Agitation Speed Research Articles

Fluoropolymers after PFAS: Mechanical and rheological comparisons of PVDF‐CTFE polymers

AbstractDue to their environmental and health impacts, the increasing need to eliminate perfluoroalkyl substances (PFAS) has driven the exploration of alternative synthetic routes for fluoropolymers. This study investigates the mechanical and rheological properties of poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) (PVDF‐CTFE) synthesized using traditional PFAS‐based methods and new “no added PFAS” approaches. Various synthesis parameters such as reaction temperature, agitation speed, and initiator concentration were varied to produce several polymer lots. The resulting PVDF‐CTFE polymers were evaluated by gel permeation chromatography, rheology, and tensile testing to assess various replacements for the legacy (i.e., added PFAS) material. Our findings indicate that the “no added PFAS” PVDF‐CTFE can achieve mechanical and rheological performance comparable to traditional methods, with certain lots (i.e., 2059) closely matching the legacy lot (i.e., 30035) due to its relatively low molecular weight when compared with other lots. The tensile strength, elongation, and viscoelastic properties from tensile testing, in‐situ pressure monitoring during compounding, and parallel plate rheology all agreed that due to its relatively low molecular weight, lot 2059 was the most appropriate replacement for 30035. This work provides a foundational understanding of how synthesis variations to eliminate added PFAS can be tuned to create materials with similar properties as those made with PFAS, guiding future developments in environmentally safer fluoropolymer production.Highlights PFAS‐free PVDF‐CTFE evaluated. Mechanical properties approached PVDF‐CTFE made with PFAS. Varied synthesis impacts assessed. Guides eco‐friendly polymer production.

Practical scaling-up of a four reactants multicomponent reaction (4-MCR)

Context: Translation of any chemical process from laboratory to pilot or commercial scale is by no means a simple linear process. This process is influenced by several parameters, such as temperature, agitation speed, the concentration of reactants, and their interactions. In addition, temperature and agitation speed are very related to heat and movement transfers, which are two critical unit operations that affect the scale-up process and reaction yield. A multicomponent reaction (MCR) is a process where more than three reagents react through two or more reactions, producing one biggest molecule. Its scale-up is complex considering the complex nature of the reaction pathway. Our project involves a 4-MCR for obtaining a 3,4-pyridone derivative, a very important product for obtaining a neuroprotective compound. Despite its importance in medicinal chemistry, no report about the scale-up of MCRs was found. Aims: To develop a practical way to scale up a multicomponent reaction with four components, from laboratory to pilot scales. Methods: A combination of the brute force method and dimensionless numbers was applied for the scale-up process based on the significant physical forces governing the process. Results: Experimentally, it was previously demonstrated that temperature and fluid agitation and their interaction are the most significant parameters affecting reaction yield. Its related unit operations, heat and movement transport, were selected as the critical physical forces for the scaling-up process. The dimensionless numbers related to those unit operations are the Nusselt and Reynold numbers. In addition to other criteria applied, those dimensionless numbers were used to calculate the agitation speed for the upper scale. Likewise, as the reaction product precipitated through the cooling process, the obstruction of the reactor discharge valve was observed. Thus, a critical agitation speed was determined at the laboratory scale by applying the Zwietering rule through direct observation of solid sedimentation in the reactor. Conclusions: The process showed high reproducibility at all scales, reaching good yields of around 73%. Product purity was higher than 99% for all batches. The method applied allows the successful scalability of the process to increase the scale to commercial.

Effect of dry fractionation of peanut oil-based diacylglycerols on crystallization properties, oxidative stability and safety.

Effect of dry fractionation of peanut oil-based diacylglycerols on crystallization properties, oxidative stability and safety.

Optimized Spirulina Fermentation with Lacticaseibacillus rhamnosus: Bioactive Properties and Pilot-Scale Validation

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.

Isotherm, Kinetic and Thermodynamic Studies of Adsorption of Naphthol Blue Black-B Dye from Aqueous Solution using Synthesised Copper Oxide Nanoparticles

The present research work examined the elimination of Naphthol Blue Black –B dye from aqueous solution by the use of copper oxide nanoparticles as suitable adsorbent. The nanoparticles that were synthesised, were characterised by using FTIR, SEM, EDX and XRD techniques. Studies on batch adsorption were performed by varying factors such as contact period, adsorbent dose, dye concentration, pH, speed of agitation, temperature and desorption studies. Batch adsorption results were explained by applying isotherms like Freundlich, Langmuir, Dubinin- Raduskevich, Temkin and Jovanoic models. Kinetic data suggested that the batch mode experiment obeys pseudo second order kinetic model. Examination of thermodynamics indicated that the process of adsorption is feasible and spontaneous.

Optimization and Bioreactor Scale-Up of Cellulase Production in Trichoderma sp. KMF006 for Higher Yield and Performance.

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.

Statistical factorial design for optimum reduction of tellurite and production of tellurium nanostructure by a novel strain Phytobacter diazotrophicus Te1.

A tellurite-reducing isolate (Te1) was recovered from a soil sample receiving industrial effluents from Ismailia Canal, Egypt. The isolate exhibited dark black colonies when grown on solid medium containing potassium tellurite, which indicated the reduction of tellurite to black tellurium. The isolate was identified using 16S rRNA gene sequencing and was submitted to GenBank as Phytobacter diazotrophicus strain Te1 (PP724698). The tellurite reduction percentage was 96.5% ± 0.354%. Moreover, energy-dispersive X-ray (EDX) analysis confirmed the presence of tellurium nanostructure, with a 3.7keV absorption peak along with phosphorus, sulfur, and oxygen, revealing a complex biogenic nature. Fourier-transform infrared (FTIR) spectroscopy identified distinct absorption peaks within the 400-4000cm-1 range, corresponding to various vibrational modes of chemical bonds, including those of lipids, proteins, polysaccharides, and free radicals. X-ray diffraction (XRD) analysis highlighted the nanoscale crystalline structure of the material, with broad peaks confirming limited crystallite size and structural disorder, and revealed tellurium peaks on a hexagonal phase at 2-theta values of 27.36°, 38.19° and 40.20°. According to the results of the response optimizer and the subsequent validation experiments, complete reduction of tellurium was achieved at a medium pH of 6.8, incubation temperature of 33.5°C, tellurite concentration of 1375μM, and agitation speed of 110rpm for 96h. Black Te nanostructure was visible intracellularly and extracellularly upon examination using the transmission electron microscope. To the best of the authors' knowledge, this is the first report of tellurite reduction by Phytobacter diazotrophicus.

Effect of processing conditions on the physical-chemical and mechanical properties of chitosan-alginate polyelectrolyte complex films for potential wound dressing application.

The combination of chitosan and alginate leads to the formation of polyelectrolyte complexes (PECs) that have been mainly used for applications such as wound dressings in biomedical areas. However, processing conditions can affect the resulting complex structure, influencing the final material properties. This work aims to evaluate the influence of processing conditions on the physical-chemical and mechanical properties of chitosan-alginate PEC films for wound dressing applications. The study was carried out using a Box-Behnken design, with controlled variables including pH, agitation speed, amounts of crosslinker and plasticizer, and the type of acid used in chitosan solubilization. Response variables were thickness, liquid absorption capacity, water vapor barrier, and mechanical properties, which are important characteristics in defining the applicability of dressings. All studied factors, as well as their interactions, showed significant effects on the properties of interest. The mathematical models obtained for the studied properties did not have a predictive character but rather a qualitative one, providing a good insight into the behavior of these materials regarding the modification of the evaluated experimental conditions, which strongly influence the characteristics of chitosan-alginate PEC films. Additional swelling and FTIR analyses performed for a selected sub-set of samples confirmed, respectively: (i) the high equilibrium values and stability at the equilibrium of the films regarding liquid absorption for both water and PBS; (ii) no degradation of the chitosan and alginate functional groups or loss of interaction between them under the considered processing conditions.

Investigation on boron removal from produced water utilizing cassava stem biochar: Understanding from equilibrium, kinetics, thermodynamics and characterization

AbstractThe present study investigates the potential of an agricultural by product cassava stem biochar, as an effective adsorbent for the removal of boron from produced water. Cassava stem biochar was prepared through controlled pyrolysis, and adsorption experiments were conducted to evaluate the removal of boron ions from produced water, considering parameters, such as pH (1–8), contact time (0–45 min), initial concentration of boron in produced water (1.3–3.8 mg/L), adsorbent dosage (0.25–1.5 g/L), temperature (20–40 °C), agitation speed (50–250 rpm) and particle size (125–2000 μm). The results revealed that cassava stem biochar exhibited a significant adsorption capacity of 3.42 mg/g for the removal of boron ions, with a notable influence of solution pH, contact time, adsorbent dosage, temperature, agitation speed, and particle size of 6, 35 min, 1.25 g/L, 25 °C, 100 rpm, and 250 μm, respectively. Freundlich isotherm and pseudo‐second order kinetic models were applied to elucidate the adsorption mechanism. Thermodynamic parameters were also determined to gain insights into the energetics of the adsorption process, and it is exothermic, feasible, and spontaneous. Hence, this study contributes to the development of cost‐effective adsorption for the remediation of boron‐contaminated water.

Exploring Arachis hypogaea bio-waste sorption potential for phytofiltration of acridine orange dye from wastewater as a new candidate for green revolution

Adsorption is a desirable, environmental friendly strategy for eliminating toxins from industrial effluents using natural resources. The effectiveness of phytofiltering an industrially significant chemical: Acridine orange dye from aqueous media utilizing inexpensive Arachis hypogaea (peanut) bio-waste as an adsorbent has been studied in this work. The major principle of this study is surface chemistry that made biosorption possible by tuning a number of adsorption-related variables, including contact duration of the solution with adsorbent, temperature, pH, adsorbent dose, and stirring rate. 1.2 g of adsorbent dose, 60 °C temperature, 90 min contact time, 100 rpm agitation speed and pH 4 was found to be best conditions giving more than 90% dye removal. FT-IR and SEM were used to assess the surface of biomaterial along with Langmuir, Freundlich, and Temkin isotherms. Freundlich isotherm proved to be more effective with R 2 value of 0.995 along with pseudo-second order model and 79.36 mg/g adsorption capacity. Thermodynamically the procedure is exothermic in nature. These favorable results indicated the suitability of Arachis hypogaea bio-waste for removal of acidic contaminants by phytofiltration on a large scale.

Statistical and neural network modeling of β-glucanase production by Streptomyces albogriseolus (PQ002238), and immobilization on chitosan-coated magnetic microparticles

β-Glucanases are a series of glycoside hydrolases (GHs) that are of special interest for various medical and biotechnological applications. Numerous β-glucanases were produced by different types of microorganisms. Particularly, bacterial β-glucanases have the privilege of being stable, easily produced, and suitable for large-scale production. This study aimed for finding potent β-glucanase producing bacterial strains and optimizing its production. Soil samples from Egyptian governorates were screened for such strains, and 96 isolates were collected. The β-glucanase activity was qualitatively assessed and quantitatively measured using 3,5-dinitrosalicylic acid (DNS) method. The highest β-glucanase producing strain (0.74 U/ml) was identified as Streptomyces albogriseolus S13-1. The optimum incubation period and temperature, determined one-variable at a time, were estimated as 4 d and 45 ͦ C, respectively. Similarly, yeast β-glucan and beef extract were selected as the best carbon and nitrogen sources, with enzymatic activities of 0.74 and 1.12 U/ml, respectively. Other fermentation conditions were optimized through response surface methodology (RSM); D-optimal design (DOD) with a total of 28 runs. The maximum experimental β-glucanase activity (1.3 U/ml) was obtained with pH 6.5, inoculum volume of 0.5% v/v, agitation speed of 100 rpm, carbon concentration of 1% w/v, and nitrogen concentration of 0.11% w/v. This was 1.76-fold higher compared to unoptimized conditions. Using the same experimental matrix, an artificial neural network (ANN) was built to predict β-glucanase production by the isolated strain. Predicted β-glucanase levels by RSM and ANN were 1.79 and 1.32 U/ml, respectively. Both models slightly over-estimated production levels, but ANN showed higher predictivity and better performance metrics. The enzyme was partially purified through acetone precipitation, characterized, and immobilized on chitosan-coated iron oxide microparticles. The optimal pH and temperature for enzyme activity were 5 and 50 °C, respectively. The immobilized enzyme showed superior characters such as higher stability at temperatures 50, 60, and 70 °C compared to the free enzyme, and satisfactory reusability, losing only 30% of activity after 6 cycles of reuse.Graphical

Thermodynamics and Adsorption of Fe2+ from Oilfield Produced Water using Clay-derived Zeolite

The study explored the potential of clay-derived zeolite (CDZ) as an adsorbent for the removal of Fe2+ ions from produced water generated from oil fields. The clay was sourced from the Ikepshi Community in the Akoko-Edo Local Government Area of Edo State, Nigeria. The zeolite was produced through a calcination process at a temperature of 600 °C, followed by dealumination and zeolite synthesis prior to its application for adsorption of Fe2+ from produced water. A variety of operational parameters were evaluated to understand their impacts on the adsorption process. These included different dosages of the adsorbent, contact time, temperature, agitation speed, and pH levels. The thermodynamics parameters were evaluated over a temperature range of 303 K to 343 K. Scanning Electron Microscopy (SEM) images displayed the characteristic silicate flakes of kaolinite clay, while Fourier Transform Infrared Spectroscopy (FTIR) results identified specific functional groups. Particularly, the presence of O-H and Si-O stretching vibrations confirmed the clay kaolinite composition. The analysis of adsorption outcomes across varying temperatures revealed negative values for Gibbs free energy ( ), and a positive entropy value ( , this indicates that the adsorption process is spontaneous and feasible, along with an increase in degree of randomness of adsorption process. The process of Fe2+ uptake on CDZ was considered as endothermic, as shown by the positive enthalpy values ( obtained thus shows a strong Vander Waal forces between the adsorbent and adsorbate.

Investigation of the Corrosion Behavior of Selected Metal Electrodes used in a Microbial Fuel Cell for Clean Energy Production

The electrodes material plays an important role in the amount of electricity produced in microbial fuel cells (MFCs). Metal electrodes used in MFCs are subject to biological and concentration cell corrosion which leads to a decrease in the cell efficiency. In the present work, the corrosion behavior of three selected electrode materials, namely, stainless steel, copper, and zinc under different operating conditions was investigated and discussed. In anode chamber, the microorganism (MO) used was Saccharomyces cerevisiae (yeast) with sodium acetate as a substrate forming the microbial corrosive solution. In the cathode chamber, the corrosive solution is aerated water. The effects of different operating parameters on the corrosion rate (CR) of these electrodes were studied such as: microorganism concentration, aeration of cathode chamber, and flow velocity in cathode chamber. The potential of the each electrode was measured to understand the corrosion behavior of electrodes and the produced current was also investigated. It was found that the corrosion rate of the electrodes in both anode and cathode chambers increases with increasing MO concentration in anode chamber and with increasing agitation speed in cathode chamber. The bio-corrosion is an important part of the corrosion occurring in microorganism chamber. The stainless steel exhibited the lowest corrosion rate for the whole investigated range of operating parameters followed by copper. The zinc electrode was found to be poor as an electrode in MFC as its corrosion rate was very high in all conditions investigated. In addition, this study showed that the air pumping in water chamber causes an appreciable increase in the corrosion rate in both chambers and an increase in the produced current.

Tailoring the Morphology of α-Cobalt Hydroxide Using Liquid/Liquid Interface and Its Application in Electrochemical Detection of Ascorbic Acid.

The exertion of nanomaterials is subjugated by factors such as size, thickness, morphology, crystallinity, and composition, however, the ability to control these parameters, particularly the morphology, through conventional synthesis methods are challenging. Nevertheless, liquid/liquid interface-assisted methods have paved the way for more precise and controlled synthesis of nanomaterials. In this study, an n-butanol/water interface was used to synthesize α-cobalt hydroxide (CH) nanostructures, and the effects of solvent ratio and stirring rate on the properties of the product were examined. The transition from pure water to pure n-butanol alters the morphology from irregular nanoflakes to flower-like structures. A 1:1 solvent ratio produced nonaggregated flower structures with an increased active surface area and minimal charge transfer resistance. The agitation speed also affected the morphology; as the stirring speed increased from zero to 150 rpm, the morphology changed from aggregated needles to flower-like structures. The sample synthesized with a 1:1 solvent ratio and 50 rpm stirring speed (BW2) exhibited enhanced electrochemical activity, which was harnessed for electrochemical sensing with minimal multiwalled carbon nanotube (MWCNT) addition. The CH/MWCNT composite effectively detected ascorbic acid (AA) across a broad linear range of 1-200 μM with a detection limit of 0.0943 μM and provided accurate AA recovery in vitamin C tablets and artificial sweat. A flexible miniature sensor was also developed for AA detection, demonstrating the potential of liquid/liquid interfaces to modulate the morphology and hence the electrochemical properties of transition metal oxides for a wide range of applications.

Methylene blue removal by durian rind derived charcoal adsorbent

Abstract Textile wastewater is characterized by its strong color and high chemical content, including contaminants such as dyes that negatively impact ecosystems. One example of a chemical dye commonly released is methylene blue (MB). Adsorption is one of the methods used to treat textile wastewater. Durian rind (DR), an agricultural waste, can be converted into sustainable carbon through a carbonization process. As a carbon material, DR has the potential to serve as an adsorbent. This study evaluates the potential of DR as an adsorbent for MB removal from solution. DR is converted into charcoal through pyrolysis and subsequently activated using sulfuric acid (H2SO4). DR, durian rind charcoal (DRC), and durian rind activated charcoal (DRAC) are tested for MB removal using a batch adsorption process. The process is optimized using the one-factor-at-a-time (OFAT) method. MB concentration is determined by UV-Vis spectrometry. The maximum MB removal efficiencies achieved by DR, DRC, and DRAC are 78.37%, 98.57%, and 98.95%, respectively, under optimal conditions: pH 6, 60 min. of contact time, 180 rpm agitation speed, 1 g adsorbent dosage, and an initial MB concentration of 100 mg/L. The Langmuir and Freundlich models are studied to determine the adsorption behavior, with results indicating that the adsorption process follows the Freundlich model (R2 = 0.9427). Pseudo-first-order and pseudo-second-order kinetic models are applied to describe the adsorption rate, with findings showing that the pseudo-second-order model best fits chemisorption (R2 = 0.9832). This study concludes that DR can be used as an effective alternative adsorbent for color removal in textile wastewater while also addressing the issue of DR waste.

Optimizing lipase production by Bacillus subtilis on cheese whey and evaluating its antimicrobial, antibiofilm, anti virulence and biosafety properties

This study optimized lipase production using cheese whey, biofilm inhibition, and antibacterial efficacy of Bacillus subtilis (DSM 1088)derived lipase against Staphylococcus aureus (ATCC 6538). Peak lipase activity, growth rate, and inhibitory potential were observed at 48 h and 30 °C. Using Plackett-Burman and Central Composite Designs (PBD and CCD), whey, peptone, and agitation speed were identified as significant factors, achieving optimal lipase activity of 1314 U/mL and an inhibitory zone diameter (IZD) of 48 mm against S. aureus. Partial purification through ammonium sulfate precipitation and dialysis increased partial purified lipase (PPL) activity by twofold and fivefold, respectively. PPL exhibited effective bactericidal properties with a minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of 1/8 and 1/16, confirming a bactericidal effect (MIC/MBC ratio ≤ 2). Biofilm inhibition assays demonstrated 95% biofilm reduction at 80 µg/mL PPL, with SEM imaging revealing significant biofilm matrix disruption. Time-kill assays showed concentration-dependent bactericidal action, while inhibition of hemolysin and protease activities (25–100%) indicated reduced S. aureus pathogenicity. Cytotoxicity assays on normal liver cells showed an IC50 > 300 µg/mL, indicating low toxicity. GC/MS analysis of oil waste before degradation identified predominantly oleic acid 3-hydroxypropyl ester and octadecane derivatives, while after degradation, it revealed enriched free fatty acids including myristic, palmitic, linoleic, and oleic acids, which could enhance antimicrobial efficacy. Molecular docking suggested that PPL inhibits essential bacterial enzymes (folic acid synthetase, RNA polymerase, DNA gyrase), potentially disrupting DNA synthesis and promoting cell death. These findings highlight B. subtilis-derived lipase as a promising bio-agent for combating biofilm-associated, drug-resistant pathogens with clinical and industrial applications.

Effective Cyanide Adsorption in Wastewater Using Buckthorn Leaves: A study on Removal Efficiency and Kinetic Analysis

Cyanide is an extremely toxic compound that prevents cellular respiration by binding to cytochrome c oxidase, that causes a speedy oxygen deficiency and potentially fatal consequences for affected organisms. Therefore, the elimination of cyanide from wastewater is of pronounced health and environmental position. The current study focuses on investigating the removal of cyanide by adsorption practice by means of buckthorn leaves as low-cost and an available adsorption medium. The cyanide removal process is conducted in a batch mode unit and under different operating conditions of temperature (25-50 °C), contact time (5-180 min), agitation speed (100-500 rpm), initial concentration (1-150 ppm), pH (1-10), and adsorbent dosage (0.1-5 g). The obtained results show that the removal efficacy is proportional to all factors except the initial concentration, and that the highest cyanide recovery rate of 95.5%is attained at pHof 8, 400 rpm for agitation speed, initial concentration of 100 ppm, adsorbent dose of 4 g, contact time of 150 min, and 50 °C of temperature. According to the correlation coefficient, the isothermal study confirm that the Langmuir model is the closest torepresenting the experimental data with a value of 0.9994, slightly ahead of the Freundlich and Temkin models. Also, the pseudo-second-order model records to be the best in representing the data kinetically with a correlation coefficient of 0.9999, which is ahead of the pseudo-first-order model (the Elovitch model), and the intra-particle diffusion model. Thermodynamically, the adsorption is endothermic and positively entropic with values of 159 kJ/mol and 571.8 J/mol K, respectively, and spontaneous at all temperatures studied.

Novel alkylammonium-enhanced bentonite for effective Cr removal from wastewater.

The contamination of water resources by tannery wastewater containing Cr(III) presents significant public health risks due to its carcinogenic nature. Addressing this critical issue, the purpose of this research is to develop and evaluate novel alkylammonium-modified bentonite adsorbents for the efficient removal of Cr(III) from tannery wastewater. Batch experiments were conducted to investigate the effects of Cr concentration (0.02-0.2mg/L), adsorbent dose (0.25-2.5g/L), pH (2.0-8.0), and temperature (293-313 K) on adsorption performance. The alkylammonium modifications enhanced the surface area and ion-exchange capacity of bentonite by 40% and 50%, respectively. Optimal conditions for Cr adsorption were identified as 313 K, 1g/L adsorbent dosage, pH2.0, 30 min of reaction time, and 150 rpm of agitation speed. The Langmuir isotherm model (R2 = 0.998 for trimethylammonium bentonite [TMB], 0.994 for triethylammonium bentonite [TEB]) confirmed monolayer adsorption, while negative Gibbs free energy values demonstrated the spontaneous nature of the process. Enthalpy changes (ΔH°) of 21.1kJ/mol (natural Navbahor bentonite [NNB]), 26.7kJ/mol (TMB), and 28.4kJ/mol (TEB) indicated endothermic reactions. This work highlights the novelty of alkylammonium-modified bentonite as a cost-effective and scalable solution for reducing Cr(III) in wastewater, providing a promising pathway for sustainable water resource management. PRACTITIONER POINTS: Optimum conditions: 313 K, 1 g/L of dose, pH 2.0, 30 min of reaction, and 150 rpm of speed. Alkylammonium-modified bentonites remove 95% of Cr ions at pH2.0 and 80% at pH7.0. The adsorption capacity of modified bentonites is 19, 21, and 22 mg/g for NNB, TMB, and TEB. The modified bentonites retained 55% of their adsorption capacity after five regeneration cycles.

Adsorption of oil from water using sugarcane bagasse: an analysis using response surface methodology

Abstract Oil and grease are common industrial pollutants, but most treatments for oil pollution are expensive, heavy in carbon footprint, and inaccessible to most. This study investigates the potential of sugarcane bagasse (SCB) as a cost-effective adsorbent for mitigating oil pollution in oil-in-water emulsions. Focusing on sunflower oil, a prominent constituent in kitchen wastewater, this research explores SCB’s efficacy in oil removal. With readily available materials and chemicals, the proposed method holds promise for replication in small-scale industries. Employing Box–Behnken and response surface methodology, the experiments performed were between temperatures of 30–60 ℃, agitation speeds of 150–210 rpm, with contact times between 5 and 60 min, adsorbent dosages of 0.006–0.036 g, and initial oil concentrations of 0.2–1%. The optimal operational parameters were identified, resulting in a noteworthy oil removal efficiency of 74.415% under specified conditions of 59.9 ℃, 9 min, 180 rpm, 0.012 g of SCB, and 0.2% initial oil concentration, underscoring the effectiveness of the adsorbent at minimal cost inputs. Further, characterization techniques such as scanning electron microscopy and Fourier-transform infrared spectroscopy were employed to highlight the structural and functional features that enable optimal adsorption. Future research can explore various types of oil and contribute to advancing a circular economy. Graphical abstract

Measurement of Oxygen Transfer Rate and Specific Oxygen Uptake Rate of h-iPSC Aggregates in Vertical Wheel Bioreactors to Predict Maximum Cell Density Before Oxygen Limitation.

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.