Robust system for the regenerative capture of aqueous pollutants with continuously synthesized and functionalized magnetic nanoparticles

Abstract

Nowadays, the design of efficient technologies for the detection and separation of environmental pollutants from aqueous solutions continues to be a challenge to the industrial sector. The present work proposes a robust microfluidic system for the continuous, rapid and effective testing of selective capture agents of aqueous pollutants based on the use of magnetic nanoparticles, MNPs. These are found of special interest due to their high specific surface area, easy functionalization and superparamagnetic behavior. In this work, MNPs with an average diameter of 8.8 ± 1.3 nm and amino-functionalization were obtained following a novel continuous synthesis that facilitated the control of the particles properties. The microfluidic capture of Cr(VI) from aqueous solutions was assessed as representative case study; followed by the successful regeneration of loaded MNPs. The obtained results prove the advantages of the proposed system: i) continuous synthesis of functionalized MNPs with rigorous size control, ii) selective and fast capture of the target compound depending on the particle?s functionalization and large surface area, respectively, ii) continuous operation that facilitates process scale-up, iii) easy regeneration of the functional materials, and iv) magnetic separation of MNPs from fluid media if needed. Furthermore, the calculated Cr(VI) maximum uptake is higher than obtained values for non-functionalized MNPs and is in the range of previously reported data for ion exchange resins, with the additional advantages already mentioned. Thus, this work constitutes a step forward in the methodological design of advanced systems with detection or separation purposes and can be extended to a wide variety of pollutants.