Cetyltrimethylammonium Bromide Research Articles

CTAB-assisted synthesis of reduced graphene oxide supported Pd nanoparticles (Pd@rGO) as a sustainable heterogeneous catalyst for C-2 arylation of indoles with arylboronic acids

A series of Pd nanoparticles (NPs) incorporated in reduced graphene oxide (rGO), viz. Pd@rGO0.16, Pd@rGO0.32, Pd@rGO0.48, and Pd@rGO1 were synthesized employing water as a solvent. The subscript values correspond to the millimoles of cetyltrimethylammonium bromide (CTAB) utilized in the synthesis process. The quantity of CTAB was varied to finely tune both the morphology and size of the resulting nanoclusters. Transmission Electron Microscopy (TEM) analysis indicated that the average particle sizes of Pd@rGO0.16 and Pd@rGO0.32 fall in the range of 4.5–5.0 nm and 20–25 nm, respectively. On the other hand, particles were found to be agglomerated in Pd@rGO0.48 and Pd@rGO1. The Pd@rGO0.16 composite was exhaustively characterized by TEM, Scanning Electron Microcopy-Energy Dispersive X-ray analysis (SEM-EDX), powder X-ray diffraction(XRD), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma atomic emission spectroscopy (ICP-AES) measurements. ICP-AES analysis of Pd@rGO0.16 indicated that 0.01 g of Pd@rGO0.16 contains 0.09 mol% Pd. The catalytic potentiality of these NPs was investigated for direct C(sp[1])-H bond activation of various indoles with aryl boronic acids. Among the four composites, Pd@rGO0.16 exhibited the best activity for the abovementioned organic transformation. Different indoles with diverse electronic groups underwent coupling with aryl boronic acids giving up to 86 % product yield. It was retrievable for up to five consecutive catalytic cycles without compromising its catalytic activity.

Understanding the surface tension reduction of the water/air interface due to the synergistic effect of the SDS-CTAB mixture: A molecular dynamics simulation study

Using molecular dynamics simulation, the surface tension is calculated and compared with experimental data to provide a microscopic interpretation of the synergistic effect on water surface tension reduction caused by a binary mixture composed of anionic and cationic surfactants. For the anionic and cationic surfactants, the sodium dodecyl sulphate (SDS) and the cetyl trimethylammonium bromide (CTAB) were used, respectively. Besides the electrostatic attraction between the anionic and cationic surfactants, resulting in a synergistic effect, other properties were analysed to study the reduction of the surface tension from a molecular level. For different SDS:CTAB composition of distinct properties of the pseudobinary mixture, such as the hydrogen bonds, order of the tails, and the arrangement of the surfactants at the interface were calculated. Those properties present different behaviours at the maximum and minimum values of the surface tension. The CTAB tails present a higher order than the SDS tails at all SDS:CTAB compositions however, the first ones show a maximum order at the minimum in the surface tension. The excess configurational energy was also calculated and shows a minimum value in the same composition as the minimum value of the surface tension.

Enhanced adsorption of Cr(VI) from aqueous solutions by CTAB-modified schwertmannite: Adsorption performance and mechanism

Schwertmannite (Sch) is recognized for its heavy metal adsorption capabilities, but is limited by several drawbacks, including a narrow pH operational range, a tendency towards agglomeration, and a relatively modest adsorption capacity, which restricts its widespread utilization. This study introduces cetyltrimethylammonium bromide (CTAB) modified Sch (CTAB-Sch), synthesized through a rapid oxidation technique using H2O2, which significantly ameliorates these limitations. The investigation finds that a CTAB concentration of 10 mM is optimal for Cr(VI) removal, with the modified sch showing significant improvements in stability, recyclability, and adsorption efficiency within a pH range of 2–7. The adsorption process is characterized as spontaneous and endothermic, conforming to pseudo-second-order kinetics and the Langmuir adsorption model, resulting in a maximum adsorption capacity of 103.02 mg/g, which is approximately twice that of its unmodified Sch. Through comprehensive experimental analysis, the efficient removal mechanism of Cr(VI) by CTAB-Sch was elucidated, involving ion exchange, electrostatic attraction, and surface complex formation. Moreover, the investigation demonstrates that CTAB plays a pivotal role in enhancing adsorption by optimizing functional group orientation, amplifying surface positive charge, augmenting hydrophilicity, and inhibiting mineral agglomeration. The findings suggest that CTAB-Sch has significant potential for treating Cr(VI)-contaminated wastewater, highlighting its advancements in adsorption technology.

An insight into physicochemical properties of hexagonal lyotropic liquid crystal templates from amphiphiles for mesoporous structural administration

Hexagonal lyotropic liquid crystals (HLLC) provide an ideal template for the fabrication of nanofiltration membranes without the flux-selectivity trade-off problem. Amphiphiles, the core components of the columnar micelles in the HLLC system, play a key role in regulating the nanostructure, their effects on dimensional stability and physicochemical properties of the system however have not been explored well. In this research, we compared the dimensional stability and physicochemical properties of HLLC templates prepared from amphiphiles with various head groups and tail lengths. The amphiphiles with charged head groups (dodecyl trimethylammonium bromide, DTAB, and hexadecyl trimethylammonium bromide, CTAB) enable more monomers to be introduced and a much smaller (∼ 1/2) pore size than that with uncharged ones (polyethylene glycol hexadecyl ether, Brij56). The tail length however mainly regulates the width of water channels with CTAB being 23.27 Å and DTAB about 17.06 Å when the head groups are identical. Although the HLLC systems with CTAB and DTAB present a little bit higher phase transition temperature, the dynamic mechanical stability is much better than that with Brij56 at room temperature, facilitating the reorientation process under an electric force with the order parameter reaching to about 0.9 and the retention of the aligned nanostructure with the absence of the force at room temperature. The study enables a better understanding of the effects of amphiphiles on HLLC templates and their tunability for advanced nanofiltration membranes.

Influence of phosphomolybdate modified with quaternary ammonium salts on enhancing the flame retardancy and antibacterial characteristics of epoxy resin/aluminum diethylphosphinate composites

In this work, we synthesized a series of compounds, denoted as xCTAB@AMP, by incorporating varying different molar fractions of cetyltrimethylammonium bromide (CTAB) into ammonium phosphomolybdate (AMP). The effects of CTAB modification on the surface characteristics, morphology and hygroscopicity of AMP were studied. Moreover, we explored the combined flame-retardant impact between xCTAB@AMP and aluminum diethylphosphinate (ADP) when incorporated into epoxy resin (EP), as well as the resulting composite's mechanical properties, thermal stability and antibacterial properties. The EP composite containing 50 molar percent CTAB-modified AMP (EP/50CTAB@AMP/ADP) demonstrated remarkable flame retardancy, achieving a UL-94 V-0 rating and increasing limiting oxygen index (LOI) to 30.0%. This formulation significantly lowered the peak heat release rate (PHRR) to 452 kW/m2, a 65% reduction to that of EP, and the total heat release (THR) to 68 MJ/m2, a 24% decrease to that of EP. Additionally, compared to EP, the peak smoke production rate (PSPR) of this composite was decreased by 30% (0.28 m2/s), the total smoke production (TSP) was reduced by 25% (30.2 m2), and peak carbon monoxide release rate (PCOP) was diminished by 34% (0.038 g/s). The combination of 50CTAB@AMP and ADP in the EP matrix exhibited an exceptional synergistic flame-retardant effect. Concurrently, the CTAB modification bolstered the interfacial interactions between AMP and the EP matrix, which enhanced the mechanical properties of EP/AMP/ADP composites. As a result, the tensile strength and elongation at break of the EP/50CTAB@AMP/ADP composite increased by 13% and 15%, respectively, compared to the EP/AMP/ADP. Moreover, the 50CTAB@AMP maintained its inherent antibacterial activity, which endowed the EP/50CTAB@AMP/ADP composite with a potent inhibitory effect against Staphylococcus aureus, a common pathogenic bacterium.

Irinotecan-loaded magnetite-silica core-shell systems for colorectal cancer treatment

Colorectal cancer represents a worldwide spread type of cancer and it is regarded as one of the leading death causes, along with lung, breast, and prostate cancers. Since conventional surgical resection and chemotherapy proved limited efficiency, the use of alternative drug delivery systems that ensure the controlled release of cytostatic agents possess immense potential for treatment. In this regard, the present study aimed to develop and evaluate the efficiency of a series of irinotecan-loaded magnetite-silica core–shell systems. The magnetite particles were obtained through a solvothermal treatment, while the silica shell was obtained through the Stöber method directly onto the surface of magnetite particles. Subsequently, the core–shell systems were physico-chemically and morpho-structurally evaluated trough X-ray diffraction (XRD) and (high-resolution) transmission electron microscopy ((HR-)TEM) equipped with a High Annular Angular Dark Field Detector (HAADF) for elemental mapping. After the irinotecan loading, the drug delivery systems were evaluated through Fourier-transform infrared spectroscopy (FT-IR), thermogravimetry and differential scanning calorimetry (TG-DSC), and UV–Vis spectrophotometry. Additionally, the Brunauer–Emmett-Teller (BET) method was employed for determining the surface area and pore volume of the systems. The biological functionality of the core-shells was investigated through the MTT assay performed on both normal and cancer cells. The results of the study confirmed the formation of highly crystalline magnetite particles comprising the core and mesoporous silica layers of sizes varying between 2 and 7 nm as the shell. Additionally, the drug loading and release was dependent on the type of the silica synthesis procedure, since the lack of hexadecyltrimethylammonium bromide (CTAB) resulted in higher drug loading but lower cumulative release. Moreover, the nanostructured systems demonstrated a targeted efficiency towards HT-29 colorectal adenocarcinoma cells, as in the case of normal L929 fibroblast cells, the cell viability was higher than for the pristine drug. In this manner, this study provides the means and procedures for developing drug delivery systems with applicability in the treatment of cancer.

Perovskites synthesized by soft template-assisted hydrothermal method: A bibliometric analysis and new insights

Hydrothermal synthesis is a technique which enables preparing many perovskites with specific crystal structures, chemical compositions, and morphologies. Thus, a bibliometric analysis of 1087 articles from the Scopus database (1975–2023) related to the keywords “perovskites” and “hydrothermal synthesis” was conducted using the VOSviewer software program. The results of the bibliometric analysis showed that the 1087 articles have 23,286 citations. Materials Letters has the highest number of publications (2.85%) regarding the journals in which these articles are published. China has the highest number of publications (34.50%) and citations (33.56%) related to these articles. Regarding the institutions affiliated with these articles, Jilin University in China concentrates 5.34% of the publications and 6.08% of the citations. In terms of authors, Han, G. has the highest number of publications (2.02%). Finally, the top three keywords with the highest number of occurrences were “perovskite”, “hydrothermal synthesis” and “scanning electron microscopy”. Based on bibliometric analysis, LaNiO3 perovskites were chosen to evaluate the influence of hydrothermal synthesis parameters on their morphologies and, consequently, how these morphologies affect their applications. Thus, the temperature and time ranges used for the synthesis parameters were 160–230 °C and 6–48 h, respectively. Furthermore, the pH range used was 7.6–13, and the mineralizers used to adjust the pH were ammonia, potassium hydroxide, and sodium hydroxide. The temperature and time ranges used for the calcination parameters were 550–800 °C and 2–6 h, respectively. Additionally, LaNiO3 perovskites obtained sphere, cube, rod, disc, and hollow morphologies. The soft templates used to obtain these morphologies were glycine, glycerin, isopropanol, polyvinylpyrrolidone (PVP), cetyltrimethylammonium bromide (CTAB), citric acid, and urea. The specific surface areas of the perovskites varied between 5.2 and 35.8 m2 g−1. Finally, the most common application for LaNiO3 perovskites was the methane reforming for hydrogen production.

Stimuli Responsive Molecular Exchange of Structure Directing Agents on Gold Nanobipyramids: Cancer Cell Detection and Synergistic Therapeutics.

Surface-engineered gold nanoparticles have been considered as versatile systems for theranostics applications. Moreover, surface covering or stabilizing agents on gold nanoparticles especially gold nanobipyramids (AuNBPs) provides an extra space for cargo molecules entrapment. However, it is not well studied yet and also the preparation of AuNBPs still remains dependent largely on cetyltrimethylammonium bromide (CTAB), a cytotoxic surfactant. Therefore, the direct use of CTAB stabilized nanoparticles is not recommended for cancer theranostics applications. Herein, we address an approach of dodecyl ethyl dimethylammonium bromide (DMAB) as biocompatible structure directing agent for AuNBPs, which also accommodate anticancer drug doxorubicin (45%), an additional chemotherapeutics agent. Upon near-infrared light (NIR, 808 nm) exposure, engineered AuNBPs exhibit (i) better phototransduction (51 °C) due to NIR absorption ability (650-900 nm), (ii) photo triggered drug release (more than 80%), and (iii) synergistic chemophototherapy for breast cancer cells. Drug release response has been evaluated in tumor microenvironment conditions (84% in acidic pH and 80% at high GSH) due to protonation and high affinity of thiol binding with AuNBPs followed by DMAB replacement. Intracellular glutathione (GSH, 5-7.5 mM) replaces DMAB from AuNBPs, which cause easy aggregation of nanoparticles as corroborated by colorimetric shifts, suggesting their utilization as a molecular sensing probe of early stage cancer biomarkers. Our optimized recipe yield is monodisperse DMAB-AuNBPs with ∼90% purity even at large scales (500 mL volume per batch). DMAB-AuNBPs show better cell viability (more than 90%) across all concentrations (5-500 ug/mL) when directly compared to CTAB-AuNBPs (less than 10%). Our findings show the potential of DMAB-AuNBPs for early stage cancer detection and theranostics applications.

Role of functional group orientation in the drug partitioning and micelle-mediated delivery of quinoline family drugs to the carrier protein

The understanding of the characteristics of the carrier vehicle and the specific drug it transports is required for designing an effective drug delivery system. We have done a comprehensive analysis of the distribution of three quinolines − quinine, quinidine, and cinchonidine − within hexadecyltrimethyl-ammonium bromide (HTAB) micelles. Further, we tracked their journey as they are transported to the carrier protein human serum albumin (HSA), using spectroscopy, calorimetry, and molecular docking methodologies. The mechanism of partitioning of the quinolines in HTAB micelles is explained based on thermodynamic parameters obtained from isothermal titration calorimetry (ITC). The partitioning coefficient obtained for the quinolines is in the range of 102-104 M−1 and is strongest for quinidine [(1.17 ± 0.78) × 104 M−1]. The stereochemistry and hydroxyl group orientation modulates the partitioning of the quinolines and also the delivery of the quinolines via micellar HTAB. The polar/electrostatic/H-bonding interactions of the hydrophilic polar head of HTAB hinders in efficient quinine delivery, while hydrophobic interactions through the micellar palisade layer facilitate the delivery of quinidine and cinchonidine. Such thorough exploration into the delivery of drugs via micelles is crucial in identifying functionalities necessary to optimize drug delivery systems for the successful delivery of drugs.

Hyaluronic acid production by Streptococcus zooepidemicus MW26985 using potato peel waste hydrolyzate.

In this research, we examined the production of hyaluronic acid (HA) by Streptococcus zooepidemicus strain MW26985 using different substrates and potato peel waste (PPW) as an affordable substrate. First, culture medium components, including carbon and nitrogen sources, were optimized for bacterial HA production. Five different carbon sources (glucose, sucrose, lactose, sago starch, and potato starch, at a concentration of 30g/L) and three distinct nitrogen sources (peptone, yeast extract, and ammonium sulfate, at a concentration of 10g/L) were investigated. Glucose, among the carbon sources, and yeast extract, among nitrogen sources, produced the most HA which was determined as 1.41g/L. Afterward, potato peel sugars were extracted by dilute acid and enzymatic hydrolysis and then employed as a cost-effective carbon source for the growth of S. zooepidemicus. Based on the results, the fermentation process yielded 0.59g/L HA from potato peel sugars through acid hydrolysis and 0.92g/L HA from those released by enzymatic hydrolysis. The supplementation of both hydrolyzates with glucose as an additional carbon source enhanced HA production to 0.95g/L and 1.18g/L using acidic and enzymatic hydrolyzates, respectively. The cetyltrimethylammonium bromide (CTAB) turbidimetric method was used to evaluate the concentration of HA in the fermentation broth using the colorimetric method. Also, the peaks observed by Fourier transform infrared (FTIR) spectroscopy confirmed that the exopolysaccharide (EPS) was composed of HA. These observations demonstrate that potato peel residues can be a novel alternative as a carbon source for the economical production of HA by S. zooepidemicus.

Novel nickel-immobilized-SiO2-TiO2 fine particles in the presence of cetyltrimethylammonium bromide as a catalyst for ultrasound-assisted-Kumada cross-coupling reaction

Kumada cross-coupling reaction is useful for producing biphenyls, where nickel and copper have been widely investigated as catalysts but mainly homogeneous ones. In this study, we investigated ultrasound-assisted-Kumada cross-coupling reaction over the heterogeneous catalysts in which Ni2+, Cu2+, or both was immobilized on aminopropylsilane-functionalized-SiO2-TiO2 prepared in the presence of cetyltrimethylammonium bromide (CTAB). The presence of CTAB effectively prevented the particle growth and therefore SiO2–TiO2 fine particles with high surface area (502 m2 g−1) were formed. The Ni2+-immobilized catalyst showed high catalytic activity for the ultrasound-assisted-Kumada cross-coupling reaction of a wide variety of substrates and was reusable three times. Performing the reaction under ultrasound irradiation was very effective in significantly accelerating the reaction rate compared with the conventional mechanical method. In contrast to Ni2+, Cu2+ was deposited on the support as crystalline Cu(OH)2 and the resulting catalysts with Cu2+ and Ni2+-Cu2+ were less active and less stable under the reaction conditions.

DNA Barcode Characteristic of Dendrobium crumenatum based on ITS2

Dendrobium crumenatum, known as the pigeon orchid, is a type of orchid that is used as medicine by local people. Identification of D.crumenatum has limitations because it is similar to the orchid species D. heterocarpum. DNA barcoding is an alternative technique for identifying D.crumenatum using molecular markers. One of the molecular markers that is reliable and widely used in DNA barcoding is ITS2. This study aims to identify the ITS2 sequence as a molecular barcode effective for D.crumenatum. Genomic DNA isolation of Dendrobium crumenatum was carried out using the Cetyl Trimethyl Ammonium Bromide (CTAB) method and DNA amplification using PCR. The results showed that DNA barcoding research using the ITS2 sequence in D. crumenatum provides specific results to distinguish D. crumenatum from other Dendrobium species. The similarity in flower morphology in D. crumenatum and D. formosum proposed as the cause of close proximity shown in phylogenetic tree. Based on these results, the ITS2 sequence is highly recommended as a molecular marker for barcoding orchids, especially D. crumenatum since its capability for differentiating between species with morphological similarities. Key words: Dendrobium crumenatum, DNA Barcoding, ITS2

Surfactant Directionally Assembled at the Electrode-Electrolyte Interface for Facilitating Electrocatalytic Aldehyde Hydrogenation.

Electrocatalytic hydrogenation of unsaturated aldehydes to unsaturated alcohols is a promising alternative to conventional thermal processes. Both the catalyst and electrolyte deeply impact the performance. Designing the electrode-electrolyte interface remains challenging due to its compositional and structural complexity. Here, we employ the electrocatalytic hydrogenation of 5-hydroxymethylfurfural (HMF) as a reaction model. The typical cationic surfactant, cetyltrimethylammonium bromide (CTAB), and its analogs are employed as electrolyte additives to tune the interfacial microenvironment, delivering high-efficiency hydrogenation of HMF and inhibition of the hydrogen evolution reaction (HER). The surfactants experience a conformational transformation from stochastic distribution to directional assembly under applied potential. This oriented arrangement hampers the transfer of water molecules to the interface and promotes the enrichment of reactants. In addition, near 100 % 2,5-bis(hydroxymethyl)furan (BHMF) selectivity is achieved, and the faradaic efficiency (FE) of the BHMF is improved from 61 % to 74 % at -100 mA cm-2. Notably, the microenvironmental modulation strategy applies to a range of electrocatalytic hydrogenation reactions involving aldehyde substrates. This work paves the way for engineering advanced electrode-electrolyte interfaces and boosting unsaturated alcohol electrosynthesis efficiency.

CTAB Surfactant Promotes Rapid, Efficient, and Simultaneous Removal of Cationic and Anionic Dyes through Adsorption on Glycerol/Citrate Polyester

The discharge of dye waste by industries has caused environmental impacts on water properties, aquatic species, and human life. The production of eco-friendly materials for dye removal from wastewater has gained increasing interest, particularly through adsorption, as it is an efficient method for removing pollutants. However, the selectivity and limited adsorption capacity of materials for simultaneously adsorbing cationic and anionic dyes make it challenging to address the prevailing dye effluent issue. In this work, a poly(glycerol citrate) polyester was prepared without a solvent, using microwave heating, and was combined with cetyltrimethylammonium bromide (CTAB) to modulate the simultaneous adsorption of cationic (Rhodamine B, RB) and anionic dyes (acid blue 113, AB and acid red 27, AR). The formation of the polyester was successfully confirmed by ATR-FTIR and the thermal properties were evaluated by TGA and DCS. In the presence of CTAB 5 mM, the material removes almost 100% of the dyes, reaching the kinetics equilibrium in 30 min following the Pseudo-second order model. Additionally, dye adsorption on the polyester in the presence of CTAB was described by the Freundlich isotherm model, indicating a heterogeneous polyester surface that promotes a multi-layer adsorption driven by electrostatic interaction and hydrogen bonds. The material showed an adsorption capacity of 73.7 ± 3.2, 82.1 ± 4.4, and 21.2 ± 0.6 mg/g for RB, AB, and AR, respectively. Our results provide evidence that the poly(glycerol citrate)/CTAB has a higher potential for application in wastewater treatment to remove both anionic and cationic dyes.

Phase Separation Derived Anisotropic Adhesive Structural Color Hydrogel Films For Flexible Electronics

AbstractHydrogels hold great promise in the field of flexible electronics. Attempts in this area tend to the microstructure design of hydrogels, giving them specific adhesion and multi‐sensing functions. Here, a novel phase separation‐derived anisotropic adhesive structural color hydrogel film is presented for visually flexible electronics. The hydrogel film is generated by template replicating colloidal crystal by using phase separation emulsions of hydrophilic monomer (acrylic acid, AA), hydrophobic monomer (lauryl methacrylate, LMA), co‐monomer ([2‐(methacryloyloxy) ethyl] dimethyl‐(3‐sulfopropyl) ammonium hydroxide (SBMA)), surfactants (hexadecyl trimethyl ammonium bromide, CTAB) and initiator (ammonium persulphate (APS)). The appearance of phase separation results in asymmetric morphologies of hydrogel film, imparting them with anisotropic adhesive performance. Attributed to the formation of inverse opal scaffold structure, the hydrogel film is featured with vivid structural color, showing superior capability in self‐reporting mechanical behavior. Additionally, benefitting from the presence of abundant ions, the hydrogel film exhibits great conductivity. Thus, the resultant hydrogel film is demonstrated with stable dual‐signal sensing properties involving color‐changing and conductivity feedback ability to respond to human activities. These features make the proposed anisotropic adhesive structural color hydrogel film highly potential in the flexible electronic field.

Preparation and Properties of Lightweight Geopolymer by Bio-Based Foaming Agent.

Lightweight geopolymers have the advantages of a wide source of raw materials, chemical corrosion resistance, high mechanical strength and excellent durability, and are expected to replace traditional building insulation materials. In this paper, a green bio-based foaming agent with a small 1 h settlement distance, high average foaming multiple and low bleeding ratio was obtained by a Cetyltrimethylammonium Bromide/yeast solution. When the amount of Cetyltrimethylammonium Bromide is 0.50 wt%, the foam prepared by the yeast and Cetyltrimethylammonium Bromide solution exhibits the improved 1 h settlement distance, the large average foaming multiple, the small bleeding ratio and uniform foam size. Subsequently, a lightweight geopolymer based on metakaolin and fly ash (or silica fume) was successfully prepared by the bio-based foaming agent, and the effects of different foam content on the properties of the geopolymer, such as dry density, water absorption, thermal conductivity, compressive strength and morphology, were studied. With an increase in foam content, the dry density, thermal conductivity and compressive strength of the geopolymer gradually decrease, the water absorption increases, regardless of whether silica fume or fly ash are added. Herein, it is confirmed that the foaming agent based on yeast can be effectively used to prepare lightweight geopolymers, which can provide vast opportunities to turn into candidates for novel inorganic thermal insulation materials.

Unraveling the Electron Transfer in Cupriavidus necator – Insights Into Mediator Reduction Mechanics

AbstractCupriavidus necator, despite lacking direct electron transfer capabilities, demonstrates efficient reduction of various redox mediators in oxygen‐free cultivation within bioelectrochemical systems. This study investigates the reduction site of ferricyanide through inhibition and expression rate analysis of oxygen and nitrate respiration chain complexes, comparing aerobic cultivation conditions with fructose as carbon and electron donor to autotrophic (CO2/H2/O2) and anodic cultivation conditions (fructose/anode). Azide inhibition identified cytochrome c oxidase as the primary complex facilitating electron transfer to ferricyanide, with a secondary role proposed for nitrite reductase NirS, demonstrating a 3.9±1.1‐fold higher expression when exposed to anodic conditions. The 2.9±0.6‐fold increase in the expression of the natural porin OmpA under anodic conditions implies its potential involvement in ferricyanide uptake. Additionally, chemically permeabilizing cell membranes with cetyltrimethylammonium bromide doubles ferricyanide reduction rates without an anode present, offering insights for optimizing redox mediation in C. necator based bioelectrochemical systems. This study opens up new possibilities for the targeted optimization of mediated electron transfer in C. necator and other organisms.

Corrosion resistance of polyvinyl butyral coatings enhanced by montmorillonite-chitosan composites

To improve the corrosion resistance of 304SS, a polyvinyl butyral/organic montmorillonite-chitosan (PVB/OMMT-Ch) composite coating was prepared by the spin coating method. The Montmorillonite was organically modified with Cetyltrimethylammonium Bromide and compounded with Chitosan to obtain OMMT-Ch. OMMT-Ch filler has been introduced into the polyvinyl butyral coating to improve the corrosion resistance of 304 stainless steel. Scanning electron microscope and transmission electron microscope observations showed that the introduction of chitosan made the montmorillonite layers rounded and loose, and the X-ray diffraction (XRD) results indicated that the interlayer spacing between the montmorillonite layers changed significantly, and the FT-IR results of the chitosan/montmorillonite insertion complexes were in good agreement with those of the XRD analyses, which showed that chitosan successfully inserted between the layers of montmorillonite. The corrosion resistance of the composite coatings in 3.5% NaCl solution was tested by Tafel polarization curves and electrochemical impedance spectroscopy. The results showed that the composite coatings doped with 0.5% OMMT-Ch had the best corrosion resistance with long-lasting protection of more than 160 days. This study suggests a novel approach for nanocomposites for dealing with the 304SS corrosion issue.

Transition metal salt catalysed green synthesis of mesoporous silica nanoparticles

Conventionally, mesoporous silica nanoparticles are prepared by catalysing silicon alkoxides using acids or bases and are highly important in storage, delivery, and catalysis. Here, for the first time, we demonstrate that a transition metal ion (such as Ni(II), Co(II), and Mn(II)) also catalyses the hydrolysis and condensation reactions of silicon alkoxides in aqueous media without any additional acid or base to synthesize mesostructured and micro/mesostructured silica nanoparticles. An aqueous solution of a transition metal salt (specifically, nitrate salts of Ni(II), Co(II), or Mn(II), or chloride and sulphate salts of Ni(II)), 10-Lauryl ether (C12H25(OCH2CH2)10OH, C12E10) and cetyltrimethylammonium bromide (C16H33N(CH3)3Br, CTAB), and tetramethyl orthosilicate (TMOS) undergoes a precipitation reaction at room temperature, yielding ultra-small ordered mesostructured silica nanoparticles. These nanoparticles are subsequently calcined to produce mesoporous silica (meso-SiO2) with a high surface area (680–871 m2/g), large pore-volume (2.2–3.71 cm3/g), and small pore-size (1.2–3.0 nm). Moreover, the counter anions of the salts play an important role in the assembly process to obtain nanoparticles with an additional well-defined secondary pore (7.5–33.4 nm or larger). Coordinated water of the metal ion and methoxy group of the silica source react to produce a complex in which two hydroxy sides are in close vicinity to speed up the condensation reaction. We propose a hydrolysis and condensation reaction mechanism for TMOS to highlight the role of the metal ion as a catalyst.

A chemical-free magnetophoretic approach for recovering magnetic particles in microalgae removal through magnetic separation

Magnetic separation can swiftly remove many substances (e.g., biomolecules, cells, and viruses) from water. In algal bloom mitigation and biomass dehydration, magnetic particles (MPs) with proper surface modifications could effectively attract and remove algae from the impaired water body. It has long been expected to recover and reuse magnetic nanoparticles or particles to reduce the algal removal cost and potential adverse effects on the environment. This study evaluated the use of a tunable magnetic field to remove algae using functionalized MPs coated with polymers: polyethyleneimine (PEI), chitosan (CTS), and cetyltrimethyl ammonium bromide (CTAB), whose recovery and reuse were examined. The results show that PEI-coated MPs and CTS-coated MPs at the coating density of 2.3 g-cationic polymers·g-MPs−1 achieved higher removal efficiencies of 88.61 ± 9.12% and 73.19 ± 0.37%, respectively, toward a model algal cell (i.e., Scenedesmus obliquus) within a 5-min separation time. In contrast, CTAB-coated MPs and pristine MPs exhibited lower removal efficiencies (47.46 ± 0.3% and 52.69 ± 0.44%, respectively). Furthermore, the removal efficiency of PEI-coated MPs was further improved to over 95% under pH 7, the highest magnetic field of 40 mT, and algogenic organic matter-free conditions. Adsorption kinetics and isotherm analysis revealed that chemical and physical interactions drive the adsorption of a monolayer of algal cells on the surface of magnetic particles. Atomic force microscopy and quartz crystal microbalance confirmed a strong adhesion force and rate between functionalized MPs and algae, which affect both algal removal efficiency and MPs recovery from algae-MPs aggregates. The extended Derjaguin−Landau−Verwey−Overbeek (EDLVO) theory predicted a strong attractive force between algae and cationic polymer-coated MPs, which supported the enhanced algal removal. Finally, almost 99% of the four MPs could be recovered from separated algae-MPs aggregates within 30 s under the strong magnetic field and exhibited excellent magnetic responsiveness and reusability in further separation cycles. This study establishes a foundation for coagulant-free algae removal and enables the potential sustainable separation processes.