accuracy assessments showed that isoflavone concentration determined by the method was within 5% of the true value. The relative standard deviation values for repeatability ranged from 0.4 to 2.2% (n = 10), and from 0.3 to 2.7% (n = 4) for intermediate precision. Isoflavone peak purity was verified by comparing sample and standard peak area ratios (262/250 nm). The limits of detection and quantitation (microg/ formula) ranged from 0.02 to 0.05 and 0.08 to 0.18 microg/g, respectively. The difference between our concentrations and those reported by others in 1995-1998 is attributable to the well-established seasonal variation in soybean isoflavone levels. Although the method was applied exclusively to ready-to-feed formula in the present study, it is equally suitable for powder and concentrated liquid infant formulas.

Low Temperature Routes to Cordierite-Like Ceramics using Chemical Processing

ABSTRACTThe reaction of SiO2 with basic magnesium compounds, in the presence of excess ethylene glycol, provides access to the hexacoordinate silicate complex, MgSi(OCH2CH2O)3. Alkali metal hydroxides provide access to pentacoordinate silicates of the type M2Si2(OCH2CH2O)5, where M = Li, Na, K, and Cs. Alumina also reacts with alkali metal hydroxides and ethylene glycol to give compounds of the type MAI(OCH2CH2O)2. HCl neutralization of the alkali metal silicates and aluminates provides the neutral metal glycolates of Si and Al. Stoichiometrically correct mixtures of these complexes form homogeneous, cordierite precursor solutions that are potentially useful for forming films, fibers and membranes of cordierite. These polymer-like materials can be heated directly in air to generate first α-cordierite and then µ-cordierite. Hydrolysis and condensation reactions, which occur in sol-gel processing, are not required. The phase transformations and chemical changes that occur during pyrolytic transformation of the preceramic materials to their target ceramic products were characterized. Methods developed during the course of these studies led to the development of heating schedules wherein well crystallized g.-cordierite could be formed at 850 °C.

Granites and hydrothermal ore deposits: a geochemical framework

AbstractThe geochemical evolution of tin-tungsten deposits and their associated sulphides can be discussed in terms of four sequential processes: acquisition of the ore-forming elements (OFEs) by the granitic magma, emplacement of these elements in minerals and residual melt of the crystallizing granite, release of the OFEs to the circulating hydrothermal fluids and transport to the depositional sites, and finally, deposition of ore minerals through interaction of these fluids with the wall rock. Based on their crystallographic behaviour, it is useful to distinguish three principal classes of OFEs, here identified as BOC, LHC, and ALC elements. BOC (bivalent octahedral cation) elements are similar to ferrous iron and here are represented mainly by Zn, Mn, and perhaps Cu. Li also belongs to this class, although it is monovalent. LHC (large highly charged cations) elements encompass As, Nb, Mo, Sn, Sb, Ta, and W and they are similar to ferric iron or titanium in their crystallographic role. ALC (alkali-like cations) are capable of occupying alkali positions and are represented mainly by Pb, Ag, and Hg.LHCs are rejected from the polymerized silicate liquid network and become enriched in the roof of the acid magma chamber, where more non-bridging oxygens are available. Transport to the roof may be enhanced by the formation of hydrous complexes, as is the pronounced enrichment of Na and Li. BOCs, along with Cl, F, and B, fractionate strongly into the vapour phase during vesiculation. HCl in the ore fluid is crucial for the alteration process and can be produced during boiling by a hydrolysis reaction of the NaCl dissolved or immiscibly present in the silicate magma.Considerable laboratory information is available concerning release mechanisms of the OFEs to hydrothermal fluids. We can distinguish congruent and incongruent dissolution, both in response to acid buildup, as well as congruent and incongruent exchange not involving HCl. Melt-fluid fractionation is also thought to be important, though the physical mechanisms are not well understood. Any of these release mechanisms may be coupled with reduction or oxidation reactions. LHC, BOC, and ALC elements respond differently to each of these mechanisms, and these differences may in part be responsible for the observed separation of ore minerals in space and time. It is suggested that LHC elements are released preferentially during acid, non-oxidizing conditions typical of early stages, while BOC elements respond more readily to later acid-oxidizing environments, as well as exchange reactions with or without oxidation.Depositional reactions have been formulated with respect to two contrasting types of country rocks: carbonates and schists. Differences are related to the process of neutralization of the HCl produced by ore deposition: carbonate dissolution on one hand and feldspar-muscovite or biotite-muscovite conversion on the other. In carbonate rocks, evaporite-related sulphates may provide the H2S necessary for sulphide precipitation, while in schists disseminated sulphides and organic matter may be important sulphur reservoirs in addition to the sulphur liberated from the granite. A variety of situations can be envisaged with respect to the sources of the OFEs and the sulphur species required for ore deposition, including granite and wall rocks. Chloride is recognized as the crucial anion for OFE release, transport, and deposition, although F and B play a role yet to be evaluated. Final HCl neutralization is an essential step in the reactions responsible for the deposition of ore minerals.The ultimate sources of the OFEs must be related to the continental material involved in the process of melt production by partial melting. Oxidized sediments provide sources for LHC and ALC elements in the form of heavy minerals and clastic feldspars and micas. Organic-rich reduced sediments are hosts to BOC and LHC elements as sulphides and ALC elements in organic matter. Remelting of igneous and metamorphic rocks can enrich LHC, BOC, and ALC elements in the melt by extraction from opaques, Fe-Mg silicates, feldspars, and micas.

Studies on the in Vitro formation of infectious DNA-protein aggregates from SV40 components

Complete SV40 virions, disrupted in vitro at pH 10.6, were reassociated by HCl neutralization into a heterogeneous group of DNA-protein aggregates. These contained lower, varying ratios of DNA:protein than control virions. After “reassociation” a portion of the DNA was sensitive to DNase treatment. This treatment led to a loss of the infectivity which had been found in the reassociated aggregates. Nucleic acid is not essential for physical reassociation since aggregates reconstituted from disrupted complete virions had varying amounts of DNA and further aggregates were readily assembled from disrupted empty shells. Disruption by the relatively mild conditions used indicates that the capsid is held in its conformation in part by noncovalent linkage. The rapid reassociation as well as the absence of low molecular weight protein after disruption suggests that there is not a total breakdown by the disruption procedure used. The nucleic acid is probably bound to the capsomeres by noncovalent linkages since disruption does lead to loss of a large amount of the DNA. The rapid in vitro reconstitution of disrupted empty particles to protein aggregates similar to native empty shells strongly suggests that orientation of capsomeres into a tertiary conformation is fairly specific when unencumbered by the presence of DNA. Successful attempts were made to synthesize infectious aggregates in vitro using disrupted [ 14C]amino acid-labeled empty shells and [ 3H]thymidine-labeled SV40 nucleoprotein complex obtained from infected cells 25 hr postinfection.

Kinetics of hydrolytic polycondensation of α,ω-dichloropropyldimethylsiloxanes in the presence of alkali and of solid emulsifiers

In the initial stages the rate of hydrolytic polycondensation of α,ω-dichloropropyldimethylsiloxanes (DCPMSO) was found to have an inverse dependence on the rate of HCl neutralization in the presence of concentrated aqueous alkali. It increased in the sequence KOH<NaOH<NH 4OH<NH 4HCO 3. The reversible formation of the siloxane bond is of first order with respect to the terminal oligomer groups at the stage determining the overall reaction rate, and of 0·5 order with respect to H 3O +. It is suggested that the rate of chain propagation is limited in the reaction zone by condensation of silanol groups. The effect of highly dispersed silica and alumina is similar to that of alkali as fas as the attainment of the equilibrium and the degree of polymerization of the final product are concerned.