Quantitative X-ray Diffraction Analysis Research Articles

Quantitative X-Ray Diffraction Analysis of Zn-Al Based Alloys

Quantitative X-Ray Diffraction Analysis of Zn-Al Based Alloys

An experimental study on the effect of the acid and heavy metal treatments on the adsorption of CH4 by sepiolite.

This study investigated methane (CH4) adsorption by natural sepiolite-obtained from Eskisehir in Turkey-and its Ag-, Cu-, Fe-, and H-exchanged forms by using a volumetric gas adsorption method. Sepiolite was modified with 1 M AgNO3, 1 M Cu(NO3)2∙3H2O, 1 M Fe(NO3)3∙9H2O, and 1 M HCl solutions at 80°C for 6h, respectively. The natural and modified sepiolite samples were characterized by using X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TG-DTG), differential thermal analysis (DTA), and the nitrogen adsorption method. Quantitative XRD analysis showed that the sample consisted primarily of sepiolite clay mineral and dolomite as an impurity in small amounts. It was found that acid and heavy metal treatments caused apparent changes in the structure and microporosity of the sepiolite samples. CH4 adsorption isotherms of clay samples were examined at temperatures of 0°C and 25°C and pressures up to 100kPa. It was determined that the CH4 adsorption capacities of sepiolite samples increased at both temperatures according to the following sequence: CuS < AgS < HS < S < FeS. CH4 adsorption values of sepiolite samples varied between 0.084mmol/g and 0.299mmol/g. It was observed that the CH4 adsorption capacities of heavy metal cation-exchange clay samples were related to the surface area.

Characterisation of Biooxidation Feed and Products for Improved Understanding of Biooxidation and Gold Extraction Performance

This paper presents a study on characterisation of refractory ore, biooxidation feed and product, and cyanidation tailings with the aim of understanding the causes of excessive continuous frothing, incomplete sulphide oxidation, high reagent consumption, high cyanidation residues and low overall recovery as encountered in biooxidation of refractory ores. Techniques involving carbon and sulphur speciation, Quantitative X-Ray Diffraction (QXRD), Scanning Electron Microscopy (SEM) and Optical Microscopy (OM) were used to characterise the ore samples, flotation concentrate (BIOX® feed), biooxidised product (BIOX® CIL Feed) and cyanidation tailings (BIOX® CIL Tails) from a biooxidation plant. The main minerals present in the ore were quartz (45%), chlorites (21%), plagioclase feldspar (13%), dolomite (5%), pyrite (2%) and mica group (2%). The flotation concentrate recorded 18% mica, and this was responsible for excessive frothing in the biooxidation circuit as confirmed by the QXRD analysis. The carry-over froth to the CIL circuit led to short-circuiting of poorly leached material into the cyanidation tailings, resulting in high cyanidation residues. Secondary refractory minerals; gypsum and jarosite, which were observed in the biooxidation product by the QXRD, have the potential to coat unreacted sulphide particles, leading to incomplete sulphide oxidation as observed here. Partially oxidised sulphides led to high consumption of reagents such as oxygen and cyanide during cyanidation. Gypsum and jarosite also encapsulated gold particles as observed in the BSED analysis. Coated gold particles had reduced access to lixiviants during the subsequent cyanidation process, leading to high leach residues. The biooxidised product (BIOX® CIL Feed) also recorded a high organic carbon content of 6.67, while analysis by BSED revealed the presence of graphitic carbon and coatings on gold surfaces; an indicator for high preg-robbing activities during cyanidation of the concentrate. Preg-robbing indices of 64.4% and 72.7% were recorded for the flotation concentrate (BIOX® feed) and BIOX® CIL feed respectively. The overarching effect of all the observations is a decrease in overall gold recovery.

Hydration of C3A/gypsum composites in the presence of graphene oxide

The interactions between graphene oxide (GO) and individual clinker phases, which are critical for understanding the mechanism of GO during the hydration of cementitious materials, remain unclear. Therefore, this study investigated the effect of GO on the thermodynamic-based solution chemistry and hydration of tricalcium aluminate (C3A), which is a main constituent phase of Portland cement, in the presence of gypsum. The pore solution composition, phase content, and morphology of C3A/GO/gypsum composites were studied by inductively coupled plasma optical emission spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. The experimental results showed that the incorporation of GO led to Ca2+ adsorption, which particularly decreased the local Ca2+ concentration near the surface of C3A. This increased the undersaturation levels of C3A and gypsum, thus facilitating their dissolution. A lower Ca2+ concentration led to a slight decrease in the supersaturation of hydrates after GO addition. Nevertheless, the introduction of GO improved the overall hydration degree, as confirmed by quantitative X-ray diffraction and thermogravimetric analysis. This improvement can be probably attributed to the higher number of nucleation sites provided by GO for precipitation. In addition, the scanning electron microscopy images of C3A/gypsum paste showed a cluster-like structure composed of coarse needle-like ettringites.

Thermal Decomposition Study on Li2O2 for Li2NiO2 Synthesis as a Sacrificing Positive Additive of Lithium-Ion Batteries

Herein, thermal decomposition experiments of lithium peroxide (Li2O2) were performed to prepare a precursor (Li2O) for sacrificing cathode material, Li2NiO2. The Li2O2 was prepared by a hydrometallurgical reaction between LiOH·H2O and H2O2. The overall reaction during annealing was found to involve the following three steps: (1) dehydration of LiOH·H2O, (2) decomposition of Li2O2, and (3) pyrolysis of the remaining anhydrous LiOH. This stepwise reaction was elucidated by thermal gravimetric and quantitative X-ray diffraction analyses. Furthermore, over-lithiated lithium nickel oxide (Li2NiO2) using our lithium precursor was synthesized, which exhibited a larger yield of 90.9% and higher irreversible capacity of 261 to 265 mAh g−1 than the sample prepared by commercially purchased Li2O (45.6% and 177 to 185 mAh g−1, respectively) due to optimal powder preparation conditions.

Accelerated carbonation of reactive MgO and Portland cement blends under flowing CO2 gas

The use of MgO-based materials for sequestration of CO2 offers technical advantages and environmental incentives. However, the understanding of accelerated carbonation of MgO-based materials in flowing CO2 gas is limited. This study elucidates the carbonation behaviour of reactive MgO cement (MC) and MgO-Portland binary cement (BC) in a simulated CO2-rich industrial exhaust. Quantitative X-ray diffraction and thermogravimetric analyses showed that nesquehonite (MgCO3·3H2O) was the major carbonation product in MC pastes, whereas CaCO3 was preferentially generated in BC pastes. The relative humidity of exhaust gas influenced CO2 diffusion and the carbonation rate; 98% humidity facilitated MC carbonation whereas 50% was favourable for BC carbonation. Although CO2 concentration determined the carbonation rate, 10% CO2 gas in the exhaust was sufficient to accelerate carbonation. The carbonation degree and compressive strength of samples cured for 7 days at 10% CO2 were comparable to the values of samples cured for 1 day at 100% CO2. The presence of acid gases during CO2 curing inhibited the carbonation and hydration processes, but the presence of Portland cement in the BC system gave good compatibility with acids and relieved the inhibitory effect. Desulphurization and denitrification of industrial exhaust gas are nonetheless desirable before CO2 curing. This study builds the foundation for utilising industrial CO2 exhaust to accelerate the carbonation of Mg-based materials.

Investigation of mineral deportment in a copper ore from Botswana

Understanding the characteristics of minerals is key in developing effective techniques for copper ore processing to maximise recovery hence income. Most studies have focused on understanding the fundamentals and principles of dissolution kinetics, oxidation and leaching of copper minerals. New developments and technologies have made it possible to reveal that copper ores are fascinating and complex minerals. Other research concentrates on chemical and mineralogical analysis, hence revealing information such as properties, compositional change and analysis. In this paper X-Ray Diffraction (XRD) and Quantitative Evaluation of Minerals Scanning Electron Microscopy (QEMSCAN) are used as tools in quantifying chemical and mineralogical attributes of a copper ore (chalcocite bearing mineral) from Botswana as the objective. Obtained information was not limited to grain size and distribution, mineral associations and liberations characteristics of economic minerals in the ore and quantitative information being the latter. XRF indicates that the copper ore contains phases such as Al203, CaO, MgO, TiO2, V2O5 and SiO2, which is the dominant mineral with 60.6 wt% as well as traces of elements Fe, S, Pb, and Co with wt% of <0.02. Scanning Electron Microscope (SEM) peaks also confirmed these elements to exist in the mineral. Quantitative X-Ray Diffraction (QXRD) analysis entailed phases present with silicates being the dominant phases and their existence on the mineral by wt%. SEM peaks showed evidence of Fe, Si, Cu, S etc. which is consistent with XRF data. In addition QESCAN also revealed grain size of cuprite particles to be greater than 45 μm with < 0.24 % liberated. The copper ore is characterized with a possibility of extracting metals or elements of economic value.

Mechanistic insights into red mud, blast furnace slag, or metakaolin-assisted stabilization/solidification of arsenic-contaminated sediment

Elevated level of arsenic (As) in marine sediment via deposition and accumulation presents long-term ecological risks. This study proposed a sustainable stabilization/solidification (S/S) of As-contaminated sediment via novel valorization of red mud waste, blast furnace slag and calcined clay mineral, which were selected to mitigate the increased leaching of As under alkaline environment of S/S treatment. Quantitative X-ray diffraction and thermogravimetric analyses illustrated that stable Ca-As complexes (e.g., Ca5(AsO4)3OH) could be formed at the expense of Ca(OH)2 consumption, which inevitably hindered the hydration process and S/S efficiency. The 29Si nuclear magnetic resonance analysis revealed that incorporation of metakaolin for As immobilization resulted in a low degree of hydration and polymerization, whereas addition of red mud promoted Fe-As complexation and demonstrated excellent compatibility with As. Transmission electron microscopy and elemental mapping further confirmed the precipitation of crystalline Ca-As and amorphous Fe-As compounds. Therefore, red mud-incorporated S/S binder achieved the highest efficiency of As immobilization (99.9%), which proved to be applicable for both in-situ and ex-situ S/S of As-contaminated sediment. These results advance our mechanistic understanding for the design of green and sustainable remediation approach for effective As immobilization.

Solidification/stabilization of flue gas desulfurization brine and coal fly ash for heavy metals and chloride immobilization: Effects of S/S conditions and zero-valent-iron pretreatment

Effective management of flue-gas-desulfurization (FGD) wastewater and coal-combustion-residues (CCRs) are major challenges in the coal-fired power industry. The zero-liquid-discharge (ZLD) method of combining FGD brines and CCRs in solidification/stabilization (S/S) is promising due to its potential of treating both wastes in the same process. This study evaluated the performance of such a ZLD method for immobilizing heavy metals (Se, As, Cd and Cr) and chloride in FGD wastewater and/or CCRs. Effects of different coal fly ash (bituminous (BCFA) and sub-bituminous (SCFA)), activating agent (Portland cement (PC) and lime) and pretreatment of brines by zero valent iron (ZVI) on the S/S process were evaluated. Short-term and long-term leaching tests were conducted to evaluate performance of the S/S solids in pollutant retainment. The pre-treatment of FGD brine by ZVI enhanced the retainment of heavy metals when BCFA was used, but not when SCFA was used since it already performed quite well without ZVI pretreatment. Quantitative X-ray diffraction and scanning electron microscopy analyses strongly indicated the formation of Friedel’s salt, Ca2Al(OH)6(Cl,OH)·2H2O, is critical in the retainment of heavy metals and chloride. SCFA contained higher lime and reactive aluminate contents than BCFA; thus, S/S solids made with SCFA contained higher amounts of Friedel’s salt.

Revisiting the Rius’ Standardless Method for the Quantitative X-Ray Diffraction Analysis of Mixtures of Inorganic Crystalline Phases

ABSTRACTAn alternative method for the standardless quantitative x-ray diffraction analysis of mixtures of inorganic crystalline phases proposed in the literature several years ago is presented. Our method requires only previously calculated μ*i values from tabulated data for all phases present in the mixtures. It does not require either the determination of calibration constants or the use of external standards, but it does require that the number of analyzed mixtures is larger than or equal to the number of phases present in them, and that the chemical composition of the mixtures are significantly different from each other. The integrated intensities of the chemically pure phases are estimated by a least-squares procedure from XRD data obtained from the mixtures. The method was tested against data published in the literature, with good results. Finally, a general expression for the “Normalized Height Law” proposed on an empirical basis by other researchers, has been theoretically derived.

Relating Ettringite Formation and Rheological Changes during the Initial Cement Hydration: A Comparative Study Applying XRD Analysis, Rheological Measurements and Modeling.

In order to gain a deeper understanding of the rheological development of hydrating ordinary Portland cement (OPC) pastes at initial state, and to better understand their underlying processes, quantitative X-ray diffraction (XRD) analysis and rheological measurements were conducted and their results combined. The time-dependent relation between phase development and flow behavior of cement paste was investigated at two different temperatures (20 and 30 °C), over a period of two hours. Regarding the phase development during hydration, ettringite precipitation was identified as the dominant reaction in the first two hours. For both temperatures, the increasing ettringite content turned out to correlate very well with the loss of workability of the reacting cement paste. An exponential relationship between ettringite growth and flow behavior was observed that could be explained by applying the Krieger-Dougherty equation, which describes the influence of solid fraction on the viscosity of a suspension.

Effect of cyclic wetting and drying on microstructure, composition and length changes of lime-based plasters

Plasters as surface layers of building structures are often exposed to cyclic wetting and drying during their service life. In this paper, the impact of cyclic wetting and drying on microstructure, composition, and length changes of lime-based plasters is investigated using mercury intrusion porosimetry, optical microscopy, qualitative and quantitative X-ray diffraction analysis, simultaneous thermal analysis, and contact dilatometry. Lime-cement- and lime-metakaolin plasters as typical representatives of this group are saturated by water at first and then subjected to five consecutive drying-wetting cycles. Hydration processes, together with carbonation and possible partial dissolution of portlandite and calcite after immersion of samples in water, are identified as the most important reactions affecting the microstructure and composition of the lime-cement plaster, while for the lime-metakaolin plaster the pozzolanic reaction resulting in monocarbonate production, together with possible portlandite and calcite dissolution, are probably the most significant factors. The measurements of hygric strain show that the wetting-drying process is near-reversible since the beginning of the second cycle, whereas capillary pressure is the dominant shrinkage/swelling mechanism.

XRD Analysis of Ferrite Ceramics with Different Heat Treatment

A comparative analysis of the structural characteristics of LiZnTi ferrites sintered at the temperature of 1280 and 1360 K was performed. The qualitative and quantitative X-ray diffraction (XRD) analysis of the samples, main phase structural analysis, and unit cell parameters were carried out using the non-standard method (Rietveld method). Diffraction patterns were recorded on an ARL X'TRA diffractometer in the CuKα1+α2 and CuKβ scanning modes.

Modal analyses of lunar soils by quantitative X-ray diffraction analysis

We used X-Ray Diffraction (XRD) and Rietveld refinement to determine the modal mineralogy of 118 lunar regolith samples (<150 µm size fraction) from all landed Apollo missions. Data were calibrated with mineral mixtures and compared to results based on an X-ray digital imaging procedure for six soils obtained by the Lunar Soil Characterization Consortium. Agreement between XRD and digital imaging for all minerals detectable in the six soils is excellent (R2 = 0.953). XRD-based ternary plots (plagioclase-total pyroxene-olivine) vary from plagioclase-dominated (highlands as represented by Apollo 16 samples) to substantial mafic abundances at the mare sites. Olivine varies in relative abundance, with the Apollo 17 mare sites having the largest abundances. Olivine reaches 20 wt% at Apollo 17, but is a minor component at Apollo 14. The results agree with trends in mineral abundances obtained from reflectance spectroscopy for the Apollo sites. In a global context, however, the spectral data display a trend of increasing olivine at roughly constant pyroxene/plagioclase, reaching values of 40% olivine in the plagioclase-pyroxene-olivine ternary plot (e.g., Eratosthenian flows in Procellarum), indicating the presence of significant volumes of olivine-rich rock types on unsampled regions of the lunar surface.

Sustainable stabilization/solidification of municipal solid waste incinerator fly ash by incorporation of green materials

Abstract: Municipal solid waste incinerator fly ash (IFA) is categorized as a hazardous waste, which requires proper treatment prior to landfilling due to its high concentrations of toxic elements. This study developed an innovative and cleaner method for stabilization/solidification (S/S) of IFA by the incorporation of supplementary cementitious materials (SCMs) and green stabilizers. Quantitative X-ray diffraction and thermogravimetric analyses indicated that toxic elements in IFA inhibited the cement hydration. Therefore, the single use of cement (10 wt%) was not efficient for the immobilization of toxic elements, especially for Pb. The incorporation of SCMs (20 wt% of binder) such as silica fume facilitated the formation of additional cement hydrates and reduced Pb leachability by 36.3%. The addition of green stabilizers such as potassium dihydrogen phosphate (KDP) and wood waste-derived biochar also improved the immobilization of toxic elements. KDP directly combined with Pb2+ to form a precipitate of Pb3(PO4)2, whereas biochar promoted the generation of cement hydrates for S/S via the effect of internal curing. The incorporation of silica fume (40 wt%) in the binder was the most effective. Overall, this study demonstrated that the selected green binders can serve as low-carbon and high-efficient material for S/S of hazardous ash residue such as IFA.

Green remediation of As and Pb contaminated soil using cement-free clay-based stabilization/solidification

Stabilization/solidification (S/S) is a low-cost and high-efficiency remediation method for contaminated soils, however, conventional cement-based S/S method has environmental constraints and sustainability concerns. This study proposes a low-carbon, cement-free, clay-based approach for simultaneous S/S of As and Pb in the contaminated soil, and accordingly elucidates the chemical interactions between alkali-activated clay binders and potentially toxic elements. Quantitative X-ray diffraction and 27Al nuclear magnetic resonance analyses indicated that the addition of lime effectively activated the hydration of kaolinite clay, and the presence of limestone further enhanced the polymerization of hydrates. X-ray photoelectron spectroscopy showed that approximately 19% of As[III] was oxidized to As[V] in the alkali-activated clay system, which reduced toxicity and facilitated immobilization of As. During the cement-free S/S process, As and Pb consumed Ca(OH)2 and precipitated as Ca3(AsO4)2·4H2O and Pb3(NO3)(OH)5, respectively, accounting for the low leachability of As (7.0%) and Pb (5.4%). However, the reduced amount of Ca(OH)2 decreased the degree of hydration of clay minerals, and the pH buffering capacity of the contaminated soil hindered the pH increase. Sufficient dosage of lime was required for ensuring satisfactory solidification and contaminant immobilization of the clay-based S/S products. The leachability of As and Pb in high-Ca S/S treated soil samples was reduced by 96.2% and 98.8%, respectively. This is the first study developing a green and cement-free S/S of As- and Pb-contaminated soil using clay minerals as an environmentally compatible binding material.

Effects of phase transformation on properties of alumina ceramic membrane: A new assessment based on quantitative X-ray diffraction (QXRD)

Alumina ceramic membranes were synthesized by pressing boehmite into disc form and sintering at different temperatures. Quantitative X-ray diffraction (QXRD) analysis was firstly used for determining the compositions of different types of alumina in membrane products. The result quantitative determined that alumina membranes experienced a series of phase transition from boehmite → γ-alumina → δ-alumina → θ-alumina → α-alumina from 450 to 1300 °C. Below 850 °C, no significant alumina transformation (i.e. γ-alumina was the dominate phase) was detected in fabricated membranes, which corresponded to stable membrane properties (i.e. porosity, BET surface area, pore size and chemical stability). At 950–1300 °C, substantial phase transformation was detected as follows, θ-alumina significantly increased from 1.21 to 61.6% (950–1125 °C), and α-alumina increased gradually from 3.98 to 100% (1100–1300 °C). Accordingly, the substantial phase transformation lead to the significant change in membrane properties at 950–1300 °C. Lower temperature (1150 °C) membrane containing 8.2% θ-alumina and 91.8% α-alumina showed comparable properties with 1300 °C consist of 100% α-alumina sintered products due to the similar alumina composition in the products. The overall results indicated that the properties of membrane were accordingly determined by the structure and content of alumina phases in membrane products. This strategy proposed a valuable method for production of lower temperature alumina-based ceramic membrane.

Tracking Holocene drift-ice limits on the northwest–southwest Iceland shelf: Comparing proxy data with observation and historical evidence

ABSTRACTWe detail variations in the weight percent (wt%) of quartz, a proxy for drift ice, in fifteen marine sediment cores from the northwest, west, and southwest Iceland shelf throughout the past 10 cal ka BP. We present the first map of iceberg distributions in Iceland waters between 1983 and 2011 and a new compilation of sea-ice records in the century from 850 to 1950 CE. The wt% of quartz, determined by quantitative X-ray diffraction (qXRD) analysis, is used to evaluate changes in the importation of drift ice. Small wt% of quartz were added to milled basalt (0% quartz), and to a mixture of non-clay and clay minerals; the qXRD method replicated 0 percent quartz, while measured 1–3 percent quartz always resulted in a “presence” estimate. The outer sites in the northwest sector lie close to the average position of the sea-ice margin between 1870 and 1920 CE; the southwest shelf sites lie south of this limit. Transects of cores along the Húnaflói and Djúpáll troughs indicate that the traces of drift ice decrease rapidly landward from the outer sites. The cores from the west/southwest of Iceland have limited amounts of quartz, generally possibly limited incursions of drift ice.

Influence of Oil Sands Composition on Bitumen Quality During Non‐Aqueous Bitumen Extraction from the Athabasca Deposit

ABSTRACTThe aim of the present work is to identify the most important species affecting a non‐aqueous bitumen extraction process and bitumen quality. This investigation was carried out on four petrologic end member samples from Syncrude's North Mine collected in 2012 (NM12), i.e., marine claystone (MC), marine sand (MS), estuarine claystone (EC), and estuarine sand (ES). Each end member was separately mixed with cyclohexane at a ratio of 40:60 (cyclohexane:end member), and the bitumen‐cyclohexane solutions were collected at different settling times (1–30 min). These solutions were analyzed to determine the amount, particle size distribution, and mineralogical composition of suspended fine solids (SFS), water content, as well as the bitumen content using a focused beam reflectance measurement (FBRM) particle size analyzer, Karl Fischer (KF) titration, x‐ray diffraction (XRD), quantitative XRD (QXRD), and elemental analysis. The SFS was composed of mainly illite and kaolinite after cyclohexane extraction from MC, MS, EC, and ES. Although mixed layer expandable clay minerals (i.e., illite‐smectite and kaolinite‐smectite) were identified in the original clay, end members (EC and MC), illite‐smectite, and kaolinite‐smectite were not observed in the SFS of the bitumen‐cyclohexane solutions obtained from the four petrologic end members. The SFS content and bitumen quality of the bitumen product were affected slightly but significantly by the end member composition and settling time, respectively. Illite and kaolinite were identified as the main minerals in the SFS of the bitumen products after relatively long settling times.

Novel synergy of Si-rich minerals and reactive MgO for stabilisation/solidification of contaminated sediment.

Disposal of significant amounts of dredged contaminated sediment poses an economic and environmental problem worldwide. Transforming contaminated sediment into value-added construction materials using low-carbon MgO cement is a sustainable option; however, the weak mechanical strength and unreliable water-solubility of MgO cement restrict its practical engineering applications. This study elucidates the potential role of industrial Si-rich minerals in the performance enhancement of MgO-based products via the promotion of magnesium silicate hydrate (M-S-H) gel formation. Quantitative X-ray diffraction and 29Si nuclear magnetic resonance analyses indicated that compositions and crystallinities of the Si-rich minerals significantly influence the formation and polymerisation of the M-S-H gel. Pulverised fly ash was found to be a promising Si-rich mineral for generating polymeric M-S-H gel, whereas incinerated sewage sludge ash samples demonstrated a low degree of polymerisation, and the use of glass powder samples gave a low yield of M-S-H. The formation of M-S-H gel enhanced the compressive strength and water resistance (strength retention after water immersion). Further experiments demonstrated that Si-modified MgO cement can transform dredged sediment into fill materials with satisfactory mechanical properties and contaminant immobilisation. Therefore, the synergy between reactive MgO and Si-rich industrial waste is a novel option for sustainable remediation and environmental applications.