This review covers extensively the synthesis & surface modification, characterization, and application of magnetic nanoparticles. For biomedical applications, consideration should be given to factors such as design strategies, the synthesis process, coating, and surface passivation. The synthesis method regulates post-synthetic change and specific applications in vitro and in vivo imaging/diagnosis and pharmacotherapy/administration. Special insights have been provided on biodistribution, pharmacokinetics, and toxicity in a living system, which is imperative for their wider application in biology. These nanoparticles can be decorated with multiple contrast agents and thus can also be used as a probe for multi-mode imaging or double/triple imaging, for example, MRI-CT, MRI-PET. Similarly loading with different drug molecules/dye/fluorescent molecules and integration with other carriers have found application not only in locating these particles in vivo but simultaneously target drug delivery/hyperthermia inside the body. Studies are underway to collect the potential of these magnetically driven nanoparticles in various scientific fields such as particle interaction, heat conduction, imaging, and magnetism. Surely, this comprehensive data will help in the further development of advanced techniques for theranostics based on high-performance magnetic nanoparticles and will lead this research area in a new sustainable direction.

The extensive use of lithium-ion batteries (LIBs) has generated a huge amount of their wastes. As waste, LIBs can be used as a source for valuable metals such as lithium, cobalt, manganese, and nickel. Like the ores of these metals, their values are recognized as raw material. This can ultimately help bring down the cost of LIB production while reducing their harmful environmental impacts. As a result, recycling has become a major opportunity for industrialists and a challenge to environmentalists all across the globe. Researchers have explored various methods to recover cobalt and lithium precious metals from worn out batteries. This review provides an overview of the recent technological solutions on the recovery from waste LIBs using organic acids-based hydrometallurgical processes concerning chemical reactions, structures, and leaching efficiency with different organic acids. Subsequently, the advantages of organic acids over inorganic acid have also been discussed with an emphasis on possible complex formations during the recovery process. At last, the potent role of process variables: reductant concentration, reaction time, temperature, solid:liquid ratio, and concentration of complexing agent during the Co and Li leaching has been discussed along with prospects in this research area. Graphical abstract