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The aim of this study was to increase feedstock availability for mineral carbonation. Acid dissolution and carbonic acid dissolution approaches were used to achieve higher Mg extractions from peridotites. Acid dissolution studies of raw dunite, heat-activated dunite, heat-transformed dunite, and twin sister dunite have not been reported in the literature. Heat-activated dunite is more reactive as compared to heat-transformed dunite, raw dunite, and twin sister dunite. The fraction of magnesium extracted from heat-activated dunite was 57% as compared to 18% from heat-transformed dunite, 14% from raw dunite, and 11% from twin sister dunite. Similarly, silicon and iron extractions were higher for heat-activated dunite compared to that of heat-transformed dunite, raw dunite, and twin sister dunite. Materials rich in forsterite (twin sister dunite and heat-transformed dunite) showed preferential Mg release and exhibited incongruent dissolution similar to that of forsterite. Heat-activated dunite (amorphous magnesium silicate rich) on the other hand behaved differently and showed congruent dissolution. Olivine did not dissolve under carbonic acid dissolution (with concurrent grinding) and acidic conditions. Under carbonic acid dissolution with concurrent grinding conditions, olivine was partially converted into nanometer sized particles (d10 = 0.08 µm) but still provided 16% Mg extraction during 4 h of dissolution.

The use of acid to obscure human remains is a tactic frequently associated with criminal activity, yet research on its effects on human dentition remains inconsistent. Dental tissues, among the body's most durable components, play a vital role in forensic identification. However, existing studies on acid dissolution of dentition often lack standardized methods, resulting in findings that are difficult to reproduce or generalize. This study addresses these gaps by examining the effects of hydrochloric acid (HCl) on permanent maxillary molars under controlled conditions, using a replicable methodology that incorporates experimental controls and evaluates the impact of handling techniques such as removal, rinsing, and drying. Five permanent maxillary molar samples were submerged in HCl (37 %) under varied handling conditions. Findings reveal that undisturbed samples dissolved more slowly than those subjected to periodic removal and rinsing, which accelerated dissolution rates by over 100 %. This highlights the significant influence of handling techniques on experimental outcomes. The study also identifies inconsistent reporting and the absence of standardized protocols in prior research as critical barriers to reproducibility. By providing a clear and replicable framework, this study advances understanding of the dissolution process and emphasizes the importance of methodological rigor in forensic science. These findings have broader implications for improving the reliability of forensic evidence and ensuring its applicability in criminal investigations. Addressing these issues is essential for enhancing public trust in forensic methods and strengthening their role in the justice system. •Clear, replicable research is critical to maintaining credibility in forensic applications.•Variability in dentition studies reveals critical gaps in forensic science's methodological rigor.•Introducing controls in forensic research can significantly improve the accuracy of findings.•It found that handling methods, like periodic rinsing, accelerate tooth dissolution compared to undisturbed conditions.•This study explores how hydrochloric acid affects human molars using a controlled, replicable approach.

Fluorite is widely utilized in the new energy, semiconductor, high-end manufacturing, and steelmaking industries. The silicon dioxide (SiO₂) content is critical for both the quality evaluation of fluorite and the design of beneficiation processes. However, the traditional fusion method suffered from several limitations, including cumbersome pretreatment, silica precipitation during acidification, and significant matrix effects caused by alkali metals introduced during fusion. To address these challenges, this study developed an innovative method employing acid dissolution for the determination of SiO₂ content in fluorite using inductively coupled plasma optical emission spectrometry (ICP OES). This method employs a mixture of nitric acid and hydrofluoric acid in a water bath to digest the sample within a closed system. Systematic optimization experiments were conducted to evaluate key parameters, including the volumes of nitric acid and hydrofluoric acid, digestion time in the water bath, and the quantity of boric acid solution, with the aim of enhancing analytical performance. Complete dissolution of silicon dioxide in fluorite was achieved by treating 0.2000 g of sample with 5.0 mL nitric acid and 2.0 mL hydrofluoric acid, followed by heating at 30 minutes. Subsequently, excess fluoride ions were complexed by adding 10 mL of a 50 mg mL-1 boric acid solution. After dilution, the samples are analyzed by ICP OES. At a dilution factor of 2500, the limit of detection (LOD) for SiO₂ was 0.974 µg g-1, with a measurement range spanning from 0.0004% to 25%. Method validation was performed by analyzing six fluorite certified reference materials in seven replicates. The results were in good agreement with certified values, with relative errors (RE) ≤ 3.61%. Seven replicate analyses of five real fluorite samples also showed consistency with results obtained using the standard alkaline fusion colorimetric method (GB/T 5159.8-2006), with relative deviations ≤ 2.71% and relative standard deviations (RSD, n = 7) ≤ 3.04%. This method employs nitric acid and hydrofluoric acid under sealed water bath digestion conditions for the dissolution of fluorite samples, effectively preventing the volatilization loss of silicon tetrafluoride formed during the reaction between fluorine and silicon. By introducing boric acid to complex excess fluoride ions, the interference caused by residual hydrofluoric acid is eliminated, thereby enabling the use of conventional sampling systems that are otherwise incompatible with hydrofluoric acid media. This approach facilitates the rapid determination of silicon dioxide in fluorite via acid dissolution combined with ICP OES analysis. The procedure is straightforward, efficient, and cost-effective, significantly enhancing analytical throughput. It is well suited for the routine and high-throughput determination of SiO₂ in large batches of fluorite samples.

Ordos Basin is rich in unconventional oil and gas resources. Shale resources are developed in source rock series. With the continuous development, many oil wells have different degrees of blockage in the production process. It has different levels of complex performance in wellhead, wellbore and formation, which seriously restricts reservoir production. The formation fluid, reservoir rock samples and plugging materials were analyzed from multiple angles by means of nuclear magnetic electron microscopy, X-ray and acid dissolution to determine the source and formation mechanism of plugging materials. The analysis results show that the main component of the formation mineral is quartz, and the formation crude oil is mainly alkane. The scale sample is a mixture of formation minerals, scaling and corrosion products, and the content varies greatly. It is considered that the particle migration in the reservoir is an important cause of inorganic damage, and the organic matter damage cooperates with the inorganic damage to make the damage more serious. On this basis, this paper puts forward the organic cleaning of wellhead and wellbore, and then inorganic plugging removal of formation plugging, and constructs the deep acidification system of 12 % HCL + 10 % HBF 4 and 10 % GT-α. The experiment shows that the effective production ratio can reach 3.6, and the effect of acidizing and plugging removal is remarkable. This study has formed an effective plugging treatment technology for shale reservoir, which can provide technical support for similar reservoir acidification.

Water-soluble metals are known to produce greater adverse human health outcomes than their water-insoluble forms. Although the concentrations of water-soluble aerosol metals are usually limited by atmospheric processes that convert water-insoluble metals to water-soluble forms, factors that control the solubilities of aerosol metals in different environments remain poorly understood. In this study, we investigated the abundance and fractional solubilities of different metals in size-fractionated aerosols collected at an urban site in Hong Kong and identified the factors that modulated metal solubilities in fine aerosols. The concentrations of total and water-soluble metals in fine and coarse aerosols were the highest during the winter and spring seasons due to the long-range transport of air masses by northerly prevailing winds from emission sources located in continental areas north of Hong Kong. The study-averaged metal fractional solubilities spanned a wide range for both fine (7.8 % to 71.2 %) and coarse (0.4 % to 47.9 %) aerosols, but higher fractional solubilities were typically observed for fine aerosols. Sulfate was found to be strongly associated with both the concentrations of water-soluble Cr, Fe, Co, Cu, Pb, and Mn and their fractional solubilities in fine aerosols, which implied that sulfate-driven acid processing likely played an important role in the dissolution of the water-insoluble forms for these six metals. Further analyses revealed that these strong associations were due to sulfate providing both the acidic environment and liquid water reaction medium needed for the acid dissolution process. Thus, the variability in the concentrations of water-soluble Cr, Fe, Co, Cu, Pb, and Mn and their fractional solubilities were driven by both the aerosol acidity levels and liquid water concentrations, which in turn were controlled by sulfate. These results highlight the roles that sulfate plays in the acid dissolution of metals in fine aerosols in Hong Kong. Our findings will likely also apply to other urban areas in South China, where sulfate is the dominant acidic and hygroscopic component in fine aerosols.

Cobalt (Co) and lithium (Li) were extracted from pure LiCoO 2 powders and actual cathode material powders from the spent lithium-ion batteries (LIBs) after l -ascorbic acid dissolution via a mechanical activation process. The influences of activation time and rotation speed on the leaching were discussed. The mechanism of the improved leaching yield was proposed based on the characterization analysis including X-ray diffraction, scanning electron microscope, BET-specific surface area and particle size analyzer. The reduced particle size, increased specific surface area of activated samples, destroyed crystal structure and amorphous state of LiCoO 2 contributed to the improved leaching efficiencies of Co and Li. With the activated process, about 99% Co and 100% Li were extracted from actual spent LIBs after 60-min grinding at 500 rpm with mild conditions. This effective process would be of great importance for recovering valuable metals from the spent LIBs at room temperature.

Fluorapatite (FA) and fluor-hydroxyapatite (FHA) have good biocompatibility to substitute for human hard tissue, whereas FA has more cytotoxic and genotoxic effects than FHA. In this study, a new method named nitric acid dissolution-recrystallization was proposed to achieve the modification of FA, and NaOH was used to introduce OH- into FA to prepare FHA in the recrystallization process. The effect and mechanism of NaOH/pH value on the modification of FA were investigated using XRD analysis, SEM detection, EDTA complexometric titration, and FT-IR measurements. XRD and SEM analyses indicated that the synthesized FHA at the pH value of 8.00 had the highest crystallinity and the largest crystal size, reaching 38.10 nm, and the crystal was in the form of short rods with a length of about 1 μm. It was found that the content of the F element in the synthesized FHA decreased as the pH value of the reaction system increased. When the pH value reached 8.00, the content of F was 0.60%, and the values of x and (2-x) in FHA [Ca 10 (PO 4 ) 6 F x (OH) 2-x ] were 0.16 and 1.84, respectively. FT-IR analysis further confirmed that the content of OH- in FHA obtained at the pH value of 8.00 was noticeably higher than that obtained at the pH value of 4.46. This work could provide a new prospect for utilizing FA to prepare FHA and be of great significance.

The development of functional materials based on metal oxides continues to grow in line with the demand for advanced materials in technological, environmental, and medical applications. In this study, superparamagnetic iron oxide nanoparticles (SPION, MF1) and manganese-doped Fe3O4 (Mn0.25Fe2.75O4, MF2) were successfully synthesized using a modified coprecipitation method. The synthesis involved magnetic separation, acid dissolution, precipitation with NH4OH, and Mn doping. Structural and optical characterizations (XRD, FTIR, UV-Vis) confirmed the formation of cubic spinel structures with notable changes in lattice parameters and crystallite size after Mn incorporation. FTIR spectra revealed O–H, C–O, Fe–O, and Mn–O vibrations, while UV-Vis analysis showed a decrease in band gap energy (from 3.11 eV to 3.07 eV) and Urbach energy (from 0.131 eV to 0.074 eV). These results demonstrate that Mn substitution enhances crystallinity and modifies the electronic properties of Fe3O4, highlighting its potential for photocatalytic and optoelectronic applications.

Preserving historic buildings requires renovation using compatible plasters that closely resemble the original ones. However, achieving this likeness requires a thorough characterization of the original plaster. This article explores the challenges of characterizing historic lime-based plasters from two architecturally interesting buildings in the Czech Republic dating back to the first half of the 20th century. Key issues include the determination of the binder-to-aggregate ratio, the fine aggregate particle size distribution, the mineralogical composition, and the degree of lime plaster carbonation. Experimental methods include X-ray diffraction analysis (XRD), pH-value determination, hydrochloric acid dissolution of binder components, sieve analysis, thermogravimetric analysis (TG), and differential scanning calorimetry (DSC). The tested plasters are compared, and the effectiveness of various approaches is evaluated. The binder-to-aggregate ratios are approximately 1:5. The plaster from one of the buildings was almost pure (lime binder + aggregate), while the second one contained other components, such as calcium silicate hydrates, gypsum, and magnesium phases.

Northern Arizona University, Flagstaff, Arizona, USA, recently installed a MIni CArbon DAting System (MICADAS) with a gas interface system (GIS) for determining the 14C content of CO2 gas released by the acid dissolution of biogenic carbonates. We compare 48 paired graphite, GIS, and direct carbonate 14C determinations of individual mollusk shells and echinoid tests. GIS sample sizes ranged between 0.5 and 1.5 mg and span 0.1 to 45.1 ka BP (n = 42). A reduced major axis regression shows a strong relationship between GIS and graphite percent Modern Carbon (pMC) values (m = 1.011; 95% CI [0.997–1.023], R2 = 0.999) that is superior to the relationship between the direct carbonate and graphite values (m = 0.978; 95% CI [0.959-0.999], R2 = 0.997). Sixty percent of GIS pMC values are within ±0.5 pMC of their graphite counterparts, compared to 26% of direct carbonate pMC values. The precision of GIS analyses is approximately ±70 14C yrs to 6.5 ka BP and decreases to approximately ±130 14C yrs at 12.5 ka BP. This precision is on par with direct carbonate and is approximately five times larger than for graphite. Six Plio-Pleistocene mollusk and echinoid samples yield finite ages when analyzed as direct carbonate but yield non-finite ages when analyzed as graphite or as GIS. Our results show that GIS 14C dating of biogenic carbonates is preferable to direct carbonate 14C dating and is an efficient alternative to standard graphite 14C dating when the precision of graphite 14C dating is not required.