Cotransport of heavy metals and SiO2 particles at different temperatures by seepage

The Promotion/Inhibition of the Seepage Transport of Copper Ions by Suspension-Colloidal Particles with Wide Size Gradation

“…The powdered copper nitrate was blue crystals in rhombic flakes and had a relative molecular mass of 187.56, and a stable copper ion solution could be readily prepared by adding water to it. To form stable chelate compounds, ethylenediaminetetraacetic acid (EDTA, C 10 H 16 N 2 O 8 ) was used as an extractant; this compound can extract heavy metal ions in soil with an efficiency of more than 99% [23,49,50]. The disodium salt of ethylenediaminetetraacetic acid (EDTA-2Na, C 10 H 14 N 2 Na 2 O 8 ) could be prepared to improve the solubility of EDTA in water.…”

“…For the case of copper ion injection alone (marked by black symbols in Figure 3), the effluent concentration was almost independent of the seepage velocity (e.g., as shown by a comparison of the data corresponding to the velocities of 0.087 cm/s and 0.173 cm/s). Compared to other heavy metal ions (e.g., Cr 2+ and Pb 2+ ), copper ions (Cu 2+ ) are very soluble in water and weakly adsorbed to the porous medium matrix [23,49]; its movement did not differ much from that of the water flow. However, in the presence of the SPs, the concentration of copper ions in the effluent generally slightly increased with increasing seepage velocity.…”

“…Thus far, many researchers have studied the influences of dif-ferent types of suspended matters (e.g., montmorillonite colloid, humic acid, and silicon powder (SP)) on the seepage migration of Pb and Cd, concluding that suspended particles can promote the transport of these heavy metal ions under certain conditions [19,20], with specific occurrence conditions given in some literature [21,22]. Bai et al [23] discussed the influence of suspended particles on the migration of lead ions in porous media under pulse injection, showing that the existence of suspended particles promotes the migration of lead ions and that this promoting effect changes significantly with changes in particle size; they attributed this finding to the socalled "size exclusion effect." In fact, the promoting effect of suspended particles gradually diminishes after their size exceeds a certain threshold, and the presence of heavy metal ions inhibits the transport of suspended particles to a certain extent, suggesting a coupling mechanism between the two.…”

The Healing Process of the Joints between Buffer Material Blocks and the Influence on Solute Migration

“…An important function of the buffer material is to block the migration of pollutant solutes. is study is based on the assumptions that solute migration does not affect the THM field (via a one-way coupled process) and occurs on a considerably longer time scale than heat conduction and Advances in Civil Engineering seepage [32,33]. erefore, the calculated results for solute migration are analysed in a separate section.…”

A Displacement‐Based Theory for Predicting the Support Force on the Shield Tunneling Surface in Sandy Soil Layers

“…Besides, similar researches also explored the induced pore water pressure in a saturated loose granular stratum during the construction of a shield tunnel using a coupled water-solid finite element model. Many scholars have studied the coupling effect of multiple physical fields to consider the influence of various complex factors on soil stress, such as the loadingunloading effect, seepage force, and the environmental temperature change caused by seasonal variation or in the process of excavation [22,23] and established relevant constitutive laws as well as the soil particle movement models by seepage [24][25][26]. Overall, the existing research shows that there is rarely a complete calculation theory of excavation surface support force based on displacement evolution.…”