scholarly journals Extracellular Polymeric Substances Facilitate the Adsorption and Migration of Cu2+ and Cd2+ in Saturated Porous Media

Biomolecules ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1715
Author(s):  
Yuhui Wu ◽  
Zhengyu Li ◽  
Yuesuo Yang ◽  
Diane Purchase ◽  
Ying Lu ◽  
...  
Keyword(s):  
Porous Media ◽  
Quartz Sand ◽  
Extracellular Polymeric Substances ◽  
Heavy Metal Contamination ◽  
Ph Value ◽  
Fate And Transport ◽  
Saturated Porous Media ◽  
Binding Force ◽  
Adsorption Behaviors ◽  
And Migration

Heavy metal contamination in groundwater is a serious environmental problem. Many microorganisms that survive in subsurface porous media also produce extracellular polymeric substances (EPS), but little is known about the effect of these EPS on the fate and transport of heavy metals in aquifers. In this study, EPS extracted from soil with a steam method were used to study the adsorption behaviors of Cu2+ and Cd2+, employing quartz sand as a subsurface porous medium. The results showed that EPS had a good adsorption capacity for Cu2+ (13.5 mg/g) and Cd2+ (14.1 mg/g) that can be viewed using the Temkin and Freundlich models, respectively. At a pH value of 6.5 ± 0.1 and a temperature of 20 °C, EPS showed a greater affinity for Cu2+ than for Cd2+. The binding force between EPS and quartz sand was weak. The prior saturation of the sand media with EPS solution can significantly promote the migration of the Cu2+ and Cd2+ in sand columns by 8.8% and 32.1%, respectively. When treating both metals simultaneously, the migration of Cd2+ was found to be greater than that of Cu2+. This also demonstrated that EPS can promote the co-migration of Cu2+ and Cd2+ in saturated porous media.

Transport and deposition of suspended particles in saturated porous media: effect of hydrodynamic forces and pore structure

2016 ◽  
Vol 16 (4) ◽  
pp. 951-960 ◽  
Author(s):  
Pengyuan Zhang ◽  
Bing Bai ◽  
Sichen Jiang ◽  
Pengcheng Wang ◽  
Huile Li
Keyword(s):  
Porous Media ◽  
Pore Structure ◽  
Flow Rate ◽  
Quartz Sand ◽  
Recovery Rate ◽  
Suspended Particles ◽  
Hydrodynamic Forces ◽  
Glass Beads ◽  
Saturated Porous Media ◽  
Longitudinal Dispersivity

In order to investigate the effects of pore structure and hydrodynamic forces on particle transport and deposition, an experimental study on the transport and deposition of suspended particles (SP) in saturated porous media (quartz sand and glass beads) was conducted under five different flow velocities at room temperature (22–25 °C). Silt particles with a mode of 10.7 μm diameter and fluorescein (as the dissolved tracer (DT)) were injected into the columns in short pulses. The SP transfer parameters were compared to the DT one. All the parameters (dispersivity, recovery rate, and deposition rate) obtained from the breakthrough data varied with the flow rate. The breakthrough curves were well described by an analytical solution of the advective–dispersive equation with a first-order deposition kinetic. The results showed that the transport of the SP was faster than the DT when the flow velocity reached a critical value which was different between the glass beads and quartz sand. The mean diameter of the recovered particles and the longitudinal dispersivity increase with flow rate; In addition, the recovery rate of SP is higher in the glass beads than in the quartz sand even under similar porosities. This study highlights the significance of pore structure and hydrodynamic forces in transport and deposition processes of SP.

scholarly journals Transport of Microplastic Particles in Saturated Porous Media

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2474 ◽  
Author(s):  
Xianxian Chu ◽  
Tiantian Li ◽  
Zhen Li ◽  
An Yan ◽  
Chongyang Shen
Keyword(s):  
Porous Media ◽  
Glass Bead ◽  
Fate And Transport ◽  
Breakthrough Curves ◽  
Polystyrene Latex ◽  
Order Kinetic ◽  
Saturated Porous Media ◽  
Convection Diffusion ◽  
Convection Diffusion Equation ◽  
First Order

This study used polystyrene latex colloids as model microplastic particles (MPs) and systematically investigated their retention and transport in glass bead-packed columns. Different pore volumes (PVs) of MP influent suspension were first injected into the columns at different ionic strengths (ISs). The breakthrough curves (BTCs) were obtained by measuring the MP concentrations of the effluents. Column dissection was then implemented to obtain retention profiles (RPs) of the MPs by measuring the concentration of attached MPs at different column depths. The results showed that the variation in the concentrations of retained MPs with depth changed from monotonic to non-monotonic with the increase in the PV of the injected influent suspension and solution IS. The non-monotonic retention was attributed to blocking of MPs and transfer of these colloids among collectors in the down-gradient direction. The BTCs were well simulated by the convection-diffusion equation including two types of first-order kinetic deposition (i.e., reversible and irreversible attachment). However, this model could not well simulate the non-monotonic retention profiles due to the fact that the transfer of colloids among collectors was not considered. The results in this study are critical to developing models to simulate the fate and transport of MPs in porous media such as soil.

COUPLING FINITE ELEMENTS APPLIED TO HYDRAULIC ANALYSIS IN SATURATED POROUS MEDIA

2019 ◽  
Author(s):  
Murilo Camargo ◽  
Pedro Cleto ◽  
Eduardo Alexandre Rodrigues ◽  
Heber Agnelo Antonel Fabbri ◽  
Osvaldo Luís Manzoli
Keyword(s):  
Porous Media ◽  
Finite Elements ◽  
Saturated Porous Media ◽  
Hydraulic Analysis
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