Differences in transport behavior of natural soil colloids of contrasting sizes from nanometer to micron and the environmental implications Academic Article uri icon

abstract

  • Transport behaviors of nanoparticles (<100nm) and clay fractions (clay particles, <2μm; coarse clay particles, 1-2μm and fine clay particles, 0.1-1μm) extracted from two natural soils (Inceptisol from Jilin and Oxisol from Hainan, China) were investigated in saturated sand columns at 1-30mM NaCl and pH5-9. Increasing NaCl concentrations decreased the mobility, while increasing pH increased the mobility of soil particles of various sizes. At pH5 and 30mM NaCl, nanoparticles and clay fractions exhibited the different transport behaviors, and ripening was observed for Inceptisol nanoparticles while blocking for Oxisol nanoparticles in breakthrough curves (BTCs). The effluent mass recoveries (MRs) of nanoparticles were much more than that of clay particles for both two soils (>1.9-fold) at all tested conditions, except for Inceptisol at pH5 and 30mM NaCl (with comparable MR). According to Derjaguin-Landau-Verwey-Overbeek (DLVO) calculations and particle-collector size ratios, both secondary energy minimum and physical straining led to the retention of clay fractions at pH5 and 30mM NaCl, whereas primary energy minimum and straining induced by simultaneous aggregation caused the retention of nanoparticles. The experimental attachment efficiency between soil particles of various sizes and sand collector for both two soils was in the order nanoparticles

authors

  • Liu, Fei
  • Xu, Baile
  • He, Yan
  • Brookes, Philip C
  • Tang, Caixian
  • Xu, Jianming

publication date

  • 2018