Surface Characteristics Of Minerals Research Articles

Effect of a Natural Surfactant (Fenugreek Seeds) on Emulsification and Mobilization of Paraffins via Pore-Scale Micromodel Experiments.

The surface characteristics of minerals have been crucial in predicting the interactions between chemicals, particularly in chemical flooding. Thus, this paper evaluates the viability of natural surfactants derived from agricultural products for oil recovery studies using a micromodel filled with paraffinic oil. The study investigates the interfacial tension, viscosity, microscopic, dilution, and oil mobilization characteristics of the natural surfactants. The experimental setup involves conducting interfacial tension measurements between the surfactant solution and paraffinic oil using the Wilhelmy plate method and was found to be 14.2, 10.92, and 9.8 mN/m. Additionally, viscosity measurements and frequency sweep analysis were performed to assess the rheological properties of the prepared emulsion, which was stabilized using a natural surfactant. Microscopic evaluation depicts that, among the prepared emulsions, n-heptane emulsion seems more stable at both 30 and 90 °C. Moreover, dilution studies were conducted for each emulsion system, and the dilution ratio was varied from 1:5 to 1:1 (emulsion/saline solution). It was found that n-heptane emulsion possesses better stability at higher dilution (until a 3:5 ratio). Oil mobilization studies are conducted using a glass micromodel to simulate reservoir conditions and observe the displacement efficiency of the surfactant solutions. The results indicate that natural surfactants exhibit competitive interfacial tension reduction and viscosity modification properties compared to commercial surfactants. Furthermore, oil mobilization studies demonstrate the effectiveness of natural surfactants in enhancing oil recovery from paraffinic oil reservoirs. These findings suggest the potential of natural surfactants derived from agricultural products as sustainable alternatives for improving the oil recovery efficiency in petroleum reservoirs.

Contribution of surface silanization process on mechanical characteristics of TPU‐based composites involving feldspar and quartz minerals

AbstractIn this study, quartz and feldspar powders were surface treated using a silane coupling agent to achieve a more compatible mineral surface with the polymer matrix. Details of surface characteristics of minerals were examined by energy‐dissipative X‐ray spectroscopy, contact angle measurements, and infrared spectroscopy. Thermoplastic polyurethane‐TPU was compounded with minerals using the melt‐blending technique. Mechanical, thermo‐mechanical, melt‐flow, and morphological characterizations of TPU and relevant composites were performed by utilizing tensile and Shore hardness tests, dynamic mechanical analysis (DMA), melt flow index (MFI) measurements, and scanning electron microscopy (SEM), respectively. Water repellency of TPU and composites were also evaluated experimentally. Effects of surface treatments were discussed by comparing the results of composites filled with pristine and modified minerals. Results revealed that enrichment of quartz and feldspar surfaces confer mechanical and thermo‐mechanical performance of composites. Mineral inclusions caused no drastic changes to the MFI parameter of TPU. The silane layer on the mineral surface displayed a barrier effect to water uptake of composites. Homogeneous dispersion and improved interfacial adhesion of mineral particles to the TPU phase were confirmed with help of SEM observations. Quartz exhibited slightly higher performance thanks to its silica‐rich composition. The findings of this research exhibited the considerable influence of the silane layer on the mineral surface on the mechanical performance of TPU‐based composites.

A designed moderately thermophilic consortia with a better performance for leaching high grade fine lead-zinc sulfide ore

Unwieldy fine sulfide ores are produced during mining; without being appropriately disposed of, they can cause environmental pollution and waste resources. This study investigated the leaching performance of a moderately thermophilic consortia (Leptospirillum ferriphilum + Acidithiobacillus caldus + Sulfobacillus benefaciens) for fine lead-zinc sulfide raw ore. The results showed this microbial community created a low pH, high ORP, and high cell concentration environment for mineral leaching, improving bioleaching efficiency. Under the action of this consortia, the zinc leaching rate reached 96.44 in 8 days, and reached 100% after 12 days. EPS analysis indicated that the consortia could mediate the secretion of more polysaccharides to ensure leaching efficiency. EPS levels and amino acids were the main factors affecting bioleaching. An analysis of mineral surface characteristics showed the consortia effectively leached pyrite and sphalerite from the fine sulfide ore, and prevented the mineral surface forming the jarosite that could hinder bioleaching. This study found that bioleaching reduced the potential environmental toxicity of the minerals, providing an important reference for guiding the bioleaching of unwieldy fine sulfide raw ore.

Collecting Agent–Mineral Interactions in the Reverse Flotation of Iron Ore: A Brief Review

Froth flotation has been widely used in upgrading iron ores. Iron ore flotation can be performed in two technical routes: direct flotation of iron oxides and reverse flotation of gangue minerals with depression of iron oxides. Nowadays, reverse flotation is the most commonly used route in iron ore flotation. This review is focused on the reverse flotation of iron ores, consisting of reverse cationic flotation and reverse anionic flotation. It covers different types of collecting agents used in reverse iron ore flotation, the surface characteristics of minerals commonly present in iron ores (e.g., iron oxides, quartz, alumina-bearing minerals, phosphorus-bearing minerals, iron-bearing carbonates, and iron-bearing silicates), and the adsorption mechanisms of the collecting agents at the mineral surface. The implications of collecting agent–mineral interactions for improving iron ore flotation are discussed.

Mineral vs. organic matter supply as a limiting factor for the formation of mineral-associated organic matter in forest and agricultural soils

Physical and chemical interactions between soil organic matter (OM) and minerals is one of the primary mechanisms for stabilizing OM in terrestrial ecosystems. Focusing on OM association with mineral surfaces, this study sought to examine mineral-associated OM from the perspectives of both mineral surface characteristics and organic matter chemistry. The research was conducted at paired-sites under North American Mid-Atlantic Coastal forest and crop production with shared environmental factors. Using carbon (C) and nitrogen (N) 1s micro- X-ray absorption near-edge fine structure (XANES) spectroscopy, we investigated the amounts and types of mineral-associated OM. Mineral specific surface area (SSA) of bulk soil was determined for three conditions: untreated, post OM removal and post iron (Fe) (oxyhydr)oxides removal. Amounts of mineral-associated OM were smaller in the agricultural soil, where greater SSA sourced from clay-sized phyllosilicates and Fe (oxyhydr)oxide minerals did not result in greater OM coverage of the mineral surface area. Although agricultural surface soil showed less abundance of phenolic C, speciation of mineral-associated OM did not differ between comparable horizons. Our results suggest that despite the plow-derived mixing of soil, which increased SSA and secondary minerals available to interact physically and chemically with OM in the plowed layer, the formation of mineral-associated OM in agricultural soil is ultimately limited by available OM.

Surface chemistry and oleate flotation of three South Australian micaceous hematites

Previous surface chemical and flotation publications involving natural hematites have mainly focussed on the so-called massive hematites, but little has been published on the characteristics of micaceous or specular hematites which find specialist applications as pigment grade iron oxides. These include use in protective paints and as an additive in resin fillers. The surface chemistry and oleate flotation characteristics of three South Australian micaceous hematites (Warrakimbo, Williamstown and Iron Knob) have been examined using zeta potential, surface titration and oleate flotation techniques. The optimum technique for investigating the surface chemical properties as a function of pH was the surface titration technique, since inherent silica in the natural hematite samples can dominate the zeta potential measurements, even though it often represented less than 1% of the overall mineral assemblage. It was also found that both oleate solution chemistry and mineral surface characteristics dominated the flotation behaviour of these hematites. Maximum hematite recoveries were obtained at neutral pH values, close to the zero point of charge of the hematites. Chemisorption was confirmed as the dominant mechanism of oleate adsorption on the surface of the hematites.

Short-term effects of plant litter addition on mineral surface characteristics of young sandy soils

Initial stages of soil development are characterized by structural changes of mineral surfaces over time. The specific surface area (SSA) is closely related to pedogenic properties and soil organic matter (SOM). Interactions between SOM and mineral surfaces induce quantitative and qualitative changes in SSA and corresponding soil properties. However, the knowledge about ranges, effects and mechanisms of organic coverage in the very initial phase of pedogenesis is very limited. Therefore, our objective was to study these processes in young sandy soils and the effects of plant litter addition. Soil samples taken from the constructed catchment “Chicken Creek” were used in a microcosm experiment over 80weeks. The silt and clay fractions of samples (<63μm) were analyzed before the experiment and after 40 and 80weeks. The effects of litter addition and weathering on SSA were assessed using the BET-N2 sorption approach. We found increases of SSA between 16.4% and 41.6% within the 80week experimental period, but a relative reduction in SSA due to organic coverage of these new surfaces after plant litter addition. The removal of the soil organic matter (SOM) by muffling increased SSA (6.8–12.9%). The results for SSA corresponded to changes in surface specific parameters like cation exchange capacity (CEC), surface enthalpy and the fractional coverage of mineral surfaces by SOM. In conclusion, the results showed that the soils were clearly in a very initial state of soil development. However, the potential of these young sandy soils to adsorb nutrients and soil organic matter as one of the main important soil functions clearly increased within the relatively short experimental period and changes in SSA indicate relatively large increases in mineral surfaces within short time periods during the initial phase of soil development compared to long-term pedogenesis.

Fundamental Controls of Dissolution Rate Spectra: Comparisons of Model and Experimental Results

Real-time microscopic observations of reacting mineral surfaces have provided a significant advance in the understanding of mineral dissolution and growth. The kinetics of surfaces are often dominated by the distribution of defects, e.g., screw dislocations, that provide a critical means of sustaining step movement and kink creation that are fundamental to dissolution and growth processes. However, in natural settings, the discontinuities created by physical grain boundaries and contacts may constitute a critical contribution to “whole rock” reactivity, a point that has been recognized in the past. Because of the complex relationship between mineral surface characteristics such as area, roughness, and reactivity, this problem requires a modeling approach that examines the relationship between rate and surface morphology. This approach is relevant to the question of whether a critical size exists that is governed by surfaces kinetics, below which the reactivity of grains is dominated by contributions from boundary sites. We discuss these results in light of experimental observations of the statistical distribution of rates using the concept of rate spectra.

Adsorption of Dicarboxylic Acids by Clay Minerals as Examined by in Situ ATR-FTIR and ex Situ DRIFT

The adsorption of dicarboxylic acids by kaolinite and montmorillonite at different pH conditions was investigated using in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) and ex situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The sorption capacity of montmorillonite was greater than that of kaolinite. Adsorption of dicarboxylic acids (succinic acid, glutaric acid, adipic acid, and azelaic acid) was the highest at pH 4 as compared with those at pH 7 and 9. These results indicate that sorption is highly pH-dependent and related to the surface characteristics of minerals. The aliphatic chain length of the dicarboxylic acids highly influenced the sorption amount at acidic pH, regardless of the clay mineral species: succinic acid [HOOC(CH2)2COOH] < glutaric acid [HOOC(CH2)3COOH] < adipic acid [HOOC(CH2)4COOH] < azelaic acid [HOOC(CH2)7COOH]. With in situ ATR-FTIR analysis, most samples tend to have outer-sphere adsorption with the mineral surfaces at all tested pHs. However, inner-sphere coordination between the carboxyl groups and mineral surfaces at pH 4 was dominant from DRIFT analysis with freeze-dried complex samples. The complexation types, inner- or outer-sphere, depended on dicarboxylic acid species, pH, mineral surfaces, and solvent conditions. From the experimental data, we suggest that organic acids in an aqueous environment prefer to adsorb onto the test minerals by outer-sphere complexation, but inner-sphere complexation is favored under dry conditions. Thus, organic acid binding onto clay minerals under dry conditions is stronger than that under wet conditions, and we expect different conformations and aggregations of sorbed organic acids as influenced by complexation types. In the environment, natural organic material (NOM) may adsorb predominantly on positively charged mineral surfaces at the aqueous interface, which can convert into inner-sphere coordination during dehydration. The stable NOM/mineral complexes formed by frequent wetting-drying cycles in nature may resist chemical/microbial degradation of the NOM, which will affect carbon storage in the environment and influence the sorption of organic contaminants.

Mechanisms of uranyl sorption

Abstract Detailed knowledge of the reactions at the water/colloid/mineral interface is crucial to model accurately actinide behaviour in nature. In this paper, we review current knowledge of the sorption of actinides and of the mechanisms of sorption, with a particular focus on uranyl. Of major interest is the influence of the aqueous uranyl species (e.g., carbonate complexes, polynuclear species, colloids) on the uranyl sorption species. We present extended X-ray absorption fine structure (EXAFS) and X-ray photoelectron spectroscopy (XPS) studies on the coordination of uranyl onto an amorphous Al phase and onto quartz, respectively. Our XPS investigations show that two components having uranyl ions in very distinct coordination environments co-exist on quartz at high uranyl surface coverage, independently of the presence of uranyl carbonate complexes or uranyl colloids in solution. One component corresponds to polynuclear surface species and/or schoepite-like surface precipitates. In the case of similar uranyl concentrations and of high carbonate solution concentrations, polymeric uranyl species are formed on quartz, whereas no such surface species occurs on the Al phase. Uranyl is found on the Al phase as mononuclear uranyl carbonato surface complexes only. These results are of importance because they suggest that mineral surface characteristics strongly control the uranyl surface species in aquifers.

Mineral dissolution rates in plot-scale field and laboratory experiments

Mineral dissolution rates were measured on identical mineral material in field and laboratory experiments. Field dissolution rates were measured in 6 small (2 m 2) plots on a spodosol in eastern Maine, U.S.A. The plots were irrigated with HCl at pH's 2, 2.5 and 3; soil solutions were collected by tension lysimeters at 25-cm depth. The composition of the soil solutions, together with the grain-size distribution and mineralogy of the soil, were used to calculate mineral dissolution rates. Laboratory dissolution experiments were performed on the 75–150-μm size fraction of soil from the site in flow-through reactors at pH-values corresponding to the pH of the bulk soil solution. The use of small plots and “untreated” minerals from the same plots eliminates many of the uncertainties encountered in previous field-laboratory comparisons. Dissolution rates observed in the field, normalized on the basis of geometrical mineral surface area, were smaller than laboratory rates by a factor of ∼200–400. The discrepancy can be explained by a number of factors. The major reason is probably imperfect contact between soil minerals and percolating solution. Macropore flow or limited exchange between water in micropores and the bulk soil solution could reduce the mineral surface area participating in the dissolution process. Retention of water in micropores could result in elevated pH-values and solute concentrations (particularly Al) near the mineral surface, resulting in lower dissolution rates. Differences in mineral surface characteristics between field and laboratory experiments can be largely excluded as a reason for the observed discrepancy since identical mineral material was used in both sets of experiments. However, part of the discrepancy might be explained by the dissolution rate not scaling with geometrical surface area.

Influence of Temperature and Mineral Surface Characteristics on Feldspar Weathering Rates in Natural and Artificial Systems: A First Approximation

Rates of alkali feldspar hydrolysis in the near‐neutral pH range are up to 3 orders of magnitude slower in natural systems than in laboratory experiments. Correcting for differences in temperature between natural weathering and laboratory systems reduces the disparity by as much as a factor of 5. Any remaining disparity can be accounted for by differences in the ratio of effective surface area to total surface area; the ratio of effective‐to‐total surface area in natural systems is generally considerably smaller than in laboratory systems. This may be related, at least in part, to experimental preparation artifacts and to the fact that naturally weathered feldspars have lost much of their most reactive surface to the formation of etch pits. Hydrological factors such as inhomogeneous access of percolating fluids to mineral surfaces may also reduce the proportion of mineral surface area reacting in natural systems.

Influence of temperature and mineral surface characteristics on feldspar weathering rates in natural and artificial systems - a first approximation

Influence of temperature and mineral surface characteristics on feldspar weathering rates in natural and artificial systems - a first approximation