## 2 Research Status on Anhydrous Hydrazine Fuel
### Research Status on UDMH Fuel
It identified the rate constants and potential reaction products of UDMH degradation using the M06-2X/6-31G* method in solute electron density (SMD). The significance of OH in decontaminating organic pollutants by plasma was discussed, and the potential applications of plasma in treating UDMH-containing wastewater were highlighted. Further research is needed to fully understand the chemical kinetics of UDMH decomposition by plasma and its potential applications. [PERSON] et al. [94] described methods for detecting and quantifying toxic chemicals like UDMH. The authors highlight the importance of developing sensitive human health and safety methods. They recommend using solid-phase microextraction and gas chromatography-mass spectrometry with internal standards and standard addition methods to quantify UDMH transformation products accurately and precisely in soil on rocket launch sites. Overall, the studies provide valuable information for environmental monitoring and risk assessment related to rocket launches. [PERSON] et al. [95] studied the use of solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) to detect and quantify transformation products of rocket fuel unsymmetrical dimethylhydrazine (UDMH) in air samples. The study identified several essential transformation products of UDMH in air, including 1,1-dimethylhydrazine, formaldehyde, and acetaldehyde. The authors suggested that this method can help assess the environmental impact of rocket fuels and develop strategies to reduce their impact. However, they noted the need for further research to validate their method and understand the environmental fate and toxicity of UDMH transformation products. The study recommends several future research directions to improve our understanding of UDMH and its impact on human health and ecosystems. [PERSON] et al. [96] explored the analysis of both intermediate and final products of UDMH (Unsymmetrical dimethylhydrazine) to comprehend the formation of harmful by-products and degradation mechanisms. The investigation involved exposing UDMH solutions to O\({}_{3}\) and examining the resulting degradation samples using SPME-GC/MS. The authors established that the 65 mm PDMS/DVB SPME fiber coating is the most effective at detecting oxidative products of UDMH under certain conditions, at pH 7, a sampling time of 10 min, and a desorption time of 1 min. The study succeeded in identifying the intermediate and final products of UDMH following treatment with O\({}_{3}\). [PERSON] et al. [97] studied removing gas-phase unsymmetrical dimethylhydrazine using TiO\({}_{2}\)-reduced graphene oxide aerogel. The study found that moist conditions were conducive to removing gas-phase UDMH, and absorption on TiO\({}_{2}\)-rGA was exothermic. The TiO\({}_{2}\)-rGA showed higher UDMH conversion under UV and VUV light, and the high conversion in a continuous fixed bed reactor indicates the usefulness of this photocatalyst system in removing gas-phase UDMH in practice. The study also noted that chemical interactions and Schottky junction formed in TiO\({}_{2}\)-rGA account for the high charge separation and transmission efficiencies, which help improve catalytic performance. Furthermore, the study confirmed earlier findings regarding the reduction in GO and the slight increase in UDMH conversion to other organics with increased humidity. The article concludes that TiO\({}_{2}\)-rGA is a promising photocatalyst for removing UDMH. [PERSON] et al. [98] proposed using supercritical water gasification (SCWG) technology to process Unsymmetrical dimethylhydrazine (UDMH), a hazardous waste commonly used as a propellant for military and space programs. They conducted experiments to study the reaction pathways and kinetics of UDMH in supercritical water. They developed a kinetic model for forming gaseous products and ammonia-nitrogen. The study found that SCWG is a practical, resourceful, and harmless utilization technology for UDMH processing.