Hexadecyltrimethylammonium Chloride Research Articles

Rubber/clay nanocomposites prepared by compounding clay gel with hydrophilically treated styrene-butadiene rubber

In this work, high-performance rubber/clay nanocomposites (NCs) were prepared by hydrophilic modification of styrene-butadiene rubber (SBR) in conjunction with gel compounding method. The hydrophilicity of SBR matrix increased by 76 % with the addition of hexadecyltrimethylammonium chloride (CTAC), which significantly enhanced the clay-rubber compatibility and processing efficiency. The vulcanization rate of the SBR/clay NC was increased by adding CTAC. The addition of CTAC greatly improved the clay dispersion and the rubber-filler interactions. With increasing the clay loading, the SBR/CTAC/clay NCs showed a gradual increase in stress at a certain strain, elongation at break, tensile strength and Shore A hardness, demonstrating an excellent reinforcing effect of the clay. The tensile strength of the SBR/CTAC/clay NC with 40 phr clay loading reached 14.0 MPa, which was 8.8 times that of the pure SBR and even better than the organoclay filled SBR NC.

CTAC-assisted monoclinic BiVO4 with oxygen defects for efficient photocatalytic performances: A combined experimental and DFT study

Developing a photocatalyst with high photocatalytic efficiency, chemical stability, and self-degradation capability is essential for optimizing photodegradation processes in environmental applications. In this study, we synthesized a monoclinic BiVO4 photocatalyst whose surface morphology was modulated by hexadecyltrimethylammonium chloride (CTAC) using a facile hydrothermal method. Experimental results demonstrated a substantial increase in the degradation rate (99%) for the CTAC-modified monoclinic BV/CT25 photocatalyst (with an initial CTAC concentration of 25 g/L) compared to the CTAC-free tetragonal BiVO4 photocatalyst (73%). This highlights the effective enhancement of photocatalytic degradation performance through CTAC modification. Furthermore, density functional theory (DFT) calculations revealed that the band gap of BV/CT25 remained unchanged, suggesting that changes in oxygen vacancies (OVs) and density of states, along with the porous lattice structure, contributed to the improved performance. These findings were further supported by FESEM, as well as EPR and XPS characterizations. In addition, photodegradation tests at various pH conditions and cyclic tests suggested that the modification enhanced the morphological stability and reusability of the modified BiVO4 photocatalysts. Overall, this study provides valuable insights into the design of next-generation photocatalysts, leveraging surfactants to control surface properties and emphasizing the key attributes of high photocatalytic efficiency, chemical stability, and improved reusability.

Phosphotungstic acid ionic liquid for efficient photocatalytic desulfurization: Synthesis, application and mechanism

Efficient mass transfer process is a critical factor for regulating catalytic activity in a photocatalytic desulfurization system. Herein, phosphotungstic acid (HPW) active center is successfully composited with a quaternary ammonium phosphotungstate based hexadecyltrimethylammonium chloride ionic liquid (CTAC-HPW) by the ion exchange method for the photocatalytic oxidative desulfurization of dibenzothiophene sulfide. The keggin structure of HPW and highly mass transfer performance organic cations synergistically enhanced the photocatalytic activity towards the effectively convertion of dibenzothiophene (DBT) with the excitation of visible light. The deep desulfurization (<10 mg·kg−1) is attained within 30 min and well stability is demonstrated within 25 cycles. Moreover, the CTAC-HPW photocatalyst projects well selectivity to interference from coexisting compounds such as olefins and aromatic hydrocarbons and universality of dibenzothiophenes, for example, 4-methyldibenzothiophene (4-MDBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). Ultimately, a possible photocatalytic desulfurization mechanism is proposed according to the GC-MS, proving that the final product is the corresponding sulfone. The trapping experiment and ESR analysis confirmed that h+ and •COOH played critical roles in oxidation process. The work offers a practicable strategy for efficiently converting DBT to DBTO2 with added value.

Allergic or Not: Final Interpretation of Doubtful Patch Test Reactions From the North American Contact Dermatitis Group, 2019-2020.

Background: Doubtful patch test reactions generally do not meet criterion for positivity in patch testing. However, the North American Contact Dermatitis Group (NACDG) allows for doubtful reactions to be coded with a final determination of "allergic/positive" based on the temporal pattern, appearance, known characteristics of the allergen, and/or other supportive patch test reactions. Objectives: To analyze NACDG data from the 2019-2020 patch test cycle to identify patterns in the interpretation and relevance of doubtful reactions. Methods: The frequency and proportions of doubtful reactions were tabulated and analyzed for patterns. Statistical analyses were limited to allergens with ≥30 doubtful reactions to ensure adequate sample size. Results: Of patch-tested patients, 31.9% (1315/4121) had ≥1 doubtful reaction. Of 2538 total doubtful reactions, 46% (n = 1167) had a final interpretation of "allergic/positive." The allergens with the highest proportion of doubtful reactions at the final visit were hydroperoxides of linalool 1% (4.5%), fragrance mix I 8.0% (3.9%), and cetrimonium chloride 0.5% (3.4%). Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) 0.02% (P < 0.001), MI 0.2% (P < 0.001), nickel sulfate hexahydrate 2.5% (P = 0.001), and neomycin sulfate 20.0% (P = 0.003) doubtful reactions were more likely to be interpreted as allergic than nonallergic. Methyldibromoglutaronitrile/phenoxyethanol 0.2% (P < 0.001), oleamidopropyl dimethylamine 0.1% (P < 0.001), formaldehyde 2.0% (P < 0.001), cetrimonium chloride 0.5% (P < 0.001), benzophenone-4 (sulisobenzone) 10% (P < 0.001), iodopropynyl butylcarbamate 0.5% (P < 0.001), cocamidopropyl betaine 1.0% (P = 0.002), and benzisothiazolinone 0.1% (P = 0.012) doubtful reactions were less likely to be interpreted as allergic. Of the 1167 doubtful reactions interpreted as allergic, 84.9% had current relevance. Conclusions: Doubtful reactions were common and approximately one half were coded with a final interpretation of "allergic/positive." Of those, most were clinically relevant. MCI/MI, MI, nickel, and neomycin were more likely to be interpreted as allergic.

Reliable quantitative detection of uric acid in urine by surface-enhanced Raman spectroscopy with endogenous internal standard

Abnormal levels of uric acid (UA) in urine serve as warning signs for gout and metabolic cardiovascular diseases, necessitating the monitoring of UA levels for early prevention. However, the current analytical methods employed suffer from limitations in terms of inadequate suitability for home-based applications and the requirement of non-invasive procedures. In this approach, creatinine, a metabolite with a constant excretion rate, was incorporated as an endogenous internal standard (e-IS) for calibration, presenting a rapid, pretreatment-free, and accurate strategy for quantitative determination of UA concentrations. By utilizing urine creatinine as an internal reference value to calibrate the signal fluctuation of surface-enhanced Raman spectroscopy (SERS) of UA, the quantitative accuracy can be significantly improved without the need for an external internal standard. Due to the influence of the medium, UA, which carries a negative charge, is selectively adsorbed by Au@Ag nanoparticles functionalized with hexadecyltrimethylammonium chloride (CTAC) in this system. Furthermore, a highly convenient detection method was developed, which eliminates the need for pre-processing and minimizes matrix interference by simple dilution. The method was applied to the urine detection of different volunteers, and the results were highly consistent with those obtained using the UA colorimetric kit (UACK). The detection time of SERS was only 30 s, which is 50 times faster than UACK. This quantitative strategy of using urinary creatinine as an internal standard to correct the SERS intensity of uric acid is also expected to be extended to the quantitative detection needs of other biomarkers in urine.

Incorporation of iron(III) into nanoporous silica spheres

Iron(III) containing silica spheres with the average diameter of 800 nm were prepared by the hydrolysis and the condensation of tetraethoxysilane in the presence of hexadecyltrimethylammonium chloride and subsequent reaction with aqueous or ethanol solution of iron(III) nitrate. The iron(III)-containing silica spheres were calcined in air at 400 °C to obtain nanoporous silica spheres containing iron(III). The location and the states of the iron in the nanoporous silica spheres were examined using scanning electron microscopy, transmission electron microscopy, elemental mapping, diffuse reflectance ultraviolet-visible absorption as well as Fe K-edge X-ray absorption spectroscopy. Iron(III) was located at the surface of the spheres as octahedrally coordinated species when iron(III) was adsorbed from ethanol solution of iron(III) nitrate. When the incorporation of iron(III) was done from the aqueous solution of iron(III) nitrate, tetrahedrally coordinated iron(III) was dispersed homogeneously through the spherical silica particles. Both of the silica spheres were microporous with the large BET surface area (ca. 1000 m2/g). The iron(III) containing silica spheres absorbed UV and were inactive for the photocatalytic degradation of methylene blue.

Highly uniform core/shell structures AuR/Ag and AuR/Ag@BSA with various shell thicknesses for surface-enhanced Raman scattering

This work indicates the synthesis of uniform core/shell nanostructures (AuR/Ag) with different thicknesses of Ag shell by the double seed method. This method consists of two self-sufficient progresses, one seed for the formation of gold nanorods (AuRs) and one for the formation of the Ag shell for the gold nanorods to form the AuR/Ag. Acid ascorbic (L-AA) acts as a weak reducing agent and hexadecyltrimethylammonium chloride (CTAC) acts as a surfactant for Ag shell. The formation and growth of the Ag shell were carefully investigated by changing the reaction factors such as temperature, time, and concentration of AgNO3. The greater the concentration of AgNO3 shelling precursor, the thicker the shell and therefore the more high-energy vibrational modes appear in the near-ultraviolet region. In survey of surface-enhanced Raman scattering effect of AuRs and AuR/Ag with Rhodamine B (RB) detector, the results show that AuR/Ag has the ability to enhance Raman signal much better than AuRs. At the same time, the thicker the Ag shell, the better the Raman signal enhancement ability.

Micellar Solubilization for High-Energy-Density and Long-Cycle-Life Aqueous Organic Redox-Flow Batteries

Functional group control has been the most widely used strategy to enhance the solubility of redox-active organic materials (ROMs) in aqueous media for aqueous organic redox-flow batteries. However, this strategy inevitably requires complicated organic synthesis, typically involving 2–4 steps with high cost and under harsh conditions, reducing the full potential of ROMs. In this study, to achieve higher ROM solubility, we introduced surfactant molecules to provide a nonpolar microenvironment via micellization. The hexadecyltrimethylammonium chloride surfactant enabled micellar solubilization, resulting in an order-of-magnitude enhancement of the solubility of (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO). In addition, the micellar solubilization elevated the redox potential of TEMPO, increasing the energy density by more than 10 times compared with that in the bare electrolyte. Furthermore, the micellar solubilization improved the cycle stability due to not only mitigated crossover but also enhanced chemical stability of TEMPO+. This strategy can be applied to various ROMs and is expected to assist in achieving practical application of organic redox-flow batteries.

Ecotoxicity and rapid degradation of quaternary ammonium compounds (QACs) subjected to combined vacuum UV and UV-C treatment

Quaternary ammonium compounds (QACs) are active ingredients in a palette of commercially available disinfectants, sanitizers, and biocides. QACs are widely used because of their broad-spectrum antimicrobial properties but the ubiquitous uses have resulted in frequent detection in aquatic and terrestrial matrices including domestic wastewater, surface waters, urban soils and sediments. An increased domestic QACs consumption has increased the environmental occurrence, and investigation of mitigation methods and effects on non-target organisms are in demand. In this study, we examined the potential ecotoxicity of six QACs and investigated the effect of combined vacuum UV (185 nm) and UV-C (254 nm) irradiation (VUV/UVC) on degradation and mitigation of ecotoxicity of QACs. The study showed that combined VUV/UVC irradiation facilitated rapid degradation of benzalkonium chloride, benzethonium chloride, didecyldimethylammonium chloride, dodecyltrimethylammonium chloride, and hexadecyltrimethylammonium chloride. The estimated half-lives varied between 2 and 7 min, and degradation was affected by the initial QAC concentrations, the UV fluence, and the water matrix. The potential ecotoxicity of QACs and VUV/UVC treated QACs was examined using a battery of test organisms that included the luminescent bacterium Aliivibrio fischeri, the gram-negative and gram-positive bacteria Escherichiacoli and Enterococcus faecalis, the freshwater microalga Raphidocelis subcapitata, and the crustacean Daphia magna. The potential for trophic transfer of QACs was investigated in a simplified aquatic food web. Test organisms from different trophic levels were included to assess adverse effects of bioactive compounds in VUV/UVC treated samples including transformation products. The study showed that several QACs were highly toxic to aquatic test organisms with EC50 and/or EC20 values < 1 μM. VUV/UVC treatment of QACs resulted in substantial photolysis of the parent compounds and comprehensive mitigation of the ecotoxicity potential. VUV/UVC represent an attractive oxidation technology for abatement QACs in contaminated water because the process does not require addition of catalysts or precursors.

Facile and innovative application of surfactant-modified-zeolite from Austrian fly ash for glyphosate removal from water solution

This study highlights a pioneering approach in the development of an efficient, affordable, and economically feasible adsorbent specifically tailored for the removal of glyphosate (Gly) from contaminated water. To accomplish this objective, a low-cost and pure NaA Zeolite (NaAZ) was synthesized with 93% crystallinity from Austrian fly ash (AFA) as a precursor for the first-time. Taguchi design was employed to optimize critical parameters such as the SiO2/Al2O3 ratio, alkalinity concentration, time, and temperature. The cation exchange capacity (CEC) and external cation exchange capacity (ECEC) are determined as critical factors for the modification process. Subsequently, the pure NaAZ was modified with hexadecyl trimethyl ammonium chloride (HDTMAC), a cationic surfactant. The utilization of surfactant-modified zeolite (SMZ) for Gly removal demonstrates its innovative application in this field, highlighting its enhanced adsorption capacity and optimized surface properties. The AFA, NaAZ, and SMZ were characterized using analytical techniques including XRD, XRF, FTIR-ATR, SEM, TGA, BET, CHNSO analyzer and ICP-OES. The adsorbent exhibited effective Gly removal through its pH-dependent charge properties (pH 2–10), with an optimized pH 6 facilitating a significant electrostatic interaction between the adsorbent and Gly. SMZ demonstrated remarkable adsorption capacity and removal efficacy, surpassing most reported adsorbents with values of 769.23 mg/g and 98.92% respectively. Our study demonstrates the significant advantage of the SMZ, with a low leaching concentration of only 6 ppm after 60 days, ensuring environmental safety, long-term stability, and public health considerations. The kinetics of the adsorption process was well described by the pseudo-second order and the Freundlich isotherm. Pore diffusion and H-bonding were postulated to be involved in physisorption, whereas electrophilic interactions led to chemisorption type of adsorption. Consequently, SMZ provides a practical significance, broad applicability and promising solution for Gly removal, facilitating sustainable water treatment.

A micellar-enhanced fluorescence photoinduced four-way calibration method for the determination of multiclass pesticides in lemon juice

In this work, a four-way multivariate calibration method for the simultaneous determination of four pesticides - carbendazim (CBZ), thiabendazole (TBZ), pirimiphos-methyl (PMM), and clothianidin (CLT) - in lemon juice is presented. Third-order data were acquired by registering the photoinduced fluorescence of the analytes as excitation-emission matrices at different times of UV-light irradiation, in the presence of organized media (direct micelles) as fluorescence enhancers. The optimal experimental conditions (pH 11.5 and 32 mmol L−1 hexadecyltrimethylammonium chloride surfactant) were determined through a central composite design using the response surface methodology. The analytes were individually calibrated, except for TBZ and CBZ due to the inner filter effect of TBZ on CBZ. Test samples containing all analytes and imidacloprid (as potential interference) were analysed. PARAFAC was utilized to evaluate both the trilinearity and quadrilinearity of the third-order data and four-way arrays, respectively. PMM was successfully determined with quadrilinear PARAFAC decomposition, whereas CLT, TBZ, and CBZ were satisfactorily modelled using U-PLS/RTL due to the loss of quadrilinearity caused by different phenomena. The profitable applicability of the analytical method in the CBZ, TBZ, PMM, and CLT determination in lemon juice samples was demonstrated, achieving limits of detection below the maximum residue levels reported by the European Commission, and mean recoveries at 90 ± 5%.

Adsorptive removal of acid red 18 dye from aqueous solution using hexadecyl-trimethyl ammonium chloride modified nano-pumice

Discharging untreated dye-containing wastewater gives rise to environmental pollution. The present study investigated the removal efficiency and adsorption mechanism of Acid Red 18 (AR18) utilizing hexadecyl-trimethyl ammonium chloride (HDTMA.Cl) modified Nano-pumice (HMNP), which is a novel adsorbent for AR18 removal. The HDTMA.Cl is characterized by XRD, XRF, FESEM, TEM, BET and FTIR analysis. pH, contact time, initial concentration of dye and adsorbent dose were the four different parameters for investigating their effects on the adsorption process. Response surface methodology-central composite design was used to model and improve the study to reduce expenses and the number of experiments. According to the findings, at the ideal conditions (pH = 4.5, sorbent dosage = 2.375 g/l, AR18 concentration = 25 mg/l, and contact time = 70 min), the maximum removal effectiveness was 99%. The Langmuir (R2 = 0.996) and pseudo-second-order (R2 = 0.999) models were obeyed by the adsorption isotherm and kinetic, respectively. The nature of HMNP was discovered to be spontaneous, and thermodynamic investigations revealed that the AR18 adsorption process is endothermic. By tracking the adsorption capacity of the adsorbent for five cycles under ideal conditions, the reusability of HMNP was examined, which showed a reduction in HMNP's adsorption effectiveness from 99 to 85% after five consecutive recycles.

Novel facile synthesis and room-temperature sintering of copper nanowires for solution-processed transparent conductive films

Copper nanowires (Cu NWs) are considered as the potential alternative material for indium tin oxide (ITO) which is widely used in various photoelectric devices. However, the effective and full solution-processed technology for Cu NWs transparent conductive films (TCFs) with excellent performance is lacking. Here, a facile “heterogeneous-self reduction” approach was proposed for Cu NWs synthesis with the yield as high as 62.2% using nether reductant nor crystal seed. Copper glycine heated with hexadecyltrimethylammonium chloride and oleylamine, decomposed continuously to release Cu atoms, which were nucleated and grown anisotropically into Cu NWs with aspect ratio > 1000. The “pickling-chemical sintering” solution-process was applied to form the Cu NWs TCFs using the synthesized Cu NWs. Oleylamine on the surface of purified Cu NWs was removed by pickling with acetic acid solution. After coating on PET film, the surface oxide of Cu NWs could be reduced to Cu (0) by NaBH4 solution, and the sintering of Cu NWs can be realized simultaneously. The Cu NWs TCF with a sheet resistance of 34.7 Ω sq–1 at a transmittance of 91.1% exhibits the excellent performance in capacitive sensing. This work is expected to promote the full-solution preparing of Cu NWs TCFs.

Enhancing electrochemical properties of commercial lithium titanate using cuprous chloride nanoparticle-modified copper foil current collectors

For the first time, CuCl nanoparticles were fabricated at ambient temperature onto the surface of a copper (Cu) foil current collector through using an immersing approach, in which the immersing solution only contained 0.6 M CuSO4 and a very small amount of hexadecyl trimethyl ammonium chloride (HTAC). For simplicity, all as-prepared CuCl nanoparticles modified copper foils were labeled as CuCl/Cu. The specimens of CuCl/Cu prepared in the presence of 4 mM, 8 mM and 12 mM HTAC were designated as specimen a, b and c, respectively. The lithium titanate (Li4Ti5O12, LTO) electrodes assembled using the as-prepared CuCl/Cu exhibited an outstanding electrochemical performance as compared to the conventional LTO electrode manufactured using the commercial bare copper foil. Such as, the initial discharge capacity (DC) value of the LTO electrode assembled using specimen b at 0.2 C was measured to be 216 mAh g−1, which was about 1.3 times that of the conventional LTO electrode (165 mAh g−1). More importantly, at 10 C after 100 cycles, the DC value of the LTO electrode assembled using specimen b was retained to be as high as 143 mAh g−1, being about 3.1 times higher than that of the conventional LTO electrode (46 mAh g−1). A room temperature immersing approach for preparing CuCl nanoparticles and a novel method to significantly improve the electrochemical behavior of the conventional LTO electrode are developed in this work, which is very meaningful not only to the development of CuCl related material science but also to the further progress of LTO based lithium ion batteries (LIBs).

Position matters in ester thiolysis by cysteine-containing peptides in micelles and vesicles

HypothesisThe interaction of peptides with nanoaggregates is an active research topic. Cysteine (Cys)-containing peptides open opportunities for developing low molecular weight compounds with interesting properties and potential applications. Knowledge of the relationship between the position of the Cys in the peptides and the aggregate interface is essential. ExperimentsWe synthesized a series of Cys-containing peptides having a variable number of glycines (Gly) as spacers between the N-palmitoyl chain at their N-terminal portion and Cys at their carboxy-terminal. The apparent pKa of the Cys-thiol group of each peptide was measured in micelles of CTAC (hexadecyltrimethylammonium chloride) and vesicles of DHDAC (dihexadecyldimethylammonium chloride). No clear correlation existed between the pKa’s and the number of Gly in the peptides. However, the rate of p-nitro-phenyl-octanoate (NPO) thiolysis by the peptides in micelles and vesicles decreased regularly with peptide length. Molecular Dynamics (MD) analysis of the peptides in CTAC micelles was carried out. FindingspKa determinations and rate dependence of the peptides in a thiolysis reaction and MD analysis strongly suggested that the higher rates observed with shorter peptides can be attributed to an increased probability of Cys being located below the micellar surface, where the carbonyl reaction center of NPO resides.

Quaternary Ammonium Compounds and Contact Dermatitis: A Review and Considerations During the COVID-19 Pandemic.

The recent global pandemic has resulted in increased use of quaternary ammonium compounds (QACs). Currently, QACs are active ingredients in 292 disinfectants recommended by the US EPA for use against SARS-CoV-2. Among QACs, benzalkonium chloride (BAK), cetrimonium bromide (CTAB), cetrimonium chloride (CTAC), didecyldimethylammonium chloride (DDAC), cetrimide, quaternium-15, cetylpyridinium chloride (CPC), and benzethonium chloride (BEC) were all identified as potential culprits of skin sensitivity. Given their widespread utilization, additional research is needed to better classify their dermal effects and identify other cross-reactors. In this review, we aimed to expand our knowledge about these QACs to further dissect its potential allergic and irritant dermal effects on healthcare workers during COVID-19.

Buried Interface Engineering Enables Efficient, Scalable, and Stable Inverted Perovskite Solar Cells

Poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] (PTAA), as an extensively used hole transport material in inverted perovskite solar cells (PSCs), has given reason for concern due to its hydrophobicity for a long time. Herein, buried interface engineering is applied for the scalable deposition of perovskite films by introducing an amphiphilic molecule hexadecyltrimethylammonium chloride on the PTAA surface, which improves the interfacial wettability of the perovskite precursor solution on the organic hole transport layer (HTL), facilitates the nucleation and growth of perovskites, and reduces the nonradiative recombination at the perovskite/HTL interface. As a result, all photovoltaic parameters of the inverted PSCs are improved significantly. The champion devices demonstrate power conversion efficiencies (PCEs) of 22.04% and 20.47% with aperture areas of 0.148 and 1.0 cm2, respectively. Moreover, the encapsulated 1.0 cm2 device exhibits excellent stability and maintains over 70% of its initial PCE after 1200 h under continuous 1 sun illumination at 65 °C in a nitrogen environment.

A Comprehensive Study on DES Pretreatment Application to Microalgae for Enhanced Lipid Recovery Suitable for Biodiesel Production: Combined Experimental and Theoretical Investigations

Cell wall disturbance is an important step in the downstream process of improving the efficiency of lipid extraction from microalgae. Surfactants have been proven to be efficient alternatives to organic solvents in the extraction process. In this study, an effective approach involving deep eutectic solvent (DES) (choline chloride and carboxylic acids) treatment supplemented with surfactants has been developed to disrupt the cell walls of microalgae and increase the extraction of lipids suitable for biodiesel production. A combination of polar and non-polar solvents (ethyl acetate and n-butanol) was used for the lipid extraction process. Microalgae biomass pretreated with choline chloride malonic acid supplemented with the surfactant hexadecyl trimethylammonium chloride (HTAC) showed the best results, improving lipid extraction by 12.365%. Further elucidation of the detailed mechanism behind the cell disruption of the microalga wall by DES was achieved using density functional theory (DFT) methods. The DFT calculations revealed that hydrogen bonds between the chloride ion of the DES and hydrogen bond donor (HBD) molecules are key factors dominating the destruction of the cell wall structure of Chlorella pyrenoidosa. The optimization of lipid extraction was performed through a single-factor experiment, which included the effects of different variables (time, temperature, dosage of surfactant, and ratio of n-butanol to ethyl acetate). An extraction period of 60 min at 80 °C with a surfactant concentration of 0.5% at a 1:2 ratio of n-butanol to ethyl acetate was found to produce the maximum lipid yield (16.97%). Transesterification reactions were used to obtain fatty acid methyl esters from the optimized extracted lipids. Thus, it was determined that C16:0 (20.04%), C18:2 (29.95%), and C18:3 (21.21%) were the most prevalent fatty acids. The potential for producing biodiesel from C. pyrenoidosa was validated by the high yields of C18 fatty acid methyl esters, and the properties of biodiesel are within the European and US standards.

Surfactant-induced intervention in interfacial polymerization to develop highly-selective thin-film composite membrane for forward osmosis process

Thin-film composite (TFC) membrane capable of superior permeability contributes to the industrial implementation of forward osmosis (FO) technology, but it is plagued with some bottlenecks including the unsatisfactory selectivity. Herein, the surfactant-induced intervention in interfacial polymerization was performed by incorporating hexadecyltrimethylammonium toluene-p-sulphonate (CTAT) into the amine aqueous solution for developing the highly-permeable TFC membrane with exceptional selectivity. The effect of CTAT incorporation on the physicochemical properties of polyamide (PA) layer was systemically investigated by conventional characterizations, so as to unravel the mechanism for the improved performance of resultant TFC-FO membrane. Besides, three typical surfactants of Tween 80, sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium chloride (CTAC) were also introduced and studied contrastively for comparison. Amongst the fabricated membranes, the optimized TFC-CTAT membrane achieves the improved water fluxes (JV) of 31.8 and 21.7 L.m-2.h−1 accompanied with the reduced specific reverse salt fluxes (JS/JV) of 0.05 and 0.04 g·L−1 in active layer facing the draw solution (AL-DS) and active layer facing the feed solution (AL-FS) orientations respectively, using 1 M NaCl solution and deionized water as draw and feed solutions. Therefore, this work provides a new perspective for constructing TFC-FO membrane with high perm-selectivity by employing suitable surfactant at the relatively low concentrations.

Transport of dimethyl phthalate on loess with modified bentonite: A batch and column test investigation

Phthalic acid ester (PAE) is a toxic pollutant commonly found in high concentrations in municipal solid waste landfills. Soil–bentonite is widely used as a barrier material to control groundwater contaminants from landfill leachates. Traditional soil–bentonite materials always have a limited capacity for organic pollutant adsorption. To address this issue, the adsorption and transport behavior of dimethyl phthalate (DMP) on loess amended with two kinds of modified bentonite (HTMAC-B, modified with hexadecyltrimethylammonium chloride; CMC-B, modified with hydrophobic cationic surfactant, and carboxymethyl cellulose) were investigated. The kinetics of DMP adsorption indicates that film diffusion contributes significantly to the kinetic adsorption of DMP on HTMAC-B. The adsorption isotherm results showed that partitioning dominated DMP adsorption on loess with both modified bentonites. Owing to the in-ionic sites in HTMAC-B, which attracted hydrophobic compounds such as DMP, the adsorption capacity of 5 % HTMAC-B-amended loess (LH) was increased by a factor of 3.2. However, because CMC-B provided mostly ionic sites, 5 % CMC-B-amended loess (LC) had a little effect on DMP adsorption. The hydraulic conductivity values of LH and LC were 5.95 × 10−10 and 1.65 × 10−11 m/s, respectively. The X-CT result showed that there is a significant porosity change for both LH and LC. Dual-porosity model reveals that the leaching process primarily affects micro-pores, rather than larger pores in the soil matrix. The predicted retardation factors for LH and LC were 38.89 and 9.67, respectively. When using loess-bentonite as barrier material, the amendment of HTMAC-B and CMC-B can help to increase the retardation ability and reduce the permeability, respectively.