Rare earth elements (REE), originally found in various low-grade deposits in the form of different minerals, are associated with gangues that have similar physicochemical properties. However, the production of REE is attractive due to their numerous applications in advanced materials and new technologies. The presence of the radioactive elements, thorium and uranium, in the REE deposits, is a production challenge. Their separation is crucial to gaining a product with minimum radioactivity in the downstream processes, and to mitigate the environmental and safety issues. In the present study, different techniques for separation of the radioactive elements from REE are reviewed, including leaching, precipitation, solvent extraction, and ion chromatography. In addition, the waste management of the separated radioactive elements is discussed with a particular conclusion that such a waste stream can be employed as a valuable co-product.

Nanofiltration processes for the removal of emerging contaminants such as nitrate are a focus of attention of research works as an efficient technique for providing drinking water for people. Polysulfone (PSF) nanofiltration membranes containing graphene oxide (GO)/Pt (0, 0.25, 0.5, 0.75, 1 wt%) nanoparticles were generated with the phase inversion pathway. The as-synthesized samples were characterized by FTIR, SEM, AFM, and contact angle tests to study the effect of GO/Pt on hydrophilicity and antibacterial characteristics. The results conveyed that insertion of GO/Pt dramatically improved the biofouling resistance of the membranes. Permeation experiments indicated that PSF membrane embracing 0.75 wt% GO/Pt nanoparticles had the highest nitrate flux and rejection ability. The membrane’s configuration was simulated using OPEN-MX simulating software indicating membranes maintaining 0.75 wt% of GO/Pt nanoparticles revealed the highest stability, which is well in accordance with experimental outcomes.

A fluidized bed reactor that is operating in the bubbling regime has been developed for the conversion of bio-oils to syngas.The reactor consists of a 7.6 cm I.D. (or internal diameter) bed, with an expanded freeboard. The volume of the reactor can be adjusted to vary the gas residence time. This reactor has been used to carry out either thermal or catalytic cracking for reforming bio-oils.A gas-atomized injector has been specially developed to feed a bio-oil, which may be viscous and contaminated with small ash and char particles. Besides, the gas-atomized nozzle allows it to remain cool until coming in contact with the fluidized particles inside the bed.This article presents the product yields and compositions obtained by thermally cracking the bio-oil at various temperatures and gas residence times. The bed temperature was varied from 500 to 700 °C. Moreover, the vapor residence time ranged from 7.8 to 27.6 seconds.Also, the effect of particle size and mass of bed was investigated. Finally, based on this study, the conversion of bio-oil to gas increased with an increase in temperature and residence time.