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Pollution Sources and Drinking Water Protection
Published in Rong Yue, Fundamentals of Environmental Site Assessment and Remediation, 2018
Nitrates (NO3−) and nitrites (NO2−) are two of the nitrogen-oxygen compounds that are used by plants and animals and eventually return to the air as nitrogen gas. Bacteria in soil and plants use oxygen to change nitrite into more stable nitrate, which can be converted back to nitrite by other bacteria when oxygen is lacking. In nature, plants use nitrate as an essential nutrient. Nitrate and nitrite salts completely dissolve in water. In commerce, the majority of nitrate is used in inorganic fertilizers. Nitrate and nitrite are also used in food preservation, some pharmaceutical drugs, and the production of munitions and explosives.
Salt Decay and Salt Mixtures in the Architectural Heritage: A Review of the Work of Arnold and Zehnder
Published in International Journal of Architectural Heritage, 2022
A final note for a particular situation of crystal growth in salt efflorescence, the so-called multiphase crystal intergrowth, which results in saline deposits composed of different types of salts. This type of case is discussed in a 2001 article by Christine Bläuer Böhm, Andreas Küng and Konrad Zehnder, with acknowledgments to Andreas Arnold for his support and feedback (Bohm et al. 2001). In the article, the authors identify four possible types of intergrowth, parallel crystal growth (in which whiskers of two or three salt species grow parallel to each other), sequential crystal growth (in which alternate sections of two distinct salt species arise in a same whisker crystal), multiphase aggregates (crusts in which a secondary salt species grows in the interstices between the crystals of the preponderant species) and crystals with solid inclusions (in which minute inclusions of a secondary salt species are present in the whiskers of the preponderant species). Cases of intergrowth, involving nitratine, niter, halite or epsomite, were observed by these authors in several monuments in Switzerland and Germany.
The use of seawater in mining
Published in Mineral Processing and Extractive Metallurgy Review, 2018
Luis A. Cisternas, Edelmira D. Gálvez
The natural deposits of nitrates or saltpeter are called caliche (Wisniak and Garces, 2001). This mineral is a conglomerate of various mineralogical species that in a high proportion are soluble in water at room temperature, being the most abundant: polyhalite, glauberite, bloedite, gypsum, and anhydrite (sulfates), halite (chloride) and nitratine, humberstonite and darapskita (nitrates). On the other hand, there are lautarita and hectorfloresite (iodates) and some chromates and perchlorates, which are in small proportions. The insoluble species (approximately 60% to 70%) that the caliche also contains are mainly quartz and other silicates (Valencia et al., 2008). The Caliche exploitation is concentrated in Northern Chile, in the Atacama Desert, and produces mainly natural sodium nitrate (a fraction then is converted into potassium nitrate) and iodine (approximately 22,000 t/year).
Solidification of simulated sodium nitrate liquid wastes and ion-exchange resins by sodium silicate-activated slag cements
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Nailia R. Rakhimova, Ravil Z. Rakhimov, Vladimir P. Morozov, Ludmila I. Potapova, Yury N. Osin
In this paper, the feasibility of solidifying nitrate solutions with concentrations of 300–700 g/L and ion-exchange resins saturated with 300–700 g/L nitrate solutions using alkali-activated slag was analyzed. The properties of the fresh and hardened pastes, the hydration products, and the microstructures of the solidified waste forms were studied. The following conclusions were reached: The AASC-based mineral matrix was suitable for the efficient solidification of nitrate solutions with concentrations of up to 700 g/L. AASC activated by NSH9 with 5% of Na2O led to acceptable setting times, and the compressive strengths of solidified waste forms that had been cured for 28 d were in the range of 33.6–41 MPa.Precipitation of NaNO3 on the surface of GGBFS partially blocks hydration and structure formation in the GGBFS-NSH9-NaNO3 system, slightly decreases the compressive strengths of the wasteforms, and decreases the quantities of the reaction products.NaNO3 precipitates in the form of nitratine NaNO3, which does not react chemically with the AASC paste mineral matrix. The main reaction products in the GGBFS-NSH9-NaNO3 system are C-(A)-S-H, calcite CaCO3, hydrotalcite, calcium silicate hydrate C-S-H (I) (CaO.SiO2.H2O), and calcium silicate hydrate (Ca1.5.SiO3.5.H2O).AASC-based matrices are feasible for use in solidification of nitrate ion-exchange resins with concentrations of up to 35%. The waste forms exhibited 28 d compressive strengths of up to 25.1 MPa, depending on the volume content of resins and the concentration of the saturated nitrate solution.