Hydrazine (Bio) synthesis and separation: Advances, state-of-the-art methods, and patent review

Abstract Hydrazine (N 2 H 4 ) is a highly versatile industrial compound valued for its energetic properties, ease of oxidation, and chemical activity, making it indispensable in various applications such as rocket fuel. Currently, industrial-scale production of N 2 H 4 relies solely on chemical processes. In nature, anaerobic ammonium oxidation (anammox) bacteria have the unique ability to synthesize N 2 H 4 in their metabolism, adding an interesting dimension to N 2 H 4 production. Recent studies revealed that anammox bacteria could be considered a potential alternative bioenergy resource for N 2 H 4 . On the other hand, since N 2 H 4 is produced at low concentrations in chemical reaction mixtures, numerous separation techniques have been investigated for this purpose and many patents have been filed over the years. Despite the extensive research on N 2 H 4 , there is a notable lack of comprehensive review studies, particularly focusing on N 2 H 4 separation methods. Besides, advancements in N 2 H 4 production routes have not been systematically reviewed in over a decade. Furthermore, there are currently no established methods for extracting N 2 H 4 from biological systems. Within these frameworks, this review first highlighted advances in N 2 H 4 (bio)production and separation processes, emphasizing critical aspects such as efficiency, safety, and technological progress. Then, several separation methods were suggested for extracting N 2 H 4 from biological matrices, considering separation approaches used in chemical reaction mixtures and synthetic wastewater compositions employed in N 2 H 4 biosynthesis. This review provides valuable insight into the detailed, historical, holistic, and up-to-date analysis of hydrazine research, spanning its production methods to separation techniques, for researchers and various industries. Graphical Abstract