Transport in Porous Media of Highly Concentrated Iron Micro- and Nanoparticles in the Presence of Xanthan Gum

Abstract

The ability of xanthan gum to act as a delivery vehicle for the transport in porous media of highly concentrated nano- and microscale zerovalent iron (NZVI and MZVI, respectively) slurries was investigated. Sand-packed column experiments were performed injecting iron suspensions at a concentration of 20 g/L, amended with xanthan gum (3 g/L), at different ionic strength values (6 x 10(-3) mM or 12.5 mM) in 0.46 m long columns. Breakthrough curves of iron, obtained by in-line continuous measurement of magnetic susceptibility, under each experimental condition showed that normalized elution concentration at the end of the injection (i.e., after 7 or 26 pore volumes) is higher for MZVI (>0.94) than for NZVI (>0.88). Additional susceptibility measurements along the column and pressure drop also confirmed that MZVI is more easily eluted than NZVI. Moreover, water flushing after the iron injection phase lead to recoveries of over 95% for MZVI, and over 92% for NZVI of the total injected iron mass. The tests proved that xanthan gum is an excellent stabilizing agent and delivery vehicle of ZVI particles and has a high potential for use in real scale remediation interventions.

Application of Nanoparticles in Enhanced Oil Recovery: A Critical Review of Recent Progress

“…As the solution pH approached the point of zero charge of nano-TiO 2 , the mobility and transport of nano-TiO 2 were limited due to the reduction of electrostatic interaction forces leading to the increase in the deposition rate coefficients. Vecchia et al [107] injected microscale zerovalent iron (ZVI) at a concentration of 20 g/L, amended with xanthan gum (3 g/L) in 0.46 m long columns. The tests proved that xanthan gum is an excellent stabilizing agent and delivery vehicle of ZVI particles.…”

Gum karaya (Sterculia urens) stabilized zero-valent iron nanoparticles: characterization and applications for the removal of chromium and volatile organic pollutants from water

“…6,7 Various natural and synthetic polymeric materials such as guar gum, xanthan gum, starch, agar agar, poly(acrylic acid) (PAA), Tween-20, polyelectrolytes (polystyrene sulphonate and polyaspartate), organic matter and CMC have been used to improve the stability, reactivity and mobility of NZVI in porous media. [8][9][10][11][12][13][14][15][16] These polymers can interact with NZVI particles and prevent aggregation by reducing particle-particle attractive forces which can increase repulsion between the particles and the porous medium. 3 Important properties such as stabilizing capacity and shear thinning exhibited by xanthan gum deemed the latter to be a suitable material for NZVI particle mobility and aggregation studies.…”

Delivery of vegetable oil suspensions in a shear thinning fluid for enhanced bioremediation

“…Owing to their shear thinning characteristics, these fluids can enhance the distribution of entrained amendments into lower permeability zones, thereby enhancing the remediation processes (Chokejaroenrat et al, 2013;Kananizadeh et al, 2015;Silva et al, 2013;Zhong et al, 2008Zhong et al, , 2011). STFs have been tested and applied as a means to deliver dissolved remedial amendments (Chokejaroenrat et al, 2013(Chokejaroenrat et al, , 2014Kananizadeh et al, 2015;Smith et al, 2008;Truex et al, 2015;Zhong et al, 2008Zhong et al, , 2011Zhong et al, , 2013 or reactive particles (Comba and Sethi, 2009;Dalla Vecchia et al, 2009;Oostrom et al, 2007;Tiraferri et al, 2008;Truex et al, 2011a,b) to the subsurface for the purpose of enhancing remediation effectiveness.…”