Aqueous process intensification through enhanced oxygen mass transfer using oxygen vector: An application to cleaner leaching

Abstract

Intensification of chemical processes has surfaced many challenging but promising areas. Enhancement of Oxygen Mass Transfer (OMT) is one such area in aqueous chemical processes. Several attempts made to alleviate OMT limitation, however, remains futile in lowering energy and material requirement. In this regard, the use of n-Dodecane, an Oxygen Vector, could be a radically promising route for enhancing OMT. The present work explores the use of n-Dodecane (Oxygen Vector) for the enhancement of OMT, corroborated with the Classical Molecular Dynamic (MD) simulations. The results showed that 2.5% (v/v) n-Dodecane addition in aqueous systems (‘Na2SO3 solution – n-Dodecane’ and ‘H2O – n-Dodecane’) would lead to enhancement up to 750%. MD simulation results confirm the transfer of oxygen from n-Dodecane-to-aqueous medium with diffusivity of 10−8 m2/s, thus becomes the dominating route for the enhancement in OMT. In addition, it has been found that n-Dodecane fraction, temperature and the rate of oxygen consumption reaction are the dictating parameters for enhancement. The concept of Oxygen Vector for enhancing OMT has been successfully exploited for cleaner leaching of metals (>95 % Cu, Ni and Co) from refractory complex sulfides at moderate temperature-pressure conditions (T∼ 95 °C and pO2∼3 Bar), which would have otherwise been possible at T > 200 °C and pO2 > 10 Bar. In addition, recyclability of n-Dodecane, Oxygen Vector, in leaching system is an added advantage. Thus, this study offers a promising route in enhancing kinetics of oxidative aqueous processes and provides suggestive insights for lowering the material and energy requirements.