Properties Of Minerals Research Articles

Effect of energy input on surface properties and dispersion of diaspore and kaolinite in flotation process

Fluid strengthening and interfacial regulation are two important means to improve the flotation recovery of fine minerals. The fluid strengthening process often affects the surface properties of minerals and thus the dispersion of minerals. The effects of energy input on the dispersion and surface properties of kaolinite and diaspore were investigated in this work. The dispersion of minerals was examined through optical observation, turbidity measurement, and particle size analysis. The surface properties of minerals were characterized by measuring the zeta potential and the contact angle. Micro-flotation was used to test the effect of energy input on flotation performance. The findings revealed that increasing energy input resulted in improved particle dispersion, reduced hetero-coagulation, modified surface properties of minerals, and facilitated the separation of kaolinite and diaspore. This research would provide theoretical and technical support for the flotation of diasporic bauxites.

Application of AFM on Identifying Mechanical Properties of Individual Minerals and Surface Properties of Crack with High Resolution in Shale

Improving the resolution and accuracy of the mechanical properties of organic-rich shale is very important. The results can reveal the mechanical properties of shale from micro scale and serve as a guide for the design of hydraulic fracture optimization parameters. This study introduced an advanced technique to obtain the mechanical properties of shale with high resolution (58.6 nm/pixel) by combining SEM, EDS, and Atomic Force Microscopy (AFM). To locate the target area in SEM and AFM accurately, a positioning technique that uses special distributions of pyrite was established. AFM PeakForce QNM mode was selected due to its advantages at capturing topography and mechanical properties in material. Results illustrated the ability of AFM to obtain the mechanical properties (modulus) of individual mineral components in shale, the detailed topography of crack, and mechanical properties of minerals in a specific area. In particular, the mechanical properties of minerals around crack explained the layered distribution of minerals around the fractures, and the cracks developed in the clay mineral layer was detected. This article demonstrates the great potential application of AFM in shale.

Environmental impacts on the structural integrity of British rhodoliths

Coralline algae form complex habitats which are biodiversity hotspots. Experimental studies suggest that climate change will decrease coralline algal structural integrity. These experiments, however, lack information on local morphological variability and how much structural change would be needed to threaten habitat formation. Here, using finite element modelling, we assess variability in cellular structure and chemical composition of the carbonate skeleton of four coralline algal species from Britain in contemporary and historical specimens collected over the last 130 years. Cellular and mineral properties are highly variable within species, between sites and through time, with structurally weaker cells in the southern species and contemporary material compared to northern taxa and historical material. Yet, temporal differences in strength were smaller than spatial differences. Our work supports long term experiments which show the adaptation potential of this group. Our results suggest that future anthropogenic climate change may lead to loss of habitat complexity in the south and expansion of structurally weaker southern species into northern sites.

Improved Bond Strength Performance of Geopolymer Mortars: Role of High Volume Ground Blast Furnace Slag, Fly Ash, and Palm Oil Fuel Ash Incorporation

Alkali-activated binders have become popular in the construction industry for their eco-friendly attributes. Various wastes from industries and agricultural sectors containing high concentrations of aluminosilicate and calcium oxides can be used to design these binders. This study evaluated the effect of high-volume granulated blast furnace slag, fly ash, and palm oil fuel ash additions on the bond strength performance of the proposed geopolymer mortars. Various levels of slag (50, 60, and 70%) and fly ash were substituted by palm oil fuel ash to determine the impact of SiO2:Al2O3, CaO:SiO2, and CaO:Al2O3 and their proportions on the geopolymerization process and the strength performance of the designed mortars. The bond strength performance of the mortars was assessed in terms of slant shear, flexural, and splitting tensile strength tests. The mineral properties of the designed mortars were obtained using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared measurements. The incorporation of fly ash and palm oil fuel ash in the mortars caused a considerable decrease in the CaO:SiO2 and CaO:Al2O3 ratios, thus reducing the geopolymerization process and strength performance. The reduction in slag from 70% to 50% was counterbalanced by the increasing content of fly ash and palm oil fuel ash, which led to a drop in the compressive strength from 97 MPa to 56 MPa. In each level of slag, the replacement of fly ash by up to 10% palm oil fuel ash added more loss in strength values. In addition, the surface morphology of prepared mortars with lower palm oil fuel ash content was significantly enhanced, indicating the presence of less porosity and unreacted particles. The achieved mortars were asserted to be extremely well matched with the concrete substrates, offering effective binders for widespread construction uses.

Performance of Thermal-, Acid-, and Mechanochemical-Activated Montmorillonite for Environmental Protection from Radionuclides U(VI) and Sr(II)

Low-cost sorption materials based on the clay mineral of the smectite group—montmorillonite—were used for the removal of radionuclides uranium (VI) and strontium (II) from contaminated water. A wide range of industrial methods such as thermal treatment, acid activation, and mechanochemical activation were applied. Complex methods, such as SEM microscopy analysis, X-ray powder diffraction (XRD), thermal analysis, and nitrogen adsorption–desorption at −196 °C, were used to assess the characteristics of the structure of the obtained materials. The thermal treatment, acid activation, and mechanochemical activation resulted in changes in the surface properties of the clay minerals: specific surface area, porosity, and distribution of active sites. It was established that the mechanochemical activation of montmorillonite significantly increases the sorption characteristics of the material for U(VI) and Sr(II) and the acid activation of montmorillonite increases it for U(VI). The appropriateness of the experimental adsorption values for U(VI) and Sr(II) on modified montmorillonite to Langmuir and Freundlich models was found. Independently of the changes induced by acid attack, calcinations, or milling, the sorption of U(VI) and Sr(II) ions on treated montmorillonite occurs on a homogeneous surface through monolayer adsorption in a similar fashion to natural montmorillonite. Water purification technologies and modern environmental protection technologies may successfully use the obtained clay-based sorbents.

Adsorption features of pigments onto iron oxides: Co-effect of the molecular structure of adsorbates and the varied surface properties of minerals

The knowledge about the adsorption properties of pigments onto different iron oxide minerals is still limited. The adsorption behaviors of three typical pigments, including amaranth (AR), tartrazine (TA), and brilliant blue (BB), onto three iron oxides (ferrihydrite, goethite, and hematite) were investigated. The primary mechanism of their interactions was the electrostatic attraction. The affinities of iron oxides toward any pigment were generally in the sequence of ferrihydrite > goethite > hematite (e.g., the maximum adsorption amounts (qmax) of AR onto the three iron oxides were 35.5 mg/g, 11.6 mg/g, and 4.2 mg/g, respectively), which was related to the differences in physicochemical properties of minerals (e.g., specific surface area, surface hydroxyl density, and crystal structure). Interestingly, for a given iron oxide, the pigment-binding capacity of the mineral was in the order of AR > TA > BB. This effect was attributed to variations in pigment molecular sizes and electrostatic interactions between pigments and minerals. The pigment-binding capabilities of iron oxides changed as the solution pH varied. Hydrogen-bonding and electrostatic interactions were the main mechanisms below and above pH > pHPZC (pH value at zero point charge), respectively. Furthermore, adding Cu2+ facilitated pigment adsorption, mainly stemming from the surface-bridging effect. Pigments also enhanced Cu2+ adsorption onto iron oxides due to the decreasing electrostatic repulsion between Cu2+ and particles as well as the complexion between Cu2+ with pigment molecules adsorbed on mineral surfaces. The insightful information demonstrates that ubiquitous iron oxide minerals can affect the fate of pigments in natural environments.

Effects of surfactant with different injection times on asphaltene adsorption behaviors on the kaolinite surfaces: A molecular simulation study

The adsorption behavior of asphaltenes on the mineral surfaces seriously reduces oil recovery, which is dependent on the molecular structure, surface properties of the inorganic minerals, and the injection time of chemicals. In the present study, the molecular dynamics (MD) simulation is performed to construct the asphaltene-kaolinite adsorption systems and the 3-(N,N-Dimethyloctadecylammonio) propane sulfonate (DOPS) surfactant flooding systems to explore the effect of DOPS injection times on the detachment of asphaltene aggregates with discrepant adsorption characteristics. The number density distribution and the interaction analysis between asphaltene and kaolinite are employed to evaluate the adsorption behaviors of asphaltene on the kaolinite-liquid interfaces. The radial distribution function (RDF) describes the relative positions of the surfactants and asphaltene aggregates. The effective free energy and the independent gradient model based on Hirshfeld partition (IGMH) method further illustrate the microscopic mechanism of asphaltene detaching by the surfactant. The simulation results indicate that intensely polar carboxylate groups and polyaromatic rings with π-conjugated structures dominate the adsorption behavior of asphaltenes. The DOPS surfactants injected after the water flooding are difficult to produce effective ways of detaching asphaltenes, while the introduced DOPS surfactants during water flooding can generate DOPS-ASPn combinations to detach asphaltene from the kaolinite surfaces. This work first investigates the effects of surfactants with different injection times on the oil detachment efficiency at a molecular scale, further deepening the understanding of oil detachment process via surfactant flooding.

Molecular dynamics simulation of the influence of doping on the water absorption characteristics of kaolinite

The large amount of water adsorbed by clay minerals in argillaceous rocks upsets the balance of the microstructure, causing large deformation and failure of the rock surrounding deep mining roadways when they encounter water. The many impurities in natural clay minerals, and the electronegativity of the system caused by doping, greatly promote the adsorption of water. Grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) methods were both used to simulate the water adsorption characteristics of kaolinite to study the effects of doping elements of different valency and the pressure on water molecules in kaolinite particles, and the extent to which these affect the adsorption conformation, relative concentration distribution, adsorptive capacity, adsorption site, the heat of adsorption and adsorption energy of the water molecules on the surface of kaolinite particles. The molecular mechanism of microscopic interactions between doped kaolinite and water molecules is illustrated. It was found that at a temperature of 25 °C and a pressure of 10 MPa, water molecules are adsorbed on the surface of kaolinite in two layers. The heat of adsorption is 1.899–2.128 kJ/mol, which is far below the critical value of 42 kJ/mol for chemical adsorption. The interaction between kaolinite and water molecules is typical of physical adsorption. The absorption energy is negative, and the system is thermodynamically stable after kaolinite absorbs water. The variation of adsorption energy values is similar to the variation pattern of absorptive capacity, and both increase logarithmically with increasing pressure; doping causes both to decrease. Doping enhances the interaction between the kaolinite surface and water molecules, promoting the adsorption of water molecules on the kaolinite surface. This work explores the adsorption behavior of water molecules on the doped kaolinite surface from a microscopic perspective, and provides a theoretical foundation for further research on the deterioration of engineering properties of kaolinite-like clay minerals in contact with water.

A Soil Hydraulic Conductivity Equation Incorporating Adsorption and Capillarity

A soil’s hydraulic conductivity is a highly nonlinear function of water content, decreasing many orders of magnitude from its saturated state to dry state. This nonlinearity is a macroscopic manifestation of microscopic soil properties of pore structure, pore connectivity, and mineral–water interaction. These microscopic soil properties are underpinned by two distinct soil–water interaction mechanisms: adsorption and capillarity. Herein, a soil hydraulic conductivity equation was developed by incorporating capillary pore flow and adsorptive film flow. The capillary pore flow is captured via a model of bundle of cylindrical capillaries, whereas the adsorptive film flow is established using a film thickness function incorporating adsorption mechanisms of the electric double layer, van der Waals, surface hydration, and cation hydration potentials. The transition between adsorptive film flow and capillary flow is delineated by a water cavitation probability function. The proposed soil hydraulic conductivity equation automatically can fulfill the five necessary physical constraints imposed by underlying soil–water interaction characteristics. The proposed hydraulic conductivity equation can capture the hydraulic conductivity data very well for a wide array of soils, and outperforms several established soil hydraulic models in full matric potential ranges, especially in the low matric potential range in which adsorptive film flow is dominant.

Performance analysis of vapor compression refrigeration system using varying concentrations of copper oxide (CuO)/mineral oil (MO) based nanosuspension

The nanofluid is being utilized for more than a decade to improve the theocentric properties of various thermal systems. In the presented work, the copper oxide (CuO) nanoparticle suspension is utilized to improve the performance of the vapor compression refrigeration system. Mineral oil is utilized as the base fluid for the synthesis of CuO-based nanosuspension. The nanosuspension is synthesized with a concentration of 0.02 wt%, 0.04 wt% and 0.06 wt%. For the refrigeration system, R600a refrigerant is used. The experimental analysis is carried out in two phases. In the first phase of the experimental analysis, the CuO-based nanosuspension is synthesized and the thermophysical properties such as thermal conductivity, specific heat, and density are evaluated. In the second phase, the synthesized nanosuspension has been incorporated into the refrigeration system. The performance parameters such as COP, power consumption, and pull-down time are investigated using R600a/MO/CuO-based nanosuspension. From the first phase of the experimentation, it is concluded the CuO nanoparticle significantly enhances the thermophysical properties of the pure mineral. A significant gain in thermal conductivity and density is noted along with a reduction in the specific heat of the pure mineral oil. Similarly, from the second phase of the experimentation, it observed that the higher average gain in the COP by 30.2%, reduction of power consumption by 12.53%, and reduction in pull down time is noted by using 0.06 wt% of CuO-MO-based nanosuspension.

Characterization of some clay deposits in southwest Nigeria for use as supplementary cementitious material in cement

Supplementary cementitious materials (SCMs) contribute to the properties of concrete through pozzolanic and hydraulic activities. Clay is an SCM used to replace part of clinker to reduce cost, CO2 emission, and make concrete durable. Nigeria has deposits of clay with pozzolanic potential when calcined and in finely divided form, thus, reducing the overdependence on Ordinary Portland Cement in concrete production. The chemical, mineral, morphology, calcination efficiency and physical properties were analyzed using X-ray fluorescence (XRF), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), Thermogravimetric analysis (TGA/DTA), particle size distribution, Brunauer–Emmett–Teller (BET), and specific surface area (SSA) by nitrogen adsorption methods. The Strength activity index (SAI) of calcined clay samples from Owode-Ketu (OK), Imotoyewa (IM), and Ifonyintedo (IF), in Ogun state-Nigeria were investigated. Compressive strength was determined by partially replacing cement in steps of 10 wt% from 0 − 40 wt% in a mortar test. Results revealed that IF clay has the highest plasticity with 52% of clay content, and the plasticity Index of 27%. Kaolinite was the dominant mineral with values greater than 35 wt% on the XRD trace, consistent with BET values above 31.22 m2/g. The oxides (SiO2 + AI2O3 + Fe2O3) satisfy the minimum requirement of “Class N pozzolan”. TGA/DTA established calcination temperatures of 600 °C, 650 °C, and 700 °C for IF, OK, and IM clays respectively at 2 h. These results agreed with FTIR data. The SAI of calcined clay (C-IF, C-OK, and C-IM) were 122%, 120.2%, and 118.8%, consistent with all the analytical results. Thus, these clays are useable in cementitious blends.

Magnetic Susceptibility of Pumice at Mount Singgalang, West Sumatera

Volcanic activity produces eruptions that release pyroclastic material at the time of the explosion. Mount Singgalang is a volcano that has experienced an eruption after 1600. Several types of volcanic rocks around the Mount Singgalang area are Basalt, Andesite, Tuff Breccia, Lava Breccia, and Pumice Tuff. Pumice is formed when saturated liquid magma gas bursts like a carbonated beverage and soon cools, causing the froth that results to solidify into a glass full of gas bubbles. Some minerals contained in pumice are obsidian, cristobalite, feldspar, and tridymite. Pumice contains magnetic minerals, namely ilmenite (FeTiO3), and magnetite (Fe3O4). The purpose of this study is to quantify the magnetic susceptibility and quantity of pumice on Mount Singgalang in West Sumatera. When utilizing the Bartington Magnetic Susceptibility Meter to analyze a sample, magnetic susceptibility parameters are utilized to pinpoint the features of a magnetic rock mineral. The value of the magnetic susceptibility of pumice on Mount Singgalang, in West Sumatera has a value that varies between 2763.3 x 10-8m3/kg - 2192.1 x 10-8m3/kg. The results showed that the tested samples had antiferromagnetic magnetic mineral properties with frequency-dependent susceptibility values (χfd), indicating that all of the measured samples contained almost no superparamagnetic (SP) grains and were generally dominated by multi-domain (MD) grains.

Physicochemical understanding of biomineralization by molecular vibrational spectroscopy: From mechanism to nature.

The process and mechanism of biomineralization and relevant physicochemical properties of mineral crystals are remarkably sophisticated multidisciplinary fields that include biology, chemistry, physics, and materials science. The components of the organic matter, structural construction of minerals, and related mechanical interaction, etc., could help to reveal the unique nature of the special mineralization process. Herein, the paper provides an overview of the biomineralization process from the perspective of molecular vibrational spectroscopy, including the physicochemical properties of biomineralized tissues, from physiological to applied mineralization. These physicochemical characteristics closely to the hierarchical mineralization process include biological crystal defects, chemical bonding, atomic doping, structural changes, and content changes in organic matter, along with the interface between biocrystals and organic matter as well as the specific mechanical effects for hardness and toughness. Based on those observations, the special physiological properties of mineralization for enamel and bone, as well as the possible mechanism of pathological mineralization and calcification such as atherosclerosis, tumor micro mineralization, and urolithiasis are also reviewed and discussed. Indeed, the clearly defined physicochemical properties of mineral crystals could pave the way for studies on the mechanisms and applications.

The Brick Industry in Ghana: Historical Contexts, Advocacy and Way Forward

The paper looked at historical antecedents of bricks industry in Ghana, its challenges and how governments and individuals have supported bricks advocacy in Ghana. The properties of clay minerals for structural products are tolerable among Ghanaian clays and though composite formulations have improve the suitability of the clay material for bricks production, its advocacy for construction in Ghana has not been fully pushed for. Through historical and descriptive methods, the study revealed that the brick industry in Ghana have suffered challenges such as poor management, limited technical-know-how, weak infrastructure, quality control and socio-cultural issues. Governments over the years have tabled good policies but implementation have been poor. The paper recommended among others that cottages and other projects such as public buildings, government affordable housing projects be built with bricks to encourage individuals to patronize bricks.

Characterizing Microbial and CO2-Induced Carbonate Minerals: Implications for Soil Stabilization in Sandy Environments

This study aimed to investigate the structure and shape of carbonate crystals induced through microbial activity and carbon dioxide reactions in the sand. The strength of sandy soil treated with carbonate minerals was subsequently determined using unconfined compression strength (UCS) tests. Sporoscarcina pasteurii bacteria were used to produce an aqueous solution of free carbonate ions (CO32−) under laboratory circumstances called microbial-induced carbonate precipitation (MICP). In CO2-induced carbonate precipitation (CICP), carbon dioxide was added to a sodium hydroxide solution to form free carbonate ions (CO32−). Different carbonate mineral compositions were then provided by adding Fe2+, Mg2+, and Ca2+ ions to carbonate ions (CO32−). In the MICP and CICP procedures, the results of scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) revealed a distinct morphology of any type of carbonate minerals. Vaterite (CaCO3), siderite (FeCO3), nesquehonite (MgCO3(H2O)3), and dolomite (CaMg(CO3)2 were produced in MICP. Calcite (CaCO3), siderite (FeCO3), nesquehonite (MgCO3(H2O)3), and high-Mg calcite (Ca-Mg(CO3)) were produced in CICP. According to UCS data, siderite and high-Mg calcite/dolomite had more effectiveness in increasing soil strength (63–72 kPa). The soils treated with nesquehonite had the lowest strength value (25–29 kPa). Mineral-treated soils in CICP showed a slightly higher UCS strength than MICP, which could be attributable to greater particle size and interlocking. This research focused on studying the mineralogical properties of precipitated carbonate minerals by CICP and MICP methods to suggest a promising environmental method for soil reinforcement.

Epileptogenic Tubers Are Associated with Increased Kurtosis of Susceptibility Values: A Combined Quantitative Susceptibility Mapping and Stereoelectroencephalography Pilot Study.

Prior studies have found an association between calcification and the epileptogenicity of tubers in tuberous sclerosis complex. Quantitative susceptibility mapping is a novel tool sensitive to magnetic susceptibility alterations due to tissue calcification. We assessed the utility of quantitative susceptibility mapping in identifying putative epileptogenic tubers in tuberous sclerosis complex using stereoelectroencephalography data as ground truth. We studied patients with tuberous sclerosis complex undergoing stereoelectroencephalography at a single center who had multiecho gradient-echo sequences available. Quantitative susceptibility mapping and R2* values were extracted for all tubers on the basis of manually drawn 3D ROIs using T1- and T2-FLAIR sequences. Characteristics of quantitative susceptibility mapping and R2* distributions from implanted tubers were compared using binary logistic generalized estimating equation models designed to identify ictal (involved in seizure onset) and interictal (persistent interictal epileptiform activity) tubers. These models were then applied to the unimplanted tubers to identify potential ictal and interictal tubers that were not sampled by stereoelectroencephalography. A total of 146 tubers were identified in 10 patients, 76 of which were sampled using stereoelectroencephalography. Increased kurtosis of the tuber quantitative susceptibility mapping values was associated with epileptogenicity (P = .04 for the ictal group and P = .005 for the interictal group) by the generalized estimating equation model. Both groups had poor sensitivity (35.0% and 44.1%, respectively) but high specificity (94.6% and 78.6%, respectively). Our finding of increased kurtosis of quantitative susceptibility mapping values (heavy-tailed distribution) was highly specific, suggesting that it may be a useful biomarker to identify putative epileptogenic tubers in tuberous sclerosis complex. This finding motivates the investigation of underlying tuber mineralization and other properties driving kurtosis changes in quantitative susceptibility mapping values.

A resin adhesive with balanced antibacterial and mineralization properties for improved dental restoration

ObjectiveAiming to develop an adhesive formulation that achieves a harmonious equilibrium between antibacterial efficacy and mineralization potential, 2-methacryloyloxy ethyl phosphorylcholine (MPC), N,N-dodecylvinylimidazole (DCV), and Sr-doped hydroxyapatite (Sr/HAp) nanorods were incorporated as functional constituents into the adhesive matrix, employing carefully optimized proportions. MethodsThe adhesive formulation comprised a blend of bisphenol A glycerolate dimethacrylate (Bis-GMA), 2-hydroxyethyl methacrylate (HEMA), and 1,6-hexanediol dimethacrylate (HDDMA) monomers. The effects of MPC and DCV additions, ranging from 1% to 4% (wt%), on various aspects such as adhesive curing kinetics, bonding strength, water contact angle, mechanical properties, and antibacterial activities against Streptococcus mutans (S. mutans) and Human Saliva Bacterial Flora (HSBF), was investigated both individually and in combination. Following the determination of the optimized MPC/DCV ratio, the effect of Sr/HAp on the mineralization potential of the adhesives was evaluated by soaking the samples in 1.5 times simulated body fluid (SBF) at 37 °C for 3 days followed by examination using scanning electron microscopy (SEM). Additionally, biocompatibility assay was conducted using L929 fibroblasts. ResultsThe introduction of MPC and DCV did not interfere the CC conversion degree of the resin blends in all the preparations. Notably, the incorporation of 3 wt% MPC demonstrated a significantly enhancement in the hydrophilicity of the adhesive, resulting in reduced bacterial adsorption. The addition of 3 wt% DCV exhibited potent antibacterial properties against attached bacteria. Furthermore, the introduction of 8 wt% Sr/HAp displayed a positive effect on mineral deposition on the adhesive surface. Importantly, all adhesive formulations demonstrated negligible cytotoxicity. Although a decrease in bonding strength was observed upon the introduction of MPC/DCV, the supplementation of Sr/HAp exhibited a reinforcing effect, effectively compensating for the decline. This beneficial outcome can be attributed to a substantial improvement in the flexural strength/modulus of the composite adhesive. SignificanceThe adhesive, simultaneously having ability in inhibiting bacteria adsorption, killing bacteria and promoted mineralization, holds great potential in achieving strong bonding strength for dental restoration applications to minimize repair failure.

Glyphosate adsorption on synthetic allophanes and halloysite: Effects of pH and mineral properties

AbstractBackgroundGlyphosate (GLP) is a widely used herbicide with possible adverse effects on human health and the environment. In soils, GLP strongly adsorbs on clay‐sized minerals, depending on pH, the amount of organic carbon, as well as the contents and properties of Al and Fe oxyhydroxides and clay minerals. Many clay‐sized minerals have already been investigated regarding GLP adsorption behavior, but information on minerals commonly found in volcanic soils is still lacking.AimThe aim of this study was to investigate for the first time the pH‐dependent adsorption of GLP on allophane and halloysite, typical minerals found in volcanic soils.MethodsGLP adsorption was studied in batch experiments at three pH values (5, 6, and 7). Synthetic allophanes with two different initial Al:Si ratios (1.4 and 1.8) and a halloysite were used as adsorbents.ResultsThe adsorption capacity (AC) increased with rising Al:Si ratio and decreasing pH. The AC of allophane was significantly higher than that of halloysite. GLP adsorption on allophane was larger than that reported for other clay minerals and Al and Fe oxyhydroxides, especially at low pH. The AC of halloysite was higher than reported for most other clay minerals.ConclusionDifferent mineral formation pathways in volcanic soils, notably the formation of halloysite versus allophanes, strongly affect the soils’ retention capacity for GLP. The high AC of allophanes may induce the low mobility of GLP in allophane‐containing soils. Long‐term use of GLP may accumulate the herbicide in these soils with potential effects on biodiversity and ecosystem services.

Do Clinical Parameters Reflect Local Bone Metabolism in Heterotopic Ossification After Septic or Aseptic THA?

Do Clinical Parameters Reflect Local Bone Metabolism in Heterotopic Ossification After Septic or Aseptic THA?

Crystal properties and interaction with flotation reagent of fluorapatite and dolomite

The difference of mineral properties is the basic condition of flotation. Studying the difference of crystal structure characteristics between fluorapatite and dolomite is helpful to understand its flotation behavior and micro-mechanism. To understand the differences in crystal and surface properties of fluorapatite and dolomite, the first-principles method based on density functional theory was used to study the crystal structure and surface properties of fluorapatite and dolomite from a microscopic perspective, and the adsorption mechanism of oleic acid ions on the surface of fluorapatite and dolomite was revealed. The results show that the activity of metal atoms in fluorapatite and dolomite crystals is different. The activity of Ca atoms in dolomite crystals is greater than that of Mg atoms. The reactivity of Ca atoms in fluorapatite crystals is low, and the reactivity of F and O atoms is high. After the surface of fluorapatite is formed, the surface of fluorapatite is mainly dominated by the fracture of F–Ca bond and O–Ca bond. The surface of dolomite is mainly dominated by the fracture of O–Ca bond and O–Mg bond. The ionicity of O–Ca bond in fluorapatite crystal is stronger, and the activity of Ca site on the surface of fluorapatite is greater than that on the surface of dolomite. The reactivity of Ca atoms on the surface of dolomite (104) is stronger than that of Mg atoms. NaOL undergoes chemical reactions on the surface of fluorapatite (001) and dolomite (104). The chemical effect of oleic acid ions on the Ca site of dolomite (104) surface is stronger than that on the Mg site. The effect of water molecules on the adsorption strength ratio of oleic acid ions on dolomite surface is less than that of water molecules on the adsorption strength of oleic acid ions on fluorapatite surface. In the absence of other conditions, the interaction strength of fluorapatite and dolomite with water molecules is similar, and the interaction between water molecules and dolomite is slightly larger than that between fluorapatite and water molecules. The effect of oleic acid ion dolomite is stronger than that of fluorapatite; the interaction between HEDP and fluorapatite is stronger than that between HEDP and dolomite.