Pretreatment Procedure Research Articles

Review on Gallium in Coal and Coal Waste Materials: Exploring Strategies for Hydrometallurgical Metal Recovery.

Gallium, a critical and strategic material for advanced technologies, is anomalously enriched in certain coal deposits and coal by-products. Recovering gallium from solid residues generated during coal production and utilization can yield economic benefits and positive environmental gains through more efficient waste processing. This systematic literature review focuses on gallium concentrations in coal and its combustion or gasification by-products, modes of occurrence, gallium-hosting phases, and hydrometallurgical recovery methods, including pretreatment procedures that facilitate metal release from inert aluminosilicate minerals. Coal gangue, and especially fly ashes from coal combustion and gasification, are particularly promising due to their higher gallium content and recovery rates, which can exceed 90% under optimal conditions. However, the low concentrations of gallium and the high levels of impurities in the leachates require innovative and selective separation techniques, primarily involving ion exchange and adsorption. The scientific literature review revealed that coal, bottom ash, and coarse slag have not yet been evaluated for gallium recovery, even though the wastes can contain higher gallium levels than the original material.

Preparation and Characterization of Supercapacitor Cells Using Modified CNTs and Bimetallic MOFs

The synthesis of CoZn-MOF was accomplished via a simple hydrothermal method. The characterization of the synthesized materials was performed using X-ray diffraction (XRD), providing a thorough understanding of their structure and content. Subsequently, carbon nanotubes (CNTs) underwent three different pretreatment procedures prior to their application as an anode in a supercapacitor (SC) arrangement, with CoZn-MOF functioning as the cathode. The use of CNTs as electrode material led to an inherent improvement in conductivity and an intrinsic increase in the specific capacitance of the supercapacitor. Galvanostatic charge–discharge measurements of the three cells with different electrodes proved that the supercapacitor based on the CNT (acetic acid)//CoZn-MOF exhibited a capacity of 0.2285 F/g, a moderate energy density of 0.1944 Whkg−1 at a power density of 26.48 Wkg−1 as compared to the other two supercapacitors (CNT (nitric acid)//CoZn-MOF and CNT (unprocessed)//CoZn-MOF). This study utilized the advantages of carbon nanotubes in supercapacitor electrodes and examined the impact of CNT pretreatment.

Fabrication of Porous Silica‐ruthenium Oxide Composite Catalysts for Hydrogenation of Carbon Dioxide Into Formic Acid

AbstractPorous silica–ruthenium oxide composite catalysts were prepared with sol–gel‐based method using a cationic surfactant, cethyltrimethylammonium bromide (CTAB), as templates to form well‐ordered nanopores in the catalyst particles. The previously reported heterogeneous catalysts for hydrogenation of carbon dioxide into formic acid generally worked as metallic state, while the catalyst in the present study worked without reduction procedure for the catalyst activation to obtain the metallic states of the active ruthenium species. The textural properties of the catalysts in this work were affected by various pretreatment procedures, and washing and calcination pretreatments were identified as effective procedures to remove the surfactant micelle templates with 2–4 times higher specific surface area and pore volumes. The catalytic activity also improved with the pretreatments, and the catalyst with washing followed by calcination showed nearly three times higher activity than the catalyst without any pretreatments. The crystalline size of the active ruthenium species and the catalytic performance of porous silica–ruthenium oxide composite catalyst was influenced by amount of TEOS, the catalyst including small RuO2 crystalline phase was obtained with high amount of TEOS and exhibited high activity for hydrogenation of carbon dioxide into formic acid with comparative TON to previously reported metallic ruthenium‐based catalysts.

Nanoengineered Nonenzymatic Paper-Based Fluorescent Platform for Pre-Dilution-Free and Visual Real-Time Home Monitoring of Urea for Early Warning of Abnormal Nitrogen-Based Unhealthy Issues.

Distorted urea levels indicate several liver, kidney, or metabolic diseases; however, traditional clinical urea detection relies on urease-based methods enslaved to well-known limitations of high-price, unstable properties, complicated sample pretreatment and analysis procedures, and difficult visual real-time monitoring. Herein, nonenzymatic paper-based fluorescent materials (UFP-BP) are strategically integrated with an on-demand fluorescent-sensor (UFP) self-aggregated nanoparticle on commercial filter paper for pre-dilution-free and visual real-time urea monitoring. The UFP is synthesized and self-aggregated into the fluorescent nanoparticles for selective urea recognition. Then, the nanoparticles are interstitially loaded on filter paper to nanoengineer the UFP-BP, achieving selective quantitative urea detection in the normal concentration range (10-1000mm). UFP and UFP-BP can successfully monitor urea levels in real rat urine, artificial simulants, and milk. The proposed sensing platform, integrated with smartphones, offers accurate, quantitative, nonenzymatic, noninvasive, pre-dilution-free, on-site, rapid, low-cost, easy-to-operate, real-time visual urea detection in food samples and human body fluids. The designed sensing system can provide early warnings of abnormal nitrogen-based health issues.

Water-Soluble Fluorescent Sensors for Quantification of Trace Cisplatin in Body Fluids from Clinical Cancer Patients.

Accurate quantification of cisplatin (cDDP) in body fluids (blood, urine, and ascites) is crucial in monitoring therapeutic processes, assessing drug metabolism, and optimizing treatment schedules for cancer patients. Nonetheless, due to the inherent fluorescence and complexity of the body fluid matrix, along with the low cDDP concentrations in these fluids during treatment, using fluorescent sensors for fluid detection remains a subject of ongoing research. Herein, a series of water-soluble cDDP-activatable fluorescent sensors was rationally constructed by introducing thioether groups to the xanthene skeleton based on the chalcogenophilicity of platinum. These sensors exhibit excellent sensitivity and certain anti-interference capabilities for sensing cDDP in living cells, rat tissues, and zebrafish. Especially, with a simplified sample pretreatment procedure, for the first time, Rh3 and Rh4 have enabled quantitative detection of cDDP levels in diversiform body fluids from clinical ovarian and bladder cancer patients. These results are highly consistent with those obtained by ICP-MS detection. This work paves the way for utilizing fluorescent sensors in clinical body fluid analysis, thus potentially revolutionizing the monitoring methods of cDDP in clinic settings.

A Cost-Effective, Eco-Friendly and Functional Wastewater Pre-Treatment Procedure Development for the Degradation of β-Lactam Antibiotic Residues Discharged from Cephalosporin Drug Manufacturing Plant

A Cost-Effective, Eco-Friendly and Functional Wastewater Pre-Treatment Procedure Development for the Degradation of β-Lactam Antibiotic Residues Discharged from Cephalosporin Drug Manufacturing Plant

Advancing biorefineries with ultrasonically assisted ionic liquid-based delignification: Optimizing biomass processing for enhanced bio-based product yields

Encouraging sustainable business needs utilization of bio-based substrate for green manufacturing of chemicals and fuels to achieve sustainable development goals set by the United Nations. One of the abundantly available bio-based substrates is lignocellulosic (LC) biomass, which requires effective pretreatment to fractionate into its structural biocomponents to maximize biorefinery potential. This study addresses the use of an inexpensive ionic liquid (triethylammonium hydrogen sulfate) [T2220][HSO4] in an ultrasound-assisted process as an environmentally acceptable pretreatment method for the delignification of LC biomass, specifically rice straw (RS). Using ionic liquid (IL)-assisted (IL, acid-IL, and alkali-IL) pretreatment procedures, the effects of IL volume, sonication time, and temperature were methodically examined for RS delignification. To evaluate the compositional changes in pretreated and raw RS, instrumental analyses were carried out. The maximum rates of 47 %, 55 %, and 64 % for the only IL, acid-IL, and alkali-IL treatments demonstrated the effect of temperature, operating time, and IL concentration on the delignification efficiency. The alkali-IL pretreatment was noteworthy for achieving a 64 % delignification rate under optimum values of IL volume (8.65 mL), sonication time (123 min), and temperature (82 °C). Artificial neural networks (ANN) and response surface methodology (RSM) were used for process modeling and optimization. With an accuracy of 0.989 in correlation coefficient, the ANN model outperformed the RSM regression model regarding forecasting delignification performance. Biorefinery of renewable biomass resources ensures the sustainable supply of materials, chemicals, and fuels. The delignification and downstream product recovery technologies are major limiting factors in the commercialization of biomass processing. The suggested [T2220][HSO4]-based ultrasonic approach provides a viable way to boost biomass valorization efficiency, which in turn improves economical and sustainable biorefinery and aids in the shift to green bio-based production.

Cu Pillar Wafer Pretreatment for Enhancing Wettability and Cleaning Cu Seed Layer

Semiconductor packaging serves the dual purpose of shielding semiconductor devices from external elements and facilitating electrical connections between chips and substrates. This intricate process, integral to transforming semiconductor devices into fully functional products, directly impacts the stability, reliability, and performance of electronic devices. With the semiconductor industry grappling with the physical constraints of miniaturization in recent years, the significance of packaging technology has surged. Modern packaging focuses not only on safeguarding devices but also on efficiently establishing electrical connectivity between chips and substrates or among different chips, transcending its conventional role.In semiconductor packaging, the establishment of interconnections holds paramount importance in enabling electrical pathways between internal and external components of semiconductor devices. Various interconnection methods, including Redistribution Layers (RDL), Through Silicon Vias (TSV), microbumps, and microvias, are employed, linking different layers or integrating multiple chips into complex three-dimensional configurations. As the demand for higher integrity mounts, the density of interconnections within semiconductor packages undergoes a notable surge, necessitating structural adaptations in these connections. Notably, the adoption of copper pillars with solder caps has supplanted conventional bonding techniques reliant on solder balls to enhance performance. This transition stems from the risks associated with traditional solder balls, such as potential damage to component chips due to their high melting temperatures. In contrast, copper pillars with solder caps offer superior electrical conductivity while mitigating the drawbacks inherent in solder balls.In contrast to methods like Damascene and TSV processes, the formation of copper micro pillars involves infusing copper into via holes created within a photoresist (PR) layer. However, PR patterning may inadvertently introduce organic impurities that hinder the adhesion of the copper seed layer. Moreover, PR exhibits relative hydrophobicity compared to metallic copper, facilitating air entrapment within PR vias. These challenges can lead to irregularities in copper electrodeposition and the formation of defects within copper pillars. Additionally, organic residues at the interface between the copper seed layer and the pillars can compromise their mechanical and electrical reliability while elevating electrical resistance. Consequently, post-treatment measures following PR patterning are imperative to optimize the copper electrodeposition process.This presentation introduces pre-treatment procedures preceding significant copper electrodeposition to ensure the attainment of flawless copper pillars. Through this study, three distinct pre-treatment methods were explored to enhance the stacking properties of PR-patterned wafers, eliminate organic impurities from the copper seed layer, and regulate the hydrophobic nature of the PR layer while eradicating copper surface oxides. By fine-tuning parameters and evaluating the quality of copper electrodeposition resulting from these pre-treatments, an optimal pre-treatment protocol for achieving defect-free copper pillars is proposed. Figure 1

Combined effect of a pretreatment and optical settings on the laser diffraction particle size distribution of soils and sediments

PurposeThe two main challenges in providing good quality granulometric data are the limitations of laser diffraction method and the insufficient chemical pretreatments. The present study aims to determine the combined effect of these two sources of error and to find optimized procedures to fit the physical and chemical parameters of the soil and sediment samples.MethodsFive soil and sediment samples with diverse characteristics were analysed. Three commonly used pretreatment procedures (FAO, USDA, Wageningen Agricultural University) were applied and compared to the “untreated” Hungarian standard. The particle size distributions (PSD) were determined by HORIBA LA-950V2 laser diffraction device with 25 optical setting combinations.ResultsThe effectiveness of pretreatment protocols was related to the particle size, SOM content, size of the aggregates, clay ratio and the order of reagents. Descriptive statistics showed which preparation processes were effective for the dispersion of different sample types. Samples containing a relatively high amount of clay and/or SOM are sensitive to disaggregation procedures, affecting their texture. The refractive index (RI) 1.40 and absorption coefficient (AC) 0.00 and 0.01 provided the highest degree of disaggregation. By the changes in the mean and median values, we could determine which optical settings gave similar results that could be characterized by the same texture classifications.ConclusionsNone of the procedures was generally considered to be the best procedure. The disaggregation efficiency of the three sample preparation methods differs for different materials. These uncertainties, combined with inadequate optical settings, make it difficult to detect poor quality granulometric data.Graphical

Granulometric composition of soils: history, development of methods, current state and prospects

The problems of determination and classification of soils by granulometric composition from the point of view of domestic and international soil science are considered. The development of methods and devices for granulometric analysis of soils was largely promoted by the works of the Department of Soil Physics and Reclamation, on the basis of which the necessity of two stages of granulometric analysis was shown, the all-Russian method of sedimentation analysis of particles by pipette method was founded, with the development of the classification of N.A. Kachinsky and names of soils by granulometry, which are fundamentally different from those generally accepted in the world practice. At present, at the first stage the method of pretreatment with 4% sodium pyrophosphate is widespread, at the second stage — measurement of granulometric composition two approaches are used — sedimentation method and laser diffractometry, which have different physical bases. The difference of final results on granulometric composition of soils is usually associated with different shape and density of solid phase of organic and mineral particles. This paper presents the studies of granulometric composition of agrodernovo-podzolic sandy loam soil (Tver region, VNIIMZ experimental site) with low content of organic matter in comparison of three methods of granulometric composition determination: laser diffractometer, sedimentometric methods of suspension pressure estimation on Pario - ISP+ (Integral Suspension Pressure) device and classical pipette method. Th e laser diffractometer for fine fractions showed systematically underestimated data with the same pretreatment procedure compared to ISP and pipette method. The ISP+ method compared to the classical pipette method gives similar results.

Pollution Monitoring via Potentiometric Membrane Sensors for the Determination of Chlorpromazine Hydrochloride in the Presence of Its Main Photo-Degradation Products in River Water

The utilization of membrane sensors for the monitoring and determination of pharmaceutical environmental pollutants has emerged as a crucial objective in recent years. Given the extensive use of chlorpromazine hydrochloride (CPZ) in medicine, its presence in the environment, particularly in surface water such as rivers, is highly probable. Prolonged exposure of river water to sunlight and the photo-degradability of CPZ may enhance its photo-degradation. For the purpose of measuring CPZ in the presence of its primary photo-degradants, two sensitive and selective membrane electrodes were developed. These were synthesized utilizing two ion-pairing agents: sodium tetraphenylborate (TPB) and phosphotungstic acid (PTA). The electrodes exhibited a linear range that extended from 1 × 10−6 M to 1 × 10−2 M. The membrane electrodes of CPZ-TPB and CPZ-PTA exhibited slopes of 59.90 ± 0.60 mV/decade and 58.90 ± 0.80 mV/decade, respectively. The sensors mentioned above showed acceptable performance in a pH range of 2.0 to 6.0. All test parameters were optimized to provide superior electrochemical performance. The fabricated membranes were effectively employed to sensitively quantify CPZ in the presence of its principal photodegradants. The developed sensors were successfully employed to quantify CPZ in river water samples without necessitating pre-treatment procedures.

Optimization of pretreatment protocol for strontium-90 analysis in marine fish bone samples.

For systematic monitoring of radioactive nuclides in marine products, this study aimed at streamlining and simplifying the analysis method for the prominent radioisotope, strontium-90 (90Sr). The DGA chelate solid-phase extraction technique was employed for enhanced efficiency. The study focused on optimizing the necessary pretreatment procedures while minimizing the steps involving HNO3 leaching. This protocol enabled the quantitative recovery of strontium, and it facilitated a rapid analysis without the need for a time-consuming evaporation step and without waiting for secular equilibrium between 90Sr and its progeny to be reached. The method incorporating the optimized pretreatment protocol was applied to three diverse marine fish species and the accurate quantification of 90Sr at background levels in surface seawater was achieved. The method obtained concentrations in bone samples from these species that ranged from 0.036 to 0.120 mBq per kg-dry, and chemical yield values were notably high, ranging from 87.7% to 92.5%.

Genotype and grain pretreatment effects on digestibility of sorghum proteins in the Ethiopian fermented bread

AbstractBackground and ObjectivesSorghum is the principal food source for smallholder farmers in Sub‐Saharan Africa. Animal proteins are beyond economic reach, and only few food legumes are well‐adapted in major sorghum‐growing regions. Hence, sorghum serves as the primary source of protein and calories. However, the low digestibility of its proteins renders the communities vulnerable to protein malnutrition. Several factors, including genotypes and processing methods, have been shown to affect the digestibility of proteins in sorghum food products. The objective of this study was to investigate the impact of grain pretreatment on the protein digestibility of Ethiopian fermented flatbread.FindingsThe effect of four grain pretreatment processes: decortication, sprouting, parching, and untreated control was compared using four diverse sorghum genotypes milled to medium (2 mm) and fine (0.5 mm) particle sizes. The in‐vitro protein digestibility (IVPD) was significantly lower in the parched samples compared to the unprocessed control, while sprouting significantly increased IVPD. Decortication appears to have no impact on IVPD. Finer particle size tended to enhance IVPD in all genotypes and for all pretreatement methods. The treatments had no significant effect on protein content except the sprouting consistently but marginally increased total protein.ConclusionsSprouting sorghum grains can significantly improve the protein digestibility of fermented breads. Given that it involves little cost, the process can be readily adopted by the local community, provided that they are educated about the impact of protein deficiency on the health and productivity of the community.Significance and NoveltyLow‐cost grain pretreatment procedures such as sprouting can have a significant impact on the availability of nutrients, especially protein, the most limiting nutrient in smallholder communities. Combining the procedure with genetically enhanced varieties and improved cropping systems that integrate food legumes can significantly enhnace protein nutrition for smallholder farmers.

Operando on-line monitoring of nanoplastics in real environmental water samples enabling an optical microfiber Mach-Zehnder interferometer

Nanoplastics pose a great threat to ecological water environments, especially for ocean water, lake water. Small-sized nanoplastic particles can enter into animal and plant bodies easily. Therefore, operando on-line quantification of nanoplastics in real environmental samples can bring a big challenge for early-stage water pollution testing and warning. Conventional nanoplastic particles detection technologies didn’t provide enough high sensitivity and accuracy due to their complicated and time-consuming sample pre-treatment procedures. To overcome these limitations, an optical microfiber was applied to detect nanoplastics in some real environmental samples. Owing to high sensitivity and superior specificity of the sensor, it could detect target polystyrene (PS) nanoplastics with sizes of 150 nm and 100 nm in pure water and mixture solution, realizing ultra-low limit-of-detections (LODs) of 1.23×10−6 mg/mL, 1.41×10−6 mg/mL and 2.31×10−6 mg/mL, 2.96×10−6 mg/mL, respectively. More importantly, such an optical device could also successfully recognize PS nanoplastics in collected lake, ocean, and wastewater samples. Thus, our proposed approach could open up a novel and advantageous way for operando on-line monitoring of nanoplastics in real water samples.

Determination of multiple analytes in urine using label-free SERS coupled with simple sample pretreatments

BackgroundA key restriction of label-free surface-enhanced Raman spectroscopy (SERS) in analysis of objects with complex composition (including with several target analytes) is the competition of mixture components for interaction with SERS-active surface. This leads to poor selectivity of the analysis of such mixtures (e.g., body fluids) and the need to use advanced sample pretreatment procedures such as HPLC or TLC. Therefore, this work aims to develop a set of simple and fast pretreatment steps (dilution, pH correction, etc.) to increase the sorption of the target analyte, reduce the sorption of admixtures, and prevent suppression of the target analyte SERS signal. ResultsWe have developed label-free SERS assay suitable for the determination of three analytes (methotrexate, cephalosporin antibiotic, and creatinine) in one real urine sample as a model matrix with complex and deviating composition. The choice of drugs is justified by the need to monitor their concentration in urine during joint drug treatment of cancer patients with concomitant bacterial infection, while monitoring creatinine concentration helps to evaluate kidney function of the patients. Additionally, three cephalosporin representatives were used in the study to maximize versatility of the assay. As a results, the optimized pretreatment steps enable to eliminate the negative influence of excess of interferences (including other analytes) and achieve precise (≤12 % RSD) and accurate (88–111 % recovery) determination of several analytes in the therapeutically relevant ranges: 300–3000 μg mL−1 for creatinine, 20–200 μg mL−1 for methotrexate and cephalosporins. SignificanceTherefore, in addition to reporting a new SERS assay for the analysis of body fluids, this study clearly demonstrates the importance of taking into account competitive adsorption processes on the SERS substrate surface. We suggest making this practice mandatory when developing any label-free SERS assay because it enables to maximize the selectivity and accuracy of the analysis as well as to simplify the analysis procedure.

Simultaneous extraction and deglycosylation for flavonoid analysis in Ginkgo biloba products using a two-phase deep eutectic solvent system

Total flavonoid content is one of the most important quality indicators of Ginkgo biloba leaves and its products, but the complex pretreatment procedures and the excessive use of organic solvents complicate the detection process. In response, an innovative and efficient two-phase deep eutectic solvent (DES) system—composed of an acidic hydrophilic DES and a hydrophobic DES—was developed to quantify flavonoids for quality control of G. biloba products. High-performance liquid chromatography (HPLC) detection conditions were optimized, followed by systematic screening and design of the two-phase DES system through adjustments to polarity, hydrophilicity, and acidity. Optimal pretreatment conditions were established through operating condition optimization. This approach enabled simultaneous extraction, deglycosylation, and enrichment of all flavonoids from G. biloba samples into the hydrophobic phase in a single step. Method validation showed strong linearity with a correlation coefficient (R2 > 0.9995). The detection (LOD) and quantification (LOQ) limits were between 0.35 and 0.37 mg/kg, and 0.92 and 0.96 mg/kg, respectively. The method also exhibited high sensitivity and accuracy, with a recovery rate of 96.91–100.39%. A greenness assessment with the ComplexGAPI tool confirmed this method’s eco-friendly advantages over conventional techniques, aligning well with green chemistry and economic principles. Ultimately, this technique effectively measured flavonoid levels in different G. biloba products. The method developed in this work not only enhances the efficiency of simultaneous extraction and deglycosylation by modifying the polarity, hydrophilicity, and acidity of the two-phase DES system, but also offers valuable insights for the advancement of environmentally friendly analysis technology for flavonoids.

Characteristics of surface modified sugarcane bagasse cellulose: application of esterification and oxidation reactions

Research on polymer matrix composites has become increasingly important in both the academic and industrial sectors. The study of polymer-natural fiber composites, known for their eco-friendly properties, has gained significance. Sugarcane bagasse fibers, abundant as discarded agricultural byproducts, offer improved properties such as density, rigidity, strength, and cost-effectiveness, enhancing sustainability. As a result, experiments were performed on cellulose fibers pre-treated from sugarcane bagasse using 5% NaOH solution by simply soaking them for 4–5 h followed by washing with water. Further modifications involved esterification using phthalic anhydride and phthaloyl chloride via steam baths at 90 °C and oxidation using sodium percarbonate with a phase transfer catalyst (Adogen) at 80 °C. These chemically altered cellulose fibers exhibited significant peak changes in the FTIR spectra, a reduced crystallinity index in the XRD pattern, increased thermal stability as evidenced by TGA curve, and improved surface roughness in the SEM analysis. This paper emphasizes successful pretreatment procedures for isolating cellulose fibers from sugarcane bagasse and introduces three chemical treatments for surface functionalization which might find applications in the preparation of biocomposites.

Highly sensitive time-resolved fluorescent microspheres lateral flow immunoassay for the quantitative detection of triadimefon and its metabolite residues in fruits and vegetables.

Ageneral one-step lateral flow immunochromatographic assay (LFIA) for the quantitative detection of triadimefon (TDF) and triadimenol(TDN) in fruit and vegetable samples was developedusing time-resolved fluorescence microspheres (TRFM) as labels. A specific anti-triadimefon monoclonal antibody (mAb) was conjugated with TRFM to fabricate LFIA test strips. A time-resolved fluorometer as an LFIA reader was applied to obtain quantitative results and assess risk ranges for the LFIA test strips. Under the optimized experimental conditions, the limits of detection (LODs) in buffer/cucumbers/tomatoes/oranges were 0.046ng/mL, 0.135µg/kg, 1.047µg/kg, and 5.811µg/kg, respectively, which are ca. 1000 times lower than that of colloidal gold-labeled strips. The recovery in cucumber/tomato/orange samples was 109.4-116.7%, 87.7-110.9%, and 88.0-111.9%, respectively, indicating that the test strips had good reliability. Coupled with the easily customizable pretreatment procedures for various samples, the LFIA results were obtained within 18min without the need for professional personnel or complicated equipment. TRFM-LFIA for TDF and TDN also shows remarkable specificity and precision. The test strips were also low-cost, portable, and convenientto use. These results indicate the test strips could be utilized as a novel strategy for on-site detection of TDF and TDN, which has the potential to expand and detect other pesticide or insecticide residues in food.

Effect of puffing on electrochemical properties of sorghum seed based porous carbon materials in supercapacitors

Biomass-based carbon materials are renewable, affordable and environmentally friendly, possessing great potential in electrochemical energy storage as electrode materials in supercapacitors due to their large specific surface area and self-doped heteroatoms. However, the electrochemical properties of these carbon materials may be influenced to some extent by pretreatment procedures of carbon precursors. For this research, a range of porous carbon materials based on unpuffed and puffed sorghum seeds were synthesized under various pre‑carbonization and activation temperatures. Among them, the puffed sorghum seed-based porous carbon (PH-R6A7), prepared through pre‑carbonization at 600 °C and KOH activation at 700 °C, exhibits a higher graphitization degree, increased N and O content, as well as a greater variety of nitrogen-containing groups and significant increasing graphite nitrogen compared to unpuffed sorghum seed-based porous carbon (PC-R6A7) fabricated under similar conditions. These improvements result in enhanced conductivity and wettability of electrode materials, thereby boosting their electrochemical properties. In a three-electrode setup employing a 6 M solution of KOH, PH-R6A7 demonstrates an exceptional specific capacitance of 523.84 F g−1 at 1 A g−1 compared with PC-R6A7 of 366.00 F g−1; even at a high current density of 20 A g−1 it maintains a high level of capacitance at 387.94 F g−1. When employed in a double-electrode configuration at the same current density (i.e., 1 A g−1), PH-R6A7 also achieves higher specific capacitance of 357.83 F g−1 than PC-R6A7 (286.89 F g−1), accompanied by an increased energy density of 12.35 Wh kg−1 and 8.85 Wh kg−1 at a power density of 249.97 W kg−1 and 4.98 kW kg−1, respectively. Furthermore, after undergoing 10,000 cycles at 2 A g−1, PH-R6A7 demonstrates a superior capacitance retention of 99.68 % and coulomb efficiency of 99.91 %. PH-R6A7 fabricated through the combination method of puffing pretreatment and carbonization activation merits acknowledgment as an electrode material of superior performance and notable practical importance.

Radiocarbon Chronology and Isotope Data of Ust-Tartasskiye Kurgany Mound 51, the Baraba Forest-Steppe

Results of radiocarbon dating of items from mound No. 51 of Ust-Tartasskiye Kurgany burial ground are presented. This is a key site of the Sargat culture in Baraba. Characteristics of samples and pretreatment procedure are provided. Twenty-four radiocarbon dates were generated. Radiocarbon ages correlate with biological ages of the deceased persons. Bayesian KDE chronology modeling suggests a short-term intense use of the site for burying those who died between the 3rd and 1st centuries BC. Based on MCMC-modeling, a conclusion is reached about two periods in the use of the space allotted for graves between 200–40 BC. Burials of the “first period” (~25 %) could have been repeatedly made before 150 BC. Most burials (~75 %) were likely arranged between 150–120 BC. The last burial in the mound (no earlier than 110 BC) is No. 13. Minor differences in 15N isotope apparently evidence various diets of males and females at the second period.