Enhanced transport of ferrihydrite colloid by chain-shaped humic acid colloid in saturated porous media

Jie Ma; Huaming Guo; Mei Lei; Yongtao Li; Liping Weng; Yali Chen; Yuling Ma; Yingxuan Deng; Xiaojuan Feng; Wei Xiu

doi:10.1016/j.scitotenv.2017.10.070

Enhanced transport of ferrihydrite colloid by chain-shaped humic acid colloid in saturated porous media

Sci Total Environ. 2018 Apr 15:621:1581-1590. doi: 10.1016/j.scitotenv.2017.10.070. Epub 2017 Oct 18.

Authors

Jie Ma¹, Huaming Guo², Mei Lei³, Yongtao Li⁴, Liping Weng⁵, Yali Chen⁵, Yuling Ma⁵, Yingxuan Deng⁵, Xiaojuan Feng³, Wei Xiu⁶

Affiliations

¹ State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China; Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, PR China; College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, PR China; Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, PR China.
² State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China. Electronic address: hmguo@cugb.edu.cn.
³ Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, PR China.
⁴ College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, PR China; Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, PR China.
⁵ Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, PR China.
⁶ State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.

PMID: 29054659
DOI: 10.1016/j.scitotenv.2017.10.070

Abstract

Both humic acid and colloid particle size effectively regulate colloid transport. However, little is known about effect of particle size and configuration of humic acid colloid (HA_colloid) on enhanced-transport of ferrihydrite colloid (FH_colloid) in porous media. Co-transport of HA_colloid and FH_colloid at different pH was systematically investigated by monitoring breakthrough curves (BTCs) in saturated sand columns. The colloid transport model and the (X)DLVO theory were used to reveal the mechanism of HA_colloid-enhanced FH_colloid transport in the columns. Results showed that HA_colloid enhanced FH_colloid transport in neutral and alkaline conditions. In neutral conditions, small HA_colloid (F-HA_colloid) with chain-shaped structure enhanced FH_colloid transport more prominently than pristine granular HA_colloid. The chain-shaped F-HA_colloid caused osmotic repulsion and elastic-steric repulsion between colloids and sand, leading to enhanced transport. However, the granular HA_colloid readily occurred as deposition due to attachment and straining, which decreased the enhanced transport of FH_colloid. In alkaline conditions, both HA_colloid and F-HA_colloid were chain-shaped, with longer chains of HA_colloid than F-HA_colloid. Ferrihydrite colloid transport was enhanced by HA_colloid more significantly than F-HA_colloid due to stronger repulsion between mixed HA_colloid-FH_colloid and sand. It suggested that regulation of particle size and morphology of HA_colloid would enhance FH_colloid transport and further help in understanding FH_colloid-facilitated contaminants transport in porous media.

Keywords: Ferrihydrite colloid; Humic acid colloid; Morphology; Transport; XDLVO.