Kinetic removal of Cr⁶⁺ in aqueous solution by carboxymethyl cellulose-stabilized nano zero-valent iron particles

Abstract

Carboxymethyl cellulose (CMC) was used in the chemical reduction method for producing dispersible nano zero-valent iron (nZVI) particles served as reactive, mobile and convenient adsorbent. CMC-stabilized nZVI particles at CMC:Fe2+ = 0.0034 molar ratio were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) assisted with probe ultrasonication dispersing tool. FTIR depicted that the CMC monomers were adsorbed onto nZVI particles primarily through carbonyl head groups via monodentate bonding. The botryoidally clusters were the predominant morphology of CMC-stabilized nZVI particles under SEM observation. Those spherical particles were evenly dispersed at sizes less than 100 nm under TEM analysis. nZVI particles stabilization with CMC (at CMC:Fe2⁺ molar ratio of 0.005) prevented the aggregation and resulted in high catalytic reactivity observed at pseudo-first order constant value, K1 of 0.0196 min1 for Cr⁶⁺ removal in aqueous solution. This study demonstrates that CMC-stabilized nZVI particle has the potential to become an effective agent for in situ subsurface environment remediation.