Dimethyl Benzyl Ammonium Chloride Research Articles

Sublethal Exposure to Common Benzalkonium Chloride Leads to Antimicrobial Tolerance and Antibiotic Cross-Resistance in Commensal and Opportunistic Bacterial Species

The production and consumer use of disinfectants has substantially increased during the COVID-19 pandemic. Benzalkonium chloride (BAC) is a mixture of alkyl benzyl dimethyl ammonium chloride compounds and is the most common active ingredient in surface cleaning and disinfecting products. Accordingly, BAC compounds are routinely in contact with microorganisms in indoor environments, which may contribute to the development of antimicrobial tolerance and cross-resistance. To investigate the impact of BAC exposure on commensal and opportunistic bacteria of public health importance, we exposed Staphylococcus epidermidis, Corynebacterium xerosis, Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa to a standard BAC mixture (BAC12–14), as well as purified BAC16. Minimum inhibitory concentrations (MICs) and antibiotic susceptibilities were determined before and after repeated exposure to sublethal BAC concentrations. MICs for Gram-negative bacteria were significantly higher than Gram-positive bacteria. Additionally, BAC12–14 MICs were significantly higher for opportunistic pathogens and BAC-tolerance was associated with antibiotic cross-resistance. These results suggest that common Gram-negative opportunistic pathogens are less sensitive to BAC-inhibition than commensal species and may preferentially develop antimicrobial tolerance upon repeated or prolonged exposure to BAC12–14. Reevaluating the formulation and concentration of BAC-containing products in efforts to limit the development of antimicrobial tolerance and antibiotic co-resistance is warranted.

Measurements and Modelling of the Micellization of Alkyl Benzyl Dimethyl Ammonium Chloride and Cetyl Trimethyl Ammonium Chloride in Various Aqueous Media at 298.15 °K

Measurements and Modelling of the Micellization of Alkyl Benzyl Dimethyl Ammonium Chloride and Cetyl Trimethyl Ammonium Chloride in Various Aqueous Media at 298.15 °K

The responses of microbial metabolic activity, bacterial community and resistance genes under the coexistence of nanoplastics and quaternary ammonium compounds in the sewage environment

Nanoplastics (NPs) and quaternary ammonium compounds (QACs) are frequently detected in sewage. However, little is known about the risks of coexistence of NPs and QACs. In this study, the responses of microbial metabolic activity, bacterial community and resistance genes (RGs) to the exposure of polyethylene (PE), polylactic acid (PLA), silicon dioxide (SiO2) and dodecyl dimethyl benzyl ammonium chloride (DDBAC) were focused on 2nd and 30th day of incubation in sewer environment. Bacterial community contributed 25.01 % to shape RGs and mobile genetic elements (MGEs) after two days of incubation in sewage and plastisphere. After 30 days of incubation, the most important individual factor (35.82 %) was turned to microbial metabolic activity. The metabolic capacity of the microbial communities in plastisphere was stronger than that from SiO2 samples. Moreover, DDBAC inhibited the metabolic capacity of microorganisms in sewage samples, and increased the absolute abundances of 16S rRNA in plastisphere and sewage samples which might be similar to the hormesis effect. After 30 days of incubation, Aquabacterium was the predominant genus in plastisphere. As for SiO2 samples, Brevundimonas was the predominant genus. QACs RGs (qacEdelta1-01, qacEdelta1-02) and antibiotic RGs (ARGs) (aac(6′)-Ib, tetG-1) significantly enriched in plastisphere. There was also co-selection among qacEdelta1-01, qacEdelta1-02 and ARGs. In addition, VadinBC27 which enriched in plastisphere of PLA NPs was positively correlated with the potentially disease-causing genus Pseudomonas. It showed that after 30 days of incubation, plastisphere had an important effect on distribution and transfer of pathogenic bacteria and RGs. Plastisphere of PLA NPs also carried the risk of spreading disease.

Effect of Protective Coatings on Wooden Elements Exposed to a Small Ignition Initiator

This paper presents the results of monitoring the behaviour of selected wood species exposed to a small ignition initiator. We specifically aimed to investigate the effect of retardant coating on the combustion process of the wood species spruce (Picea abies), red spruce (Larix decidua), Scots pine (Pinus sylvestris), ash (Fraxinus excelsior L.), beech (Fagus sylvatica), and oak (Quercus robur) when exposed to a small initiator of ignition. At the same time, we studied the effect of different types of fungicidal agents (based on N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine; alkyl (C12–16) dimethylbenzyl ammonium chloride or 3-iodo-prop-2-inylbutylcarbamate) on the effectiveness of a flame retardant (containing ferric phosphate) applied to the selected fungicide-treated wood samples. The experimentally obtained mass-loss and flame-spread results were statistically evaluated using the QtiPlot software program. A significant dependence of mass loss and surface flame spread on wood species was the primary focus. It was only confirmed for the surface-flame-spread variable. The dependence of the effect of fungicide treatment on the effectiveness of the selected retardant was confirmed. Fungicidal coatings with the active ingredient alkyl/benzyl (C12–16) dimethylbenzyl ammonium chloride indicated the lowest mass loss rate and flame spread for all wood samples.

Quaternary ammonium compounds promoted anoxic sludge granulation and altered propagation risk of intracellular and extracellular antibiotic resistance genes.

Surfactants could influence sludge morphology and disinfectants were linked to antibiotic resistance genes (ARGs). Thus, the response of activated sludge and ARGs to long-term quaternary ammonium compounds (QACs) exposure required further investigation, which is a popular surfactant and disinfectant. Here, three sequencing batch reactors were fed with 5mg/L most frequently detected QACs (dodecyl trimethyl ammonium chloride (ATMAC C12), dodecyl benzyl dimethyl ammonium chloride (BAC C12) and didodecyl dimethyl ammonium chloride (DADMAC C12)) for 180 d. The long-term inhibitory effect on denitrification ranked: DADMAC C12>BAC C12>ATMAC C12. Besides, obvious granular sludge promoted by the increase of α-Helix/(β-Sheet + Random coil) appeared in DADMAC C12 system. Moreover, intracellular ARGs increased when denitrification systems encountered QACs acutely but decreased in systems chronically exposed to QACs. Although replication and repair metabolism in ATMAC C12 system was higher, ATMAC C12 significantly promoted proliferation of extracellular ARGs. It was noteworthy that the propagation risk of extracellular ARGs in sludge increased significantly during sludge granulation process, and intracellular sul2 genes in sludge and water both increased with the granular diameter in DADMAC C12 system. The universal utilization of QACs may enhance antibiotic resistance of bacteria in wastewater treatment plants, deserving more attention.

Balance the rapid release of insecticide microcapsules using double-layer shielding effect when the foliar application

The development of microencapsulation is currently blocked by the mismatch between the release rate and pest-control demand in terms of improving the photostability of pesticides. Achieving both long-term stability and quick release of pesticides through the use of microcapsules (MCs) is an effective way to increase pesticide efficiency. Sodium lignosulfonate and four types of polyalkyl quaternary ammonium salts (PQAS) were used as shell materials in the fabrication of four types of microcapsules by electrostatic self-assembly. The effects of the PQAS alkyl chain length on the morphology, zeta potential, molecular electrostatic potential, particle size distribution, encapsulation efficiency, release behaviour, anti-photolysis performance, and field application effects of the MCs were investigated. The four types of MCs were spherical and 0.5–3 μm in size, and they had an encapsulation efficiency of more than 75 %. The X-ray diffraction results showed that the longer the alkyl chain of PQAS was, the looser the material formed by electrostatic attraction was. With the increase of the alkyl chain length of PQAS, the MCs shell was looser and easier to deform, leading to rapid nuclear release. Therefore, the MCs shells were looser and more prone to deformation with increasing PQAS alkyl chain length, resulting in the quick release of the core. This quick release of the core to the bottom of the microcapsules and the loose shell formed a double-layer structure, which effectively prevented ultraviolet degradation. Therefore, abamectin MCs with quick-release and favourable anti-photolysis performances showed advantages in controlling Plutella. xylostella and Pieris. rapae insect pests. Octadecyl dimethyl benzyl ammonium chloride can be used to fabricate loose MCs by electrostatic self-assembly, which achieves both rapid and long-term pest control.

Effect of different types of surfactants adsorption characteristics on the wettability of coking coal dust

To investigate the effect of different types of surfactants adsorption characteristics on the wettability of coking coal dust, Guoyang coking coal and three different surfactants - dodecyl dimethyl benzyl ammonium chloride (DDBAC), sodium alcohol ether sulphate (AES), coconut diethanolamide (CDEA) - were used. Firstly, the amount of surfactant adsorbed on coal dust were determined using spectrophotometry. Secondly, the contact angles of surfactants on coal tablets was determined. Subsequently, the relationship between the amount of surfactant adsorbed on the coal dust surface and the contact angle was analysed. Finally, the influence mechanism of the amount of the surfactant adsorbed on the coking coal dust surface on wettability was discussed. The experimental results suggest that the adsorption isotherm of cationic surfactant DDBAC on the coal dust surface is bilayer LS-type, while the adsorption isotherm of anionic surfactant AES and non-ionic surfactant CDEA are L-type and S-type, respectively. Additionally, when the concentration of the solution was 0.05%, the amount of AES adsorbed on the coking coal dust surface was estimated to be 64.9 mgg−1, which was 4.19-fold higher than DDBAC (i.e. to 15.5 mgg−1) and 2.2-fold higher than CDEA (i.e. to 29.5 mgg−1), nearly reaching adsorption saturation. The R2 of the amount of DDBAC, AES, and CDEA adsorbed on the coal dust surface affecting the contact angle was 0.9944, 0.99238, and 0.9923, respectively. The adsorption amount of anionic surfactant AES on the coal dust surface at 0.05% is 64.9 mgg−1, and the adsorption isotherm of surfactant on the coal dust surface is L-type, which is more conducive to enhancing the wettability of coking coal dust. Thus, the amount and adsorption isotherm form of the surfactant adsorbed on the coal dust surface are critical factors affecting the coal dust wettability, which provides a theoretical basis for the reasonable selection of surfactants to improve the coal dust suppression efficiency.

Disinfectant dodecyl dimethyl benzyl ammonium chloride (DDBAC) disrupts gut microbiota, phospholipids, and calcium signaling in honeybees (Apis mellifera) at an environmentally relevant level

One of the impacts of the Coronavirus disease 2019 (COVID-19) pandemic has been a profound increase in the application amounts of disinfectants. Dodecyl dimethyl benzyl ammonium chloride (DDBAC) is a widely used disinfectant, yet its hazards to non-target species remain largely unknown. We are unaware of any studies assessing DDBAC’s impacts on honeybee, a pollinator species that is a useful indicator of environmental pollution essential for many forms of agricultural production. Here, we assessed the potentially negative effects of DDBAC on honeybees. After conducting a formal toxicity evaluation of DDBAC on honeybee mortality, we detected an accumulation of DDBAC in the honeybee midgut. We subsequently studied the midgut tissues of honeybees exposed to sub-lethal concentrations of DDBAC: histopathological examination revealed damage to midgut tissue upon DDBAC exposure, microbiome analysis showed a decreased abundance of beneficial midgut microbiota, lipidomics analysis revealed a significant reduction in cell membrane phospholipids with known functions in signal transduction, and a transcriptome analysis detected altered expression of genes involved in calcium signaling pathways (that variously function in calcium absorption, muscle contraction, and neurotransmission). Thus, our study establishes that DDBAC impacts honeybee midgut functions at multiple levels. Our study represents an early warning about the hazards of DDBAC and appeals for the proper stewardship of DDBAC to ensure the protection of our ecological environment.

Seed germination responses of broomrape species (Phelipanche ramosa and Phelipanche aegyptiaca) to various sanitation chemicals

AbstractBranched broomrape, an obligate root parasitic weed, has recently re-emerged in tomato fields in several California counties. California produces more tomato than any other state, and the outbreak of this noxious weed could potentially wreak havoc on the industry’s economy. Preventive measures must be taken to stop or reduce the spread of branched broomrape seeds to other areas. Branched broomrape can produce thousands of tiny seeds, which can easily spread with farm machinery over short and long distances. To prevent branched broomrape seed dispersal, sanitation and disinfection of farm equipment are necessary before entering a new farm. We tested the effectiveness of various ammonium compounds, including didecyl dimethyl ammonium chloride (DDAC), alkyl dimethyl benzyl ammonium chloride (ADBC), didecyl dimethyl ammonium bromide (DDAB), ammonium bromide (AB), and ammonium chloride (AC) on prevention of branched broomrape seed germination. Dose-response analysis showed that three chemical products, ADBC, DDAB, and DDAC, could completely inhibit branched broomrape seeds (potentially making them nonviable) at 1%, 1%, and 10% wt/vol concentrations, respectively. These three compounds were further tested in an exposure duration experiment that additionally included Egyptian broomrape. Only 10 min of exposure to these compounds was needed to prevent germination of both branched and Egyptian broomrape seeds at 1% (ADBC, DDAB) and 10% wt/vol (DDAC). Lower concentrations can provide similar inhibition effects when combined with longer exposure times. Egyptian broomrape seeds were more sensitive than branched broomrape seeds. Findings suggest that quaternary ammonium compounds could be used as potential sanitation agents to disinfect agriculture machinery from branched and Egyptian broomrape seeds.

Circular adsorptive utilization of benzalkonium chloride via construction of ionic microenvironment in dopamine quinone-functionalized acrylic fiber surface

A novel dopamine quinone-functionalized acrylic fiber (PANdpqF) was successfully synthesized, which adsorbed the disinfectant dodecyl dimethyl benzyl ammonium chloride (DDBAC) to in-situ construct a highly efficient catalyst (DDBAC@PANdpqF) for the cyclization of CO2 with epoxide. The successful preparation of PANdpqF was proved by 13C Cross Polarization-Magic Angle Spinning nuclear magnetic resonance, X-ray photoelectron spectroscopy, Fourier transform infrared, and scanning electron microscopy. High adsorption capacity of DDBAC on PANdpqF has been demonstrated by ultraviolet analysis, and the theoretical maximum adsorption capacity was calculated as 666.67 mg/g. Based on comprehensive analysis, the corresponding adsorption mechanism is proposed in which chloride ion of DDBAC is added to o-quinone moiety through Michael addition, followed by the formation of phenoxy and quaternary ammonium ion pair. DDBAC@PANdpqF was well applicable to catalyze the cyclization of CO2, and the yield could reach 93.7% even with a low catalyst loading. The possible cooperatively catalytic mechanism was proposed correspondingly, in which phenolic hydroxyl helps to activate CO2 and epoxide, phenoxy anion attacks CO2 as a nucleophile, and quaternary ammonium cation stabilizes the anionic intermediates. Overall, the functionalized acrylic fiber adsorbed environmentally harmful disinfectant DDBAC to furnish a highly active catalyst for the transformation of greenhouse gas CO2 into useful carbonates, which provides a new method for advanced environmental pollution control.

Alkyl dimethyl benzyl ammonium chloride as a new cleaner for washing treatments for historical printed paper

PurposeThe main aim of this study is to study the effect of alkyl dimethyl benzyl ammonium chloride on removing stains, yellowness and harmful metal ions on historical printed paper, as well as the effect of this cleaner on optical and chemical properties of treated paper.Design/methodology/approachThe assessments after and before treatment were carried out using digital microscopy, infrared spectroscopy (FTIR), pH measurement, color change and finally scanning electron microscopy.FindingsThe results showed that the concentrations used under study (1% and 3%) cleaned the paper efficiently without any observed effect on the chemical composition of cellulose, which was confirmed by IR spectra. The most stains that completely disappeared were the soil spots, also the pH values had improved significantly after treatment, which confirms that the detergent is effective in neutralizing the acidity of cellulose. Moreover, the color change revealed an increase in the chromatic lightness of the paper after treatment, which agreed with the results of the scanning electron microscopy examination, as the paper appeared free of dirt, and the fibers and bundles became more cohesive.Originality/valueTo the best of the authors’ knowledge, this study is a unique study, as there is no previous literature that has indicated the use of the effect of alkyl dimethyl benzyl ammonium chloride washing treatments for printed historical paper, as it was limited only to making disinfection materials and water purification products.

Disinfectant and heavy metal resistance profiles in extended spectrum β-lactamase (ESBL) producing Escherichia coli isolates from chicken meat samples

Biocidal compounds are frequently used as disinfectants in poultry industry and their widespread usage has risen concern due to the co-selection and persistence of antimicrobial resistance among bacteria. In this study, extended spectrum β-lactamase producing (ESBL) Escherichia coli isolates (n = 60) obtained from chicken meat were characterized by Pulsed Field Gel Electrophoresis (PFGE) and further tested for disinfectant and heavy metal resistance phenotypically and genotypically. Plasmid replicon types of these isolates were also determined. ESBL producing E. coli isolates were found to be resistant to ciprofloxacin (48.3 %) and gentamicin (15 %). The majority of these isolates (46.5 %) carried blaCTX-M-55 gene. The isolates showed higher minimal inhibitory concentrations to cetylpyridinium chloride (90 %), cetyltrimethylammonium bromide (50 %), hexadecyltrimethylammonium bromide (46.7 %), triclosan (38.3 %), benzalkonium chloride (28.3 %), chlorhexidine (21.7 %), acriflavine (3.3 %), benzethonium chloride (1.7 %) and N-alkyl dimethyl benzyl ammonium chloride (1.7 %), but 18.3 % of the isolates were resistant to triclosan. Of the quaternary ammonium compounds (QACs) tolerance genes, mdfA, sugE(c), ydgE and ydgF were most present in all isolates, but the qacE, qacG, oqxA and oqxB genes were not detected. Of genes mediating the heavy metal resistance, the zitB gene was detected in all isolates, whereas the copA and cueO genes were detected in 96.67 % and 95 % of isolates, respectively. The IncFIB plasmid was commonly present (93.3 %) in ESBL producing E. coli isolates. Consequently, given the detection of genes mediating disinfectant and heavy metal resistance commonly in ESBL producing E. coli isolates as well as high rate of MICs against disinfectant compounds, the use of QACs for decontamination of the facilities may not be as effective as expected in poultry sector in Turkey.

Performance of dodecyl dimethyl benzyl ammonium chloride as bactericide and corrosion inhibitor for 7B04 aluminum alloy in an aircraft fuel system

In this study, the broad-spectrum antimicrobial property of dodecyl dimethyl benzyl ammonium chloride (DDBAC) was investigated against three species of bacteria, Lysinibacillus sphaericus ( L. sphaericus ), Acinetobacter lwoffii ( A. lwoffii ), and Sediminibacterium salmoneum ( S. salmoneum ) isolated and purified from a naval aircraft fuel system. Through the inhibition zone method and minimum inhibitory concentration test, DDBAC was found to have a good antimicrobial performance with a minimum inhibitory concentration of 64 mg/L. The influence of DDBAC on the corrosion behavior of fuel tank material was evaluated by electrochemical measurements, such as polarization curve and electrochemical impedance spectroscopy (EIS). The polarization curve indicated that DDBAC suppressed anodic and cathodic reactions as a mixed-type corrosion inhibitor, and the inhibition efficiency was 68.38% at the concentration of 80 mg/L after 28 days of immersion. The EIS results showed that DDBAC inhibited the corrosion of 7B04 aluminum alloy in the concentration range of 40–120 mg/L. The DDBAC adsorption on the aluminum alloy surface was in agreement with the modified Langmuir adsorption isotherm model. The quantum chemical calculations proved that a lone pair of electrons of nitrogen atoms in DDBAC were able to form coordinate bonds with the empty orbital in aluminum, resulting in a tight chemisorption layer on the aluminum alloy surface and corrosion inhibition.

Effect and mechanism of quaternary ammonium salt ionic liquid as a collector on desulfurization and desilication from artificial mixed bauxite using flotation

An quaternary ammonium ionic liquid (1401) was synthesized through tetradecyl dimethyl benzyl ammonium chloride and sodium isobutyl xanthate. Firstly, it was used as a flotation collector for reverse flotation of silicates and sulfur from diaspore-type high-sulfur and high silicon bauxite. Results demonstrated that maximum Al2O3 recovery of 50.8% were achieved, the sulfur content and the ratio of A/S were 0.65% and 3.24. The results showed the 1401 has a stronger collecting ability and selectivity for diaspore compared with dodecyl trimethyl ammonium chloride and N-butyl xanthate. The adsorption mechanism of 1401 on the surface of diaspore, kaolinite and pyrite was studied by Fourier transform infrared spectroscopy (FTIR), zeta potential and X-ray photoelectron spectroscopy (XPS) analysis. Results indicated that physical adsorption was occurred between the 1401 and the surface of diaspore, kaolinite, and the adsorption amount on the surface of kaolinite is much greater than that of diaspore. And the chemisorption between the 1401 and pyrite was occurred and suggested that 1401 was preferred to adsorb on the surface of diaspore and pyrite. These results indicate that the quaternary ammonium ionic liquid 1401 can be used as the collector for reverse flotation of diaspore, providing new ideas for the utilization of bauxite.

Advanced oxidation of dodecyl dimethyl benzyl ammonium chloride by VUV/UV/chlorine: Synergistic effect, radicals, and degradation pathway

Quaternary ammonium compounds (QACs) are crucial ingredients in many cleaning agents, disinfectants and personal care products. They are widely detected in aquatic environments. In this study, vacuum ultraviolet (VUV)/UV/chlorine was used to degrade dodecyl dimethyl benzyl ammonium chloride (DDBAC, a typical QAC). The degradation efficiency of VUV/UV/chlorine on DDBAC was the highest among chlorine, UV, VUV/UV, UV/chlorine and VUV/UV/chlorine. During the VUV/UV/chlorine process, with chlorine concentration increasing from 0 to 700 μM, the degradation rate constant of DDBAC increased from 0.16 to 0.22 min−1 then decreased to 0.17 min−1. When the chloride concentration was 10 mM and 50 mM, the degradation rate constant of DDBAC decreased by 31% and 55%, respectively. Inorganic anions and organic compounds in the reverse osmosis concentrate inhibited the degradation of DDBAC by quenching radicals. The degradation mechanisms of DDBAC degradation during the VUV/UV/chlorine process include UV photolysis and oxidation by OH, Cl and other reactive species. With the increase in pH from 5 to 10, the OH concentration decreased from 18.7 × 10−14 M to 7.5 × 10−14 M, and the Cl concentration decreased from 8.8 × 10−14 M to 2.1 × 10−14 M. At pH 5–10, contributions of OH and Cl to DDBAC degradation were 30%−44% and 18%−37%, respectively. Degradation mechanisms of DDBAC mainly include hydrogen abstraction, hydroxylation, and cleavage of the C-N bond. The concentrations of four chlorinated products (trichloromethane, monochloroacetic acid, dichloroacetic acid, and trichloroacetic acid) mostly initially increased and then decreased.

Biochar assisted cellulose anaerobic digestion under the inhibition of dodecyl dimethyl benzyl ammonium chloride: Dose-response kinetic assays, performance variation, potential promotion mechanisms

This study evaluated the inhibitory effect and mitigation strategy of dodecyl dimethyl benzyl ammonium chloride (DDBAC) suppression on anaerobic digestion. With the 12 h-suppression, only 16.64% of anaerobes were alive, and acetotrophic methanogens were significantly inhibited. As for batch test, DDBAC suppression significantly prolonged the start-up of systems and decreased the biogas production. In cellulose semi-continuous digestion process, the DDBAC suppression induced volatile fatty acids accumulation and pH decrease. However, the biochar amended reactor effectively mitigated the DDBAC suppression and achieved 370.5 mL/d·g-chemical-oxygen-demand biogas production. Moreover, 17.8% more protein in extracellular polymeric substances was secreted as the bio-barrier to defense the DDBAC suppression. Furthermore, microbial analysis showed that biochar addition selectively enriched directed interspecies electron transfer (DIET) participant bacteria (Anaerolineaceae and Syntrophomonas) and methanogens (Methanosaeta and Methanobacterium). Meanwhile, the potential metabolic pathway analysis showed that the abundance of amino acids and energy metabolism were increased 28% and 8%, respectively. The abundance of encoding enzyme related to hydrogenotrophic and acetotrophic methanogenesis enriched 1.88 times and 1.48 times, respectively. These results showed the performance and mechanisms involved in DIET establishment with ethanol stimulation biochar addition.

Influences of charge properties and hydrophobicity on the coagulation of inorganic and organic matters from water associated with starch-based coagulants

In this work, two series of binary graft cationic starch-based coagulants (CS-DMCs and CS-DMLs) with different hydrophobicities and charge densities (CDs) were prepared by graft copolymerization of acrylamide with 2-(methacryloyloxy)-N,N,N- trimethylethanaminium chloride and acryloyloxyethyl dimethyl benzyl ammonium chloride, respectively, on the starch (St) backbone. Kaolin particles, sodium humate (NaHA), and bovine serum albumin (BSA) were used as the simulated sources of inorganic colloidal particles and different organic pollutants in the micropolluted turbid surface water. The influences of the CD and hydrophobicity associated with the St-based coagulants on the removal of kaolin particles, NaHA, and BSA from single, binary, and ternary pollutant aqueous systems were investigated systematically. On the basis of the apparent coagulation performance, the floc characteristics, and the zeta potentials of the supernatants after coagulation, the coagulation mechanisms associated with the structural features of the St-based coagulants and the pollutants treated were explored and discussed in detail. The St-based coagulants with a higher CD and a stronger hydrophobicity showed better coagulation performance due to the synergistic effects of charge neutralization and hydrophobic association. The maximum efficiencies of the optimized St-based coagulant in removal of Kaolin, NaHA and BSA were 93.85%, 100% and 97.52% in their respective single pollutant systems. In addition to these simulated water samples, a real micropolluted turbid surface water tested and compared, further confirming the superiority of the hydrophobically modified cationic St-based coagulants, especially in the purification of organic pollutants in water.

Nanoscale Biocompatible Structures Generated from Fluorinated Tripodal Phenylenes on Gold Nanoprisms.

Modification of gold substrates with a stable, uniform and ultrathin layer of biocompatible materials is of tremendous interest for the development of bio‐devices. We present the fabrication of hybrid systems consisting of triangular prism gold nanoparticles (Au@NTPs) covalently covered with tripod‐shaped oligo(p‐phenylenes) featuring trifluoromethyl groups. Their synthesis is accomplished using a biphenyl boronic ester as the key compound. Au@NTPs were prepared through a seedless procedure using 3‐butenoic acid and benzyldimethyl ammonium chloride, and modified with aminothiol groups. Coverage of this amine‐modified gold substrate with a self‐assembled monolayer (SAM) of tripod‐shaped molecules is carried out in ethanolic solution. The hybrid system avoids up to 70 % of protein corona formation, and allows unspecific attachment for bulky adsorbates, providing an optimal biosensing platform. Chemical composition and morphology are analyzed by transmission electron microscopy (TEM), UV‐visible spectroscopy and field emission scanning electron microscopy (FESEM).

Adverse Outcome Pathway for Antimicrobial Quaternary Ammonium Compounds

ABSTRACT Quaternary ammonium compounds (QACs) or quats are a large class of antimicrobial chemicals used in households and institutions as sanitizers and disinfectants. These chemicals are utilized as food processing sanitizers, algicides, in the process of water treatment, and preservatives in cosmetics. The aim of this study was to determine an Adverse Outcome Pathway (AOP) whereby two widely used QACs, alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC), may result in respiratory tract and gastrointestinal tract effects. When inhaled or ingested, these QACs are incorporated into the epithelial cell membrane at the point of contact. With sufficient dosage, the epithelial membrane is disrupted, reducing its fluidity, and releasing cellular contents. Further, ADBAC and DDAC might disrupt mitochondrial functions leading to decreased ATP production. Both events might lead to cell death, either attributed to direct lysis, necrosis, or apoptosis. Pro-inflammatory mediators are recruited to the tissue, inducing inflammation, edema, and excess mucus production. The primary tissue-level adverse outcome is epithelial degeneration and dysplasia. Most important, no apparent metabolism or distribution is involved in QAC action. Based upon this knowledge, it is suggested to replace default Uncertainty Factors for risk assessments with a set of Data Derived Extrapolation Factors.

How does coal interact with organic groups in an aqueous solution?

Interactions between coal matrix and organics are vital for adsorption [1], surfactant adsorption on lignite [2-5], and solid–liquid separation of coal slurry [6-10]. Herein, for studying the interaction between hydrophobic surface (coal surface) and small molecules (organics), we measured interactions between organics [nitro and phenyl, pyridine, phenyl, alkyl chain (hexyl) or cycloalkyl (hexyl)] and the coal matrix (liptinite or inertinite) using atomic force microscopy. The strength of interaction followed the order: nitro and phenyl > pyridine > phenyl > alkyl chain (hexyl) > cycloalkyl (hexyl), and liptinite > inertinite. The liptinite has a greater hydrophobicity than inertinite, the greater the attraction force. The lignite surface and coal slurry were modified in an aqueous solution using five surfactants (dodecyl trimethyl ammonium chloride, DTAC; hexadecyl trimethyl ammonium chloride, CTAC; octadecyl trimethyl ammonium chloride, STAC; hexadecyl dimethyl benzyl ammonium chloride, HDBAC; and cetyl pyridine chloride, CPC). Subsequently, the moisture adsorption on treated lignite coal surface and the sedimentation of the treated tails was compared to characterize hydrophobic modifications which showed the order of CTAC > HDBAC > DTAC > CPC > STAC. Thus, the interaction between coal surface and organics needs to consider two rules: 1) The desolvation or the hydrophobic property of the coal surface; 2) The VDW force of the organics. The nature of the difference between rules No. 1 and 2 is that with the size of hydrophobic molecules increased to a surface, the H-bond structure between water molecules in the around would change a lot, which formats great hydrophobic property or desolvation. SynopsisInteraction between organic reagents and coal reveals the mechanism of restraining moisture reabsorption of lignite and solid–liquid separation of coal slurry by organics.