Cetyltrimethylammonium Bromide Concentration Research Articles

MOF-Derived ZrO2-Supported Bimetallic Pd-Ni Catalyst for Selective Hydrogenation of 1,3-Butadiene.

A series of MOF-derived ZrO2-supported Pd-Ni bimetallic catalysts (PdNi/UiO-67-CTAB(n)-A500) were prepared by co-impregnation and pyrolysis at 500 °C under air atmosphere using UiO-67-CTAB(n) (CTAB: cetyltrimethylammonium bromide; n: the concentration of CTAB; n = 0, 3, 8, 13, 18) as a sacrificial template. The catalytic activity of PdNi/UiO-66-CTAB(n)-A500 in 1,3-butadiene hydrogenation was found to be dependent on the crystal morphology of the UiO-67 template. The highest activity was observed over the PdNi/UiO-67-CTAB(3)-A500 catalyst which was synthesized using UiO-67-CTAB(3) with uniform octahedral morphology as the template for the 1,3-butadiene selective hydrogenation. The 1,3-butadiene conversion and total butene selectivity were 98.4% and 44.8% at 40 °C within 1 h for the PdNi/UiO-67-CTAB(3)-A500 catalyst, respectively. The catalyst of PdNi/UiO-67-CTAB(3)-A500 can be regenerated in flowing N2 at 200 °C. Carbon deposited on the surface of the catalyst was the main reason for its deactivation. This work is valuable for the high-efficiency bimetallic catalyst's development on the selective hydrogenation of 1,3-butadiene.

Effects of ion doping on the dielectric and electro-optical properties of chiral nematic liquid crystal

This study presents experimental findings pertaining to the use of the cationic surfactant cetyltrimethylammonium bromide (CTAB) as a dopant dispersed in cholesteric liquid crystal. The impact of the additive on the electrical and dielectric properties was investigated by dielectric spectroscopy. Compared with that in the pure counterpart, the dielectric relaxation frequency increased due to the added ions in the cholesteric liquid crystals impregnated with 0.01–0.5- wt% CTAB. Furthermore, by analyzing the dielectric spectra in a specific frequency range, the DC conductivity, ion density, and diffusion coefficient were calculated and compared. By fitting the experimental data into the Arrhenius equation, the activation energy was obtained as well. Our experimental results illustrated that all these physical properties were strongly dependent on the CTAB concentration and the temperature. This work also involved the electro-optical measurement in combination with the observation of optical texture. The ion addition provoked electrohydrodynamic flows in a surfactant-dispersed mixture, generating a homogeneous and transparent uniform lying helix state between two low-transmission optical states—the focal conic and dynamic scattering states. The operating frequency range of the dynamic scattering state was significantly broadened by the ionic dopant.

Synthesis of high-performance polymethylsilsesquioxane xerogels by improving acid catalytic conditions in aluminum chloride aqueous solution

Organic and inorganic acids are common catalysts to promote the hydrolysis of methyltrialkoxysilanes, but they are challenging to modulate the inherent CH3SiO1.5 backbone of polymethylsilsesquioxane (PMSQ) xerogels. Here, an aluminum chloride aqueous solution is proposed for the first time as an acid catalyst to enhance the hydrolysis of methyltriethoxysilane (MTES). This approach allows the PMSQ xerogels to have a more flexible [-Al-O-]m-[SiO]n backbone structure. The optimal concentration of aluminum chloride and surfactant cetyltrimethylammonium bromide in the MTES sol was 1.069 mmol/L and 0.885 mmol/L, respectively, endowing the as-synthesized PMSQ xerogel with a high compression strength of 0.450 MPa and maximum compression strain of 76.1%. Notably, the tiny incorporation of alumina phase (0.4 mol%) in the Si-O-Si backbone made the PMSQ xerogels hydrophobic up to 400 °C for 1 h in the air. The PMSQ xerogels possessed superior thermal insulation properties (32.0–38.0 mW/(m·K)) and could be processed into desired large-sized shapes.

Solubilization and physicochemical parameters of 2-chloro and 4-chlorophenol in micellar media of cetyltrimethylammonium bromide and sodium dodecyl sulphate at different temperatures

Solubilization and thermodynamic parameters of 2-chloro and 4-chlorophenol in micellar media of Cetyltrimethylammonium bromide (CTAB) and Sodium dodecyl sulphate (SDS) are elaborated in this study. The effect of the addition of 2-chloro and 4-chlorophenol on the critical micelle concentrations (CMCs) of CTAB and SDS was investigated by using the conductivity method at different concentrations (5 mmolL−1 to 25 mmolL−1) and temperatures (25 °C to 45 °C). The plot of specific conductance versus concentration of surfactant was used to determine CMC value. The CMC values of CTAB and SDS were observed to decrease, and thus the addition of 2-chloro and 4-chlorophenol favors micellization. In addition, it was observed that the CMC values of CTAB and SDS gradually increased with an increase in temperature. Various types of thermodynamic parameters such as standard Gibbs free energy of micellization (ΔGm°), standard enthalpy of micellization (ΔHm°) as well as standard entropy of micellization (ΔSm°) were determined and explained thoroughly to investigate the interactions between additives and surfactant. The magnitudes of ΔGm°andΔHm° were shown to be negative in the whole system, which shows that the processes of micellization were energetically spontaneous and exothermic. The thermodynamic parameters of transfer (ΔGm.tr°, ΔHm.tr° and ΔSm.tr°) from water to 2-chloro and 4-chlorophenol were also calculated and discussed with appropriate reasoning.

Exploring the Impact of Cationic Surfactant Ctab on Bleu Brilliant G 250 De Cosmassie: Implications for Health Management and Environmental Sustainability

Background: Surfactants are ubiquitous in both natural and industrial processes due to their unique ability to reduce surface tension and facilitate interactions between hydrophilic and hydrophobic substances. Cationic surfactants like cetyltrimethylammonium bromide (CTAB) are of particular interest because of their widespread applications in areas such as healthcare and environmental management. The interaction between surfactants and dyes, such as Bleu Brilliant G 250 de Cosmassie, is critical in industrial processes, especially in the textile industry where wastewater treatment poses significant environmental challenges. Objective: The aim of this study was to explore the thermodynamic behavior of CTAB when combined with Bleu Brilliant G 250 de Cosmassie in aqueous solutions at room temperature. It sought to determine the critical micelle concentration (CMC) and the degree of counter-ion dissociation (α), and to calculate the changes in Gibbs free energy (ΔGm), enthalpy (ΔHm), and entropy (ΔSm) of the system. Methods: The study employed conductometric and spectrophotometric techniques to analyze the CTAB-dye interactions. Solutions were prepared with varying concentrations of CTAB and Bleu Brilliant G 250 de Cosmassie in deionized water, ensuring solvent purity through stringent conductivity and pH monitoring. Electrical conductance was measured at different temperatures to determine the CMC, while absorbance spectra were recorded to observe changes in the interaction between the surfactant and dye. The degree of counter-ion dissociation was calculated by the slope ratio method, and thermodynamic parameters were computed using established equations. Results: The conductometric studies revealed an increase in CMC with temperature, indicating a stabilization of surfactant monomers at higher temperatures. For CTAB and Bleu Brilliant system 1, the CMC was found to be 0.8 with α valued at 0.83. For system 2, the CMC values were 1.55 and 1.6 with α values of 1.01 and 0.91, respectively. Thermodynamically, the system displayed a Gibbs free energy of micellization of -33.09 KJ/mol, an enthalpy change of -6.53, and an entropy change of 0.1325 JK^-1 mol^-1. Conclusion: The study concluded that the interaction between CTAB and Bleu Brilliant G 250 de Cosmassie is influenced significantly by temperature, which affects the micellization behavior and thermodynamic properties. The findings contribute to a better understanding of the fundamental thermodynamic parameters influencing surfactant-dye interactions, providing insights that may improve industrial processes and environmental sustainability.

Effect of surfactant on dynamics and gas-liquid mass transfer for single carbon dioxide bubbles

In carbonation reaction, the impact of surfactants on the movement and mass transfer behavior of carbon dioxide bubbles were crucial for the production of high-quality silicon dioxide products. The study employed the Matlab image processing system to investigate the shapes, motion velocities, and rise path of single carbon dioxide bubbles within varying concentrations of cetyltrimethyl ammonium bromide (CTAB) solutions. This exploration aimed to elucidate the effect of CTAB on the movement and mass transfer coefficient (MTRC) of single carbon dioxide bubbles. Alterations in the CTAB solution concentration and bubble sizes significantly influenced the mass transfer and movement characteristics of single carbon dioxide bubbles. The conclusion was drawn through the computation of the MTRC of single carbon dioxide bubbles in deionized water and CTAB solutions: the addition of CTAB significantly reduced the mass transfer efficiency of carbon dioxide in deionized water, with the MTRC of CTAB solutions decreasing as the solution concentration increased. Utilizing the stagnant cap model, it can be concluded that CTAB's reduction of the MTRC of carbon dioxide was attributed to the high viscosity of the medium, low bubble velocity, stable flow conditions, and intensified adsorption degree of CTAB molecules at the gas-liquid interface. According to the significant periodic trajectories of single carbon dioxide bubbles in the stable range, the correlation between the trajectories of compressible bubbles in surfactant solution and mass transfer in liquid phase was established, and the previous method based on rigid sphere model was modified. The paper proposed the mechanism of CTAB's influence on single carbon dioxide bubbles, offering crucial theoretical insights into the industrial application of surfactants in the carbonation process for producing silicon dioxide.

Performance of hydrogel beads composites derived from sodium alginate-cetyltrimethylammonium bromide toward congo red dye adsorption from aqueous solution

The complex process for treating industrial wastewater frequently necessitates the employment of efficient treatment techniques to eliminate harmful contaminants before discharge, such as congo red (CR) dye. In this study, adsorption methods were utilized to eliminate CR by employing hydrogel bead composites derived from sodium alginate (SA) and cetyltrimethylammonium bromide (CTAB). Various concentrations of CTAB, including 0.1 wt%, 1 wt%, and 3 wt%, denoted as SC1, SC2, and SC3 respectively, were examined. The results demonstrated that SC3 has higher swelling percentage and lowest carboxyl group (COOH). Experiments were carried out under different pH levels, CR concentrations, and adsorption durations for removal of CR. The maximum CR adsorption capabilities of SC1, SC2, and SC3 obtained were as 141.08 mg/g, 144.50 mg/g and 153.24 mg/g for SC1, SC2 and SC3, respectively. The Freundlich and pseudo-second-order models demonstrate the best fit for both isotherm and kinetic analysis across all samples, suggesting a multilayer adsorption process and chemisorption mechanism. Reusability studies revealed strong performance, underscoring the hydrogel beads' potent adsorption capability for CR dye.

Enhanced electrochemical properties of cobalt oxide nanoparticle electrode modified with low concentration of cationic surfactant

Metal oxides are proficient electrode materials for supercapacitors because of their physiochemical properties, especially their wide range of oxidation states that facilitate charge transfer in redox reactions and compatibility with electrolytes. Their performances can be further improved by adding surfactants, which also help with controlled synthesis, inhibit aggregation, and alter surface characteristics. The functional groups present in the surfactant molecule can undergo chemical bonding with the surface of the metal oxide, thereby modifying their surface chemistry and electronic characteristics. Recent research has focused on increasing the specific capacitance of cobalt oxide owing to its large surface area and size. The surfactants help to control the surface modification as a size-reducing agent and improve the electrochemical properties. Herein, A facile co-precipitation method is employed in synthesising cobalt oxide without cationic surfactant cetyltrimethylammonium bromide (CTAB) and with different concentrations of CTAB, followed by calcination. Herein, we compare the electrochemical properties with varying concentrations of surfactant-assisted Co3O4. The modified Co3O4 electrode with a low surfactant concentration (CO 1) exhibits a highly specific capacitance of 531F/g at 5 mV/s with a potential window of 0.7 V. The CO 1 electrode is suitable for supercapacitor devices with a specific capacitance of 296F/g at 0.8 A/g. Moreover, the asymmetric supercapacitor composed of CO1//AC demonstrated a remarkable energy density of 46.2 Wh/Kg and a robust power density of 800 W/kg. These results indicate that the hierarchical porous structure accelerates electron and ion movement, lowers charge transfer resistance, and improves hybrid electrode capacitive properties.

Micellar Matrices for Spectrophotometric Determination of 5-Aminosalicylic Acid in Medicinal Preparations Using Response Surface Methodology and Box-Benken Plans

Determination of the content of insoluble pharmaceutical substances in dosage forms is an urgent task, since their dosage is very important for the optimal ratio between the therapeutic effect and ensuring the necessary bioavailability. The use of micellar media as a matrix allows increasing solubility. This report presents the results of the influence of the micellar system consist from cetyltrimethylammonium bromide, CTAB, dimethyl sulfoxide, DMSO and water on the determination of the content of 5-aminosalicylic acid (5-ASA) in pharmaceutical substances and in dosage forms. 5-ASA is widely used for the treatment of inflammatory bowel diseases, ulcerative colitis and Crohn's disease. To obtain the optimal matrix, the methodology of the response surface (MRS) and three-level Box-Benken plans (BBP) were used. The intensity of the absorption band of 5-ASA (A330), which reflects the acid content, was used as the target function. The independent factors were: the concentration of CTAB (pC(CTAB), mol/l); the acidity of medium (pH); the proportion of DMSO in the binary solvent (αDMSO). The BBP consisting of fifteen compositions were compiled and response surfaces constructed. Optimal conditions for the determination of 5-ASA by the absorption band A330 are: pC(CTAB) = 1.1, pH = 7.6, α(DMSO) = 0.3. In this matrix, the content of 5-ASA in the pharmaceutical substance was established and good metrological performance was achieved. The use of MRS and BBP contributes to the development of effective methods for quality control of 5-ASA dosage forms from different manufacturers.

Optimization of a Rare Earth and Aluminum Leaching Process from Weathered Crust Elution-Deposited Rare Earth Ore with Surfactant CTAB

Ammonium sulfate is typically employed as a leaching agent in the in situ leaching of weathered crust elution-deposited rare earth ore. However, it is associated with challenges such as low efficiency in mass transfer for rare earth (RE) leaching, high usage of the leaching agent, and prolonged leaching duration. To address the issues mentioned above, the surfactant cetyltrimethyl ammonium bromide (CTAB) was compounded with 2% ammonium sulfate to form a leaching agent in this paper. The effects of CTAB concentration, temperature, pH, and leaching agent flow rate on the rare earth (RE) and aluminum (Al) leaching mass transfer process from RE ore were investigated using chromatographic plate theory. The results revealed that CTAB addition improved the RE mass transfer process while moderately inhibiting the Al mass transfer efficiency. Increasing the temperature and pH of the leaching solution led to higher theoretical plate numbers for RE and Al leaching, lowered theoretical plate height (HETP), and enhanced leaching mass transfer efficiency. However, under high temperature and alkaline conditions, the mass transfer efficiency begins to decrease, indicating that high temperature and alkaline conditions are not conducive to the synergistic enhancement of RE and Al leaching by CTAB. Considering that clay minerals have good pH buffering properties, adjusting the pH of the leaching solution during rare earth ore leaching operations was deemed unnecessary. The optimal mass transfer conditions for leaching RE and Al were identified as 2% ammonium sulfate concentration, 0.00103 mol/L CTAB concentration, pH range of 5.2–5.5 for the leaching solution, 0.6 mL/min leaching solution flow rate, and room temperature. The rare earth leaching mass transfer effect could be enhanced during summer operations.

Effect of CTAB premicelle and micelle formation on Bromophenol Blue spectra

AbstractThe interactions between surfactants and dyes in aqueous solutions are essential for gaining insights into dyeing processes across various industries and for driving advancements in chemical research. This paper investigates the interaction between the anionic dye bromophenol blue (BPB) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) in aqueous solutions. It was observed that the absorbance value at the maximum absorption peak of BPB changes systematically with increasing CTAB concentration, revealing the critical premicelle concentration (cpc) and critical micelle concentration (cmc) of CTAB. Employing a micellization model and measuring the electric conductivity across different concentrations of CTAB, the micellization thermodynamic parameters of CTAB, both in the absence and presence of BPB, were determined. The findings indicate that the associative interaction between BPB and CTAB significantly influences the formation of CTAB micelles.

Cationic surfactant modified iron nanoparticles for removal of orange II in batch mode: Kinetics, isotherms, mechanistic, and thermodynamic approach

AbstractThe interaction of cetyltrimethylammonium bromide (CTAB) with orange II has been studied spectrophotometrically. CTA‐Orange II complex was isolated from an aqueous solution with chloroform. The results indicate that the CTAB interacts in 1:1 stoichiometry with orange II. CTAB capped FeNPs were used as an adsorbent to the removal of CTA‐Orange II complex. Energy dispersive x‐ray spectroscope (EDX), Fourier transform infrared spectroscope (FTIR), surface scanning microscope (SEM), and transmission electron microscope (TEM) were used to determine the morphology of FeNPs. The effect of contact time, pH, and concentration of orange II were examined on the removal of dye and surfactant. The removal of orange II followed pseudo‐second‐order kinetic and Langmuir isotherm model. The maximum adsorption capacity (Qmax) of CTAB‐FeNPs for orange II was 1288.9 mg/g at 30°C. CTA‐Orange II complex was adsorbed onto the adsorbent through several types of interaction (e.g., electrostatic attractions, van der Waals interactions, hydrogen bonding and n‐π stacking interactions). The sorption of orange G was also studied at different CTAB concentrations. The results implied that the maximum sorption amount was almost half of the orange II adsorption. The findings reveal the feasibility of CTAB capped FeNPs to be used as an excellent and low‐cost adsorbent for the removal of various water pollutants, more specifically anionic dyes.

CTAB-Modulated Electroplating of Copper Micropillar Arrays for Non-Enzymatic Glucose Sensing with Improved Sensitivity.

Micropillar array electrodes represent a promising avenue for enhancing detection sensitivity and response current. However, existing methods for depositing electrode materials on micropillar arrays often result in uneven distribution, with the thin sidewall layer being less conductive and prone to corrosion. In addressing this issue, this study introduces electroplating to enhance the copper layer on the sidewall of micropillar array electrodes. These electrodes, fabricated through standard microelectronics processes and electroplating, are proposed for non-enzymatic glucose detection, with the copper layer deposited via electroplating significantly enhancing sensitivity. Initially, the impact of cetyltrimethylammonium bromide (CTAB) concentration as an inhibitor on the surface morphology and sensitivity of the plated layer was investigated. It was discovered that CTAB could decrease surface roughness, hinder the development of large and coarse grains, generate small particles, and boost sensitivity. Compared to the uncoated electrode and plating without CTAB, sensitivity was elevated by a factor of 1.66 and 1.62, respectively. Subsequently, the alterations in plating morphology and detection performance within a range of 0.3 ASD to 3 ASD were examined. Sensitivity demonstrated a tendency to increase initially and then decrease. The electrode plated at 0.75 ASD achieved a maximum sensitivity of 3314 μA·mM-1·cm-2 and a detection limit of 15.9 μM. Furthermore, a potential mechanism explaining the impact of different morphology on detection performance due to CTAB and current density was discussed. It was believed that the presented effective strategy to enhance the sensitivity of micropillar array electrodes for glucose detection would promote the related biomedical detection applications.

Effect of cetyltrimethylammonium bromide on flocculation and filtration of bentonite suspensions

Separation of bentonite from wastewater is challenging because bentonite, is highly dispersible in water. Using cationic polymer flocculants has a high flocculation effect on bentonite. However, the flocculation mechanism is unclear. In this study, flocculation, filtration, and bentonite adsorption behavior are investigated using cetyltrimethylammonium bromide (CTAB) as cationic small molecule; subsequently, the flocculation mechanism of bentonite is explored. The flocculation effect increases and the filtration time is reduced with increasing CTAB concentration. In particular, when more than 1500 ppm of CTAB is used, the filtration time is reduced to 2–3 min. Bentonite forms secondary flocculates after the formation of primary flocculates with increasing CTAB concentration. Additionally, the adsorption behavior reveals that CTAB is inserted between the layers, and it is excessively adsorbed on the bentonite surface. The increase CTAB concentration was effective in improving the shortening the filtration time owing to the formation of large bentonite flocculates.

In Situ Fabrication of SnO2 Nanowalls for Robust Acetylene Sensing at Low Temperature.

Acetylene (C2 H2 ) monitoring in real time and online is essential for erasing transformer risks and guaranteeing normal equipment operation and operator safety. This study examines the direct fabrication of ultrathin SnO2 nanowalls on Ag-Pd substrates using a simple solvothermal method that doesn't demand the use of any additional motivators or templates. The thickness and shape of the nanowalls can be controlled by varying the cetyl trimethyl ammonium bromide (CTAB) concentration in the solvent. As observed, the gas sensor (SnO2 -3) fabricated by 2.4 g CTAB exhibits superior gas-sensing features. This is primarily due to the hollow structure constructed by the arrangement of nanowalls, which delivers not only enough gas diffusion pathways but also enough reaction sites during the gas sensing processes. The findings suggest that low-cost SnO2 nanowalls created using a straightforward procedure could be taken into consideration as prospective candidates for use in industrial C2 H2 sensing applications.

Enhancing solubilization of Nebivolol hydrochloride through tuning pluronic F-127 with ionic Surfactants: An experimental and theoretical investigation

In the present work, the interaction of the antihypertensive drug Nebivolol hydrochloride (NBL) with nonionic surfactant pluronic F-127 (F-127) is investigated in an aqueous medium. Two ionic surfactants, viz., cationic, cetyl trimethyl ammonium bromide (CTAB) and anionic, sodium tetradecyl sulphate (STS) were added to F-127 to improve the physicochemical properties of the single micellar medium. The characterization techniques employed were, FTIR, UV–visible spectroscopy, dynamic light scattering, zeta potential, antioxidant, conductivity, and FESEM studies. The critical micellar concentration (CMC) of CTAB and STS are estimated from the conductivity experiments which is lowered due to the addition of F-127 and NBL. The lowering of CMC is attributed to the solubilization of NBL in the binary micellar mediums. The extent of binding of NBL in F-127, F-127 + CTAB, and F-127 + STS were quantified by determining the binding constant values using the Benesi–Hildebrand (B-H) plot from UV absorbance data. They were, 838.2 M−1 for F-127 1100.7 M−1 for F-127 + CTAB and 1836.5 M−1 for F-127 + STS systems. There was an increase in the size of the micelle due to the encapsulation of the drug in both binary micellar systems. The zeta potential (ZP) values displayed enhanced stability of the drug in binary micellar systems. The radical scavenging activity (RSA %) of NBL was estimated to be 16.5 % in F-127, 24.7 % in F-127 + CTAB, and 44.9 % in F-127 + STS systems. The encapsulation efficiency (EE %) for the above three systems were 14.7 %, 16.4 % and 18.5 %, respectively. The surface parameters and the interactions were verified through molecular docking studies. The results suggest that the properties of F-127 can be improved by tuning with ionic surfactants to solubilize NBL. To our knowledge, this is the first report of NBL solubilization in mixed micellar systems. Similar studies with other drug systems can be applied to get improved results.

Monodispersed, Micron-Sized Supermicroporous Silica Particles by Cetyltrimethylammonium Bromide-Mediated Preparation.

In this study, we present a novel modified Stöber method utilizing cetyltrimethylammonium bromide (CTAB) as a mediator for the preparation of monodispersed, micron-sized supermicroporous silica particles. Observed results show prepared silica particles ranging in size from 0.64 to 1.36 μm with an increase in CTAB concentration from 1.0 to 5.0 mM. The particles exhibited low polydispersity (<5%), a high Brunauer-Emmett-Teller surface area (570 to 1064 m2/g), and pore volumes ranging from 0.22 to 0.39 cm3/g. The pore size, determined using the Barrett-Joyner-Halenda method from the adsorption branches of the isotherms, was approximately 1.9 nm, specifically 1.83, 1.85, and 1.90 nm, as the CTAB concentration increased from 1.0 to 2.5 and 5.0 mM, respectively. The resulting particles displayed a narrow distribution of pore diameters. In addition, to obtain an in-depth understanding of the role of CTAB on the preparation of silica particles, a possible mechanism is also investigated using conductivity, dynamic light scattering (DLS), zeta potential, FT-IR spectra, and transmission electron microscopy. Our findings demonstrate that CTAB plays multiple roles in the hydrolysis/condensation of TEOS (tetraethyl orthosilicate) and subsequent nucleation and growth of silica particles. CTAB acts as a template for superporosity, a stabilizer for colloids, and an accelerator for nucleation and growth, leading to formation of monodispersed micrometer silica particles. Further characterization through FT-IR and 29Si solid NMR spectra revealed that the micron silica particles were obtained with inhomogeneity in the condensation degree, allowing for selective etching through hot incubation to form micron-sized hollow silica spheres.

A two-stage design enhanced biodegradation of high concentrations of a C16-alkyl quaternary ammonium compound in oxygen-based membrane biofilm reactors

Quaternary ammonia compounds (QAC), such as hexadecyltrimethyl-ammonium (CTAB), are widely used as disinfectants and in personal-care products. Their use as disinfectants grew during the SARS-CoV-2 (COVID-19) pandemic, leading to increased loads to wastewater treatment systems and the environment. Though low concentrations of CTAB are biodegradable, high concentrations are toxic to bacteria. Sufficient O2 delivery is a key to achieve high CTAB removal, and the O2-based Membrane Biofilm Reactor (O2-MBfR) is a proven means to biodegrade CTAB in a bubble-free, non-foaming manner. A strategy for achieving complete biodegradation of high-concentrations of CTAB is a two-stage O2-MBfR, in which partial CTAB removal in the Lead reactor relieves inhibition in the Lag reactor. Here, more than 98 % removal of 728 mg/L CTAB could be achieved in the two-stage MBfR, and the CTAB-removal rate was 70 % higher than for a one-stage MBfR with the same O2-delivery capacity. CTAB exposure shifted the bacterial community toward Pseudomonas and Stenotrophomonas as the dominant genera. In particular, P. alcaligenes and P. aeruginosa were enriched in the Lag reactor, as they were capable of biodegrading the metabolites of initial CTAB monooxygenation. Metagenomic analysis also revealed that the Lag reactor was enriched in genes for CTAB and metabolite oxygenation, due to reduced CTAB inhibition.

Construction of in situ C/N/S co-doped mesoporous Li4Ti5O12 nanosheets for high-rate and large-capacity lithium-ion batteries

The low capacity of Li4Ti5O12 (LTO) under high-rate charging/discharging limits its development in energy applications. Two-dimensional (2D) nanosheets equipped with mesopores offer promising opportunities to realize high-rate and long-term lithium-ion batteries. This paper successfully synthesized C/N/S co-doped lithium titanate nanosheets with rich oxygen vacancy concentration (CNSLTO) in a single step. C, N and S are doped into the LTO bulk phase, providing bulk oxygen vacancies and active sites. Partial Ti4+ conversion to Ti3+ is promoted by co-doping and introducing rich oxygen vacancies, improving the electrical conductivity. In addition, the effect of CTAB concentration on the morphology and electrochemical properties of the materials was studied experimentally. The optimized CNSLTO nanosheets have a relatively high specific surface area (99.38 m2 g−1) and numerous mesoporous, achieving outstanding performance and excellent cycling stability at high-rate as lithium-ion anode materials. The CNSLTO exhibits excellent rate capacity (171.7–152.6 mA h g−1 at 0.5–20 C) and cycling performance (97.6 % after 1000 cycles at 10 C). Additionally, the discharge-specific capacity of the LFP//CNSLTO full battery at 10 C (122.2 mA h g−1) was superior to the LFP//LTO (77.8 mA h g−1).

CTAB induced growth and shrinkage of Pluronics® P103 micelles: Experimental and theoretical rationale

This study offers an insight into the concentration influence of a cationic surfactant- cetyltrimethylammonium bromide (CTAB) having a 16-carbon long alkyl side chain that influences the self-assembly and micellization behaviour of a linear triblock copolymer based on ethylene oxide (EO) and propylene oxide (PO) Pluronic® P103 in aqueous solution. The work makes an exclusive use of a variety of methodologies, such as high sensitivity differential scanning calorimetry (HSDSC), phase behaviour study, dynamic light scattering (DLS), and small-angle neutron scattering (SANS). The investigation on the clouding behaviour demonstrates that the cloud point value of 5 %w/v P103, which is typically in the vicinity of 90 °C, rises up to more than 100 °C with the addition on of very low concentration of CTAB. The DLS technique predicted the change in hydrodynamic diameter (Dh) of micelles with temperature and in varying CTAB concentration. The SANS results inferred the morphological changes in the micelles. A comprehensive approach revealing the relationship between the molecular orbital energies of the tested P103 and CTAB were assessed by utilising the computational simulation method with the Gaussian 09 calculation window and Gauss View 5.0.9 software. The perception of CTAB-stabilized Pluronics® micelles is predicted to be much improved from the evaluated optimised descriptors. Additionally, our examined micellar system revealed the solubilization enhancement of a model hydrophobic dye orange-OT utilizing UV–vis spectroscopy.