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Chemical Rocket Propellants
Published in D.P. Mishra, Fundamentals of Rocket Propulsion, 2017
In UDMH [(CH3)2N2H2], two hydrogen atoms in hydrazine are substituted with two methyl radicals. Although it is the least efficient of the hydrazine derivatives as it has the lowest freezing point (215.9 K), higher boiling point (336.5 K), and has enough thermal stability to be used in large regenerative cooled engines. It is widely used with oxidizer N2O4 as it is more stable than hydrazine. It is used routinely in several countries like India, China, and Russia. However, UDHM is commonly used as blended fuel along with hydrazine. For example, Aerozine 50 is a mixture of 50% UDMH and 50% hydrazine, which has been used in lunar landing and takeoff engines. Aerozine 50 is almost as stable as UDMH and provides better performance.
What Are Rockets?
Published in Travis S. Taylor, Introduction to Rocket Science and Engineering, 2017
The Long March family of rockets shown in Figure 1.22 has been in evolution since the 1970s and is mostly derivatives of the Dong Feng ICBMs. In English, the rocket nomenclature for the Long March rockets is sometimes an LM and sometimes a CZ. More commonly, the CZ seems to be used for some reason. The rockets typically use liquid propellants, such as unsymmetrical dimethylhydrazine (UDMH) and a tetroxide (dinitrogen tetroxide) oxidizer. The rockets range in capabilities from small payloads for LEO to heavy payloads for GEO.
Preparation and characterization of graphene oxide/O-carboxymethyl chitosan (GO/CMC) composite and its unsymmetrical dimethylhydrazine (UDMH) adsorption performance from wastewater
Published in Environmental Technology, 2023
Jun Su, Ying Jia, Ruomeng Hou, Yuanzheng Huang, Keke Shen, Zhaowen Hao
Unsymmetrical dimethylhydrazine (UDMH, (CH3)2NNH3) is a high-energy liquid rocket propellant with good performance [1]. The large amount of UDMH wastewater generated by its leakage and emergency disposal poses a major threat to the environment and humans. UDMH can lead to carcinogenic, mutagenic, convulsive, teratogenic, embryotoxic, and other adverse consequences [2]. Hence, UDMH is known as a highly dangerous toxic substance with the maximum permissible concentration in ambient water as low as 0.02 mg · L−1 [3]. Therefore, the removal of UDMH is highly significant and desirable.
A novel CWPO/H2O2/VUV synergistic treatment for the degradation of unsymmetrical dimethylhydrazine in wastewater
Published in Environmental Technology, 2021
Xu Meng, Pingchuan Zeng, Junru Wang, Yamin Shao, Min Wu, Henmei Ni, Yingping Zheng, Yueming Sun
As one of the liquid fuels widely used as a high energy propellant in present various strategic missiles and spacecraft launches due to its good thermal stability, large combustion heat and high specific impulse, unsymmetrical dimethylhydrazine (UDMH, (CH3)2NNH3) is planned to stay in use for the next 25–50 years [1–4]. Despite the fact inclining the use of greener and more ecological rocket fuels in space and defense programmes, the consumption of UDMH is estimated to continuously increase in the future decades owing to its unique physicochemical characteristics in contrast to the solid propellants [1,5,6]. What’s more, in some developing countries, UDMH/Trioxide system is still used as the major liquid fuel for rockets and missiles because of the high heat of combustion and specific pressure of UDMH [7], and a large amount of polluted wastewater will be produced after launching rockets and missiles. In addition, UDMH is now a common contaminant in wastewater [8] and is also a primary eco-toxicant which can accumulate in natural ecosystems and evolve into other highly toxic products while decomposing. For example, exposed to natural conditions, UDMH is spontaneously oxidized to some toxic substances. An important one of them is called as NDMA, a refractory toxic compound with acute carcinogenic and mutagenic properties [9]. It has been declared by the U.S. Environmental Protection Agency (USEPA) [10] that NDMA is a probable human carcinogen posing a cancer risk associated with a concentration of 0.7 ng L–1 in drinking water determined during the UDMH treatment process without UV or VUV irradiation [11–13]. It is commonly produced in the process of catalytic wet peroxide oxidation with hydrogen peroxide as an oxidant in the presence of Cu, Fe, Co salts supported on carriers as catalysts [14,15]. Therefore, the maximum permissible concentration for UDMH in ambient water is as low as 10–5 g L–1 [9].
Reversible photochromic photocatalyst Bi2O3/TiO2/Al2O3 with enhanced visible photoactivity: application toward UDMH degradation in wastewater
Published in Journal of Environmental Science and Health, Part A, 2020
As the propellant of launch vehicles, 1,1-dimethylhydrazine (UDMH) is widely used in the launch tests of satellites, spacecraft and other military devices.[1] In the process of spacecraft launch, engine testing, storage and transportation, a large amount of UDMH waste is often generated. UDMH and its by-products, such as N-nitrosodimethylamine (NDMA),[1,2] are considered carcinogenic toxins[3] and represent a serious health hazard to the population once present in water under natural conditions without treatment. UDMH is known as a primary eco-toxicant with a maximum permissible concentration in water as low as 0.02 mg·L–1.[4] There are many conventional treatment methods for wastewater containing UDMH, which can be classified as physical, chemical and biological methods. The physical treatment with activated carbon or ion exchange requires a post-treatment to separate UDMH and regenerate the adsorbent or ion exchange resin, which can consume a large amount of energy. Chemical methods, such as H2O2/O3/UV, catalytic oxidation of Cu, Fe and Co salts combined with H2O2/O3 (i.e., heterogeneous Fenton) are trapped in order to continue to produce O3, resulting in high energy consumption and high operating costs.[5] Moreover, O3 will corrode equipments, and selectively oxidizes organics, which cannot completely mineralize pollutants. Biological methods have been developed to treat UDMH-containing wastewater, including plant and microbiological methods.[6] However, the tolerance concentration of water hyacinth to UDMH is only about 75 mg·L–1. The microbial method requires longer reaction times and, as a result, could not meet the demand for treating higher concentrations of UDMH in wastewater. Furthermore, NDMA is formed as a highly toxic intermediate with these methods. Recently, hydrodynamic cavitation[7,8] was developed to remove UDMH from wastewater. Although it avoids the generation of NDMA and other toxic by-products in the treated samples, high energy is still needed to form high pressure gas bubbles in the liquid and then explosively develop to collapse.