Agar agar improves stability and mobility of milled ZVI used in groundwater remediation

Autor(en)

Doris Schmid, Vesna Micic Batka, Milica Velimirovic, Frank von der Kammer, Thilo Hofmann

Abstrakt

Submicron-scale milled zerovalent iron (milled ZVI) particles produced by grinding macroscopic raw material could provide a cost-effective alternative to nano-scale zerovalent iron particles for in situ groundwater remediation. Application of particles for in situ remediation requires optimal particle delivery to the contaminated zone, which is influenced both by the injection technique and the mobility of the particles in the subsurface.
Milled ZVI has shape of a flake with a lateral size of several micrometers and a thickness of less than 100 nm. Bare milled ZVI particles aggregate fast in aqueous suspension and remain immobile in the subsurface [1]. In order to improve mobility of milled ZVI particles in the subsurface, an optimal stabilization of the particle suspension was required.

Potential of different polymers (agar agar, carboxymethyl cellulose, guar gum, starch and lignin sulfonate) to increase the stability of milled ZVI suspension was firstly tested. Based on the outcomes of a detailed characterization of such modified suspensions in terms of particle size, zeta potential, particle sedimentation rate and suspension viscosity, agar agar was selected as the most efficient stabilizer.

Mobility of agar agar-stabilized milled ZVI suspension was then tested in flow-through columns packed with porous media with different texture and mineralogical composition. Agar agar-stabilized suspension of milled ZVI showed a considerably higher mobility potential compared to that of pure aqueous suspensions where no breakthrough was observed. Particle breakthrough in the stabilized suspension varied between 0.84 and 0.97. The particle breakthrough observed for various porous media depended on the sediment texture, while the geochemical heterogeneity within the sediments had only a minor impact.

References
[1] Köber R, Hollert H, Hornbruch G, Jekel M, Kamptner A, Klaas N, Braun J. Nanoscale zero-valent iron flakes for groundwater treatment. Environmental Earth Sciences, 72 (2014) 3339–3352.

Acknowledgement
This research was conducted within the framework of the European Union NanoRem project (FP7 - Grant Agreement Nr. 309517).

Organisation(en)

Publikationsdatum

2016

ÖFOS 2012

104023 Umweltchemie, 104002 Analytische Chemie, 105906 Umweltgeowissenschaften, 210004 Nanomaterialien

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/agar-agar-improves-stability-and-mobility-of-milled-zvi-used-in-groundwater-remediation(5dfa8c30-99a0-45fe-8d12-34b6aee990ac).html