XRF Techniques Research Articles

Study on the Extraction of Rare Earth Elements (REEs) from Phosphogypsum Using Gluconobacter Oxydans Culture Solution

With the rapid development of modern industry, particularly in the fields of electric vehicles and renewable energy technologies, the demand for rare earth elements (REEs) has surged dramatically. Phosphogypsum (PG), which is an industrial waste product generated during the production of phosphoric acid through the sulfuric acid process, is rich in REEs. However, traditional chemical leaching methods pose environmental pollution and resource wastage issues. This study aims to explore the feasibility and optimal conditions for bioleaching REEs from phosphogypsum using Gluconobacter oxydans (G. oxydans). The phase composition and components of phosphogypsum, as well as the growth characteristics and leaching efficiency of G. oxydans, were analyzed in detail using SEM, EDS, XRD, and XRF techniques. Experimental results indicate that G. oxydans can effectively leach REEs from phosphogypsum under conditions of 28 °C, an agitation speed of 150 rpm, and a liquid-to-solid ratio of 4:1, with a maximum leaching efficiency of 24.67%. Moreover, it is revealed in the study that G. oxydans exhibits selectivity in leaching REEs. Specifically, the leaching efficiency for Nd is significantly enhanced at low pH values. This research provides a theoretical basis and practical application example for the efficient and environmentally friendly recovery of REEs from phosphogypsum.

Metasomatism and REE mineralization of the Zilair Formation sedimentary rocks in the Khudolaz complex gabbro massif exocontact zone (Chebarkul area, Southern Urals)

Relevance. West-Magnitogorsk zone (Southern Urals) hold a lot of Early Carboniferous gabbroic and granitoid intrusions which associated with various mineralization types (Ti-Fe, Cu-Ni-PGE, Au), but information about REE mineralization is scarce. Contact hydrothermal-metasomatic processes rarely form the economic REE mineral deposits, but they can provide valuable information about the behaviors of rare earth elements. Aim. Mineralogical and geochemical characteristics of metasedimentary rocks from exocontact zone of the Khudolaz complex gabbro massif, study of rare earth minerals, determination of the formation conditions and sources of mineralizing fluids. Methods. Minerals were studied using optical and scanning electron microscopy; the bulk composition of the rocks was determined by XRF and ICP-MS analytical techniques; vapor-liquid fluid inclusions in calcite were studied using microthermometry and Raman spectroscopy; the isotopic composition of carbon and oxygen was determined for metasedimentary silicate-carbonate metasomatites. Results and conclusions. In the Khudolaz complex gabbro massif exocontact zone, the Zilair Formation sedimentary rocks undergo recrystallization associated with hydrothermal-metasomatic processes and manifested as the formation of globular and granoblastic textures, stylolites, the formation of metacrystals of various rock-forming and accessory minerals, including rare earth minerals (synchisite-(Ce), CaCe(CO3)2F, and REE-rich clinozoisite, (Ca,REE)2Al3O[Si2O7][SiO4](OH)). According to microthermometry of vapor-liquid fluid inclusions in calcite, the formation of REE-bearing minerals occurred at temperatures not lower than 150 °С. The sources of rare earth elements could be both the Zilair Formation sedimentary rocks and gabbro, as evidenced by the increase in REE concentrations and isotopic composition of oxygen and carbon in silicate-carbonate metasomatites (δ18OSMOW =13.80…15.98 ‰, δ13С = –5.64…–2.18).

Performance, adsorption and kinetic study of AgY zeolite for DBT desulfurization

This study focuses on preparing and evaluating AgY zeolite as an adsorbent for the desulfurization (ADS) of dibenzothiophene (DBT) using a model fuel. Kinetic models and adsorption isotherms were investigated for this process. The AgY zeolite characterization was studied using XRD, BET, and XRF. XRD and XRF techniques revealed that AgY zeolite was successfully prepared with 21.42% wt. Ag. The BET results showed that the pore volume of AgY zeolite was 0.3596 cm³/g and the surface area was 531 m²/g. The desulfurization study was done with an initial sulfur content of 100–460 ppm. With 93% sulfur removal from the initial concentration of 100 ppm, ultra-deep desulfurization was achieved. The effect of contact time on the adsorption efficiency was investigated within a range of 10-120 min, and the results showed that most sulfur removal (52%) occurred after 10 minutes, while it reached 75% after 120 min with a sulfur capacity of 57.5 mg S/g. The results indicated that the Langmuir isotherm model was the most suitable to describe the process with R² of 99.29%, while the pseudo-second-order was the most fitted kinetic model to the data with R² of 98.57%.

Employment of Fe3O4/Fe2TiO5/TiO2 Composite Made Using Ilmenite for Elimination of Methylene Blue

A novel material was created from natural ilmenite sand, and methylene blue (MB) was used to test the material’s capacity to remove colors from wastewater. The material was synthesized by neutralizing the acid leachate obtained by Ilmenite sand digestion, followed by drying at 180 °C. It was characterized by XRD, Raman, TEM, SEM, XPS, XRF, and BET techniques. The crystal nature of the composite is Fe3O4/Fe2TiO5/TiO2. The surface area, average pore size and total pore volume of the composite are 292.18 m2/g, 1.53 nm, and 0.202 cc/g, respectively. At pH 10, 10 mg/L MB, and 10 mg of the material resulted in a maximum adsorption capacity of 24.573 mg/g. Using 5 mg/L increments, the dye concentration was adjusted between 10 and 25 mg/L, yielding equilibrium adsorption capacities of 24.573, 31.012, 41.443, and 52.259 mg/g with 10, 15, 20, and 25 mg/L, respectively. The greatest adsorbent capacity of 24.573 mg/g was achieved with 10 mg of the adsorbent and 10 mg/L MB. The adsorbent dosage ranged from 10, 25, 45, 65, and 100 mg. MB was adsorbed via pseudo-second-order kinetics with an adsorption capacity of 24.863 mg/g. The intraparticle diffusion model showed that MB adsorption occurs in three stages, with intra-particle diffusion constants of 1.50, 2.71, 3.38, and 4.41 g/mg min1/2. Adsorption followed the Langmuir isotherm model. The obtained thermodynamic parameters ΔG, ΔH, and ΔS were −27.5521 kJ/mol at 298 K, 2.571 kJ/mol, and 0.101 kJ/mol, respectively. Regeneration studies of the adsorbent were carried out for five cycles, indicating some activity loss after each cycle.

Structural and Ammonia Adsorption Properties of the Gördes Clinoptilolite After HCl Acid Treatment

The effect of activation with HCl on the ammonia adsorption characteristics of natural Gördes clinoptilolite was studied in order to evaluate the usability of this mineral in various environments where ammonia removal is required, such as livestock facilities. Clinoptilolite was treated with HCl solutions (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 M) at 90°C for 4 h. XRD, XRF, FT-IR, TGA, DTA and N2 adsorption techniques were used for structural and thermal characterization of the adsorbents. NH3 adsorption isotherms were measured volumetric analysis at 298 K up to 100 kPa. Acid activation not only caused textural and structural changes such as removal of exchangeable cations but also affected the thermal behavior and gas retention of the clinoptilolite. Nitrogen adsorption results showed that it is possible to improve the specific surface area and micropore area values of clinoptilolite with acid activation up to 1.5 M. In addition, the NH3 adsorption capacities of clinoptilolite samples (4.33-5.01 mmol.g-1) were compared with the ammonia removal data of natural and synthetic zeolites (1.77 - 9.32 mmol.g-1) reported in previous studies.

Promoting Sustainability in the Cement Industry: Evaluating the Potential of Portuguese Calcined Clays as Clinker Substitutes for Sustainable Cement Production

The cement industry significantly contributes to global CO2 emissions, posing several challenges for a future low-carbon economy. In order to achieve the target established by the European Sustainable Development Goals of reaching carbon neutrality by 2050, the European Cement Association (Cembureau) has devised a comprehensive roadmap based on five key approaches, referred to as the 5C strategies. Portland clinker is one of the crucial concerns, since its production emits over 60% of the cement manufacturing emissions. Therefore, supplementary cementitious materials (SCMs) to partially replace clinker content in cement have gained significant attention in providing alternatives to traditional clinker in cement production. This paper evaluates the potential of Portuguese calcined clays (CCs) as viable substitutes for clinker to enhance sustainability in cement manufacturing. More than 50 clays were characterised through chemical and mineralogical analyses to assess their reactivity and suitability for calcination using the strength activity index (SAI), along with XRD, XRF, and TGA techniques. This study investigated the calcination conditions that provide the best clay reactivity, which were subsequently used for calcination. This investigation is part of a project to evaluate the behaviour of calcined clays through mechanical, hydration, and durability properties. The findings indicate that Portuguese calcined clays exhibit promising pozzolanic activity. Furthermore, these clays could significantly reduce CO2 emissions and raw material consumption in cement production. This research underscores the potential of local calcined clays as a sustainable clinker substitute, promoting eco-friendly practices in the construction industry.

Nano-pumice derived from pumice mine waste as a low-cost electrode catalyst for microbial fuel cell treating edible vegetable oil refinery wastewater for bioenergy generation and reuse

This study aimed to assess nano-pumice (NP) from pumice mining waste as a local, cost-effective anode catalyst in microbial fuel cells (MFCs) for treating edible vegetable oil refinery wastewater (EVORW) and generating bioenergy. Pumice mining waste was converted into nano in three stages: crushing up to ≤3 cm, reducing the size of the previous step particles to 150 μm and converting the previous step particles to <100 nm. Nano-pumice prepared was coated on the carbon cloth (CC) to increase anode surface area of MFC. Two MFCs were utilized, with MFC-1 serving as a control and MFC-2 incorporating a CC electrode coated with nano-pumice. The surface morphology, elemental and chemical composition, and textural characterization of CC, pumice, NP, and CC coated with NP were analyzed using FE-SEM, EDX, XRF, and BET techniques. MFC-2 achieved a maximum power density of 30±4W/m³ at a current density of 55±5A/m³. The MFC-1 reached a maximum power density of 18±4W/m³ at a current density of 35±6A/m³. In MFC-2, the EVORW treatment achieved maximum removals of COD (94 ± 2 %), NH4+-N (85 ± 4 %), TP (76 ± 5 %), SO42− (68 ± 6 %), TSS (81 ± 2 %), and TDS (73 ± 1 %). MFC-1 achieved removal efficiencies of 66 ± 3 % for COD, 57 ± 6 % for NH4+-N, 48 ± 3 % for TP, 45 ± 3 % for SO42−, 65 ± 3 % for TSS, and 61 ± 1 % for TDS. MFC-2 power density rose significantly, reaching 61 ± 3 % (1.6 times) higher than MFC-1and it also demonstrated a superior ability to improve raw wastewater quality compared to MFC-1. The MFC with the CC/NP anode exhibited both excellent power production and high COD removal efficiency, making nano-pumice a suitable anode catalyst for MFC applications.

Synthesis and characterization of ceramic refractories based on industrial wastes

The possibility of reusing ceramic roller waste to produce cordierite and mullite refractories was investigated. Five batches were designed using wastes representing ceramic roller waste, magnesite, and silica sand, shaped and fired at 1300 °C/2 h, and one batch was selected at 1200 °C. The chemical composition and precipitated phases of the used raw materials and the fired batches were analyzed using XRF and XRD techniques, respectively. Densification parameters, morphology, microstructure and electrical properties were also studied to evaluate the effect of the formed phases on the properties of fired materials. Bulk density increases with an increase in mullite and a decrease in cordierite, and it also increases with increasing temperature, whereas porosity and water absorption show a opposite behavior to density (it decreases with an increase in mullite and temperature). The main phases developed after firing at 1300 °C/2 h were cordierite, mullite, corundum, baddeleyite, and spinel. Bending strength increases with increasing mullite percentage and density, and decreasing grain size and porosity. The microstructure develops and becomes finer with increasing mullite percentage and density. The grain size of the crystals was very fine at 1200 °C/2 h and increased at 1300 °C/2 h. Broadband dielectric spectroscopy was employed to study the electrical and dielectric behavior of the investigated samples. The increase in mullite concentration shows a remarkable increase in ε’, especially at lower frequencies, as it is three times higher than that of M10. At f > 103 Hz ε’, frequency independence is accompanied by an increase in mullite concentrations due to the lag of dynamics fluctuations after the alteration of the electric field. The generation of new free ions leads to the enhancement of conductivity as the mullite concentration increases.

Artificial Neural Network Modeling of the Removal of Methylene Blue Dye Using Magnetic Clays: An Environmentally Friendly Approach

In this study, the effectiveness of Fe3O4-based clay as a cost-effective material for removing methylene blue (MB) dye from aqueous solutions was evaluated. The structural properties of the clay and Fe3O4-based clay were analyzed using SEM, XRF, BET, XRD, FTIR, and TGA techniques. In this research, the effects of various aspects, such as adsorbent amount, contact time, solution pH, adsorption temperature, and initial dye concentration, on the adsorption of Fe3O4-based clay are investigated. The experiments aimed at understanding the adsorption mechanism of Fe3O4-based clay have shown that the adsorption kinetics are accurately described by the pseudo-second order kinetic model, while the equilibrium data are well represented by the Langmuir isotherm model. The maximum adsorption capacity (qm) was calculated as 52.63 mg/g at 25 °C, 53.48 mg/g at 30 °C, and 54.64 mg/g at 35 °C. All variables affecting the MB adsorption process were systematically optimized in a controlled experimental framework. The effectiveness of the artificial neural network (ANN) model was refined by modifying variables such as the quantity of neurons in the latent layer, the number of inputs, and the learning rate. The model’s accuracy was assessed using the mean absolute percentage error (MAPE) for the removal and adsorption percentage output parameters. The coefficient of determination (R2) values for the dyestuff training, validation, and test sets were found to be 99.40%, 92.25%, and 96.30%, respectively. The ANN model demonstrated a mean squared error (MSE) of 0.614565 for the training data. For the validation dataset, the model recorded MSE values of 0.99406 for the training data, 0.92255 for the validation set, and 0.96302 for the test data. In conclusion, the examined Fe3O4-based clays offer potential as effective and cost-efficient adsorbents for purifying water containing MB dye in various industrial settings.

Optimization of Progressive Freeze Crystallization Process by Response Surface Methodology for the Treatment of Electroplating Wastewater for Copper (II) Sulphate Recovery

&lt;p style="line-height:200%;text-align:justify;text-indent:0cm;text-justify:inter-ideograph;"&gt;&lt;span style="line-height:200%;" lang="EN-US"&gt;For the copper-containing electroplating wastewater generated by a semiconductor company, the recovery of copper salts by progressive freeze crystallization and its process parameters were experimentally optimized and studied.&amp;nbsp;Based on the results of single-factor experiments, according to the principles of Box-Behnken Design experimental design for response surface methodology to investigate the effects of coolant temperature, agitation rate, and freezing time on salt removal and optimize process parameters. The optimization results of the response surface method showed that the optimal conditions were when the coolant temperature was -8°C, the stirring rate was 264 r&lt;/span&gt;&lt;span style="font-family:Symbol;line-height:200%;" lang="EN-US"&gt;×&lt;/span&gt;&lt;span style="line-height:200%;" lang="EN-US"&gt;min&lt;sup&gt;-1&lt;/sup&gt;, and the freezing time was 78 min.&amp;nbsp;Three validation experiments were conducted under optimum conditions, and salt removal was obtained as 60.13 ± 4.10%, which is more in line with the predicted values.&amp;nbsp;Treatment of copper-containing electroplating wastewater using tertiary freezing under response surface optimized experimental conditions.&amp;nbsp;At this time, the total ice rate of the wastewater was about 65.00%, and the conductivity was also concentrated from 2.17&amp;nbsp;mS&lt;/span&gt;&lt;span style="font-family:Symbol;line-height:200%;" lang="EN-US"&gt;×&lt;/span&gt;&lt;span style="line-height:200%;" lang="EN-US"&gt;cm&lt;sup&gt;-1&lt;/sup&gt; of the raw water to 2.99&amp;nbsp;mS&lt;/span&gt;&lt;span style="font-family:Symbol;line-height:200%;" lang="EN-US"&gt;×&lt;/span&gt;&lt;span style="line-height:200%;" lang="EN-US"&gt;cm&lt;sup&gt;-1&lt;/sup&gt; with a total concentration ratio of 1.38.&amp;nbsp;In addition, a higher concentration of concentrated liquid was obtained in the third freezing, while a crystalline salt precipitated from the bottom of the reactor. The precipitate was analyzed mainly as copper sulfate pentahydrate using XRD, XRF, EDS, and other characterization techniques.&lt;/span&gt;&lt;span lang="EN-US"&gt; Theoretical calculations show that pre-cooling of raw wastewater reduces energy consumption by up to 20.40%.&lt;/span&gt;&lt;/p&gt;

Evolution mechanism of element Ni on matrix, surface and interface during static soaking of copper-nickel alloy

This article uses XRF, WLI, SEM, EDS, XPS and EIS techniques to characterize the surface element segregation and the state of corrosion product films under different periods of artificial seawater immersion. The research results show that when the film is intact, a uniform Ni-rich layer is formed below the film due to the preferential dissolution of Cu elements, which weakens the segregation degree of Ni elements on the surface of the substrate. At the same time, Ni elements enter the film in the form of doping, which increases the resistance of the film. When the film layer is damaged, the Ni-rich layer between matrix and surface will be rapidly converted to NiO, the enrichment state of Ni element will be destroyed, and the segregation degree will be increased. However, NiO only plays a temporary protective role, and it is easy to hydrolysis into loose Ni (OH)2, resulting in the film layer fall off. After the matrix is exposed, the Cu element is preferentially dissolved again, and the nickel-rich layer is re-formed on the substrate surface.

Influence of Integral Crystalline Waterproofing on Concrete Properties: Dosage Impact and Microstructural Analysis

The present research study aims to investigate the properties and performance of concrete containing an integral crystalline waterproofing (ICW) admixture, added at an optimal dosage to resist water without compromising structural integrity. To achieve this, an experimental program was conducted on specimens with ICW dosage variations ranging from 0 to 4.8 kg/m2. The impact on water absorption, pulse velocity, and microstructural characteristics was tested and analyzed using XRF and EDS techniques. The findings reveal that increasing the dosage decreases water absorption by approximately 43% at maximum dosage compared with the control. A 41% increase in pulse velocity indicates a denser concrete matrix. The principle of optimization is highlighted, as an overdose of ICW generates a non-structural crystalline gel at the bottom of the specimens. The optimum dosage range for ICW to improve water resistance without adverse effects on structural performance was determined to be 3.2 to 4.0 kg/m2. This research introduces a novel approach by evaluating the comprehensive performance of concrete in relation to ICW dosage, providing valuable insights into the practical application of ICW admixture to enhance concrete quality and durability. Doi: 10.28991/CEJ-2024-010-10-02 Full Text: PDF

Elaboration of fibrous structured activated carbon from olive pomace via chemical activation and low-temperature pyrolysis

The objective of this study is to examine the preparation of activated carbon with a fibrous structure obtained from olive pomace through a chemical activation process using phosphoric acid (H3PO4) as the activating agent under air at a lower temperature. According to the findings, the most effective conditions to achieve high-performance activated carbon were 22 vol% of H3PO4, a 2-h chemical activation impregnation residence time at 50 °C, and a 500 °C pyrolysis temperature for 1 h. Structural analysis revealed that activated carbons possess highly developed textural and structural properties, resulting in an iodine value of 923 mg/g and a specific surface of 1400 m2/g. In addition to its microporosity, the produced carbon exhibits a highly developed fibrous structure, providing excellent adsorption properties. To confirm these results, SEM, FT-IR, XRF, XRD, Raman, and TGA techniques were employed. The fibrous carbon produced will expand the use of renewable carbon materials for removing various types of contaminants, including organic and inorganic pollutants in water, and numerous other industrial applications.

Application of a new method to estimate micronutrient concentration percentages in dried celery plants using LIBS and XRF techniques

Application of a new method to estimate micronutrient concentration percentages in dried celery plants using LIBS and XRF techniques

Distribution of Heavy Metals along the Mediterranean Shoreline from Baltim to El-Burullus (Egypt): Consequences for Possible Contamination

This work is mainly concerned with the effect of anthropogenic activities, the presence of black sand spots, factory construction, and shipping, in addition to other activities like agriculture, on soil heavy metal pollution along the Mediterranean shores of Lake El-Burullus, Egypt, to assess the contamination levels and to identify possible sources and the distribution of these metals. This study focuses on the various heavy metal contamination levels in El-Burullus Lake coastal sediments. Sediment samples were collected and analyzed by the XRF technique for heavy metals, including Cr, Cu, Ni, Zn, Zr, Pb, Ba, Sr, Ga, Rb, V, and Nb. Statistical analyses, including correlation coefficient, factor analysis, and cluster analysis, were employed to understand the interactions and sources of these metals. The highest concentrations recorded were for Zr (84–1436 mg/kg) and Pb (1–1166 mg/kg), with average concentrations of 455.53 mg/kg and 79.27 mg/kg, respectively. Cr, Zr, Nb, and Pb showed average values higher than the average shale concentration, indicating potential pollution. Correlation analysis revealed strong associations between several metals, suggesting common sources of both natural and anthropogenic origin and similar distribution patterns. Factor analysis indicated four main factors accounting for 94.069% of the total variance, with the first factor heavily dominated by Cr, Ni, Zn, and Ba. The contamination factor (Cf) and degree (DC) analyses revealed varying contamination levels, with most metals exhibiting the greatest values in the western half of the area. The pollution load index (PLI) indicated high-quality sediment samples without significant pollution. Our findings highlight the importance of continued monitoring and management techniques to reduce possible environmental and health concerns associated with these pollutants.

Migmatite-Gneiss-Granite Basement of Southwestern Nigeria: Mineralogical and Geochemical Evidence for a Possible Common Ancient Protolith

Nigeria occupies southern section of the Pan-African orogenic belt and migmatite-gneiss-granite terrain forms a major component of its basement complex. Field geology, optical mineralogy and geochemical study of this rock unit in Idanre area, SW Nigeria were undertaken with a view to characterize them, elucidate their tectonic significance, and determine their origin. Major, trace and Rare Earth Elements (REE) composition were determined by XRF and ICP-MS techniques respectively in Bureau Veritas, Vancouver, Canada.

Experimental Investigation of Recycling Cement Kiln Dust (CKD) as a Co-Binder Material in Cemented Paste Backfill (CPB) Made with Copper Tailings

Cement production may involve excessive use of natural resources and have negative environmental impacts, as energy consumption and CO2 emissions can cause air pollution and climate change. Cement kiln dust (CKD), a by-product waste material, is also a primary issue associated with cement production. Utilizing CKD in mining applications is a pathway to eco-sustainable solutions. Cemented paste backfill (CPB) made with mine tailings is an efficient method for void backfilling in underground mines. Therefore, this study investigated the eco-sustainable utilization of CKD as a co-binder material that can partially replace cement in CPB prepared with copper tailings. At 7, 14, 28, 56, and 90-day curing times, the experimental campaign measured the physical and mechanical parameters of the cured CPB samples, including density, UCS, and elastic modulus (stiffness). Additionally, the CPB-cured mixes were analyzed using XRF, X-ray XRD, SEM, and EDX techniques to link the mineral phases and microstructure to mechanical performance. Four proportions (5, 10, 15, and 20%) of CKD represented in 75 samples were prepared to replace ordinary Portland cement (OPC) in the CPB mixtures, in addition to the reference mix (control) with 0% CKD. As all combinations exceed the compressive strength of CPB required for achieving stability in underground mines, the results showed that CKD could be utilized advantageously as a partial substitute for OPC with a proportion of up to 20% in the CPB mixture. When tested after 90 days, the combination modified with 5% CKD exhibited comparatively higher compressive strength than the control mixture.

Enhanced removal of methylene blue and procion deep red H-EXL dyes from aqueous environments by modified-bentonite: Isotherm, kinetic, and thermodynamic

This study aims to enhance local bentonite's effectiveness in removing methylene blue and procion deep red dyes from aqueous media through organic modification with cetyltrimethylammonium bromide surfactant. Raw and modified bentonites were analyzed using XRF, XRD, FTIR, BET/BJH, and DSC techniques. The modified bentonite showed a crystalline structure and mesoporous morphology with a heterogeneous surface. Optimal adsorption conditions for MB dye were 0.2 g adsorbent dose, 60 min contact time, 60 mg/L initial concentration, and pH 8, achieving a maximum sorption capacity of 6.418 mg/g. For PDR dye, optimal conditions were a 0.125 g adsorbent dose, 40 mg/L initial concentration, 30 min contact time, and acidic pH, with a maximum adsorption capacity of 8.503 mg/g. Isotherm analysis indicated the Langmuir model best fits the adsorption data, suggesting a mono-layer adsorption process. Kinetic investigations revealed that the adsorption follows a pseudo-second-order model, indicating a chemisorption mechanism. Thermodynamic results showed exothermic adsorption for MB and endothermic adsorption for PDR. This work highlights the potential of surfactant-modified bentonite as a cost-effective sorbent for treating polluted aqueous systems, effectively removing both cationic and anionic dyes.

Feasibility Analysis of Bacterial-Treated Coal Gangue for Soil Improvement: Growth-Promoting Effects of Alfalfa

The long-term storage of coal gangue (CG) mountains causes serious environmental problems such as water and air pollution. Thus, sustainable reclamation practices are urgently needed to minimize the environmental impacts brought by CG mountains. Pikovskaya medium was employed to screen microorganisms, which were subsequently utilized to promote the solubilization of CG. XRF, SEM, XRD, and HPLC techniques were employed to characterize the CG before and after bacterial treatment. In this study, we have successfully isolated and purified a bacterial strain, identified as Stenotrophomonas bentonitica BII-R7, which possesses the ability to facilitate the solubilization of nutrient elements from CG. Factors including initial inoculation ratio, incubation time, CG particle size, CG concentration, pH, and temperature were examined to investigate their effects on the biosolubilization of CG. Furthermore, the mechanism underlying the CG solubilization was also probed. Our data demonstrated that low-molecular-weight organic acids, such as acetic acid and formic acid, may harbor a crucial role in promoting the solubilization of CG. Lastly, we found that Stenotrophomonas bentonitica BII-R7, in conjugation with CG, can increase the alfalfa seed germination percentage and promote the growth of alfalfa. Together, these data provide evidence that bacterial-treated CG can be utilized for soil improvement and land reclamation.

Synthesis and Characterization of Calcium Phosphate Using Two Stages of Process

Calcium phosphate, a naturally occurring biomaterial found in human and animal bones and teeth, possesses desirable properties such as strength, biocompatibility, and the ability to stimulate tissue growth. This study investigates the synthesis of calcium phosphate through a precipitation method without calcination. The process involves dissolving raw materials in phosphoric acid, followed by precipitation using KOH as the precipitating agent. The resulting precipitate was then calcined for 3 hours. The calcium phosphate product was characterized using XRF, XRD, and SEM-EDX techniques. The results indicate a Ca-P molar ratio ranging from 1.855 to 2.302, with the predominant phase identified as β-calcium pyrophosphate. SEM analysis reveals a plate-like morphology with agglomerated particles ranging in size from 888 nm to 7.79 μm. The synthesized calcium phosphate holds potential for various biomedical applications due to its unique properties and composition.