Search Results (206)

In this work, biochars were produced by pyrolysis of exhausted olive pomace and evaluated as low-cost adsorbents for the removal of methylene blue (MB) from aqueous solutions. The biochar obtained at 400 °C for 1 h, which exhibited the best adsorption performance, was characterized by FTIR, N₂ adsorption–desorption isotherms, SEM-EDX, and proximate analysis, revealing a mesoporous structure with a relatively low specific surface area but enriched in surface functional groups, likely due to the partial degradation of lignocellulosic components. Adsorption experiments were conducted to optimize operational parameters such as solid particle size (2–3 mm), agitation speed (75 rpm), and bioadsorbent dosage (1 g per 0.05 L of MB solution), which allowed for dye removal efficiencies close to 100%. Kinetic studies showed that MB adsorption followed a pseudo-second-order model, while equilibrium data at 30 °C were best described by the Langmuir isotherm (R² = 0.999; SE = 4.25%), suggesting monolayer coverage and strong adsorbate–adsorbent affinity. Desorption trials using water, ethanol, and their mixtures resulted in low MB recovery, whereas the addition of 10% acetic acid significantly improved desorption performance. Under optimal conditions, up to 52% of the retained dye was recovered. Full article

The escalating demand for sustainable and eco-friendly production processes has necessitated the exploration of renewable resources for the synthesis of valuable chemicals. This study investigated the fermentative synthesis of gluconic acid (GA) and xylonic acid (XA) from hydrolyzed palm fronds by using Gluconobacter oxydans. The key variables examined included agitation speed, inoculum ratio, and composition of fermentation media. In a synthetic medium, maximum GA concentration reached 52.82 ± 12.88 g/L at 65 h using 150 rpm agitation and 15% (v/v) inoculation, while maximum XA concentration achieved 2.31 ± 1.43 g/L at 96 h using 220 rpm agitation and 9% (v/v) inoculation. In the hydrolysate medium, the maximum GA concentration was 3.24 ± 0.66 g/L at fermentation onset using 220 rpm agitation and 15% (v/v) inoculation, while the maximum XA concentration reached 0.62 ± 0.04 g/L at 24 h using 190 rpm agitation and 5% (v/v) inoculation. These findings demonstrate the feasibility of utilizing palm fronds as a renewable feedstock for the sustainable synthesis of high-value biochemicals, promoting waste valorization, and contributing to the advancement of a circular bioeconomy. Full article

This work investigates the potential industrial applications of two sodium bentonite samples (white and yellow), obtained from raw Ca-rich bentonite from Maputo Province in Southern Mozambique. Bentonite bio-organoclays were successfully developed from two Mozambican montmorillonite clays through the intercalation of protonated dimer fatty acid-based polyamide chains using a solution casting method. X-ray diffraction (XRD) analysis confirmed polymer intercalation, with the basal spacing (d₀₀₁) increasing from approximately 1.5 nm to 1.7 nm as the polymer concentration varied between 2.5 and 7.5 wt.%. However, the extent of intercalation was limited at this stage, suggesting that polymer concentration alone had a minimal effect, likely due to the formation of agglomerates. In a subsequent optimization phase, the influence of temperature (30–90 °C), stirring speed (1000–2000 rpm), and contact time (30–90 min) was evaluated while maintaining a constant polymer concentration. These parameters significantly enhanced intercalation, achieving d001 values up to 4 nm. Statistical Design of Experiments and Response Surface Methodology revealed that temperature and stirring speed exerted a stronger influence on d001 expansion than contact time. Optimal intercalation occurred at 90 °C, 1500 rpm, and 60 min. The predictive models demonstrated high accuracy, with R² values of 0.9861 for white bentonite (WB) and 0.9823 for yellow bentonite (YB). From statistical modeling, several key observations emerged. Higher stirring speeds promoted intercalation by enhancing mass transfer and dispersion; increased agitation disrupted stagnant layers surrounding the clay particles, facilitating deeper penetration of the polymer chains into the interlayer galleries and preventing particle settling. Furthermore, the ANOVA results showed that all individual and interaction effects of the factors investigated had a significant influence on the d₀₀₁ spacing for both WB and YB clays. Each factor exhibited a positive effect on the degree of intercalation. Full article

The demand for strategic elements, including nickel and cobalt, increases each year due to rapid technological advancements. However, due to their scarcity and environmental concerns, the development of sustainable recycling processes supported by green-energy technologies is becoming essential. In this study, a process relying on indirect bioleaching was used to recover nickel and cobalt from three different superalloy residue powders as a second source of metals, as part of a wider study to recycle superalloys within a waste process. A comparison between the three methods was carried out to analyse the bioleaching mechanisms of the target metals. Acidolysis was selected for further study due to its set-up simplicity and superior recovery rates. Variations in agitation speed of the lixiviant processing the Ni 30167 superalloy revealed that 270 rpm achieved the optimal active metal surface–oxidising agent interaction, with 60% and 70% dissolution rates after 24 h for nickel and cobalt, respectively. For the Re 30168 superalloy, extraction rates of 60% and 50% were obtained in 48 h for nickel and cobalt, respectively. The effect of hydrogen peroxide as an additive to improve metal solubilisation and overcome passivation, are discussed together with the challenges posed by the presence of iron, the materials’ elemental complexity, and its interaction with different oxidising agents. Full article

The transesterification process for biodiesel production is constrained by high thermal input, prolonged residence time, and intensive mechanical agitation. This study investigates process intensification via hydrodynamic cavitation using a custom-built Shockwave Power Reactor (SPR), enabling continuous biodiesel synthesis from soybean and used cooking oils. A statistically designed experimental matrix was applied to evaluate the reactor’s transient–stable thermal regime and the influence of operational parameters: rotor speed (1700–3415 rpm), volumetric flow rate (60–105 mL/min), methanol-to-oil molar ratio (6:1 to 12:1), and alkali catalyst type (NaOH or KOH). For benchmarking, conventional alkaline transesterification was optimized. The FAME yields from the SPR system exceeded 96.5% and complied with EN14103 standards. Specific energy analysis showed that cavitation-enhanced transesterification reduced energy consumption and peak temperature compared to traditional methods. The SPR’s capacity to induce high shear and localized turbulence under controlled cavitation offers a promising pathway for low-energy, scalable biodiesel production. Full article

This study reports the synthesis of activated carbon from dwarf elder, a lignocellulosic precursor, yielding a material with a high specific surface area (500.43 m²/g) and mesoporous structure (median pore radius: 3.88 nm). The physicochemical properties of the obtained carbon were characterized using field-emission scanning electron microscopy (FE-SEM), Brunauer–Emmett–Teller (BET) analysis, and Fourier-transform infrared spectroscopy (FTIR), confirming its suitability for aqueous-phase sorption applications. Batch experiments demonstrated carbon’s efficacy in adsorbing amlodipine besylate (AMB), a model pharmaceutical pollutant, with a maximum capacity of 325.9 mg/g under optimized conditions (pH 10.0, room temperature). Systematic evaluation of key parameters, such as initial AMB concentration, sorbent dosage, pH, and agitation speed revealed that sorption kinetics adhered to pseudo-second-order and Elovich model. The high efficiency of the synthesized carbon material, coupled with its low-cost and eco-friendly synthesis, positions it as a promising candidate for the scalable remediation of AMB and structurally related pharmaceuticals from contaminated water sources. Full article

This study aimed to identify kiwi kefir-like beverages with high levels of viable probiotic cells and low levels of calories, acids, and alcohol. To achieve this, microbiological and chemical characterizations were conducted on beverages inoculated with varying amounts of kefir grains (GW) and incubated at different agitation speeds (A), following a second-order orthogonal factorial design. For each experimental condition, three 24-h batch cultures were performed using three successive passages of kefir grains. Higher GW levels promoted greater nutrient consumption and metabolite production. However, an intermediate GW (1.80 g) resulted in the highest growth of lactic acid bacteria (LAB), acetic acid bacteria (AAB), yeasts, and free biomass in the fermented medium. Optimal agitation levels also enhanced nutrient consumption, free biomass, and metabolite pro-duction. AAB and yeast counts increased with higher agitation speeds, while LAB counts de-creased. Three beverages, produced during the second (A = 86 rpm, GW = 2.81 g) and third (A = 38 rpm, GW = 2.60 g; A = 86 rpm, GW = 1.80 g) kefir grain passages, exhibited LAB and yeast counts above 10⁶; CFU/mL, along with low total sugar and ethanol concentrations. These beverages may be considered suitable as potentially probiotic, low-alcohol, and low-calorie functional drinks. Full article

In many paper applications the paper is supposed to disintegrate into its constituating fibers after disposal. This happens in water with only very little input of mechanical energy. The aim of this work is to understand the natural aging processes in different pulp types and their impact on the disintegration behavior under low agitation. We first introduce a laboratory testing method to assess the disintegration performance of various paper types in water under low mechanical energy input. Then we investigated the changes in paper disintegration and the corresponding physical properties over a nine-month period of paper storage. We measured wet strength, water retention value WRV, speed of water penetration, and contact angle. Our findings reveal substantial degradation of disintegration over time for unbleached paper. In contrast, for bleached paper the changes are much less pronounced. The best predictor of paper dispersibility turned out to be wet tensile strength. Furthermore, we found a strong relation between deterioration of dispersibility and fiber wetting (contact angle) and fiber swelling (WRV). We hence conclude that the observed decrease of low agitation paper dispersibility over time is related to a deteriorated water uptake into the fibers and fiber-fiber bonds which prevents the breaking of the bonds by the water. As potential aging mechanisms related to water uptake we identified hornification, crosslinking and lignin self-sizing as major factors influencing fiber-water interactions and ultimately the disintegration behavior. Full article

Sustainable bio-based products derived from fermentation are gaining increasing interest. The present study was designed to determine the interaction of Lacticaseibacillus rhamnosus 23.2 bacteria with spirulina in a 3 L glass bioreactor and the effect of aeration and agitation speed on the final product biomass and antioxidant capacity. The fermentation medium contained only glucose, an inorganic salt mixture, and spirulina powder. The estimated biomass and antioxidant activity were found to be 3.74 g/L and 84.72%, respectively, from the results of the optimization model. Scale-up was performed with the obtained optimization data, and three pilot-scale fermentations were carried out in a 30 L stainless steel bioreactor. As a result of pilot production, the obtained bioactive products were freeze-dried, and their antibacterial, antioxidant, total phenolic properties, and cytotoxic activity were investigated. The pilot production results showed that the increase in bacterial cell number was around 3–4 log after 24 h of fermentation. An inhibitory effect against pathogenic bacteria was observed. A strong radical scavenging effect was found in antioxidant analyses. Total phenolic substance content was 26.5 mg gallic acid equivalent (GAE) g⁻¹, which was the highest level in this study. Cytotoxic activity showed that bioactive products had a cytotoxic effect against Caco-2 adenocarcinoma cells. This study emphasizes the potential of Arthrospira platensis biomass as a substrate for the production of lactic acid bacteria (LAB)-based bioproducts. It is thought that the results obtained from this study may position potential innovative strategies in the food, pharmaceutical, agriculture, and cosmetic industries. Full article

Lactic acid bacteria (LAB) play a crucial role in probiotics, functional foods, and sustainable biotechnologies due to their ability to produce bioactive metabolites such as short-chain fatty acids, bacteriocins, vitamins, and exopolysaccharides. These metabolites aid in gut health, pathogen inhibition, and enhanced productivity in the food, pharmaceutical, and aquaculture industries. However, the high production cost remains a major challenge, necessitating cost-effective media formulations and bioprocess optimization. This review explores strategies for maximizing LAB yields and functionality through the precision control of key cultivation parameters, including temperature, pH, and agitation speed, ensuring probiotic viability in compliance with regulatory standards (≥10⁶ CFU/g or mL). Furthermore, advances in metabolic engineering, synthetic biology, and the utilization of agro-industrial by-products are driving cost-efficient and eco-friendly LAB production. By integrating scalable fermentation technologies with sustainable resource management, LAB have the potential to bridge the gap between food security, environmental sustainability, and biotechnological innovation. This review provides a comprehensive overview of recent advances in LAB cultivation and bioprocess optimization, ensuring high-quality probiotic production for diverse industrial applications. Full article

Background: Agitation is a frequent and challenging symptom in schizophrenia and bipolar disorder, characterized by heightened motor activity, emotional distress, and potential aggression. This symptom is most observed during acute episodes, representing a significant burden on patients, caregivers, and healthcare systems. Agitation is a leading cause of emergency department visits and psychiatric hospitalizations, necessitating prompt and effective interventions to ensure safety and mitigate its far-reaching impact. Traditional treatments, including high-potency antipsychotics and benzodiazepines, remain first-line options but are associated with significant drawbacks such as sedation, extrapyramidal symptoms, tolerance, and limited applicability in certain patient populations, especially those with respiratory or cardiac depression and the elderly. Non-pharmacologic strategies like de-escalation techniques and environmental modifications are invaluable but may be impractical in acute care settings, as speed and efficiency are critical in emergent settings. These limitations, including the onset of extrapyramidal symptoms with high-dose antipsychotics and the development of tolerance with benzodiazepines, highlight gaps in care, including the need for faster-acting, safer, and more patient-friendly alternatives that reduce reliance on physical restraints and invasive interventions. Methods: This review explores the evolution of treatments for agitation, focusing on alternative and innovative approaches. To highlight these treatments, an extensive review of the literature was conducted utilizing PubMed, Google Scholar, Embase.com, and other search engines. Results: Key developments include sublingual dexmedetomidine, recently FDA-approved, which offers sedation without respiratory depression and a non-invasive administration route. Similarly, subcutaneous olanzapine provides a more convenient alternative to intramuscular injections, reducing injection-related complications. Other emerging treatments such as gabapentin, pregabalin, and ketamine show promise in addressing agitation in specific contexts, including comorbid conditions and treatment-resistant cases. A comparative analysis of these therapies highlights their mechanisms of action, clinical evidence, and practical challenges. Conclusions: Future directions emphasize intranasal delivery systems, novel pharmacologic agents, and potential roles for cannabinoids in managing agitation. These innovations aim to balance rapid symptom control with improved patient safety and experience. The set back with these emerging techniques is a lack of standardized dosing and protocols. They also face ethical concerns, including the chance of misuse or abuse, as well as regulatory barriers, as they lack FDA approval and their legality changes between states. This review underscores the clinical, practical, and ethical considerations in advancing care for agitated patients, paving the way for more effective and compassionate management strategies in psychiatric settings. Full article

This study optimized operating parameters to enhance cellulase production and evaluated scale-up feasibility in submerged fermentation (SmF) using Trichoderma sp. KMF006. Flask-scale experiments assessed the effects of Avicel:cellulose ratios (4:0–0:4), agitation speeds (150–210 rpm), and turbulence (baffled vs. non-baffled flasks), with optimized conditions applied to a 10 L bioreactor. A 3:1 Avicel:cellulose ratio (A3C1) significantly accelerated cellulase production, reaching peak activity 6 days earlier than Avicel alone. An agitation speed of 180 rpm was optimal, balancing enzyme activity and energy efficiency. Turbulence enhanced cellulase yields, with baffled flasks increasing EG, BGL, and CBH activities 19.9-, 6.2-, and 8.9-fold, respectively, compared to the control. Biochar further improved cellulase production but only under turbulent conditions, demonstrating a synergistic effect. At the bioreactor scale, the A3-180_Imp (A3C1, 180 rpm, impeller-induced turbulence) achieved the highest enzymatic activity (33.60 U/mL EG, 3.46 U/mL BGL, and 0.63 U/mL CBH). The filter paper unit (FPU) was 84 FPU/mL, a two-fold increase compared to the control. However, excessive turbulence at 210 rpm reduced enzyme stability, emphasizing the importance of balancing shear stress. These findings provide a systematic framework for optimizing SmF conditions, highlighting the significance of balancing hydrodynamic conditions for efficient cellulase production at an industrial scale. Full article

A better understanding of mixing times for mixed solvent systems in laboratory-scale vessels is crucial for improving mixing-sensitive processes such as antisolvent crystallisation. Whilst mixing in agitated vessels has been extensively studied using solutions of additives in the same solvent, there is very limited literature on the mixing of different miscible solvents and none which would be relevant to antisolvent crystallisation processes. In this work, the mixing times of water–ethanol systems in a 1 litre vessel, agitated by a pitched blade impeller with probes used as baffles, were investigated in the transitional flow regime using both experimental and computational fluid dynamics (CFD) approaches. We studied two scenarios: adding sodium chloride tracer to premixed water–ethanol solutions and adding ethanol containing a tracer to water. Mixing was investigated experimentally through conductivity measurements and computationally using large eddy simulations with the M-Star CFD software package. Empirical correlations from the Dynochem engineering toolbox were also used for comparison. The results showed significant run-to-run variability in the mixing times from both experiments and CFD simulations, with experimental ranges being notably wider than CFD ones under the given conditions. While the CFD simulations showed consistent mixing times across different solvent compositions, the experimental mixing times decreased with increasing ethanol content. The mixing times were approximately inversely proportional to the impeller speed. The CFD simulations indicated that 25–40 impeller rotations were required for homogenisation, while the experiments needed 25–100 rotations. The Dynochem correlations predicted 40 rotations, independent of speed, but could not capture the inherent variability of the mixing times. Full article

To address the issue of a poor seed-filling performance and seeding quality in air-suction corn seed metering devices during high-speed operation, an energy-efficient precision corn seeder with dual-side-disturbance-facilitated guiding slots is designed. The dual-side-disturbance-promoting method effectively increases the seed agitation, directing the corn seeds toward the suction holes and improving the seed-filling quality. The theoretical design of the dual-side guiding slot angles results in an upper-side guiding slot angle range of 29° to 19° and a lower-side guiding slot angle range of 72° to 90°. Bench tests are conducted to further optimize the parameter range, with the negative suction chamber pressure, upper-side guiding slot angle, and lower-side guiding slot angle as the experimental factors and the seedling qualification rate, missed sowing rate, and double-sowing rate as the evaluation indicators. An orthogonal experiment is carried out to analyze the interaction effects of factors on the evaluation indicators, followed by parameter optimization and verification tests. When the negative suction chamber pressure is 3.7 kPa, the upper-side guiding slot angle is 26.9°, and the lower-side guiding slot angle is 72.9°, the verification test results show a qualification index of 97.7%, a missed sowing index of 1.3%, and a row-spacing variation coefficient of 1%. The operational speed adaptability test results show that when the working speed is ≤14 km/h, the seed metering device achieves a qualification index above 97.1%, a missed sowing index below 1.5%, and a double sowing index below 1.4%, indicating good adaptability to working speeds. The comparison test results show that when the operating speed is between 8 and 12 km/h, the air-suction seed metering device with dual-side-disturbance-facilitated guiding slots achieves a 2.1% increase in the qualification index, significantly improving seeding quality. The energy consumption comparison test results indicate that under the same operational speed and approximately equal seeding quality, the air-suction seed metering device with dual-side guiding slots and dual-side-disturbance-facilitated air suction requires a reduction in negative pressure of more than 0.7 kPa, resulting in lower energy consumption. Full article

The prediction of the cell yield in large-scale bioreactor culture is an important factor for various cell therapy bioprocess operations to ensure consistency in cell quality and efficient use of resources. However, the shear sensitivity of cells used in cell therapy manufacturing can make such predictions difficult, particularly in large-scale suspension cultures that have significant stresses without representative scale down models. The PBS Vertical-Wheel (VW) bioreactors have been demonstrated to provide a homogeneous hydrodynamic environment with low shear for cell culture at various scales (0.1–80 L) and is thereby employed for various shear-sensitive cells. In this study, the oxygen transfer rate for surface aeration for three large-scale VW bioreactors was measured along with the specific oxygen uptake rate (sOUR) of iPSCs cultured in the bioreactors. The oxygen mass transfer coefficient was measured in PBS-3/15/80 L bioreactors at different agitation rates, headspace gas flowrates, and working volumes using the static gassing-out method. The sOUR of iPSCs was measured using the dynamic method in the PBS-0.1 L Mini with a custom DO probe configuration. The results from both experiments were combined to calculate the theoretical maximum cell density before oxygen limitation across VW bioreactors at 2 L/3 L/10 L/15 L/50 L/80 L working volumes at a different agitation speed and aeration rate. Full article