Search Results (1,199)

This study developed an automated multistage countercurrent extraction device and applied it to the separation and extraction of phenolic acids—including neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, isochlorogenic acid A, isochlorogenic acid B, and isochlorogenic acid C—from an aqueous extract of Lonicera japonica Thunb. The extraction process was optimized by systematically evaluating critical parameters such as liquid–liquid equilibrium pH, internal diameter of the tee connector, phase flow rate ratio, and the number of extraction stages. The apparent partition coefficients of all six phenolic acids increased with decreasing aqueous pH, with fitted pKa values ranging from 3.7 to 4.3. A reduction in tee diameter (0.75 mm) was found to enhance mass transfer efficiency. Increasing the flowrate of both phases (20 mL/min), the organic-to-aqueous phase ratio (4:1), and the number of extraction stages (3 stages) significantly improved both stage efficiency and overall extraction yield. Under optimized conditions, the target chlorogenic acids were efficiently enriched, with their total content increasing from 50.3 mg/g to 70.1 mg/g in the solid residue after three countercurrent stages. The automated multistage countercurrent extraction system demonstrated robust performance, suggesting promising potential for applications in the preparation of traditional Chinese medicine ingredients or as an automated sample pretreatment method in analytical workflows. This study provides a novel and green technological solution for efficient separation of complex TCM systems. Full article

Heavy metal ions in wastewater endanger ecology and human health, requiring cost-effective treatments. This study innovatively converts abandoned basalt fibers (BFs) into high-performance adsorbents (BFSN) via NaOH etching and chelation with nitrilotriacetic acid (NTA)/carboxymethyl starch (CMS), introducing target functional groups. Characterizations (XPS, FTIR, zeta potential) reveal Cu²⁺/Pb²⁺ adsorption mechanisms: -COO⁻ chelation, N-containing group ion exchange, and electrostatic adsorption. Kinetics fit a pseudo-first-order model (R² > 0.98) and isotherms fit the Langmuir model, confirming monolayer chemisorption. BFSN has excellent thermal stability (≤2% mass loss at 800 °C) and post-adsorption integrity (≈0.11% mass loss post-loading). Waste-derived BFSN, cheaper than commercial adsorbents, has strong economic viability. This “waste-to-value” approach offers efficient, sustainable large-scale heavy metal wastewater remediation, advancing waste utilization and ecological restoration in water treatment. Full article

Missing values in hourly outdoor air temperature series are common and can bias building energy assessments that rely on uninterrupted temperature profiles. This paper examines how the polynomial degree can be used to reconstruct incomplete temperature data from the duration curve, which affect the energy indicators of an air-source heat pump (ASHP). Using an operational dataset from Opole, Poland (1 September 2019–31 August 2020; 5.1% gaps), global polynomials of degree n = 3…11 were fitted to the sorted hourly temperatures, and the reconstructions were mapped back to time. The reconstructions drive a building–ASHP model evaluated for two supply-water regimes (L_WT, leaving water temperature = 35 °C and 45 °C). Accuracy is assessed with mean absolute error (MAE), root-mean-square error (RMSE), and R² on observed, filled, and full subsets—including cold/hot tails—and propagated to energy metrics: seasonal space-heating demand (Q_season); electricity use (E_el); seasonal coefficient of performance (SCOP); peak electrical power (P_el,max); seasonal minimum coefficient of performance (COP_min); and the share of error due to filled hours (WFE_fill). All degrees satisfy $\left|{RE}_{Q_{season}}\right|\le 2\%$. For L_WT = 35 °C, relative changes span ${RE}_{E_{el}}$ ≈ −2.22…−1.63% and ${RE}_{N_{el,max}}$ ≈ −21.6…−7.7%, with ${ER}_{SCOP}$ ≈ +0.53…+0.80%. For L_WT = 45 °C, ${RE}_{E_{el}}$ remains ≈ −0.43% across degrees. A multi-criterion selection (seasonal bias, stability of energy indicators, tail errors, and WFE_fill) identifies n = 7 as the lowest sufficient degree: increasing n beyond seven yields negligible improvements while raising the overfitting risk. The proposed, data-driven procedure makes degree selection transparent and reproducible for gap-filled temperature inputs in ASHP studies. Full article

This study investigates the efficiency of biocarbon derived from Prosopis juliflora shells in removing Astrazon pink dye from aqueous solutions. The biocarbon obtained from the thermochemical process was characterised using FTIR Spectroscopy, SEM microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDS), and XRD. Batch adsorption experiments were conducted to assess various factors, including the Potential of Hydrogen (pH), Dosage of biocarbon, Astrazon pink dye concentration, temperature, and Time of contact. Similarly, Adsorption isotherm models, including the Langmuir and the Freundlich isotherms, were used to evaluate the adsorption capacity. In contrast, pseudo-first-order and pseudo-second-order models were used to analyse the kinetics of dye adsorption. The interactive effects of selected variables on the removal of Astrazon Pink dye from synthetic water were determined using Response Surface Methodology (RSM). The maximum dye uptake, 98.54%, was achieved with a biochar dose of 8 g/L at 50 ppm dye concentration, pH 7.5, and 35 °C. The Freundlich adsorption isotherm model and the pseudo-second-order kinetic model are the better-fitting models for the dye adsorption process, with R² values of 0.99. Consequently, the thermodynamic parameters indicate that the process is endothermic and spontaneous. Full article

Schinus molle L. is a tree commonly found in agricultural fields, deserts, and semi-arid areas of central Mexico. Its distinctive aroma makes it a source of essential oil, extracted mainly from the bark and fruits. The leaves contain phenolic compounds, and their extracts have demonstrated antimicrobial activity. Obtaining these extracts requires a prior drying process. This study aimed to evaluate the effect of convective drying on phenolic compounds in pirul leaves and determine the thermodynamic properties of the process, including the effective diffusivity of water vapor (D) and activation energy (Ea). Drying kinetics were conducted at different air-drying temperatures (30, 40, and 50 °C) at a constant rate of 1 ms⁻¹, and the results were fitted to the second Fick’s law and semi-empirical models. After drying, a decrease in total flavonoid content was observed as the drying temperature increased, with losses of 37%, 49%, and 62% at 30, 40, and 50 °C, respectively. The final values ranged from 37.96 to 21.02 mg QE/100 g of dry leaf. The D varied between 1.32 × 10⁻¹² and 6.71 × 10⁻¹² m² s⁻¹, with an Ea of 66.06 kJ mol⁻¹. The fitting criteria (R², RMSE, AIC/BIC) indicated that the Logarithmic model best described the kinetics at 30–40 °C, while Page was adequate at 50 °C. These findings suggest an inverse relationship between drying temperature and flavonoid content, while higher temperatures accelerate water vapor diffusivity, reducing the processing time, as observed in plant matrices. Full article

Antimony (Sb), as a toxic heavy metal, has drawn worldwide attention, and its efficient removal from water has become increasingly urgent. In this study, an iron-modified alkaline lignin chitosan (Fe-ALCS) gel bead is prepared by the freeze-drying method to remove Sb(III) from the aqueous solution. The static adsorption experiment discusses the various environmental influences on the adsorption performance of Fe-ALCS for Sb(III) removal. The adsorption mechanism is explored by combining adsorption kinetics, isothermal adsorption, and characterization methods (such as FTIR, XRD, XPS, etc). The results show that the equilibrium adsorption capacity of Sb(III) decreases with the increase in pH and mass–volume ratio. With the increase in the initial Sb(III) concentration, Q_e showed a rapid increasing trend in the range of 50–100 mg/L and continued to rise with the extension of contact time (t), reaching the maximum value at 3540 min. Under the optimal conditions of pH = 3, m/v = 1.0 g/L, and C₀ = 20 mg/L, the removal efficiency (R_e) value is 95.07%, which is still approximately 86.8% after five adsorption–desorption cycles. The maximum adsorption capacity is 266.58 mg/g fitted by the Langmuir model. The adsorption mechanism is mainly related to the iron-based active site of Fe–O(OH), where the O–H on its surface undergoes ligand exchange with Sb(OH)₃ to form a stable Fe–O–Sb coordination structure. Additionally, C–OH, C–O, and other functional groups in ALCS also contribute to Sb adsorption. Fe-ALCS is an environmentally friendly, renewable, and convenient biomass adsorbent with good potential for wastewater treatment. Full article

During the operation of steel cable-driven radiation-resistant robots in nuclear industrial environments, the tensile force of a steel cable is influenced by temperature variations, which can cause significant detection errors. To address this problem, this study proposes a temperature-compensated axial force characterization method for steel cables based on the magnetoelastic effect, aiming to ensure the measurement accuracy of magnetoelastic sensors. The principle of the magnetoelastic measurement method involves magnetizing the steel cable. When subjected to tensile forces, the magnetization characteristics of the steel cable change, thereby altering the detection signal of the magnetoelastic sensor. By analyzing the relationship between steel cable tension and variations in the detection signal, effective force measurement can be achieved. First, experiments are conducted to investigate the influence of temperature on the detection signals of a magnetoelastic sensor under zero-load conditions. Then, additional tests are performed to examine the combined effects of a tensile force and temperature on the sensor’s signals. Finally, based on the experimental data, axial force prediction models are constructed using both surface fitting and a backpropagation neural network (BPNN). The results demonstrate that, compared to the resistance values, inductance exhibits superior stability under temperature variations. In the temperature range of 20–50 °C, the inductance variation is approximately 0.15 μH, which indicates improved suitability for characterizing the axial force of steel cables. It is also shown that under isothermal conditions, the inductance increases linearly with the applied tensile force, exhibiting a slope of approximately 0.025 μH/kN. Both the surface fitting-based and BPNN-based axial force prediction models demonstrate high accuracy, with absolute prediction errors consistently below 5% compared to actual data. Full article

The accurate determination of the equilibrium moisture content (EMC) of gel-related powdery samples requires strictly controlled conditions and a long time period. In this study, the adsorption and desorption isotherms of two fructooligosaccharide (FOS) powders and three inulin powders were determined using a dynamic moisture sorption analyzer at 0.1–0.9 water activity (a_w) and 20–35 °C, respectively. The adsorption and desorption isotherms all exhibited type IIa sigmoidal curves; the desorptive isotherm was smooth, the FOS adsorption curves had three inflection points, and the inulin adsorption curves had five inflection points. Large hysteresis between the adsorption and desorption isotherms occurred at 0.1–0.7 a_w for FOS and 0.1–0.6 a_w for inulin. Seven equations, Boquet, Ferro–Fontan, Guggenheim–Anderson–de Boer (GAB), Generalized D’Arcy and Watt (GDW), modified GAB (MGAB), Peleg, and our developed Polynomial, were found to fit the isotherms of the FOS and inulin samples; for adsorption, the best equations were Ferro–Fontan and GDW, and for desorption, the best equations were Polynomial and MGAB. The GDW and MGAB equations could not distinguish the effect of temperature on the isotherms, while the Polynomial equation could. The mean adsorptive monolayer moisture content (M₀) values in FOS and inulin samples were predicted as 7.29% and 7.94% wet basis, respectively. The heat of moisture sorption of FOS and inulin approached that of pure water at about 32.5% and 22.5% wet basis (w.b.) moisture content (MC), respectively. Fourier Transform Infrared Spectroscopy (FTIR) showed that the peaks in inulin with absorbance values above 0.52 and in FOS with absorbance values above 0.35 were at 1020, 1084, and 337 cm⁻¹; these could represent the amorphous structure (primary alcohol C-OH), C-O group, and hydroxyl functional group, respectively. Microscopic structure analysis showed that inulin powder particles were more round-shaped and adhered together, resulting in hygroscopic and sticky characteristics, with a maximum equilibrium moisture content (EMC) of 34% w.b. In contrast, the FOS powders exhibited irregular amorphous particles and a maximum EMC of 60% w.b. As hydrogels, 3–10% FOS or inulin addition reduced the peak, trough, final, breakdown, and setback viscosities of rice starch pasting, but increased the peak time and pasting temperature. FOS addition gave stronger reduction in the setback viscosity and in amylose retrogradation of rice starch pasting than inulin addition. The differential scanning calorimeter (DSC) showed 3–10% FOS addition reduced the amylopectin aging of retrograded paste of rice starch, but 5–7% inulin addition tended to reduce. These results suggest that FOS and inulin have strong hygroscopic properties and can be used to maintain the freshness of starch-based foods. These data can be used for drying, storage, and functional food design of FOS and inulin products. Full article

Functional beverages enhance the nutritional value of their ingredients by increasing the levels of bioactive components, such as probiotics. To achieve consumer acceptance, functional beverages must be both palatable and nutritious. This study investigates the fermentation of quinoa and cherimoya at two temperatures (25 °C and 32 °C) using water kefir grains. The aim was to create a fermented mix that is both balanced and appealing to consumers. The response variables measured were the concentrations of lactic acid bacteria (LAB) and yeasts (CFU mL⁻¹), as well as the overall liking (OL). Ten semi-trained panellists evaluated them using a seven-point hedonic scale. All three developed models for LAB and yeast growth, and OL exhibited R² values exceeding 0.8, indicating a strong model fit and simultaneous optimisation considering the three key responses. At a temperature of 25 °C, the mass fractions of the mixes containing quinoa puree (QP) and cherimoya juice (CJ) were 0.13 and 0.87, respectively. Under optimal conditions, the LAB and yeast increased by 4.2 and 4.4 log units, respectively. Moreover, a significant 62% increase in protein levels and a notable 82% decrease in ascorbic acid were observed after 48 h of fermentation, likely caused by the Maillard reaction. Full article

This work aims to apply polymeric PBAT/PLA fibers electrospun with TiO₂ in the photodegradation of the dye Red BF-4B in an aqueous solution and the dye’s subsequent reuse. Initially, the influence of the solution pH was evaluated, and the results showed more significant dye degradation at pH values below the pHpcz (7.42). Kinetic studies show that at 15 mg·L⁻¹, the highest percentage of degradation occurs at 600 min of reaction time; however, degradation equal to (or greater than) 65% was observed at all evaluated concentrations, with the kinetic data being well fitted by the pseudo-first-order model. Additional studies demonstrated the reuse of polymeric films for dye removal, with removal efficiencies ranging from 86.60% to 93.07% over six consecutive reuse cycles. Each cycle consisted of a 600 min removal process, simulating repeated practical applications. After the photocatalytic process, the polymeric fibers remained cylindrical, with several fractures. Diameter decreases of 31.61% and 7.95% were observed after the first and sixth cycles, respectively, with possible exposure of TiO₂. The vibrational spectra indicate changes in the bands at 1755 and 1714 cm⁻¹, attributed to C=O (PLA) and C-O (PBAT) stretches, respectively, suggesting a possible conformational change in the polymers. The thermal profiles showed only slight changes after the cycles. X-ray diffractograms indicate that degradation of the polymeric matrix leads to greater exposure of the embedded TiO₂ particles. The combined results from different characterization techniques provide evidence of the degradation of the polymeric material. Full article

Hydrogen has been explored as a greener alternative for greenhouse gas emissions reduction. Sodium borohydride (NaBH₄) is a favorable hydrogen carrier due to its high hydrogen content, safe handling, and rapid hydrogen release. This work presents a novel synthesis of the catalyst CoFe₂O₄/Fe₂O₃ using nanocellulose fibers (TCNF) as reactive templates for metal adsorption and subsequent calcination. The resulting material was tested for H₂ production from basic NaBH₄ aqueous solutions (10–55 °C). The catalyst’s composition is 74.8 wt% CoFe₂O₄, 25 wt% Fe₂O₃, and 0.2 wt% Fe₂(SO₄)₃ with agglomerated spheroidal particles (15–20 nm) and homogeneous Fe and Co distribution. The catalyst produced 1785 mL of H₂ in 15 min at 25 °C (50 mg catalyst, 4.0% NaBH₄, and 2.5 wt% NaOH), close to the stoichiometric maximum (2086 mL). The maximum H₂ generation rate (HGR) reached 3.55 L min⁻¹ g_cat⁻¹ at 40 °C. Activation energies were determined using empirical (38.4 ± 5.3 kJ mol⁻¹) and Langmuir–Hinshelwood (L–H) models (42.2 ± 5.8 kJ mol⁻¹), consistent with values for other Co-ferrite catalysts. Kinetic data fitted better to the L–H model, suggesting that boron complex adsorption precedes H₂ evolution. Full article

Excessive release of ammonium (NH₄⁺) into aquatic ecosystems can promote eutrophication. In this study, the natural adsorbents, coal (C) prepared from Hawthorn (Acacia caven) and coal fly ash obtained from C, were used to remove NH₄⁺ from aqueous systems through batch adsorption–desorption studies. Both adsorbents were physically and chemically characterized, while Fourier-transform infrared spectroscopy and zeta potential were used to understand the surface functional groups and surface charge characteristics. CFA showed a higher pH, BET specific surface area, electrical conductivity and higher % values for CaO and MgO than C. Kinetic studies of NH₄⁺ adsorption at pH = 4.5 for both materials fitted the pseudo-second-order model giving the r² of 0.970–0.983 and the χ² of 0.008–0.005 and at pH = 6.5 only for C with the r² of 0.986 and the χ² of 0.013. Meanwhile, the adsorption isotherm data at pH = 4.5 for both materials and 6.5 for CFA complied with the Freundlich model (r² > 0.965 and χ² < 0.012), suggesting that NH₄⁺ adsorption onto both adsorbents at those pH values occurred through the formation of a multilayer adsorption on heterogeneous surfaces. This indicates that the dominant adsorption of both adsorbents was physisorption with no site-specific interaction. Based on these results, CFA is proposed as a promising and economical material for the removal of NH₄⁺ from aqueous systems. Full article

This paper presents an electrical thermometry method designed for kilowatt(kW)-level Gallium Nitride (GaN) High Electron Mobility Transistors (HEMTs). The dependence of the drain current on the channel temperature in GaN HEMTs is utilized as a means to measure the transient channel temperature. However, in kW-class GaN HEMTs, the gate current can reach tens of milliamperes, and trap-induced capture resulting from high doping concentrations can both influence the drain current. Through modifications to the gate bias circuit, the gate voltage self-biasing phenomenon caused by the gate current is mitigated. A theoretical model is derived to express the relationship between the drain current and the channel temperature. Experimentally, amplifier modules equipped with kW-level HEMTs were placed on thermal stages set at 45 °C, 60 °C, and 80 °C. The transient drain current curves and the corresponding channel temperature profiles were measured. The measured drain current versus channel temperature curves at different ambient temperatures were fitted and compared with the theoretically derived formula. The relative error between the measured and calculated drain current values at the same channel temperature was found to be within 1%. Full article

This study was conducted to investigate the effect of hydrogen peroxide (H₂O₂) pretreatment on the anaerobic digestion performance of dairy wastewater. Initial physicochemical characterization revealed that the substrate is highly enriched in volatile solids (approximately 90.67%), indicating its strong potential for anaerobic biodegradation. Given this favorable composition, biochemical methane potential (BMP) assays were performed under mesophilic conditions (37 °C) to quantify biogas and methane generation from the untreated and pretreated dairy effluent. To enhance substrate biodegradability and increase methane yield, an oxidative pretreatment using various doses of H₂O₂ was applied. This pretreatment aimed to disrupt the complex organic matter and promote the solubilization of chemical oxygen demand (COD), especially in its soluble form (sCOD), which is more readily assimilated by methanogenic microorganisms. The experimental results demonstrated a significant improvement in biogas production efficiency. While the untreated sample yielded approximately 100 mL CH₄/g VS, the pretreated substrate achieved a maximum of 168 mL CH₄/g VS, marking a substantial enhancement. Gas composition analysis further revealed that methane accounted for nearly 45% of the total biogas produced under optimal conditions. The dosage of 0.2 g H₂O₂ per g of volatile solids (VS) resulted in the highest improvement in methane production after thermal treatment C1, followed by 1.35 g H₂O₂/g VS, and then 0.5 g H₂O₂/g VS. Furthermore, the kinetics of methane production were assessed by fitting the experimental data to the modified Gompertz model. This model enabled the determination of key parameters, such as the maximum specific methane production rate and the duration of the lag phase. The high coefficient of determination (R²) values obtained confirmed the excellent agreement between the experimental data and the model predictions, highlighting the robustness and reliability of the modified Gompertz model in describing the anaerobic digestion process of dairy waste subjected to oxidative pretreatment. Full article

Karst aquifers are critical yet vulnerable water resources in semi-arid Mediterranean regions, where structural complexity, nonlinearity, and delayed hydrological responses pose significant modeling challenges under increasing climatic and anthropogenic pressures. This study examines the Jebel Zaghouan aquifer in northeastern Tunisia, aiming to simulate its natural discharge dynamics prior to intensive exploitation (1915–1944). Given the fragmented nature of historical datasets, meteorological inputs (rainfall, temperature, and pressure) were reconstructed using a data recovery process combining linear interpolation and statistical distribution fitting. The hyperparameters of the artificial neural network (ANN) model were optimized through a Bayesian search. Three deep learning architectures—Multi-Layer Perceptron (MLP), Convolutional Neural Network (CNN), and Long Short-Term Memory (LSTM)—were trained to model spring discharge. Model performance was evaluated using Kling–Gupta Efficiency (KGE′), Nash–Sutcliffe Efficiency (NSE), and R² metrics. Hydrodynamic characterization revealed moderate variability and delayed discharge response, while isotopic analyses (δ¹⁸O, δ²H, ³H, ¹⁴C) confirmed a dual recharge regime from both modern and older waters. LSTM outperformed other models at the weekly scale (KGE′ = 0.62; NSE = 0.48; R² = 0.68), effectively capturing memory effects. This study demonstrates the value of combining historical data rescue, ANN modeling, and hydrogeological insight to support sustainable groundwater management in data-scarce karst systems. Full article