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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.

Crystallization fouling in heat exchangers, subsurface energy production, and membrane technology remains a challenge. The reactive crystallization process is governed by whether growth or nucleation dominates the precipitation process. However, there is little direct experimental evidence on the fundamentals of nucleation and growth on surfaces over a wide range of supersaturations. We investigated the crystallization fouling of BaSO4 at 10 different supersaturations (saturation ratios from 6.6 to 457.1). We show that deposition behavior changes from a growth-dominated regime to a nucleation-dominated regime as the supersaturation increases; these changes in the dominant regime affect the resilience of the surface deposits. At low supersaturations, crystals have a secondary order, which increases their surface resilience. At high supersaturations, where nucleation processes dominate, crystals aggregate on the surface with no discernible secondary structure. At a saturation ratio of 457, nucleation processes are accelerated, causing previously aggregated crystals to become isolated. Due to increased isolation, the crystal resilience decreases, and the crystals become more vulnerable to detaching from the surface. To characterize surface deposition, we introduced the sticking factor as a measure of the stickability. We present an analysis of the stickability of BaSO4, CaCO3, and CaSO4, based on published data, and observe mean sticking factors of 1.15%, 0.80%, and 0.11%, respectively.

Carbon Storage in geological media has been widely considered as a solution to reduce the environmental footprints of anthropogenic emissions of CO2 from point sources. The depleted hydrocarbon chalk fields in the Danish North Sea are potential candidates for carbon storage1 , as they comprise a significant pore volume and many are approaching the final stages of production lifetime. To develop cost effective and insignificant risk CO2 storage solutions in depleted hydrocarbon chalk reservoirs and to unlock the main storage potential in Denmark a new multidisciplinary CO2 storage research program2 has been initiated at the Danish Offshore Technology Centre. The scope for CO2 storage in carbonate reservoirs is potentially large as carbonate reservoirs, including limestones, dolomites and chalks, comprise one of the most prevalent types of hydrocarbon reservoir worldwide. However, the geochemical response of chalk and other fractured and layered carbonate rocks to CO2 and the geomechanical consequences must be investigated carefully to de-risk a storage scenario. The research program includes modelling studies covering a wide range of coupled simulations including chemical reactions and transport phenomena at different length scales. In addition, the program comprises laboratory experiments on core flooding at representative reservoir temperature and pressure condition, geochemical analyses and geomechanical tests under similar in-situ conditions. The chemical processes that can take place at the surface of the rock in contact with natural formation water and dissolved CO2 can lead to potential reservoir changes, both upon injection and over time. CO2 may be injected as supercritical CO2 in which case solvation of the gas will take place upon contact with the formation water in place, or it may be injected in the form of carbonated water which will lead to a direct acidi

The addition of dairy ingredients (buttermilk powder and/or sodium caseinate) to the cheese feed before spray drying, as well as the age of the cheese used as raw material on reconstitution behavior of cheese powder without emulsifying salt were studied. Cheese powders made with addition of 2% sodium caseinate plus 2% buttermilk powder showed increased wettability and the lowest amount of fat on the surface, but a delayed dispersibility. Powders made using only buttermilk powder (4%) and powders produced with 45 weeks old cheese exhibited faster dispersibility, but reduced total rehydration. Reconstituted powders produced with 16 weeks old cheese showed the best total rehydration. The amount of surface fat, lactose, and protein interactions with water in the cheese casein network are pointed to be the main reasons for the differences observed, as they affect particle size distribution or ability of the powder components to interact with the water.

Polymeric microfluidic chips offer a number of benefits compared to their glass equivalents, including lower material costs and ease and flexibility of fabrication. However, the main drawback of polymeric materials is often their limited resistance to (organic) solvents. Previously, thiol-ene materials were shown to be more solvent resistant than most other commonly used polymers; however, they still fall short in “harsh” chemical environments, such as when chlorinated solvents are present. Here, we show that a simple yet effective treatment of thiol-ene materials results in exceptional solvent compatibility, even for very challenging chemical environments. Our approach, based on a temperature treatment, results in a 50-fold increase in the chloroform compatibility of thiol-enes (in terms of longevity). We show that prolonged heat exposure allows for the operation of the microfluidic chips in chloroform for several days with no discernable deformation or solvent-induced swelling. The method is applicable to many different thiol-ene-based materials, including commercially available formulations, and also when using other commonly considered “harsh” solvents. To demonstrate the utility of the solvent compatible thiol-enes for applications where chloroform is frequently employed, we show the continuous and uniform production of polymeric microspheres for drug delivery purposes over a period of 8 hours. The material thus holds great promise as an alternative choice for microfluidic applications requiring harsh chemical environments, a domain so far mainly restricted to glass chips.

Interactions between organic molecules in aqueous environments, whether in the fluid phase or adsorbed on solids, are often affected by the cations present in the solution. We investigated, at nanometre scale, how surface carboxylate interactions are influenced by dissolved divalent cations: Mg2+, Ca2+, Sr2+ and Ba2+. Self assembled monolayer (SAM) surfaces with exposed terminations of alkyl, -CH3, carboxylate, -COO- or dicarboxylate, -DiCOO-, were deposited on gold coated tips and substrates. We used atomic force microscopy (AFM), in chemical force mapping (CFM) mode, to measure adhesion forces between various combinations of SAMs on the tip and substrate, in solutions of 0.5 M NaCl, that contained 0.012 M of one of the divalent cations. The type of cation, the number of carboxyl groups that interact and their structure on the SAM influenced adhesion between the surfaces. The effect of the reference solution, which only contains Na+ cations, on adhesion force was mainly attributed to van der Waals and hydrophobic forces, explaining lower force in systems that are more hydrophilic, i.e., -COO--COO-, and higher force for more hydrophobic systems. For charged surfaces, i.e., -COO- and -DiCOO-, in divalent cation solutions, results were consistent with ion bridging. The inclusion of a hydrophobic surface, i.e., the -CH3-COO- or -CH3-DiCOO- system, decreased the possibility for strong cation bridging with the charged surface, resulting in lower adhesion. For systems including -COO-, the adhesion force series followed the inverse cation hydrated radius trend (Na+~ Mg2+

An understanding of the mechanisms that control the adsorption of organic molecules on clay minerals is of interest in several branches of science and industry. Oil production using low salinity injection fluids can increase yields by as much as 40% over standard injection with seawater or formation water. The mechanism responsible for the low salinity response is still debated, but one hypothesis is a change in pore surface wettability. Organic contamination in soil and drinking water aquifers is a challenge for municipal water suppliers and for agriculture. A better understanding is needed for how mineral species, solution composition and pH affect the desorption of low molecular weight organic ligands from clay minerals and consequently their wettability. We used X-ray photoelectron spectroscopy under cryogenic conditions to investigate the in situ composition in the mineral–solution interface region in a series of experiments with a range of pH and ion concentrations. We demonstrate that both chlorite and kaolinite release organic molecules under conditions relevant for low salinity water flooding. This release increases with a higher solution pH but is only slightly affected by the character of the organic ligand. This is consistent with the observation that low salinity enhanced oil recovery correlates with the presence of chlorite and kaolinite. Our results indicate that the pore surface charge and salinity of formation water and injection fluids are key parameters in determining the low salinity response. In general, our results imply that clay mineral surface charge influences the composition in the interface through an affinity for organic molecules.

The wettability of mineral surfaces controls a range of phenomena in natural and industrial processes. In reservoirs, rock wettability determines the effectiveness of oil production; thus, modification of mineral surface properties can lead to enhanced oil recovery. Recent work reports that potential determining ions in seawater, Mg2+, Ca2+, and SO42–, are responsible for altering the wettability of calcite surfaces. In favorable conditions, e.g., elevated temperature, calcium at the calcite surface can be replaced by magnesium, making organic molecules bind more weakly and water molecules bind more strongly, rendering the surface more hydrophilic. We used atomic force microscopy in chemical force mapping mode to probe the adhesion forces between a hydrophobic CH3-terminated AFM tip and a freshly cleaved calcite {10.4} surface to investigate wettability change in the presence of Mg2+ and SO42– at 75 and 80 °C. We made submicrometer scale maps of adhesion force and contact angle and demonstrated that the adhesion force between the hydrophobic tip and calcite decreases when both Mg and SO4 are present. Surface analysis with X-ray photoelectron spectroscopy showed Mg associated with calcite even after rinsing with CaCO3-saturated deionized water, suggesting sorption on or in calcite. When the calcite-saturated solution of MgSO4 was replaced by calcite-saturated NaCl at the same ionic strength, adhesion force increased again, indicating that the effect is reversible and suggesting Mg replacement by Ca. Experiments with solutions of Na2SO4 and MgCl2 suggest that Mg2+ uptake is favored when SO42– is also present

Laboratory core flood and field scale tests have demonstrated that 5–40% more oil can be released from sandstone reservoirs by injecting low salinity water, rather than high salinity fluids, such as seawater or formation water. The effect has been explained by a change in wettability of the minerals that form the pore surfaces, as a result of the decrease in divalent cation concentration. We have previously demonstrated that, even for solvent cleaned core samples, mineral surfaces retain a significant quantity of carbon containing material and this affects wettability and response to changed salinity. Here we quantified the response of sandstone core plug material in its preserved state (i.e., after storage in kerosene) and after the same core plug material was treated with ethanol and ozone to remove adsorbed organic compounds. We used the chemical force microscopy (CFM) mode of atomic force microscopy (AFM) to directly measure the adhesion force for two types of molecules on pore surfaces of individual sand grains that were plucked from an oil reservoir core plug. We functionalized AFM tips with alkane or carboxylate, so they resembled tiny oil droplets and measured adhesion to the sand grain surfaces in artificial seawater (ASW; 35,600 ppm) and in ASW diluted to ∼1,500 ppm (ASW-low). Both before and after the ethanol/ozone treatment, and for both the alkane and the carboxylate functionalized tips, the adhesion was lower in ASW diluted to ∼1,500 ppm than in ASW. For both alkane and carboxylate, the difference in adhesion between ASW and ASW-low was higher before the ethanol/ozone treatment. We attribute this change in response to the salinity dependent force caused mainly by the electric double layer (EDL) at the sand grain surfaces. We interpret the higher adhesion difference, before a very thorough ethanol/ozone treatment, to be a result of the loss of the organic material that was originally adsorbed on these surfaces, which adds to the charge density and there

Graphene oxide (GO) is believed to become applicable in biomedical products and medicine, thereby necessitating appropriate safety evaluation dependent on their applications and the route of administration. We have examined the effect of GO form (in solution versus immobilized) and oxidation state on two related elements of innate immunity: the complement system and interleukin-6 (IL-6) release in human blood. In solution, there was a decrease in GO-mediated complement activation with decreasing surface oxygen content (and altered oxygen functionality), whereas with immobilized GO complement response were reversed and increased with decreasing oxygen content. GO solutions, at concentrations below complement activating threshold, did not induce IL-6 release from human blood leukocytes, and further dampened lipopolysaccharide-induced IL-6 release in the whole blood. The latter effect became more profound with GO's having higher oxygen content. This protective role of GO solutions, however, disappeared at higher concentrations above complement-activating threshold. We discuss these results in relation to GO surface structure and properties, and implications for local administration and development of GO-based implantable devices.