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Effect of Flow Rate and Particle Concentration on the Transport and Deposition of Bare and Stabilized Zero-Valent Iron Nanoparticles in Sandy Soil

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Department of Soil Science, College of Food and Agricultural Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia
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Department of Soils and Water, Faculty of Agriculture, Suez Canal University, Ismailia 41522, Egypt
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Author to whom correspondence should be addressed.
Sustainability 2019, 11(23), 6608; https://doi.org/10.3390/su11236608
Received: 11 November 2019 / Revised: 18 November 2019 / Accepted: 21 November 2019 / Published: 22 November 2019
Efficient application of nanoscale zero-valent iron (nZVI) particles in remediation processes relies heavily on the ability to modify the surfaces of nZVI particles to enhance their stability and mobility in subsurface layers. We investigated the effect of sodium carboxy-methyl-cellulose (CMC) polymer stabilizer, pH, particle concentration, and flow rate on the transport of nZVI particles in sand columns. Breakthrough curves (BTCs) of nZVI particles indicated that the transport of nZVI particles was increased by the presence of CMC and by increasing the flow rate. The relative concentration (RC) of the eluted CMC–nZVI nanoparticles was larger at pH 9 as compared to RC at pH 7. This is mainly attributed to the increased nZVI particle stability at higher pH due to the increase in the electrostatic repulsion forces and the formation of larger energy barriers. nZVI particle deposition was larger at 0.1 cm min−1 flow due to the increased residence time, which increases the aggregation and settlement of particles. The amount of CMC–nZVI particles eluted from the sand columns was increased by 52% at the maximum flow rate of 1.0 cm min−1. Bare nZVI were mostly retained in the first millimeters of the soil column, and the amount eluted did not exceed 1.2% of the total amount added. Our results suggest that surface modification of nZVI particles was necessary to increase stability and enhance transport in sandy soil. Nevertheless, a proper flow rate, suitable for the intended remediation efforts, must be considered to minimize nZVI particle deposition and increase remediation efficiency. View Full-Text
Keywords: nanoscale zero-valent iron nanoparticles (nZVI); carboxy-methyl-cellulose (CMC); transport; flow rate; sandy soil nanoscale zero-valent iron nanoparticles (nZVI); carboxy-methyl-cellulose (CMC); transport; flow rate; sandy soil
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Ibrahim, H.M.; Awad, M.; Al-Farraj, A.S.; Al-Turki, A.M. Effect of Flow Rate and Particle Concentration on the Transport and Deposition of Bare and Stabilized Zero-Valent Iron Nanoparticles in Sandy Soil. Sustainability 2019, 11, 6608.

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