Role of nitrous acid in the absorption of nitrogen oxides in alkaline solutions

1984 ◽  
Vol 23 (2) ◽  
pp. 260-264 ◽  
Author(s):  
Giorgio Carta
Keyword(s):  
Nitrogen Oxides ◽  
Nitrous Acid ◽  
Alkaline Solutions

scholarly journals Mechanisms of passivation and chloride-induced corrosion of mild steel in sulfide-containing alkaline solutions

2021 ◽  
Author(s):  
Shishir Mundra ◽  
John L. Provis
Keyword(s):  
Mild Steel ◽  
Surface Film ◽  
Critical Role ◽  
Chloride Concentration ◽  
Alkaline Solutions ◽  
Sulfide Concentration ◽  
Chloride Induced Corrosion ◽  
Alkaline Sulfide ◽  
High Sulfide

AbstractThe pore fluid within many concretes is highly alkaline and rich in reduced sulfur species, but the influence of such alkaline-sulfide solutions on the surface film formed on steel reinforcement is poorly understood. This study investigates the critical role of HS− in defining mild steel passivation chemistry. The surface film formed on the steel in alkaline-sulfide solutions contains Fe(OH)2 and Fe–S complexes, and the critical chloride concentration to induce corrosion increases at high sulfide concentration. However, this behavior is dependent on the duration of exposure of the steel to the electrolyte, and the nature of the sulfidic surface layer.

scholarly journals THE ROLE OF ALKALINE PHOSPHATASE IN OSTEOGENESIS

1951 ◽  
Vol 93 (5) ◽  
pp. 415-426 ◽  
Author(s):  
Robert S. Siffert
Keyword(s):  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Bone Matrix ◽  
Living Cells ◽  
Alkaline Solutions ◽  
Human Beings ◽  
Acid Media ◽  
Weakly Acid

The role of alkaline phosphatase in osteogenesis has been investigated by histochemical techniques with particular attention to its relationship to phosphate metabolism and matrix elaboration. The upper tibial epiphysis mainly, and other epiphyses as well of growing rabbits, and the costochondral junctions of newborn human beings were studied, as were bone grafts in growing rabbits. The findings in the newborn human beings were identical with those in the rabbits. Phosphatase activity and free phosphate localization do not universally coincide. The enzyme appears to be intimately related to preosseous cellular metabolism and to the elaboration of a bone matrix that is chemically calcifiable. It remains possible, however, that phosphatase may be in some way involved in making inorganic salts available to the calcifiable matrix. If this function does exist it is a secondary one, since the elaboration of bone matrix, which is always associated with phosphatase activity, can and does occur in the absence of calcification. Calcification may occur later, in the absence of the enzyme. There is evidence to suggest that cartilage matrix is utilized in the formation of bone matrix. Phosphatase is physiologically active only in the presence of living cells. Where it is demonstrable in the absence of living cells, as in the cartilage remnants of the metaphysis, it appears to be physiologically inactive. Since phosphatase is temporarily inactivated in weakly acid media, and readily reactivated by alkaline solutions it is possible that the enzyme might survive in a physiologically inactive state in weakly acid tissues, and yet remain capable of histochemical demonstration in vitro in an alkaline medium. Phosphatase is not related to the disappearance of chondroitin sulfate.

Key Role of Equilibrium HONO Concentration over the Soil 

2021 ◽  
Author(s):  
Fengxia Bao ◽  
Hang Su ◽  
Uwe Kuhn ◽  
Yafang Cheng
Keyword(s):  
Gas Phase ◽  
Hydroxyl Radicals ◽  
Nitrous Acid ◽  
Measurement Method ◽  
Oxidative Capacity ◽  
Sources And Sinks ◽  
Dynamic Chamber ◽  
Open Question ◽  
Actinic Radiation

<p>Nitrous acid (HONO) is an important component of the nitrogen cycle. HONO can also be rapidly photolyzed by actinic radiation to form hydroxyl radicals (OH) and exerts a primary influence on the oxidative capacity of the atmosphere. The sources and sinks of HONO, however, are not fully understood. Soil nitrite, produced via nitrification or denitrification, is an important source for the atmospheric HONO production. [HONO]*, the equilibrium gas phase HONO concentration over the soil, has been suggested as key to understanding the environmental effects of soil fluxes of HONO (Su et al., 2011). But if and how [HONO]* may exist and vary remains an open question. In this project, a measurement method using a dynamic chamber has been developed to derive [HONO]* and the atmospheric soil fluxes of HONO can accordingly be quantified. We demonstrate the existence of [HONO]* and determine its variation in the course of soil drying processes. We show that when [HONO]* is higher than the atmospheric HONO concentration, HONO will be released from soil; otherwise, HONO will be deposited on soil. This work advances the understanding of soil HONO emissions, and the evaluation of its impact on the atmospheric oxidizing capacity and the nitrogen cycling.</p>

Silica and silica–titania intercalated MCM-36 modified with iron as catalysts for selective reduction of nitrogen oxides – the role of associated reactions

2020 ◽  
Vol 10 (23) ◽  
pp. 7940-7954 ◽  
Author(s):  
Aleksandra Jankowska ◽  
Andrzej Kowalczyk ◽  
Małgorzata Rutkowska ◽  
Włodzimierz Mozgawa ◽  
Barbara Gil ◽  
...  
Keyword(s):  
High Temperature ◽  
Nitrogen Oxides ◽  
Selective Reduction ◽  
Fe Species

Fe-MCM-36 zeolites are effective catalysts for high-temperature NH3-SCR – their activity is related to effective NO to NO2 oxidation over Fe2O3 species, while high N2-selectivity is attributed to dispersed Fe-species active in N2O decomposition.

scholarly journals Boosting alkaline hydrogen evolution: the dominating role of interior modification in surface electrocatalysis

2020 ◽  
Vol 13 (9) ◽  
pp. 3110-3118 ◽  
Author(s):  
Zhao Li ◽  
Wenhan Niu ◽  
Zhenzhong Yang ◽  
Abdelkader Kara ◽  
Qi Wang ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Water Dissociation ◽  
Alkaline Solutions ◽  
Great Promise ◽  
Hydrogen Fuel ◽  
Practical Utilization

The alkaline hydrogen evolution reaction (A-HER) holds great promise for clean hydrogen fuel generation but its practical utilization is severely hindered by the sluggish kinetics for water dissociation in alkaline solutions.

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