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Americium is a highly radioactive actinide element found in used nuclear fuel. Its adsorption on aluminum (hydr)oxide minerals is important to study for at least two reasons: (i) aluminum (hydr)oxide minerals are ubiquitous in the subsurface environment and (ii) bentonite clays, which are proposed engineered barriers for the geologic disposal of used nuclear fuel, have the same ≡AlOH sites as aluminum (hydr)oxide minerals. Surface complexation modeling is widely used to interpret the adsorption behavior of heavy metals on mineral surfaces. While americium sorption is understudied, multiple adsorption studies for europium, a chemical analog, are available. In this study we compiled data describing Eu(III) adsorption on three aluminum (hydr)oxide minerals—corundum (α-Al2O3), γ-alumina (γ-Al2O3) and gibbsite (γ-Al(OH)3)—and developed surface complexation models for Eu(III) adsorption on these minerals by employing diffuse double layer (DDL) and charge distribution multisite complexation (CD-MUSIC) electrostatic frameworks. We also developed surface complexation models for Am(III) adsorption on corundum (α-Al2O3) and γ-alumina (γ-Al2O3) by employing a limited number of Am(III) adsorption data sourced from literature. For corundum and γ-alumina, two different adsorbed Eu(III) species, one each for strong and weak sites, were found to be important regardless of which electrostatic framework was used. The formation constant of the weak site species was almost 10,000 times weaker than the formation constant for the corresponding strong site species. For gibbsite, two different adsorbed Eu(III) species formed on the single available site type and were important for the DDL model, whereas the best-fit CD-MUSIC model for Eu(III)-gibbsite system required only one Eu(III) surface species. The Am(III)-corundum model based on the CD-MUSIC framework had the same set of surface species as the Eu(III)-corundum model. However, the log K values of the surface reactions were different. The best-fit Am(III)-corundum model based on the DDL framework had only one site type. Both the CD-MUSIC and the DDL model developed for Am(III)-γ-alumina system only comprised of one site type and the formation constant of the corresponding surface species was ~ 500 times stronger and ~ 700 times weaker than the corresponding Eu(III) species on the weak and the strong sites, respectively. The CD-MUSIC model for corundum and both the DDL and the CD-MUSIC models for γ-alumina predicted the Am(III) adsorption data very well, whereas the DDL model for corundum overpredicted the Am(III) adsorption data. The root mean square of errors of the DDL and CD-MUSIC models developed in this study were smaller than those of two previously-published models describing Am(III)-γ-alumina system, indicating the better predictive capacity of our models. Overall, our results suggest that using Eu(III) as an analog for Am(III) is practical approach for predicting Am(III) adsorption onto well-characterized minerals.

Despite the prevalence and toxicity of heavy metals in the environment, arsenic and cobalt are of particular concern due to their high mobility and bioaccumulation potential, particularly in contaminated groundwater. Herein, we studied the adsorption behavior of commercially available sorbents, including Fluorosorb-100 (FS-100), Fluorosorb-200 (FS-200), and Filtrasorb-400 (F-400), for the removal of arsenite (As(III)) and cobalt (Co(II)), aiming at the selection of filter media in terms of future groundwater remediation. Kinetic analysis revealed that As(III) adsorption followed a pseudo-second-order model, while Co(II) showed mixed first- and second-order behavior, reflecting sorbent-dependent mechanisms. Equilibrium isotherm modeling revealed strong correlations with both Langmuir and Freundlich models, confirming heterogeneous adsorption sites and multilayer interactions. FS-100 demonstrated the highest affinity for As(III) (qₘ = 0.46 mg/g) and F-400 exhibited the greatest adsorption capacity for Co(II) (qₘ = 1.00 mg/g), while FS-200 consistently showed relatively weaker adsorption for both metals. Desorption studies indicated predominantly irreversible binding, with minimal release of As(III) from F-400 and Co(II) from FS-200 and F-400, even at high concentrations. Overall, these findings highlight that commercially available sorbents can effectively capture arsenite and cobalt, offering cost-effective and scalable options for heavy-metal removal in groundwater remediation systems under realistic environmental conditions.

This paper focuses on the distributed generation (DG) controller of a PV-based microgrid. An independent DG controller (IDGC) is designed for PV applications to improve Maximum-Power Point Tracking (MPPT). The Extreme-Learning Machine (ELM)-based MPPT method exactly estimates the controller’s reference input, such as the voltage and current at the MPP. Feedback controls employ linear PI schemes or nonlinear, intricate techniques. Here, the converter controller is an IDGC that is improved by directly measuring the converter duty cycle and PWM index in a single DG PV-based MG. It introduces a fast-learning Extreme-Learning Machine (ELM) using the Moore–Penrose pseudo-inverse technique and online sequential ridge methods for robust control reference (CR) estimation. This approach ensures the stability of the microgrid during PV uncertainties and various operational conditions. The internal DG control approach improves the stability of the microgrid during a three-phase fault at the load bus, partial shading, irradiance changes, islanding operations, and load changes. The model is designed and simulated on the MATLAB/SIMULINK platform, and some of the results are validated on a hardware-in-the-loop (HIL) platform.

Coal mine tailings can lead to a range of environmental problems, including toxic metal contamination, soil erosion, acid mine drainage, and increased salinity. Mine spoils from coal mining activities accumulated as gob piles are difficult to reclaim due to constraints such as a steep slope, unsuitable pH, insufficient nutrient supply, metal toxicity, low water-holding capacity, and poor soil structure. We investigated the efficiency of low-cost amendments on coal gob spoils from Carthage Coal Field (CCF) in New Mexico in improving the quality of coal gob spoils. Gob spoil was incubated for 90 days with various rates of organic amendments such as biochar, compost, and a biochar–compost mix. Gob spoil quality parameters such as the pH, water-holding capacity, and total and plant-available nitrogen and phosphorus content of the gob spoil were measured over a period of 90 days. Both biochar and compost amendment led to a significant increase (40–60% for biochar and 70% for compost, p < 0.05) in water-holding capacity of the coal gob spoil. Plant-available nitrogen content increased from <200 mg N/kg to between 400 and 800 mg N/kg in the amended gob spoil. The period of incubation was a significant factor in the improvement of plant-available nitrogen content. Plant-available phosphorus content also increased; compost amendment was more effective than biochar in increasing plant-available P. This study provides crucial information about the optimum organic amendments that would help in optimizing a sustainable reclamation method for CCF.

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants of growing environmental and human health concern, widely detected across various environmental compartments. Effective remediation strategies are essential to mitigate their widespread impacts. This study compared the performance of two types of commercially available sorbent materials, granular activated carbon (GAC, Filtrasorb-400) and organoclays (OC-200, and modified organoclays Fluoro-sorb-100 and Fluoro-sorb-200) for the removal of three representative PFAS compounds: perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorooctane sulfonic acid (PFOS) from water. Both organoclays and modified organoclays outperformed GAC, likely due to electrostatic interactions between the anionic PFAS compounds and the cationic functional groups of the modified organoclays. A pseudo-second-order kinetic model best described the rapid sorption kinetics of PFOA, PFNA, and PFOS. For PFOA, OC-200 demonstrated the highest adsorption capacities (qmax = 47.17 µg/g). For PFNA and PFOS, Fluoro-sorb-100 was the most effective sorbent, with qmax values at 99.01 µg/g and 65.79 µg/g, respectively. Desorption studies indicated that the sorption of the three PFAS compounds on these commercially available sorbents was largely irreversible. This study highlights the effectiveness and sorption capacities of different types of commercial sorbents for PFAS removal and offers valuable insights into the selection of reactive media for PFAS removal from water under environmentally relevant conditions.

Per- and polyfluoroalkyl substances (PFAS) are fluorinated and refractory pollutants that are ubiquitous in industrial wastewater. Photocatalytic destruction of such pollutants with catalysts such as TiO2 and ZnO is an attractive avenue for removal of PFAS, but refined forms of such photocatalysts are expensive. This study, for the first time, utilized milled unrefined raw mineral ilmenite, coupled to UV-C irradiation to achieve mineralization of the two model PFAS compounds perfluorooctanoic acid (PFOA) and perfluoro octane sulfonic acid (PFOS). Results obtained using a bench-scale photocatalytic reactor system demonstrated rapid removal kinetics of PFAS compounds (>90% removal in less than 10 h) in environmentally-relevant concentrations (200–1000 ppb). Raw ilmenite was reused over three consecutive degradation cycles of PFAS, retaining >80% removal efficiency. Analysis of degradation products indicated defluorination and the presence of shorter-chain PFAS intermediates in the initial samples. End samples indicated the disappearance of short-chain PFAS intermediates and further accumulation of fluoride ions, suggesting that original PFAS compounds underwent mineralization due to an oxygen-radical-based photocatalytic destruction mechanism induced by TiO2 present in ilmenite and UV irradiation. The outcome of this study implies that raw ilmenite coupled to UV-C is suitable for cost-effective reactor operation and efficient photocatalytic destruction of PFAS compounds.

Uranium contamination in subsurface environments is a matter of great concern throughout the world. Fate and transport of uranium in the subsurface can be controlled by U(VI) adsorption and reduction onto common iron (oxy)hydroxides and clay minerals. Aqueous U(VI) can also exchange uranium atoms with solids comprised of uranium which can potentially lead to changes in the morphology of the uranium-containing solids and affect their stability.First, the performance of multiple surface complexation models (SCMs) on adsorption of U(VI) onto goethite was analyzed for a broad range of input conditions. Individual models could fit the data for which they were parameterized, but they performed poorly when compared with experimental data covering a broader range of conditions. We developed a series of robust models with different levels of complexity following a systematic roadmap. Goethite-uranyl-carbonate ternary surface complexes were required in every model. A triple plane model with a dimeric goethite-uranyl complex was found to provide the best fit, but the performance of a double layer model with bidentate goethite-uranyl and goethite-uranyl-carbonate complexes was also comparable. The models that ignore the bidentate feature of uranyl surface complexation consistently performed poorly. The goodness of fit for the models that ignore adsorption of carbonate was not significantly compromised compared with their counterparts that considered carbonate adsorption. This approach of model development for a large and varied dataset improved our understanding of U(VI)-goethite surface reactions and can lead to a path for generating a single set of reactions and equilibrium constants for including U(VI) adsorption to goethite in reactive transport models.Second, multiple SCMs for U(VI) adsorption onto montmorillonite were reviewed, and their performance for a large range of input conditions was evaluated. A new SCM was developed using a large and varied composite dataset to generate a model that would provide effective simulation over the full range of input conditions. This new model also employed a state-of-the-art technique to account for the spillover charge effect when estimating edge surface potential. The new model was comprised of four edge-site U(VI) surface complexation reactions and a single cation exchange reaction. Out of the four edge-site species, one was a U(VI)-carbonate ternary surface species that was only significant at an elevated carbonate concentration. The overall performance of the new model was robust, performing better than any of the models reviewed in this study for the composite dataset. This U(VI)-montmorillonite robust model along with robust models for other such minerals can be integrated with a reactive transport model which will help better predict uranium fate and transport in environmental conditions.Third, the extent of reduction of U(VI) adsorbed to chemically reduced montmorillonite was investigated at different pH and sodium concentrations using X-ray absorption spectroscopy and chemical extractions. Nearly 100% of U(VI) was reduced to U(IV) at low sodium concentration at both pH ~3 and ~6. The extent of U(VI) reduction at high sodium concentration and pH ~6 was only 70%. Surface bound U(VI) on unreduced montmorillonite was much more easily extracted into solution with bicarbonate than surface bound U(IV) generated due to reduction of U(VI) adsorbed onto reduced montmorillonite surface. U(IV) immobilized onto the clay surface by cation exchange is more resistant to bicarbonate-induced mobilization than uranium bound to the montmorillonite edge sites. We developed a non-electrostatic surface complexation model to interpret the equilibrium adsorption of U(IV) to reduced montmorillonite as a function of pH and sodium concentration. Our findings establish the importance of structural Fe(II) in low iron content smectites in controlling uranium mobility in subsurface environments.Finally, uranium atom exchange between aqueous U(VI) and the solid associated uranium species was probed using a 236U isotope tracer at pH 7 and 1 mM dissolved inorganic carbon condition. No isotope exchange was observed between aqueous U(VI) and the UO2(s) even after 47 days of reaction. However, occurrence of isotope exchange between aqueous U(VI) and the U(VI) adsorbed onto montmorillonite was observed within timescales of 5 minutes. X-ray photoelectron spectroscopy provided evidence for the presence of U(V) and U(VI) species on the U(IV) oxide surface.

This study focuses on comparative machining performance evaluation and economic assessment between recently developed nanocomposite AlTiSiN coating (deposited by scalable pulsed power plasma, S3P method) with AlTiN coated (accomplished by two different techniques, namely arc deposition method and the S3P technique) carbide tools in turning of hardened AISI H10 hot work steel (65 HRC) under dry environment. For the purpose of evaluating machining performance under different cutting factors (depth of cut, axial feed, and cutting speed), several machinability criteria (cutting temperature, crater wear, flank wear, chip morphology, surface roughness’ and cutting force) were analyzed. Finally, a creative way concerning cost assessment for economical hard machining has been proposed. Due to the development of enhanced machined surface morphology, lower cutting force and minimum temperature, improved chip morphology, and reduced tool wear, it is highlighted that AlTiSiN coated tools are superior to both AlTiN (LATUMA) and S3P-AlTiN coated tools. S3P-AlTiN and AlTiN (LATUMA) were the same coating material; however, AlTiN performed better due to the smooth coating and higher micro-hardness gained by S3P technique. The tool life of AlTiSiN coated inserts is 17% and 55% longer, respectively, when compared to the tool life obtained while using S3P-AlTiN and AlTiN (LATUMA) coated tools for dry machining. According to the findings, the hard turning process employing an S3P-AlTiSiN coated carbide insert is more cost-effective in a dry environment than using AlTiN (LATUMA) and the S3P-AlTiSiN coated carbide inserts, with a minimal machining cost per component in Indian rupees of Rs. 27.53 compared to Rs. 30.93 and Rs. 28.93, respectively. The nanostructured AlTiSiN coating accomplished by S3P technique significantly reduced tool wear (VB = 0.061–0.136 mm), improved surface finish (Ra = 0.576–1.458 µm), and higher surface quality, resembling cylindrical grinding. Graphical abstract

With the significant improvement of human civilization there is a spur in the urban, rural and industrial development, which has a profound effect on the surrounding natural environment. Increased utilization of natural resources is often associated with accumulation of waste materials whose management is crucial for sustainable development of life. Availability of different microorganisms in the soil facilitates the degradation of wastes through their potential enzymatic activities. Pectinase seems to be one of the important enzymes produced by a wide variety of microorganisms contained in the soil. It is mainly involved in maceration and rotting of plant extracts and debris by hydrolysis of 1,4-alpha glycosidic bonds of de-esterified pectate of plant call wall. In this paper we report molecular identification of some pectinase producing Aspergillus species selected from soil samples of five different zones of Bhubaneswar city using molecular biology and computational techniques. Among fifteen fungal isolates studied from these five zones Aspergillus parvisclerotigenus was potent for pectinase production next to Aspergillus niger in form of halozone of 0.6 mm. Its 28S rDNA sequence also had some significant identity (>90%) with different subspecies of Aspergillus. We hope that our findings will helpful in genetic manipulation for improvement of fungal strains of isolates. Again large scale use of the improved Aspergillus strains can degrade plant biomass & diverse industrial wastes which will reduce environmental pollution of capital urban like Bhubaneswar.