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There is a strong global demand for sulfate-free personal cleansing products. The objective of sulfate-free personal cleansing technology should not be aimed solely at the absence of "sulfate" wording in the list of ingredients, but on the true benefits both in personal use and in environmental effects. These include but are not limited to safety, mildness, and sensory effect for the individual and renewability, low carbon footprint, low water footprint, biodegradability, and sustainability for the environment. In addition, some surfactants or their precursors contain 1,4-dioxane as a by-product of their manufacturing, which is a major safety concern. This paper will deal with sulfate-free cleansing in two parts. Part I will examine the issues surrounding sulfates. Part II will show the benefits of amino acid-based surfactants for cleansing products, and specifically show why glutamates and alaninates are the best choices for safer and more efficacious cleansing. Several metrics will be included to support these conclusions. [ABSTRACT FROM AUTHOR]

This article explores the influence of various factors on the intensity of the chromatographic peak of 1,4-dioxane using gas chromatography with headspace analysis (GC-HS). The effects of adding water and sodium chloride to shampoo samples and the impact of headspace vial filling on peak height were examined. Experimental results showed that reducing the volume of vial filling significantly enhances the dioxane signal. Adding water to shampoo samples decreases the peak height while adding sodium chloride increases both peak height and area. Furthermore, increasing the amount of shampoo in the vial was observed to have minimal impact on peak height. A methodology for determining 1,4-dioxane in shampoo samples was validated, including checks for specificity, linearity, accuracy, and method convergence. The calculated data demonstrate that the methodology meets the requirements for precision and accuracy, with an analysis uncertainty of 8.9% and an average deviation of 3.7%, respectively. This confirms the reliability and accuracy of the method for determining dioxane in shampoo samples. The findings of this study are important for the quality control of 1,4-dioxane in cosmetic products. The data can also improve shampoo manufacturing processes and enhance product quality control. [ABSTRACT FROM AUTHOR]

This study discussed the effect of ferric salt addition on UV/electro-chlorine advanced oxidation process using a train of electrolytic and UV flow cells with an ozone-free low-pressure mercury vapour lamp (total irradiance:0.60 W at 254 nm). Ferric salt addition enhanced 1,4-dioxane degradation at an electrolytic current of 0.100 A. By contrast, an inhibitory effect of ferric salt addition was observed at a current of 0.500 A. The enhanced accumulation of free chlorine at a current of 0.500 A directly decreased the 1,4-dioxane degradation rate by scavenging reactive radicals like HO˙ and Cl˙. However, at an electrolytic current of 0.100 A, UV irradiance was relatively excessive for electrochemical chlorine production. The excess UV energy enhanced the photoreduction of FeOH2+, followed by the Fenton-type reaction of Fe2+ and HOCl, which produced HO˙ and consumed free chlorine. As a result, the free chlorine concentration decreased, and the reaction efficiency between the reactive radicals and 1,4-dioxane improved. Thus, the addition of ferric salt to a UV/electro-chlorine system is recommended when the UV irradiance in the system is excessive compared to the electrochemical chlorine supply. [ABSTRACT FROM AUTHOR]

Air quality, both outdoor and indoor, is the most critical element that we must protect for the entire environment. While the deterioration of air quality primarily causes respiratory diseases in living things, it also causes corrosive effects on nonliving things, such as corrosion caused by acid rain, which results from air pollution. Therefore, it is necessary to monitor and prevent air pollution by various methods. WHO plays an active role in protecting air quality through its mission. Plants are indispensable beings for the environment and life. They balance the CO2 concentration, temperature, and humidity in the air. Plants use CO2, light, and water during photosynthesis, which is necessary for their growth and development. They reduce the CO2 concentration in the environment. In addition, plants, depending on their leaf characteristics, can trap particulate matter in the atmosphere. Many studies have proven that plants positively affect indoor and outdoor air quality. In this review, we aim to summarize the results of some selected studies, provide information about the air purification capacities of the researched plants, and emphasize the topic's importance. [ABSTRACT FROM AUTHOR]

1,4‐Dioxane is a probable human carcinogen and a persistent aquatic contaminant. Cometabolic biodegradation of 1,4‐dioxane is a promising low‐cost and effective treatment technology; however, further demonstration is needed for treating landfill leachate. This technology was tested in two full‐scale moving bed biofilm reactors (MBBRs) treating raw landfill leachate with tetrahydrofuran selected as the cometabolite. The raw leachate contained on average 82 μg/L of 1,4‐dioxane and before testing the MBBRs removed an average of 38% and 42% of 1,4‐dioxane, respectively. First, tetrahydrofuran was added to MBBR 1, and 1,4‐dioxane removal was improved to an average of 73%, with the control MBBR removing an average of 37% of 1,4‐dioxane. During this period, an optimal dose of 2 mg/L of tetrahydrofuran was identified. Tetrahydrofuran was then fed to both MBBRs, where the 1,4‐dioxane removal was on average 73% and 80%. Cometabolic treatment at the landfill significantly reduced the concentration of 1,4‐dioxane received from the landfill at a downstream wastewater treatment and indirect potable reuse facility, reducing the load of 1,4‐dioxane from 44% to 24% after the study. Practitioner Points: Cometabolic degradation of leachate 1,4‐dioxane with THF in MBBRs is a feasible treatment technology and a low‐cost technique when retrofitting existing biological treatment facilities.The MBBRs can be operated at a range of temperatures, require no operational changes beyond THF addition, and operate best at a mass ratio of THF to 1,4‐dioxane of 24.Source control of 1,4‐dioxane significantly reduces the concentration of 1,4‐dioxane in downstream wastewater treatment plants and potable reuse facilities. [ABSTRACT FROM AUTHOR]

The refractive index ${n_D}$ n D for the mixture (1,4-dioxane (1) + water (2)) was measured over the whole composition range at different temperatures and atmospheric pressure. From measured values of the refractive indices, the molar refraction ${R_m}$ R m , reduced molar free volumes ${{{V_m}} \over {{R_m}}}$ V m R m , molecular radii $r$ r and internal pressure, ${P_{int}}$ P int were calculated. On the other hand, some excess parameters were also deduced. The obtained results have been discussed and interpreted in terms of the type and nature of specific intermolecular interactions existed between the components. Furthermore, we have used nine mixing rules for refractive index proposed by different authors to calculate the refractive indices of the present mixture. A comparative study was carried out between the measured and calculated indices. The Redlich–Kister polynomial equation has been used to fit the presented excess parameters to derive the adjustable fitting coefficients and estimate the standard error values. [ABSTRACT FROM AUTHOR]

The combination of ozone and hydrogen peroxide (O3/H2O2), or the peroxone process, has often been used as an advanced oxidation process (AOP) in groundwater remediation and drinking water applications. This historical precedent sometimes leads to the misconception that H2O2 addition is required to achieve AOP conditions during ozonation. This is not the case for secondary or tertiary wastewater effluent applications, in which ozone reacts with abundant dissolved organic carbon (DOC) to generate hydroxyl radicals (∙OH). This study demonstrates the use of ozone with and without H2O2 addition to yield ∙OH exposures (up to 10−9 M-s) capable of achieving > 0.5-log10 attenuation of the industrial contaminant and probable human carcinogen 1,4-dioxane. This low molecular weight compound is commonly used as a surrogate when establishing AOP design criteria for potable reuse applications. DOC-normalized ozone doses (i.e., O3/DOC ratios) of ~ 1.0 and ~ 1.3 achieved 0.5-log10 attenuation of 1,4-dioxane with O3/H2O2 and O3, respectively. Also, a predictive model based on ∙OH exposure was accurate within approximately ± 10%. These results suggest that ozonation's role as an AOP, even in the absence of H2O2, should be acknowledged in regulatory frameworks to reduce unnecessary treatment redundancy and facilitate broader implementation of potable reuse. [ABSTRACT FROM AUTHOR]

Biodegradation of 1,4-Dioxane at environmentally relevant concentrations usually requires the addition of a primary electron-donor substrate to sustain biomass growth. Ethane is a promising substrate, since it is available as a degradation product of 1,4-Dioxane's common co-contaminants. This study reports kinetic parameters for ethane biodegradation and co-oxidations of ethane and 1,4-Dioxane. Based on experiments combined with mathematical modeling, we found that ethane promoted 1,4-Dioxane biodegradation when the initial mass ratio of ethane:1,4-Dioxane was < 9:1 mg COD/mg COD, while it inhibited 1,4-Dioxane degradation when the ratio was > 9:1. A model-independent estimator was used for kinetic-parameter estimation, and all parameter values for 1,4-Dioxane were consistent with literature-reported ranges. Estimated parameters support competitive inhibition between ethane as the primary substrate and 1,4-Dioxane as the secondary substrate. The results also support that bacteria that co-oxidize ethane and 1,4-Dioxane had a competitive advantage over bacteria that can use only one of the two substrates. The minimum concentration of ethane to sustain ethane-oxidizing bacteria and ethane and 1,4-Dioxane-co-oxidizing bacteria was 0.09 mg COD/L, which is approximately 20-fold lower than the minimum concentration reported for propane, another common substrate used to promote 1,4-Dioxane biodegradation. The minimum 1,4-Dioxane concentration required to sustain steady-state biomass with 1,4-Dioxane as the sole primary substrate was 1.3 mg COD/L. As 1,4-Dioxane concentrations at most groundwater sites are less than 0.18 mg COD/L, providing ethane as a primary substrate is vital to support biomass growth and consequently enable 1,4-Dioxane bioremediation. [ABSTRACT FROM AUTHOR]

Bioremediation is a promising approach for mitigating commingled contaminations of chlorinated ethenes (CEs) and 1,4-dioxane (DX). However, aerobic bioremediation to simultaneously remove CEs and DX remains challenging. This study aimed to explore the ability of Pseudonocardia sp. D17 (D17) to aerobically degrade CEs and its applicability for concurrent removal of CEs and DX. Aerobic degradation experiments of individual CEs revealed that D17 could degrade trichloroethene (TCE), three isomers of dichloroethene (DCE), and vinyl chloride (VC), and the trend of its degradation ability was cis-1,2-DCE (cDCE) > VC > TCE > trans-1,2-DCE > 1,1-DCE. Notably, the CE-degrading activity of D17 was expressed even without any auxiliary substrates. Further, when TCE, cDCE, or VC was co-present with DX (each at 1 mg/L), D17 could degrade both compounds without any significant inhibition (for TCE and cDCE) or with only a transient and reversible suspension of its DX degradation ability (for VC). These findings indicated that D17 is a promising agent for the aerobic bioremediation of CEs and DX co-contamination and provide novel insights into the future development of efficient aerobic bioremediation strategies.

1,4-Dioxane concentration in most contaminated water is much less than 1 mg/L, which cannot sustain the growth of most reported 1,4-dioxane-metabolizing pure cultures. These pure cultures were isolated following enrichment of mixed cultures at high concentrations (20 to 1,000 mg/L). This study is based on a different strategy: 1,4-dioxane-metabolizing mixed cultures were enriched by periodically spiking 1,4-dioxane at low concentrations (≤1 mg/L). Five 1,4-dioxane-metabolizing pure strains LCD6B, LCD6D, WC10G, WCD6H, and WD4H were isolated and characterized. The partial 16S rRNA gene sequencing showed that the five bacterial strains were related to Dokdonella sp. (98.3%), Acinetobacter sp. (99.0%), Afipia sp. (99.2%), Nitrobacter sp. (97.9%), and Pseudonocardia sp. (99.4%), respectively. Nitrobacter sp. WCD6H is the first reported 1,4-dioxane-metabolizing bacterium in the genus of Nitrobacter. The net specific growth rates of these five cultures are consistently higher than those reported in the literature at 1,4-dioxane concentrations

Personal care products (PCPs) are intended for regular application by consumers and therefore assuring the safety of these products is very important. Recently, benzene contamination has been highlighted in certain PCPs. The present study applies selected ion flow tube mass spectrometry (SIFT-MS) to a simultaneous headspace analysis of benzene, 1,4-dioxane, and formaldehyde—all known or suspected carcinogens—in nine haircare products with supporting qualitative analysis by gas chromatography–mass spectrometry (GC-MS). Headspace-SIFT-MS method development is compatible with the method of standard additions, which is necessary for the quantitation of volatile impurities in these complex emulsions. Benzene was quantified above the low-ng g−1 limit of quantitation (LOQ) in three products, dioxane above the sub-μg g−1 LOQ in all products, and formaldehyde above the low-μg g−1 LOQ in two products, providing a quantitative analysis at concentrations relevant to consumer safety. This study facilitated the development of generic workflows for SIFT-MS method development and application in routine analysis of PCPs. The assessment of workflows for SIFT-MS compared to a conventional GC-MS analysis suggests that 8- to 30-fold throughput enhancements may be possible for quantitative and screening analysis using SIFT-MS.

There is a strong global demand for sulfate-free personal cleansing products. The objective of sulfate-free personal cleansing technology should not be aimed solely at the absence of “sulfate” wording in the list of ingredients, but on the true benefits both in personal use and in environmental effects. These include but are not limited to safety, mildness, and sensory effect for the individual and renewability, low carbon footprint, low water footprint, biodegradability, and sustainability for the environment. In addition, some surfactants or their precursors contain 1,4-dioxane as a by-product of their manufacturing, which is a major safety concern. This paper will deal with sulfate-free cleansing in two parts. Part I will examine the issues surrounding sulfates. Part II will show the benefits of amino acid-based surfactants for cleansing products, and specifically show why glutamates and alaninates are the best choices for safer and more efficacious cleansing. Several metrics will be included to support these conclusions.

The overall objective of this study was to develop cost-effective treatment processes for 1,4-dioxane removal that were safe and easy to scale up. Degradation of 1,4-dioxane was conducted and compared for the first time by heterogeneous photocatalysis and a photo-Fenton-like process under cool white fluorescent light in mild conditions, using two types of commercial nanoparticles–titanium dioxide (TiO2) and nanoscale zero-valent iron (nZVI), respectively. Both types of nanoparticles removed >99.9% of 1,4-dioxane in a short period of time. Hydroxyl radicals (·OH), superoxide radicals (·O2-), and hydrogen peroxide (H2O2) were detected in both degradation processes; photogenerated holes (h+) were critical in the degradation of 1,4-dioxane by the photocatalytic process using TiO2. 1,4-Dioxane can be degraded at pH 7 in TiO2/light system and at pH 3 in nZVI/light system, and faster degradation of 1,4-dioxane at even higher concentration was achieved in the former system. Increase in light intensity accelerated 1,4-dioxane degradation, which followed first order kinetics in both systems. In wastewater effluent, the removal of 1,4-dioxane was slower than that in deionised water, which likely reflected the complex compositions of the wastewater effluent. Under combined UVA and visible light illumination, a two-stage degradation process was proposed for 1,4-dioxane for the first time by TiO2 nanoparticles; this study also demonstrated for the first time 1,4-dioxane degradation by the photo-Fenton-like process using nZVI. The cost-effective solutions using commercial nanoparticles under fluorescent light developed in this study can be potentially applied to treat water contaminated by high concentrations of 1,4-dioxane in large-scale. [ABSTRACT FROM AUTHOR]

This work reports the development of novel curcuminoid-based electrochemical sensors for the detection of environmental pollutants from water. In this study, the first set of electrochemical experiments was carried out using curcumin-conjugated multi-walled carbon nanotubes (MWCNT–CM) for 1,4-dioxane detection. The MWCNT–CM/GCE showed good sensitivity (103.25 nA nM−1 cm−2 in the linear range 1 nM to 1 µM), with LOD of 35.71 pM and LOQ of 108.21 pM. The second set of electrochemical experiments was carried out with bisdemethoxy curcumin analog quantum dots (BDMCAQD) for hydrazine detection. The BDMCAQD/GCE exhibited good sensitivity (74.96 nA nM−1 cm−2 in the linear range 100 nM to 1 µM), with LOD of 10 nM and LOQ of 44.93 nM. Thus, this work will serve as a reference for the fabrication of metal-free electrochemical sensors using curcuminoids as the redox mediator for the enhanced detection of environmental pollutants. [ABSTRACT FROM AUTHOR]

Personal care products (PCPs) are intended for regular application by consumers and therefore assuring the safety of these products is very important. Recently, benzene contamination has been highlighted in certain PCPs. The present study applies selected ion flow tube mass spectrometry (SIFT-MS) to a simultaneous headspace analysis of benzene, 1,4-dioxane, and formaldehyde—all known or suspected carcinogens—in nine haircare products with supporting qualitative analysis by gas chromatography–mass spectrometry (GC-MS). Headspace-SIFT-MS method development is compatible with the method of standard additions, which is necessary for the quantitation of volatile impurities in these complex emulsions. Benzene was quantified above the low-ng g−1 limit of quantitation (LOQ) in three products, dioxane above the sub-μg g−1 LOQ in all products, and formaldehyde above the low-μg g−1 LOQ in two products, providing a quantitative analysis at concentrations relevant to consumer safety. This study facilitated the development of generic workflows for SIFT-MS method development and application in routine analysis of PCPs. The assessment of workflows for SIFT-MS compared to a conventional GC-MS analysis suggests that 8- to 30-fold throughput enhancements may be possible for quantitative and screening analysis using SIFT-MS. [ABSTRACT FROM AUTHOR]

Chlorinated volatile organic compounds (CVOCs) are often found in combination with 1,4-dioxane which has been used as a solvent stabilizer. It would be desirable to separate these compounds since biodegradation of 1,4-dioxane follows an aerobic pathway while anaerobic conditions are needed for biodegrading CVOCs. Conventional adsorbents such as activated carbon (AC) and carbonaceous resins have high adsorption capacities for 1,4-dioxane and CVOCs but lack selectivity, limiting their use for separation (Liu et al., 2019). In the current work, two macrocyclic adsorbents, β-CD-TFN and Res-TFN, were examined for selective adsorption of chlorinated ethenes in the presence of 1,4-dioxane. Both adsorbents exhibited rapid adsorption of the CVOCs and minimal adsorption of 1,4-dioxane. Res-TFN had a higher adsorption capacity for CVOCs than β-CD-TFN (measured linear partition coefficient, Kd 2140 -9750 L·kg−1 versus 192-918 L·kg−1 for 1,1, DCE, cis-1,2-DCE and TCE, respectively) and was highly selective for CVOCs(TCE Kd ∼117 Kd for 1,4-dioxane). By comparison, TCE and 1,4-dioxane adsorption on AC was approximately equal at 100 µg·L−1 and approximately 1/3 of the adsorption of TCE on the Res-TFN. The greater adsorption and selectivity of Res-TFN suggest that it can be used as a selective adsorbent to separate CVOCs from 1,4-dioxane to allow separate biodegradation.

Equilibrium solubility of antitubercular agent pyrazinamide in mixed solvents is scarce in the literature. Thus, the mole fraction solubility of this drug in aqueous-cosolvent mixtures of 1,4-dioxane or ethanol has been determined at 298.15 K by means of flask shake and UV–Vis analysis. Solubilities were adequately correlated with the modified Nearly Ideal Binary Solvent/Redlich–Kister model. Moreover, some expressions for the local mole fraction of cosolvents and water around the pyrazinamide molecules in solution were derived on the basis of the inverse Kirkwood Buff integrals. Pyrazinamide is preferentially solvated by water in water-rich mixtures and cosolvent-rich mixtures, but preferentially solvated by cosolvent in mixtures with intermediate compositions. [ABSTRACT FROM AUTHOR]

This study aims to compare the 1,4-dioxane removal functions of four willow (Salix spp.) strains during the two seasons (summer and autumn) and to elucidate the function of phytoremediation (volatilization, metabolism, and accumulation) of 1,4-dioxane-containing water by willow during the two seasons. This investigation tests the removal performance of 1,4-dioxane from solution by the strains; KKD strain which shows extremely fast-growing, HB471 which shows similar characteristics as KKD, FXM strain which shows relatively strong drought tolerance, and SEN which shows relatively strong insect resistance. Pot tests of 1,4-dioxane removal by willow revealed significant differences in removal rates between the summer and autumn seasons. In all four willow strains, the autumn removal rates decreased to 15.7 to 25.4% of the summer removal rates. The strain with the highest removal rate was KKD (37.5% of the exposure) during the summer season, making it the most promising strain. When comparing the percentage contribution of 1,4-dioxane removal by plant function in KKD, removal by transpiration was the largest contributor in both summer and autumn. However, in the autumn season, the contribution of transpiration to 1,4-dioxane removal was smaller, while the contribution of accumulation increased. This occurred because transpiration decreased during the autumn, causing 1,4-dioxane absorbed from the roots to remain in the plant body instead of being transpired. Considering the application of willow in arid lands, the importance of water management was suggested, as a decrease in transpiration was found to affect removal performance. [ABSTRACT FROM AUTHOR]

1,4-dioxane is a potential carcinogen in water and is difficult to deal with due to its robust cycloether bond and complete miscibility with water. To remove 1,4-dioxane in an economically viable and environmentally friendly way, a series of carbon aerogels were synthesized as adsorbents for 1,4-dioxane. The experiment results showed that adsorption performances were closely related to the preparation conditions of carbon aerogels, such as the molar ratio, heating rate, pyrolysis temperature and residence time, which were carefully controlled. Scanning electron microscope analysis revealed the presence of a three-dimensional porous network structure in carbon aerogels. Brunauer–Emmett–Teller analysis results demonstrated an increase in specific surface area (673.89 m2/g) and total pore volume after carbonization, with an increase in mesoporous porosity and a decrease in microporosity. When considering each variable individually, the highest specific surface area of prepared carbon aerogels was achieved at a pyrolysis temperature of 800 °C, a holding time of 1 h, and a heating rate of 2 °C/min. Under optimal experimental conditions, the adsorption removal of 1,4-dioxane by carbon aerogels exceeded 95%, following quasi-second-order kinetics and Langmuir isothermal adsorption isotherms, indicating that monolayer adsorption on the surface of carbon aerogels occurred. The maximum adsorption capacity obtained was 67.28 mg/g at a temperature of 318 K, which was attributed to the presence of a large proportion of mesopores and abundant micropores simultaneously in carbon aerogels. Furthermore, with the interference of chlorinated solvents such as trichloroethylene (TCE), the removal efficiency of 1,4-dioxane had no obvious inhibition effect. Regeneration experiments showed that after five continuous cycles, the carbon aerogels still kept a comparable adsorption capacity, which illustrates its potential application in 1,4-dioxane-polluted water purification. [ABSTRACT FROM AUTHOR]

During storage and transportation, some classes of hydrocarbons in diesel fuel can undergo chemical transformations over time due to ambient temperature, sunlight, and oxygen in the air. As a result of these reactions, there are changes in the composition of the fuel, such as sediment, color change, turbidity, which have a negative effect on the physico-chemical indicators of the fuel. Such a change can cause engine wear and adversely affect engine efficiency, performance, emissions and durability. The main objective of this study is to investigate antioxidant additives to delay the aging process in diesel fuels. The compounds 1,4 dioxane and 3-hydroxy-1-(2-hydroxyphenyl)-3-(4-nitrophenyl)-propan-1- one were selected for this study. UV rays have been used to stimulate the aging process. As a result of research, the use of 1,4-dioxane has significantly improved the chemical stability, density and kinematic viscosity of fuel and its use in diesel fuel has shown greater stabilization potential. [ABSTRACT FROM AUTHOR]

[Display omitted] A copper-catalyzed three-component coupling sequence for 2-arylquinolines formation from aromatic aldehydes, anilines and 1,4-dioxane has been described. Unexpectedly, 1,4-dioxane served as a C 2 building block in this transformation. This formal [4 + 2] approach provides rapid access to 2-arylquinolines with broad substrate scope under mild conditions. [ABSTRACT FROM AUTHOR]

This article provides an overview of the bioremediation of groundwater plumes containing admixtures of chlorinated volatile organic compounds (CVOCs) and 1,4-dioxane. The remediation of these plumes has historically focused on the reductive dechlorination of the CVOCs. Many of the remaining plumes are relatively large, and contaminant concentrations are diluted below the concentrations that can sustain reductive dechlorination. Cometabolic processes can decrease contaminant concentrations below the thresholds needed to support direct metabolism but typically require the addition of a substrate, such as high-purity propane. Relatively intensive site characterization and monitoring is necessary to implement bioremediation. [ABSTRACT FROM AUTHOR]

Aerobic cometabolism is a viable method for treating groundwater contaminated with 1,4-dioxane. Although at least one biochemical pathway by which 1,4-dioxane is used as a sole source of carbon and energy has been elucidated, comparatively little is known about the products formed during cometabolic degradation. The objective of this study was to identify the main products formed during cometabolism of 1,4-dioxane by the mixed propanotrophic culture ENV487. During biodegradation of 14C-1,4-dioxane, soluble products accumulated that were concentrated by lyophilization and then separated into fractions using high-performance liquid chromatography. Formate accounted for 51% of the 14C-labeled compounds recovered, based on co-elution with authentic material. The identity of formate as the main product was confirmed using a formate dehydrogenase assay. Other products identified that represented at least 4% of the 14C products recovered included acetate, glycerate, glycolaldehyde, ethylene glycol, and glycolate. All these compounds are readily biodegradable in an aquifer environment. This is consistent with the expectation that the endpoint for aerobic cometabolism of 1,4-dioxane by propanotrophs in a mixed culture environment is carbon dioxide. [ABSTRACT FROM AUTHOR]

Resting cell batch kinetic studies were performed to evaluate the alcohol-dependent cometabolic degradation of chlorinated aliphatic hydrocarbons (CAHs) and 1,4-dioxane (1,4-D) by Rhodococcus rhodochrous strain ATCC 21198. This strain grew on diverse alcohols, organic acids, esters, and other organic compounds. Only growth on 2-butanol resulted in labeling of monooxygenase enzymes and the ability to oxidize propylene, the cylic ether 1,4-D, and its close structural analog tetrahydrofuran. In single compound rate tests, 2-butanol-grown cells exhibited faster degradation rates for less chlorinated compounds. The rates of degradation are ranked as follows from high to low: vinyl chloride > cis-dichloroethene (cis-DCE) >1,1-dichoroethane >1,1-dichoroethene (1,1-DCE) >1,4-D > 1,1,1-trichoroethane (1,1,1-TCA) >1,1,2-trichoroethene. All rates were significantly lower than isobutane-grown cells. 2-Butanol-grown cells exhibited a lag period before cometabolic degradation of most CAHs, including cis-DCE; however, production of cis-1,2-dichloro-1,2-epoxyethane (cis-DCE epoxide) was detected with no lag. Cells grown on 1-butanol, 2-butanol, or 2-ethyl-1-butanol also cometabolically degraded 1,4-D and various CAHs. However, compared to cells grown on 1-butanol or 2-ethyl-1-butanol, cells grown on 2-butanol had a larger transformation capacity and faster degradation rates and were able to fully degrade (>99% removal) a mixture of 1,4-D, cis-DCE, and 1,1,1-TCA. With CAH mixtures, alcohol-grown cells degraded cis-DCE faster than both 1,1,1-TCA and 1,4-D. sec-Butyl-acetate (sBA) was demonstrated as a potential slow-release substrate that hydrolyzes to yield 2-butanol and acetate. Cells grown on this ester degraded a mixture of 1,1,1-TCA and 1,4-D at rates faster than 2-butanol-grown cells. The cometabolic transformation of 1,1,1-TCA and 1,4-D was also observed in reactors where growth occurred with sBA as the growth substrate. [ABSTRACT FROM AUTHOR]

In order to search for efficient antioxidants of the pyrazolone series, sulfur-containing derivatives of 2,4-dihydro-3H-pyrazol-3-one and 1H-pyrazole (1a–e) were studied in the model system of radical chain oxidation of 1,4-dioxane. The antioxidant activity of these compounds was determined. The rate constant for the reaction of peroxyl radicals with inhibitor 1 (k7) and stoichiometric inhibition coefficient (f) were calculated at 333 K. Sulfur-containing 2,4-dihydro-3H-pyrazol-3-ones exhibit a higher antioxidant activity fk7 = (5.7–9.2)·104 L mol−1 s−1) than 4-(pentylsulfanylmethyl)-3,5-dimethyl-1H-pyrazole fk7 ⩽ 2 · 103 L mol−1 s−1), which is possibly due to the presence of the hydroxyl group in the pyrazolone cycle in the hydroxy form. The stoichiometric coefficients of inhibition for 4-(benzylsulfanylmethyl)-5-methyl-, 5-methyl-4-(pentylsulfanylmethyl)-, and 5-methyl-4-(propylsulfanylmethyl)-2,4-dihydro-3H-pyrazol-3-ones f = 0.95–1.3) indicate the "decay" of one peroxyl radical on one inhibitor molecule. In the case of 5-methyl-4-[(2-propylsulfanyl)methyl]-2,4-dihydro-3H-pyrazol-3-one, the stoichiometric coefficient of inhibition decreases f = 0.59). [ABSTRACT FROM AUTHOR]

1,4-dioxane pollution is characterized by its early identification, widespread sources and extensive distribution. The pollutant is highly mobile and persistent in the water environment and is classified as a B2 (probable) human carcinogen. After reviewing recent researches on the pollution status, transport and transformation characteristics of 1,4-dioxane in the water environment, as well as the environmental pollution remediation and treatment technologies, and the status of environmental regulation, this paper addresses that the distribution of 1,4-dioxane in water bodies is significantly correlated with chlorinated hydrocarbon pollutants such as 1,1,1-trichloroethane (1,1,1-TCA) and trichloroethylene (TCE). It is noteworthy that 1,4-dioxane often occurs in symbiosis with 1,1,1-TCA and has a similarity contamination plume distribution to 1,1,1-TCA. The natural attenuation of 1,4-dioxane in groundwater environment is weak, but there is a certain degree of biological oxidation attenuation. Current methods for treating 1,4-dioxane pollution mainly include extraction-treatment technology, advanced oxidation treatment technology, modified biological treatment technology and phytoremediation technology, all of which have their limitations in practical application. Currently, there is no environmental regulation available for the 1,4-dioxane pollution worldwide, and no enforceable standard established for defining the health trigger levels of 1,4-dioxane in drinking water. Research on this contaminant in China is generally limited to the site or laboratory scale, and there are no studies on the environmental risk and quality standards for 1,4-dioxane in the water environment.

Cosmetics and personal care products (PCPs) are a few of the most commonly used products across the globe with a whopping market share of approximately USD 500 billion. These products are used for cleansing purposes and for improving the quality and beauty of the face, hair, and skin. There are many chemical substances involved in the manufacturing of cosmetics and PCPs. These chemical substances incorporated in cosmetics or PCPs are crucial to develop high-quality products with superior appearance, applicability, and stability; however, excessive use of such chemicals in cosmetics and PCPs has become a safety concern as many of these are reported to cause severe health complications. Overuse of cosmetics and PCPs with hazardous material should be minimized, especially by pregnant women and children. Gynecologists advise pregnant women not to use cosmetics and PCPs with hazardous chemicals. The implementation of a lawful framework is crucial to establish the safety of cosmetics and PCPs. Cosmetic companies/industries must be strictly regulated and made compliant to the guidelines in order to protect human health and minimize safety concerns. In this review, hazardous chemicals incorporated in the personal care products/cosmetics and their related risk and health complications have been discussed in detail. Additionally, regulatory status and clinical trials of chemical substances that involve toxicity and causing severe complications have also been discussed.

Electron beam (e-beam) treatment uses accelerated electrons to form oxidizing and reducing radicals when applied to water without the use of external chemicals. In this study, electron beam treatment was used to degrade 1,4-dioxane in several water matrices. Removal improved in the progressively cleaner water matrices and removals as high as 94% to 99% were observed at a dose of 2.3 kGy in secondary effluent. 1,4-dioxane removal was confirmed to be primarily through hydroxyl radical oxidation. The calculated electrical energy per order was found to be 0.53, 0.26, and 0.08 kWh/m3/order for secondary effluent (Avg. total organic carbon (TOC) 9.25 mg/L), granular activated carbon effluent (TOC 3.46 mg/L), and ultrapure water, respectively, with a 70% generation and transfer efficiency applied. HIGHLIGHTS Electron beam treatment was used to successfully remove 1,4-dioxane from water and wastewater.; No bromate was formed despite high bromide concentrations and bromate removal was observed.; Energy use was comparable to other conventional AOPs without requiring additional chemicals.;

ABSTRACT Assembling a functional consortium and identifying novel degraders from contaminated environments are still challenging due to the large diversity of microorganisms and the difficulty in isolating pure cultures. Here, we constructed a relatively simple functional consortium by enriching 1,4-dioxane-degrading-consortia using a culture-dependent dilution-to-extinction (DTE) method and reported a new key dioxane-degrader Shinella sp. Our results showed that serial dilution and reculture led to a divergence in the degradation ability of each consortium. Next-generation sequencing data revealed that the divergence in degradation performance was due to the reassembly of microbiota in the DTE process, which occurred most notably in 10−8 and 10−9 dilutions. The shift in community structure at 10−9 prevented the recovery of 1,4-dioxane degradation capacity, and the newly dominant taxa, Xanthobacter and Acinetobacter, struggled to replace the original dominant genus Shinella for 1,4-dioxane biodegradation. Combining differential analysis of community structure and metabolic function, we confirmed that Shinella species have a stronger 1,4-dioxane degradation ability than Xanthobacter species in the enriched consortium. In addition, we verified our findings using our isolated dioxane-degrading bacteria, Shinella yambaruensis, resulting in the rapid recovery of degradation performance of a 10−9 dilution consortium with Xanthobacter and Acinetobacter as the dominant microbiota. Taken together, this study provides a strategy for self-assembling functional consortiums and identifying the key degraders to explore the underlying biological mechanisms of enriched contaminant-degrading consortia. IMPORTANCE Assembling a functional microbial consortium and identifying key degraders involved in the degradation of 1,4-dioxane are crucial for the design of synergistic consortia used in enhancing the bioremediation of 1,4-dioxane-contaminated sites. However, due to the vast diversity of microbes, assembling a functional consortium and identifying novel degraders through a simple method remain a challenge. In this study, we reassembled 1,4-dioxane-degrading microbial consortia using a simple and easy-to-operate method by combining dilution-to-extinction and reculture techniques. We combined differential analysis of community structure and metabolic function and confirmed that Shinella species have a stronger 1,4-dioxane degradation ability than Xanthobacter species in the enriched consortium. In addition, a new dioxane-degrading bacterium was isolated, Shinella yambaruensis, which verified our findings. These results demonstrate that DTE and reculture techniques can be used beyond diversity reduction to assemble functional microbial communities, particularly to identify key degraders in contaminant-degrading consortia.

The release of 1,4-dioxane probably contributes to the deterioration of marine habitats, animal health, and human liver and kidneys. The formulation of 1,4-dioxane in glycols, which has been applied for dehumidifying agents in refineries, may need to be replaced to ensure public health. Further, it is necessary to identify and precisely determine the levels of 1,4-dioxane in glycols for food quality control and environmental safety regulation. The objectives of this study were to validate a liquid–liquid extraction (LLE) method for 1,4-dioxane analysis and to optimize the LLE conditions using a response surface methodology (RSM). With consideration of the food matrix and its applications, polyethylene glycol 200 was used as the model system and analyzed by gas chromatography with flame ionization detection. In the experiments for the optimum extraction temperature and time of 1,4-dioxane in ultrasonic treatment, they were 20 °C and 10 min, respectively. The experimental conditions and results were analyzed by RSM with the Box–Behnken design, and the optimal extraction conditions for the LLE were determined to be coded with three independent variables (sample weight, solvent volume, and centrifugation speed). The amount of 1,4-dioxane increased as the amount of sample increased, whereas the amount of 1,4-dioxane decreased as the amount of solvent increased. This information can help to find the analytical methods for regulating the 1,4-dioxane content and its precise quantification in food products. [ABSTRACT FROM AUTHOR]

A novel method to quantify 1,4‐dioxane in finished cleaning products using headspace gas chromatograph with mass spectrometry (HS GC/MS), single ion monitoring, and a fully deuterated internal standard has been developed. The method generates very linear calibration curves with a R2 of at least 0.99, excellent accuracy with spike/recovery of 97%–102%, and effective precision of 1%–7%RSD for different cleaning products. The method also produces an instrument limit of quantitation (LOQ) of <20 ppb, and sample LOQ of <100 ppb. The method robustness was demonstrated with a ten‐lab round‐robin exercise that showed that even with some unexpected deviations from the method, excellent analytical results were obtained from the different labs. This new method will be valuable to evaluate consumer products impacted by government regulation to limit 1,4‐dioxane concentrations in complex matrices. [ABSTRACT FROM AUTHOR]

This work reports the development of novel curcuminoid-based electrochemical sensors for the detection of environmental pollutants from water. In this study, the first set of electrochemical experiments was carried out using curcumin-conjugated multi-walled carbon nanotubes (MWCNT–CM) for 1,4-dioxane detection. The MWCNT–CM/GCE showed good sensitivity (103.25 nA nM−1 cm−2 in the linear range 1 nM to 1 µM), with LOD of 35.71 pM and LOQ of 108.21 pM. The second set of electrochemical experiments was carried out with bisdemethoxy curcumin analog quantum dots (BDMCAQD) for hydrazine detection. The BDMCAQD/GCE exhibited good sensitivity (74.96 nA nM−1 cm−2 in the linear range 100 nM to 1 µM), with LOD of 10 nM and LOQ of 44.93 nM. Thus, this work will serve as a reference for the fabrication of metal-free electrochemical sensors using curcuminoids as the redox mediator for the enhanced detection of environmental pollutants.

The occurrence of 1,4-dioxane in the water has received significant attention due to its possible adverse effects to the environment and human health. The conventional techniques used for wastewater treatment are insufficient for the complete removal of 1,4-dioxane. Therefore, there is a need to develop technologies that can provide higher and faster 1,4-dioxane degradation capabilities. In this study, Electrochemical oxidation of 1,4-dioxane in laboratory water and electroplating industry wastewater was carried out in batch and plug flow reactor (PFR) configurations. Different process parameters were investigated and process optimization was performed. For the batch reactor, complete degradation of 1,4-dioxane from laboratory water was observed in 40 min with a pseudo-first order rate constant of 0.1076 min−1. For the simulated plating industry wastewater, 85.4% 1,4-dioxane was removed, while TOC and COD removals were 51% and 79%, respectively. For the PFR, 91% 1,4-dioxane degradation were observed for simulated wastewater, while COD removal was 99%. Since the electrochemical PFR showed the best performance, plating industry wastewater was treated via PFR under optimized conditions where 83% 1,4-dioxane degradation was achieved. Metal removals from the wastewater were also ranged between 88 and 99% via PFR. The electrical energy per order (EE/O) value of electrochemical treatment of 1,4-dioxane via electrochemical PFR was 6.62 kWh/m3 during the treatment of plating wastewater. 1,4-dioxane-2-one and 1,4-dioxane-2-ol were identified for the first time during electrochemical treatment of plating wastewater. [ABSTRACT FROM AUTHOR]

The potential of a native digestate microbial community for 1,4-dioxane (DX) biodegradation was evaluated under low dissolved oxygen (DO) concentrations (1–3 mg/L) under different conditions in terms of electron acceptors, co-substrates, co-contaminants and temperature. Complete DX biodegradation (detection limit of 0.01 mg/L) of initial 25 mg/L was achieved in 119 days under low DO concentrations, while complete biodegradation happened faster at 91 and 77 days, respectively in nitrate-amended and aerated conditions. In addition, conducting biodegradation at 30 ˚C showed that the time required for complete DX biodegradation in unamended flasks reduced from 119 days in ambient condition (20–25 °C) to 84 days. Oxalic acid, which is a common metabolite of DX biodegradation was identified in the flasks under different treatments including unamended, nitrate-amended and aerated conditions. Furthermore, transition of the microbial community was monitored during the DX biodegradation period. While the overall richness and diversity of the microbial community decreased, several families of known DX-degrading bacteria such as Pseudonocardiaceae, Xanthobacteraceae and Chitinophagaceae were able to maintain and grow in different electron-accepting conditions. The results suggested that DX biodegradation under low DO concentrations, where no external aeration was provided, is possible by the digestate microbial community, which can be helpful to the ongoing research for DX bioremediation and natural attenuation. Highlights: 1,4-dioxane was completely degraded by the native digestate microbial community. Biodegradation rate increased in nitrate-amended and aerated conditions. Trichloroethylene and temperature affected 1,4-dioxane biodegradation rate. Overall richness and diversity of the microbial community decreased. Pseudonocardiaceae, Xanthobacteraceae and Chitinophagaceae were DX-degraders. [ABSTRACT FROM AUTHOR]

The aim of the work was to analyze the preferential solvation process, and determine the composition of the solvation shell of cyclic ethers using the calorimetric method. The heat of solution of 1,4-dioxane, 12-crown-4, 15-crown-5 and 18-crown-6 ethers in the mixture of N-methylformamide with water was measured at four temperatures, 293.15 K, 298.15 K, 303.15 K, and 308.15 K, and the standard partial molar heat capacity of cyclic ethers has been discussed. 18-crown-6 (18C6) molecules can form complexes with NMF molecules through the hydrogen bonds between –CH3 group of NMF and the oxygen atoms of 18C6. Using the model of preferential solvation, the cyclic ethers were observed to be preferentially solvated by NMF molecules. It has been proved that the molar fraction of NMF in the solvation shell of cyclic ethers is higher than that in the mixed solvent. The exothermic, enthalpic effect of preferential solvation of cyclic ethers increases with increasing ring size and temperature. The increase in the negative effect of the structural properties of the mixed solvent with increase in the ring size in the process of preferential solvation of the cyclic ethers indicates an increasing disturbance of the mixed solvent structure, which is reflected in the influence of the energetic properties of the mixed solvent. [ABSTRACT FROM AUTHOR]

A novel, direct Csp3−Csp3 coupling reaction of β‐chlorophenone with alkanes using 2‐(tert‐butylperoxy)‐2‐methylpropane (DTBP) as the oxidant and 2,2′‐bipyridine (bpy) as the effective additive was developed. A variety of β‐chloropropiophenones were well tolerated, and afforded alkylated products in moderate to good yields. A mechanistic study indicated a free radical pathway was involved in this alkyl‐alkyl cross‐coupling reaction. [ABSTRACT FROM AUTHOR]

1,4-Dioxane is a contaminant of emerging concern and a probable human carcinogen that has been widely detected in aqueous environments. However, the removal of 1,4-dioxane by conventional water and wastewater treatment plants had proven to be ineffective due to its unique physicochemical properties. The development of innovative technologies for both in-situ and ex-situ treatment of 1,4-dioxane to meet increasingly strict standards is in urgent need. This review summarizes the current available physicochemical and biological treatment technologies for the removal of 1,4-dioxane from both water and wastewater and the strategies that may potentially fulfill the stringent 1,4-dioxane standard were discussed. Advanced oxidation processes (AOPs), such as ultraviolet radiation coupled with H2O2 (8–10 mg L−1), had shown efficient 1,4-dioxane destruction and had already been applied for both water and wastewater treatment processes. On the other hand, more than 30 pure microbial strains and microbial communities that can metabolically or metabolically degrade 1,4-dioxane were reported. Biodegradation has been proven to be a feasible and cost-effective approach for 1,4-dioxane remediation. Suspended growth bioreactor, immobilized cell bioreactor, and biofiltration systems were the most commonly used biological approaches to remove 1,4-dioxane from contaminated water. Though 1,4-dioxane easily desorbs after the adsorption by materials such as granular activated carbon (GAC) and zeolite, temporary 1,4-dioxane removal by adsorption followed by 1,4-dioxane biodegradation in the bioaugmented adsorption media may be a feasible strategy treating 1,4-dioxane contaminated water. Overall, the treatment chain that combines physical-chemical processes and biodegradation has a great potential for synergistic removal of 1,4-dioxane at lower operating costs. [ABSTRACT FROM AUTHOR]

Ultraviolet advanced oxidation processes (UV-AOPs) were compared using sodium perborate (UV/NaBO3 AOP) or hydrogen peroxide (UV/H2O2 AOP) for 1,4-dioxane removal from tertiary wastewater effluent. Both UV-AOPs were also tested with the addition of acetic acid. Results revealed that sodium perborate performed similarly to hydrogen peroxide. The UV/NaBO3 AOP with 6 milligrams per liter (mg/L) as H2O2 resulted in 43.9 percent 1,4-dioxane removal, while an equivalent UV/H2O2 AOP showed 42.8 percent removal. Despite their similar performance, NaBO3 is approximately 3.3 times more expensive than H2O2. However, the solid form of NaBO3 can provide a major benefit to remote and mobile operations. Unlike H2O2 solution, which degrades over time and requires repeated costly shipments, NaBO3 is a convenient source of H2O2, and a long-term supply can be shipped at once and mixed into solution as needed. The addition of acetic acid to a UV/H2O2 AOP was found to enhance 1,4-dioxane removal, increasing treatment effectiveness by 5.7%. [ABSTRACT FROM AUTHOR]

1,4-dioxane is a potential carcinogen in water and is difficult to deal with due to its robust cycloether bond and complete miscibility with water. To remove 1,4-dioxane in an economically viable and environmentally friendly way, a series of carbon aerogels were synthesized as adsorbents for 1,4-dioxane. The experiment results showed that adsorption performances were closely related to the preparation conditions of carbon aerogels, such as the molar ratio, heating rate, pyrolysis temperature and residence time, which were carefully controlled. Scanning electron microscope analysis revealed the presence of a three-dimensional porous network structure in carbon aerogels. Brunauer–Emmett–Teller analysis results demonstrated an increase in specific surface area (673.89 m2/g) and total pore volume after carbonization, with an increase in mesoporous porosity and a decrease in microporosity. When considering each variable individually, the highest specific surface area of prepared carbon aerogels was achieved at a pyrolysis temperature of 800 °C, a holding time of 1 h, and a heating rate of 2 °C/min. Under optimal experimental conditions, the adsorption removal of 1,4-dioxane by carbon aerogels exceeded 95%, following quasi-second-order kinetics and Langmuir isothermal adsorption isotherms, indicating that monolayer adsorption on the surface of carbon aerogels occurred. The maximum adsorption capacity obtained was 67.28 mg/g at a temperature of 318 K, which was attributed to the presence of a large proportion of mesopores and abundant micropores simultaneously in carbon aerogels. Furthermore, with the interference of chlorinated solvents such as trichloroethylene (TCE), the removal efficiency of 1,4-dioxane had no obvious inhibition effect. Regeneration experiments showed that after five continuous cycles, the carbon aerogels still kept a comparable adsorption capacity, which illustrates its potential application in 1,4-dioxane-polluted water purification.