Stabilization of Iron (0) in plasma treated semi porous polylactic acid based particles for in situ groundwater remediation

Abstract

This study aims at incorporating reactive zero valent iron (ZVI) nanoparticles into water dispersible, biodegradable polymeric particles acting as a slow release reservoir of ZVI for targeting groundwater contaminants in situ. In order to accomplish the goal, three simple steps were adopted such as: 1) electrojetting of PLA (polylactic acid) with FeCl3 (∼17 wt%) to yield ∼700 nm sized monodisperse spherical particles (PLA_FeCl3) 2) surface modification of PLA_FeCl3 particles using oxygen plasma to enhance surface hydrophilicity and porosity (∼ 75%) 3) reduction of plasma treated PLA_FeCl3 particles in presence of NaBH4 to produce ZVI (size: 20–50 nm) entrapped PLA particles (PLA_ZVI) with high encapsulation efficiency of iron (∼85%). The plasma treated semi-porous PLA_ZVI particles exhibited slow and sustain release of iron (∼90% in ∼100 hrs) that were further employed to completely decontaminate both methyl orange (hydrophilic dye) and trichloroethylene (hydrophobic waste). Interestingly, the plasma treated particles were recyclable up to fourth batch, whereas the non-plasma treated one hardly show any recyclability due to burst release of surface entrapped iron from the latter. Moreover, the plasma treated hydrophilic particles provided stable dispersion (96 hrs) and prolonged reactivity (∼10 days in sand column) in water as opposed to non-plasma treated particles displaying 1 min dispersion stability in water. As a result, the plasma treated particles displayed smooth transportability through sand column (>80%) with negligible attachment efficiency (α = 1.1) onto sand particles. These attributes make them a potential alternative to bare ZVI (transportability <20%) for targeting hazardous pollutants by injecting them in groundwater.