20 years of microwave technology developments using a coaxial antenna: From human health to green chemistry applications

The global interest on microwave assisted chemistry (MAC) is due to the important benefits for the sustainable growth of green chemical industries and environmentally friendly progress of society. MAC has been firstly developed using oven-type microwaves (MWs) assisted reactors, which requires difficult and expensive industrial scale-up. In 2002, the development of coaxial dipole antenna allowed a direct application of MWs in situ in the reaction media, opening a crucial, novel versatile technological solution, making MW-assisted processes feasible in any configuration at any industrial level. Here, we present an overview of the technological development of 20 years research using a coaxial MW antenna for green chemistry and human health applications. The major MW technology breakthroughs described in these short-review are: i) MW-induced thermoablation machine, ii) in situ MW heating in open glassware chemical reactors, iii) electrodeless MW/ultraviolet (UV) lamps and photoreactors, iv) MW-high pressure reactor and v) solventless/simultaneous MW/UV/ultrasound (US) configurations. Applications for the synthesis of nanocatalysts, nanoparticles and polymers, advanced oxidative decomposition photochemical processes, solvothermal extraction of valuable products and biomass processing are discussed. Remarks on the scaling up of the extraction processes and frontier applications addressed to the treatment of current and future outbreak pandemic emergences are also shown.