Dimethyl Benzyl Ammonium Chloride Research Articles

Ultra-stable dextran conjugated prodrug micelles for oxidative stress and glycometabolic abnormality combination treatment of Alzheimer's disease

Sophisticated nanomedicines are continually being developed, but big obstacles remain before they finish the drug release mission. The first challenge is rupture possibility of structure when infinite dilution, competitive reaction of electrolytes and protein in blood circulation. In addition, low responsive drug release efficiency in the lesion site remains the major challenge for clinical application of nanomedicine combination treatment. In this study, we discussed the opportunities for Alzheimer's disease (AD) combination therapy based on the thermodynamically ultra-stable dextran conjugated prodrug micelles. Dextran-nateglinide conjugated prodrug micelles (NA) and dextran-vitamin E succinate conjugated prodrug micelles (VES) presented ultra-low critical micelle concentration of ~10−5 mM and high physiological stability when challenged by NaCl, sodium dodecyl sulphate (SDS), dodecyl dimethyl benzyl ammonium chloride (DDBAC) and no rupture of structure happened. The NA/insulin polymer-drug conjugate micelles (NA/INS PDC) and VES/insulin polymer-drug conjugate micelles (VES/INS PDC) efficiently cleaved by reactive oxygen species (ROS), leading to over 80% release of the encapsulated and conjugated drugs. The combination of nateglinide and insulin, vitamin E succinate and insulin improved the glucose metabolism, reduced oxidative stress, improved the mitochondrial function and recovered the cognitive capacity of mice. This work demonstrated a paradigm for specific and high efficacy AD combination therapy.

Treatment of laryngeal pathology associated with gastroesophageal reflux disease

To increase the effectiveness of the treatment of laryngeal pathology associated with gastroesophageal reflux disease (GERD), to determine the indications for the appointment of anti-inflammatory therapy to these patients. 120 patients were examined and treated, 58 of them men and 62 women, aged 30 to 82 years with GERD-associated laryngeal pathology. Three groups of patients were formed, comparable in age and gender, in accordance with the type of pachydermia in interarytenoid region; type 1 (40 patients) - pachydermia did not go beyond the middle of the interarytenoid cartilage (according to G.F. Ivanchenko), less than 3 mm, without signs of perifocal inflammation; type 2 (40 patients) - pachydermia of large size, extending beyond the middle of the interarytenoid cartilage with a spread to the entire interarytenoid region (according to G.F. Ivanchenko), often in combination with hyperkeratosis or epithelial dysplasia; type 3 (30 patients) - pachydermia of large size in combination with severe perifocal inflammation. All patients received antireflux therapy. Each group is divided into two subgroups: patients who did not receive anti-inflammatory therapy, and patients who received anti-inflammatory therapy, the basis of which was inhalation with degassed alkaline mineral water, as well as according to indications acetylcysteine, benzyldimethylammonium chloride 0.01% or hydroxymethylquinoxalindioxide, with severe swelling of the mucous membrane - budesonide. All patients completed the questionnaire "Reflux Symptoms Scale" before and after treatment. In group 2 patients (with type 2 pachydermia), the effectiveness of anti-inflammatory therapy was 75%. Of the 20 patients in this group, after inhaled therapy, 4 patients had pachydermia in interarytenoid region disappeared, 11 patients had type 1 pachydermia visualized, 5 (25%) patients had no pronounced dynamics. In group 3 patients (with type 3 pachydermia), the effectiveness of inhaled treatment was 100%, out of 15 patients after inhaled therapy, type 2 pachydermia was diagnosed in 8 patients, type 1 pachydermia - in 7 patients. In 4 patients, complex therapy led to the complete disappearance of reflux-associated laryngeal granulomas without surgical treatment. The effectiveness of inhaled therapy in relation to patient complaints after a month was 87%, while the effectiveness of treatment of patients without inhalation was 45%. Indications for the appointment of inhaled anti-inflammatory therapy in patients with reflux-associated pathology of the larynx are the presence of complaints of hoarseness, dryness, tickling, lump in the throat and chronic cough, endolaryngoscopic signs of exacerbation of chronic inflammation of the mucous membrane of the posterior larynx.

РАЗРАБОТКА РЕЖИМОВ ПРИМЕНЕНИЯ УНИВЕРСАЛЬНОГО ДЕЗИНФИЦИРУЮЩЕГО СРЕДСТВА И КОМПОЗИЦИЙ НА ЕГО ОСНОВЕ ДЛЯ ОБЕЗЗАРАЖИВАНИЯ СКОРЛУПЫ ЯИЦ

Disinfecting properties have been investigated of universal disinfectant at the base of alkyl dimethyl benzyl ammonia chloride and alkyl dimethyl (ethyl) benzyl ammonium chloride (UDC) and some compositions on its base (K1, K2 and K3). Application of 1% UDC solution and K1 (1.0% UDC and 2.0% cleaning and degreasing composition) for table egg disinfection with mechanical (2 min) and manual (5 min) ways has been established to decrease KMAFAnM on shell to normative traits and to inactivate coli group bacteria and Salmonella enteritidis. Disinfection does not influence on eggshell color and structure and on sensory qualities of egg content.

Advanced Oxidation of Dodecyl Dimethyl Benzyl Ammonium Chloride by Vuv/Uv/Chlorine: Synergistic Effect, Radicals, and Degradation Pathway

Advanced Oxidation of Dodecyl Dimethyl Benzyl Ammonium Chloride by Vuv/Uv/Chlorine: Synergistic Effect, Radicals, and Degradation Pathway

The impact of bacterial diversity on resistance to biocides in oilfields

Extreme conditions and the availability of determinate substrates in oil fields promote the growth of a specific microbiome. Sulfate-reducing bacteria (SRB) and acid-producing bacteria (APB) are usually found in these places and can harm important processes due to increases in corrosion rates, biofouling and reservoir biosouring. Biocides such as glutaraldehyde, dibromo-nitrilopropionamide (DBNPA), tetrakis (hydroxymethyl) phosphonium sulfate (THPS) and alkyl dimethyl benzyl ammonium chloride (ADBAC) are commonly used in oil fields to mitigate uncontrolled microbial growth. The aim of this work was to evaluate the differences among microbiome compositions and their resistance to standard biocides in four different Brazilian produced water samples, two from a Southeast Brazil offshore oil field and two from different Northeast Brazil onshore oil fields. Microbiome evaluations were carried out through 16S rRNA amplicon sequencing. To evaluate the biocidal resistance, the Minimum Inhibitory Concentration (MIC) of the standard biocides were analyzed using enriched consortia of SRB and APB from the produced water samples. The data showed important differences in terms of taxonomy but similar functional characterization, indicating the high diversity of the microbiomes. The APB and SRB consortia demonstrated varying resistance levels against the biocides. These results will help to customize biocidal treatments in oil fields.

Detection of benzalkonium chloride on glass surfaces using silver nanoparticles

AbstractRaman reporter‐based surface‐enhanced Raman scattering (SERS) has been used to investigate the detection of one member of a class of the cationic surfactant quaternary ammonium compounds, alkyl dimethyl benzyl ammonium chloride, also known as benzalkonium chloride (BAC). For this study, SERS was performed using silver nanoparticles (AgNPs). Density functional theory (DFT) of BAC on Ag6 clusters was introduced to estimate binding at the level of the B3LYP/LANL2DZ basis sets. As the chain length increased from n = 8 to 18, the binding energies were expected to increase by 2.1 kcal/mol. Methylene blue (MB) Raman reporter molecules were subsequently treated on BAC thin‐film‐covered glass surfaces. Atomic force microscopy (AFM) images were used to determine the coverage of BAC on the glass, and field‐emission electron microscope (FE‐SEM) images revealed the surface morphologies of the SERS substrates. A standard calibration curve was prepared to quantify BAC within a concentration range of 0.0036805 to 36 805 ppm (r2 ≥ 0.99), according to the BAC‐correlated SERS intensities of MB Raman peaks at ~1620 cm−1 adsorbed on AgNPs. A molecular dynamics (MD) simulation supported strong adsorption of BAC on glass surfaces.

Flotation separation of quartz from gypsum using benzyl quaternary ammonium salt as collector

Phosphogypsum is a kind of industrial by-product, which could be used as building materials instead of natural gypsum after removing impurities. Flotation is an effective method to remove the silicon-containing impurity quartz in the phosphogypsum. In this work, a surfactant tetradecyl dimethyl benzyl ammonium chloride (TDBAC) was first used as the collector of quartz to be separated from gypsum. The flotation behaviors of quartz and gypsum were investigated by micro-flotation experiments. The flotation mechanisms were analyzed through Zeta potential testing, Fourier Transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Micro-flotation results show that TDBAC exhibited outstanding collecting capacity and selectivity for quartz over the wide pH range of 2.5–9.5. FTIR results declared that TDBAC could be successfully adsorbed on the surface quartz. The analysis results of zeta potential and XPS indicate that the interaction mechanisms of TDBAC with quartz were involved electrostatic attraction and hydrogen-bond interaction, whereas the adsorption onto gypsum surface was only by the weak electrostatic attraction and hydrogen-bond interaction. The results of this work showed that TDBAC is expected to be an effective collector of quartz for removing silicon impurity from the industrial phosphogypsum.

Reproductive toxicity assessment of alkyl dimethyl benzyl ammonium chloride and didecyl dimethyl ammonium chloride in CD® rats.

AimTo determine the potential of alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC) to induce reproductive toxicity in CD® rats in two independent 2‐generation reproduction studies conducted according to Good Laboratory Practices and standardized testing guidelines.Materials and MethodsMale and female rats (parents and offspring) were allowed continual free access to diets containing concentrations of ADBAC (0, 300, 1,000, or 2,000 ppm) or DDAC (0, 300, 750, or 1,500 ppm), beginning with F0 generation adults at 10 weeks prior to breeding.ResultsNo clinical signs of toxicity were observed in parental rats or their offspring in either study. Dietary exposure of parental rats to ADBAC or DDAC at the highest concentrations produced transient decreases in body weight and/or body weight changes with no or minimal corresponding reduction in food consumption. Offspring (F1 and F2) in the highest concentration group in each study also exhibited reduced body weights, often with a corresponding reduction in weight change, beginning on postnatal day (PND) 14 through weaning on PND 28. This reduction in pup body weight corresponded to initiation of self‐feeding.ConclusionsBased on reduced body weights, the no observed adverse effect level (NOAEL) for adult and offspring systemic toxicity was 1,000 ppm for ADBAC and 750 ppm for DDAC (equivalent to approximate daily oral doses of 59 and 45 mg/kg/day, respectively). The reproductive and developmental NOAEL for F0, F1, and F2 generation male and female rats was 2,000 ppm for ADBAC and 1,500 ppm for DDAC (equivalent to approximate daily oral doses of 118 and 91 mg/kg/day, respectively).

Evaluation of Commercial Disinfectants for Efficacy at Inactivating Enterobacter sakazakii (Cronobacter spp.) in Water: A Preliminary Study

This study was conducted to evaluate the efficacy of commercial disinfectants at inactivating Enterobacter sakazakii (Cronobacter spp.) in water. Disinfectant I contained 6.15% sodium hypochlorite, and disinfectant II contained both 2.25% n-alkyl dimethylbenzyl ammonium chloride and 2.25% n-alkyl ethylbenzyl ammonium chloride. Disinfectant I was added to distilled water to obtain a range of residual chloride concentrations at 50 ppm intervals with a maximum of 1-1,000 ppm. Disinfectant II was prepared at concentrations ranging from 1-200 ppm with 5 ppm intervals. Exposure time for all solutions was 10 min. In total, 58 E. sakazakii (Cronobacter spp.) strains were tested in this study. Nine isolates were obtained from clinical samples, and 49 isolates were obtained from environmental samples. Seven strains (6 clinical and 1 environmental) were able to survive in 100 ppm disinfectant I, and a maximum of 5 ppm of disinfectant II. Fifty one strains (3 clinical and 48 environmental) were not killed in 10 ppm of disinfectant I and 1 ppm of disinfectant II in water. In conclusion, this study demonstrated that clinical E. sakazakii (Cronobacter spp.) strains displayed 5- to 10-fold higher resistance to disinfectants than environmental E. sakazakii (Cronobacter spp.) strains. Disinfectant II, containing quaternary ammonium compounds, was shown to be more potent in inactivating E. sakazakii (Cronobacter spp.) in water used to clean infant formula manufacturing equipment than disinfectant I.

A novel NH2-rich polymer/graphene oxide/organo-vermiculite adsorbent for the efficient removal of azo dyes

A multifunctional polyethyleneimine-graphene oxide/organo-vermiculite composite (PGO/OVt) was successfully fabricated by introducing OVt (modified by dodecyl dimethyl benzyl ammonium chloride, 1227) and polyethyleneimine (PEI) onto GO. For PGO/OVt, the proportion of GO was 25%, while OVt accounted for 75%, which can not only effectively reduce the cost of GO-doped adsorbents, but also ensure a high adsorption efficiency. Various analyses, including FT-IR, XPS, AFM, SEM, TEM, TG-DTG, and XRD were used to characterize the structures and surfaces of PGO/OVt. The surface properties of graphene oxide (GO), the hydrophobicity of OVt, and abundant amino functional groups in polyethyleneimine made PGO/OVt an excellent, versatile adsorbent of Congo Red (CR) and Acid Red 1 (AR-1) in single and binary-dyes system. In single-dye systems, due to the existence of hydrogen bonding, π-π, hydrophobic, and electrostatic interactions between adsorbent and dyes, PGO/OVt exhibited excellent adsorption capacities of 570 mg/g and 365 mg/g for CR and AR-1, respectively. The adsorption processes were well described by pseudo-second-order kinetics (R2 > 0.99) and the Langmuir isotherm model (R2 > 0.98). The thermodynamic parameters demonstrated that the adsorption processes were nonspontaneous and endothermic. In the binary-dyes system, the maximum adsorption amount of CR was 491 mg/g, and that of AR-1 was 384 mg/g. The influence intensity factor (φ) revealed that the effect between the two components changed from competition to synergy with the variation of initial concentration. The synergistic effect indicated the possible presence of a π-π stacking effect between the molecules of adsorbed and dissociative dyes. Based on the obtained results, the resulting PGO/OVt was an efficient, and a lower cost adsorbent containing GO (GO-doped adsorbent). This work provided a reference for the development of GO composite adsorbents.

The enhanced adsorption of Ampicillin and Amoxicillin on modified montmorillonite with dodecyl dimethyl benzyl ammonium chloride: Experimental study and density functional theory calculation

The quaternary ammonium surfactant-dodecyl benzyl ammonium chloride (DDBAC) was applied to modify Ca-montmorillonite (Ca-Mt) to obtain organo D-Mt that was used as the adsorbent for micropollutants-ampicillin (AMP) and amoxicillin (AMX). The XRD characterization indicated that DDBAC intercalated the interlayer space of Ca-Mt. When the amount of modifier was 1.4 CEC, the basal spacing enlarged from 1.53 nm to 2.97 nm, and the arrangement of modifier molecules were sloped in the interlayer of Ca-Mt along the longest axis. The saturated adsorption capacity of D-Mt-1.4 for AMP and AMX was 30.86 mg/g and 13.29 mg/g, respectively, while the saturated adsorption capacity of Ca-Mt for two contaminants was only 0.36 mg/g and 0.16 mg/g, respectively. The adsorption of the two pollutants was more consistent with Freundlich adsorption isotherm second-order kinetic model, and the thermodynamic study suggested that adsorption was more likely to occur at higher temperatures, which means that the adsorption of two pollutants was a spontaneous endothermic process. Moreover, Multiwfn wavefunction program based on Density Functional Theory (DFT) was applied to reveal the microadsorption mechanism of D-Mt to two pollutant molecules. This work confirmed that Ca-Mt functionalized by DDBAC was promising adsorbents for micro-contaminants of antibiotics and the insight of the adsorption mechanism from the atomic level, providing theoretical guidance for architecting high performance adsorbent.

Core/Shell Dual‐Responsive Nanocarriers via Iron‐Mineralized Electrostatic Self‐Assembly for Precise Pesticide Delivery

AbstractIt is desirable for a simple and universal method to synthesize stimuli‐responsive nanocarriers to targeted delivery of pesticides. In this study, a novel pH‐value and laccase dual‐responsive nanopesticide system loaded with lambda‐cyhalothrin (LC) is established by iron mineralization after electrostatic self‐assembly between sodium lignosulphonate (SL) and dodecyl dimethyl benzyl ammonium chloride (DDBAC). These nanoparticles are core–shell structures in which iron mineralization plays a key role in stabilizing the nanoparticles. This synthesis strategy is suitable for encapsulating hydrophobic and low‐volatility compounds. The encapsulation of the nanocarriers prolongs the half‐life of the LC under UV irradiation by 4.4‐fold. After irradiation, the mortality of Agrotis ipsilon treated by the LC@SL/DDBAC/Fe is approximately 39% higher than that treated by emulsifiable concentrate (EC) at the concentration of 1 mg L−1. The dual‐responsive property of lignin‐based nanoplatform to alkalinity and laccase enable cargo release on demand. Although the toxicity of EC and LC@SL/DDBAC/Fe to A. ipsilon is similar, that of LC@SL/DDBAC/Fe to Brachydanio rerio is decreased by 11.57‐fold, and the toxicity selective pressure is enhanced by 11‐fold compared with EC. The SL/DDBAC/Fe nanocarriers represent a simple preparation procedure, excellent environmental safety, and dual‐responsive release profiles and can offer a promising nanoplatform for precise pesticide delivery.

Determination of Azide Ions in Blood by Pentafluorobenzyl Derivation Followed by GC-MS.

Objective To establish a method for determination of the azide ions in blood by gas chromatography-mass spectrometry （GC-MS） following pentafluorobenzyl derivatization. Methods A blood sample of 0.2 mL was placed into a 10 mL glass test tube, and the internal standard sodium cyanide, derivatization reagent pentafluorobenzyl bromide and catalyst tetradecyl benzyl dimethyl ammonium chloride were added in turn. After vortex mixing, the mixture was heated with low-power microwave for 3 min. After centrifugation, the organic phase was taken for GC-MS analysis. Results The azide ions in blood had a good linear relationship in the mass concentration range of 0.5 to 20 μg/mL. The lowest detection limit was 0.25 μg/mL and the relative recovery was 91.36%-94.58%. The method was successfully applied to a case of death from sodium azide poisoning. The mass concentration of azide ions in the blood of the dead was 11.11 μg/mL. Conclusion The method developed in this paper has strong specificity and is easy to operate, which is suitable for the rapid detection of azide ions in blood.

Amphiphilic magnetic copolymer for enhanced removal of anionic dyes: Fabrication, application and adsorption mechanism

Magnetic separation technology is an efficient and feasible way to achieve rapid recovery of adsorbents, thus, the use of magnetic adsorbents has attracted the attention of many researchers. However, currently reported magnetic adsorbents have limited adsorption capacity due to insufficient adsorption sites and reactive groups. In this work, a novel magnetic chitosan-based amphiphilic adsorbent (PFSC) was synthesized by using UV-light irradiation method to combine with acryloyloxyethyl dimethylbenzyl ammonium chloride (AO), a molecule containing benzyl groups. PFSC and its precursors were carefully characterized, and their adsorption performances for the removal of anionic dyes were explored. The characterization results showed that the magnetic copolymers with a type of microsphere structure were successfully synthesized. Moreover, PFSC exhibited superior adsorption efficiency and pH resistance compared to those of an unmodified chitosan-based magnetic adsorbent (FSC). The maximum adsorption capacities of PFSC towards orange II (OG), acid red 88 (AE) and red amaranth (RM) were 955.0, 1075.8 and 567.5 mg/g at pH 3.0, respectively. The adsorption kinetics and isotherms of PFSC were consistent with that of a pseudo-second order kinetic model and the Langmuir isotherm model. In addition, adsorption-desorption experiments showed that PFSC could be rapidly separated and efficiently recycled even after 4 uses. More importantly, the FTIR and XPS results revealed that electrostatic adsorption and π-π stacking interactions were the main adsorption mechanisms for the PFSC-enhanced removal of anionic dyes.

A High Antibacterial Weakly Alkaline Barrier Slurry with the Tunable Selectivity

Barrier chemical mechanical planarization (CMP) is a critical process in the manufacturing of integrated circuits (ICs). Bacterial infestation, the material removal rate (MRR) selectivity and slurry aging are important factors in the evaluation of barrier CMP slurry. In this paper, H2O2 concentration in a lower level was used to adjust the rate selectivity and enhance removal rate on copper to ensure the trench copper thickness reaches the target value. The effects of dodecyl dimethyl benzyl ammonium chloride (DDBAC) and 1,2-Benzisothiazol-3-one (BIT) on bacteria growth were investigated. The total organic carbon analysis and the after-cleaning defect map of the patterned wafer proved the DDBAC and BIT contained in the barrier slurry could prevent bacteria formation within four weeks. The effect of aging on the performance was investigated systematically for the slurry contained containing H2O2, DDBAC and BIT. Aging has been shown to have a small effect on zeta potential, particle size and viscosity of the slurry. The polishing rate and pH decrease with time due to chemical degradation of a part of H2O2. Luckily, the rate selectivity still remains at a high value over time and the barrier slurry after 30d has an effective performance in topography modification.

Electroanalysis of Benzalkonium Chloride in Ophthalmic Formulation by Boron‐doped Diamond Electrode

AbstractBenzalkonium chloride (BAK) is a mixture of alkyl benzyl dimethyl ammonium chlorides, which is used primarily as a biocide, surfactant, preservative, and antimicrobial agent in the pharmaceutical industry, in particular in ophthalmologic and nasal solutions. However, BAK may cause harmful consequences on the eye structures of the anterior segment. Control of BAK identity and content is necessary by applying a sensitive detection method. This study unravels the use of a glassy carbon (GC) electrode and a pristine boron‐doped diamond electrode (BDD) for the detection of four BAK homologs in a non‐aqueous medium using square wave voltammetry (SWV). The BDD provided more reproducibility of the oxidation potential than GC with a correlation coefficient of 0.999. The irreversible oxidation peak was very broad and deconvoluted into 3 peaks corresponding to C12, C14, and combined C16–C18 to reflect their concentration ratio in the mixture. The method was then extended to the detection of the C12 homolog in the ophthalmic formulations with a limit of detection (LOD) of 0.4 μg/mL. The estimated BAK levels in three ophthalmic formulations were in agreement with the specified values by the manufacturers. The results were validated by high‐performance liquid chromatography (HPLC) with ultraviolet (UV) detection, confirming the presence of a single homolog (C12) in the eye drops.

Prenatal developmental toxicity of alkyl dimethyl benzyl ammonium chloride and didecyl dimethyl ammonium chloride in CD rats and New Zealand White rabbits.

The prenatal developmental toxicity potential of alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC) was evaluated in regulatory‐compliant studies. Pregnant female CD rats (25/group) and New Zealand White rabbits (16/group) were administered ADBAC (0, 10, 30, or 100 mg/kg/day and 0, 1, 3, or 9 mg/kg/day, respectively), or DDAC (0, 1, 10, or 20 mg/kg/day and 0, 1, 3, or 10 mg/kg/day, respectively), by oral gavage on gestation days (GD) 6–15 for rats and GD 6–18 for rabbits. At scheduled termination (GD 21 for rats; GD 29 for rabbits), maternal necropsies were conducted and live fetuses were weighed and examined for external, visceral, and skeletal malformations and variations. Clinical signs of maternal toxicity were observed in rats and rabbits dosed with ADBAC, resulting in no‐observed‐adverse‐effect levels (NOAELs) of 10 and 3 mg/kg/day, respectively. Despite the treatment‐related maternal toxicity of ADBAC, the NOAEL for prenatal developmental toxicity was 100 and 9 mg/kg/day for rats and rabbits, respectively, the highest doses evaluated. Repeated oral doses of DDAC resulted in maternal toxicity in both species at the top two doses, with 25% mortality noted in rabbits at 10 mg/kg/day. No teratogenic effects were observed at any dose for either species. However, increased incidence of dead fetuses per litter and decreased fetal body weights were observed in rabbits at the maternally lethal dose of 10 mg/kg/day. The NOAEL for maternal toxicity of DDAC was 1 mg/kg/day for both species and the NOAEL for prenatal developmental toxicity was 20 and 3 mg/kg/day, for rats and rabbits, respectively.

Removal of fine particles in coal fired power plant by chemical coagulation

The fine particle dust produced by coal-fired power plants is one of the important sources of air pollutants. Wet electrostatic precipitator (WESP) is one of the effective methods to remove fine particle dust. However, the traditional wet electrostatic precipitator still has low collection efficiency for the superfine particle dust. To improve the collection efficiency and the chemical coagulation method is applied to the wet electrostatic precipitator. Experiments are carried out by varying the chemical coagulation agent type, concentration, surfactant species. The results show that: Adding chemical coagulants can promote the coagulation effect of fine particles, and Xanthan gum (XTG) has the best coagulation effect; the concentration of chemical coagulant also affects the coagulation effect and collection efficiency of dust, the optimal concentration of XTG is 1.0×10−2 g/L; among the surfactants, dodecyl dimethyl benzyl ammonium chloride (1227) has the best effect, and the dust removal efficiency can reach 98.80%. Through experimental exploration, the chemical coagulation method has a good application prospect in wet electrostatic precipitators.

Study of Burning Behaviors and Fire Risk of Flame Retardant Plywood by Cone Calorimeter and TG Test

A flame retardant composition was prepared by using phosphoguanidine, guanidine sulfamate, disodium octaborate tetrahydrate and dodecyl dimethyl benzyl ammonium chloride. Veneers were immersed in such flame retardant mixture to prepare plywood. The combustion characteristics and thermal stability of plywood were assessed using a cone calorimeter and TG. Results showed that: (1) High concentration and loading of flame retardant were beneficial for the fire resistance of the plywood. (2) The limiting oxygen index (LOI) and residual mass of plywood processed using the flame retardant was increased by 87.52% and 58.66% compared to those of the untreated plywood, while the average heat release rate (av-HRR), total heat release (THR), effective heat of combustion (EHC), total smoke release (TSR), CO yield (COY), CO2 yield (CO2Y) and oxygen consumption were decreased by 44.3%, 82.9%, 47.0%, 86.0%, 89.9%, 50.1% and 83.1%, respectively. (3) Treated plywood which had a low fire growth index (FGI) displayed a later combustion heat release rate peak and slower flame spread than observed for the untreated material. Combustion of treated plywood displayed a higher fire performance index (FPI), indicating a longer time to ignition. This suggests that burning structures from this material would be subject to a longer time for escape from the structure and would present lower fire risk than similar structures containing treated plywood. (4) TG results demonstrated that the presence of the flame retardant can decrease the pyrolysis temperature for hemicellulose and cellulose, change the decomposition and reaction progress for plywood degradation and promote dehydration carbonization and accelerated charformation. Moreover, the formed char was more stable than that combustion of untreated plywood. (5) The flame retardant contains nitrogen (N), phosphorus (P), boron (B), chlorine (Cl) and guanidine (Gu) compounds. The adhesive also contains N and P compounds. These substances display flame resistance and supplement each other to generate flame retardance than any one used alone. By changing the thermolysis and thermal decomposition processes, the heat release and smoke release from plywood, undergoing combustion was reduced. This controlled generation of combustible substances and promoted dehydration and carbonization to form char. As a result, the flame resistance of plywood was improved significantly. The probability of smoke asphyxia or poisoning death of those trapped in structures containing treated plywood during fire accidents can be decreased dramatically.

Applications of UV/H2O2, UV/persulfate, and UV/persulfate/Cu2+ for the elimination of reverse osmosis concentrate generated from municipal wastewater reclamation treatment plant: Toxicity, transformation products, and disinfection byproducts

Reverse osmosis concentrate (ROC) resulting from treatment of municipal wastewater reclamation involves high concentrations of recalcitrant pollutants. This study evaluated the toxicity of an ROC containing harmful biocides during representative UV synergistic oxidation processes (SOPs) (e.g., UV/hydrogen peroxide (H2O2), UV/persulfate (PS), and UV/PS/Cu2+). Treated ROC exhibited up to 1.3–2.3 times higher toxicity than the parent compounds such as dodecyl trimethyl ammonium chloride (DTAC) and dodecyl dimethyl benzyl ammonium chloride (DDBAC). Based on the intermediates identification, the major toxic intermediates were screened through silico assessment using the quantitative Ecological Structure-Activity Relationship (ECOSAR) tool. The transformation products (TPs) of hydroxylation and ketonization were the major formed reactions from the UV/PS/Cu2+. Also, some cytotoxic TPs were accumulated during the UV/H2O2 and UV/PS oxidations, where the carbonaceous-disinfection byproducts were more than the nitrogenous-disinfection byproducts. In the presence of chloride and bromide, chlorate and bromate could be formed during the UV-SOP; they were influenced by the different water matrix in comparison with the different ROC. Also, the formation of the total organic halogen species (TOX) was found to follow this order: UV/PS/Cu2+ < UV/H2O2 < UV/PS. In this study, the predicted cytotoxicity using the correlation between the TOX and the cytotoxicity was more acceptable than that of the cytotoxicity index method. Further, the R-square of the correlation between the TOX and the cytotoxicity for the UV/H2O2 and UV/PS was 0.82 and 0.79, respectively. The predicted cytotoxicity using the TOX correlation method in the ROC could also be used to monitor and prevent the application of different oxidations in municipal wastewater reclamation treatment plants.