We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Fate and cotransport of Pb(II) and Cd(II) heavy ions with bentonite colloidal flow in saturated porous media: The role of filter cake, counter ions, colloid concentration, and fluid velocity
Summary
Researchers studied how colloidal bentonite clay particles transport lead and cadmium heavy ions through porous sand, simulating conditions near oil and gas drilling waste sites. They found that the formation of an external filter cake significantly delayed heavy ion breakthrough and reduced outlet concentrations of cadmium and lead by 86% and 93% respectively. The study suggests that colloid-mediated transport is a key mechanism for heavy metal migration in contaminated groundwater environments.
This study examines the transport and retention of colloidal particles and heavy ions in porous sand, focusing on the environmental risks associated with waste from oil and gas drilling. Experimental and numerical models assess the influence of flow rate, external filter cake layer, and ionic strength on bentonite clay particles and heavy ions, such as cadmium (Cd) and lead (Pb), in near-wellbore (high-flux) and far-field (low-flux) scenarios. Colloidal filtration theory and the one-dimensional convection-dispersion equation with two-site kinetic model for attachment and detachment were utilized to calibrate and predict the transport of colloidal suspension in porous media. The research investigates the role of internal and external filter cakes on sand column pressure distribution and heavy ion absorption. Results indicate that the mobility of colloids and heavy ions is influenced by the ionic strength and pH of the carrying fluid. Colloidal clay suspensions show a higher affinity for Pb (II) absorption, while Cd (II) exhibits increased mobility in both clean sand and colloidal environments. Notably, the formation of an external filter cake significantly delays the breakthrough of heavy ions, up to four times longer than in clean sand, and reduces Cd (II) and Pb (II) outlet concentrations by 86% and 93%, respectively. This cake also limits clay concentration and particle size passage. High clay concentrations or injections under high ionic conditions induce clay bridging in pore throats, enhancing internal filtration and heavy ion retention. Conversely, low clay fluxes allow freer particle passage, increasing heavy ion loads and outlet concentrations.
Sign in to start a discussion.
More Papers Like This
Influence of Soil Colloids on Ni Adsorption and Transport in the Saturated Porous Media: Effects of pH, Ionic Strength, and Humic Acid
Soil colloids — tiny particles naturally suspended in soil water — were found to significantly influence the transport of nickel through saturated sandy media. The presence of colloids increased nickel mobility, and the effect varied with pH, ionic strength, and humic acid content. Understanding colloid-facilitated metal transport is important for assessing how nickel and other heavy metals spread from contaminated sites into groundwater.
Transport and deposition of microplastic particles in saturated porous media: Co-effects of clay particles and natural organic matter
Researchers performed column experiments to study how clay particles and natural organic matter affect microplastic transport through saturated porous media, finding that both colloids reduced MP mobility through heteroaggregation and that their combined presence produced the greatest reduction in transport.
Experimental Confirmation of the Interception History Paradigm for Colloid (Micro and Nanoparticle) Transport in Porous Media
Laboratory experiments confirmed the interception history paradigm for colloid filtration under chemically unfavorable conditions, demonstrating that microplastics and other colloidal particles follow predictable deposition patterns in porous media—providing mechanistic data relevant to modeling MP transport through soils and aquifers.
Transport characteristics of DNA-tagged silica colloids as a colloidal tracer in saturated sand columns; role of solution chemistry, flow velocity, and sand grain size
Researchers evaluated DNA-tagged silica colloids as environmental tracers in saturated sand columns and found their transport behavior closely matched conventional colloid transport theory, validating their use for tracking subsurface water flow and contaminant pathways.
Effects of clay minerals on the transport of nanoplastics through water-saturated porous media
Column experiments with clay-containing saturated porous media showed that clay minerals reduced nanoplastic transport by enhancing particle retention through bridging flocculation and charge neutralization, with kaolinite having greater retention effects than montmorillonite, informing predictions of nanoplastic mobility in clay-rich soils.