Industrial Surfactants Research Articles

The mechanism of cytotoxicity of 4-nonylphenol in a human hepatic cell line involves ER-stress, apoptosis, and mitochondrial dysfunction.

4-Nonylphenol (4-NP) is an emerging environmental pollutant widely diffused in waters and sediments. It mainly derives from the degradation of alkyl phenol ethoxylates, compounds commonly employed as industrial surfactants. 4-NP strongly contaminates foods and waters for human use; thus, it displays a wide range of toxic effects not only for aquatic organisms but also for mammals and humans. After ingestion through the diet, it tends to accumulate in body fluids and tissues. One of the main organs where 4-NP and its metabolites are concentrated is the liver, where it causes, even at low doses, oxidative stress and apoptosis. In the present study, we analyzed the effects of 4-NP on a human hepatic cell line (HepG2) to deepen the knowledge of its cytotoxic mechanism. We found that 4-NP, in a range of concentration from 50 to 100 μM, significantly reduced cell viability; it caused a partial block of proliferation and induced apoptosis with activation of caspase-3 and overexpression of p53. Moreover, 4-NP induced-apoptosis seemed to involve both an ER-stress response, with the appearance of high level of GRP78, CHOP and the spliced XBP1, and a dysregulation of mitochondrial physiology, characterized by an overexpression of main markers of mitochondrial dynamics. Our data support the idea that a daily consumption of 4-NP-contaminated foods may lead to local damages at the level of gastrointestinal system, including liver, with negative consequences for the organ physiology.

Integrative omics analysis reveals the protective role of vitamin C on perfluorooctanoic acid-induced hepatoxicity

IntroductionPerfluorooctanoic acid (PFOA) is a compound used as an industrial surfactant in chemical processes worldwide. Population and cross-sectional studies have demonstrated positive correlations between PFOA levels and human health problems. ObjectivesMany studies have focused on the hepatotoxicity and liver problems caused by PFOA, with little attention to remediation of these problems. As an antioxidant, vitamin C is frequently utilized as a supplement for hepatic detoxification. MethodsIn this study, we use a mouse model to study the possible role of vitamin C in reducing PFOA-induced liver damage. Based on comparative transcriptomic and metabolomic analysis, we elucidate the mechanisms underlying the protective effect of vitamin C. ResultsOur results show that vitamin C supplementation reduces signs of PFOA-induced liver damage including total cholesterol and triglyceride levels increase, liver damage markers aspartate, transaminase, and alanine aminotransferase elevation, and liver enlargement. Further, we show that the protective role of vitamin C is associated with signaling networks control, suppressing linoleic acid metabolism, reducing thiodiglycolic acid, and elevating glutathione in the liver. ConclusionThe findings in this study demonstrate, for the first time, the utility of vitamin C for preventing PFOA-induced hepatotoxicity.

Synthesis of alkyl phosphates and investigation of their surface-active properties in an alkaline surfactant polymer system for enhanced oil recovery

Chemical flooding is a technique of enhanced oil recovery (CEOR) using formulations containing alkaline components, surfactants and polymers (ASP technology). The development and synthesis of novel highly efficient industrial surfactants take this technology to a new level, allowing the chemical composition of reagents to be tailored to the reservoir conditions of fields in Western Siberia. Alkyl phosphates with various structures are one type of the surfactants that can be used in ASP technology. This work aimed to synthesize and examine the properties of commercial (semi-industrial) alkyl phosphates and alkoxylated alkyl phosphates of mixed composition that meet the requirements of an efficient surfactant component of an ASP-flooding formulation. The synthesis was carried out using industrial fatty alcohols by the phosphating reaction with phosphorus pentoxide. A mixture of monoand disubstituted phosphoric acid esters of a defined ratio can be obtained by target tailoring of the feedstock properties (structural changes, molecular weight distribution in alcohols) and the synthesis conditions. This mixture, requiring no addition of cosurfactants, is an effective multi-component surfactant for an ASP-system. In this work, three effective alkyl phosphates and alkoxylated alkyl phosphates blends were synthesized. The composition of the synthesized phosphoric esters was evaluated by high-resolution mass spectrometry (HRMS), infrared (IR) spectroscopy and potentiometric titration. At reservoir temperature, the obtained samples provided sufficient solubility in an oil-displacing aqueous solution in the technologically required salinity interval, compatibility with other components, low interfacial tension (IFT) values at the interface between ASP solution and oil from Western Siberia fields, and the formation of the sufficient volume of the emulsion phase in a phase experiment. The primary laboratory research data proved the efficiency of the synthesized surfactants in ASP technology in the fields of Western Siberia.

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.

Legacy and Emerging Per- and Polyfluoroalkyl Substances: Analytical Techniques, Environmental Fate, and Health Effects

Due to their unique chemical properties, per- and polyfluoroalkyl substances (PFAS) have been used extensively as industrial surfactants and processing aids. While several types of PFAS have been voluntarily phased out by their manufacturers, these chemicals continue to be of ecological and public health concern due to their persistence in the environment and their presence in living organisms. Moreover, while the compounds referred to as “legacy” PFAS remain in the environment, alternative compounds have emerged as replacements for their legacy predecessors and are now detected in numerous matrices. In this review, we discuss the historical uses of PFAS, recent advances in analytical techniques for analysis of these compounds, and the fate of PFAS in the environment. In addition, we evaluate current biomonitoring studies of human exposure to legacy and emerging PFAS and examine the associations of PFAS exposure with human health impacts, including cancer- and non-cancer-related outcomes. Special focus is given to short-chain perfluoroalkyl acids (PFAAs) and ether-substituted, polyfluoroalkyl alternatives including hexafluoropropylene oxide dimer acid (HFPO-DA; tradename GenX), 4,8-dioxa-3H-perfluorononanoic acid (DONA), and 6:2 chlorinated polyfluoroethersulfonic acid (6:2 Cl-PFESA; tradename F-53B).

К ВОПРОСУ ОБ ЭКОТОКСИЧНОСТИ И ЭФФЕКТИВНОСТИ РАЗЛИЧНЫХ КЛАССОВ ПРОМЫШЛЕННЫХ НЕИОНОГЕННЫХ ПАВ, ИСПОЛЬЗУЕМЫХ ПРИ ОЧИСТКЕ МЕТАЛЛИЧЕСКИХ ПОВЕРХНОСТЕЙ В ПРОЦЕССЕ КАПИЛЛЯРНОГО КОНТРОЛЯ ДЕТАЛЕЙ АВИАЦИОННОЙ ТЕХНИКИ (обзор)

A review of modern classes of nonionic surfactants used for cleaning metal surfaces is carried out. The following aspects are considered: efficiency of cleaning metal surfaces, ecotoxicity, biodegradability, impact on human health. The most promising class of surfactants – alkyl polyglycosides (APG) – for cleaning metal surfaces, including in the process of capillary control, has been determined. It is noted that APGs have shown high efficiency in removing even such contaminants as denatured protein and burnt corn starch from metal surfaces. In addition, APGs have the highest emulsifying ability among industrial surfactants, which effectively affects the reduction in surfactant consumption when cleaning the surfaces.

Effect of pH or Metal Ions on the Oil/Water Interfacial Behavior of Humic Acid Based Surfactant.

Humic acid, a kind of widespread organic macromolecule on earth, is naturally formed through the microbial biodegradation of plant, animal, and microorganism residues. Because of the large number of active functional groups (phenolic hydroxyl and carboxyl), humic acid has been considered as a biocompatible, green, and low-cost biosurfactant recently. In this work, based on the sensitivity of humic acid to the external chemical environment, the oil/water interfacial behavior of sodium humate at different pH or in the presence of metal ions is closely investigated. Sodium humate is significantly enriched toward the oil/water interface at either low pH or high metal-ion concentration to adjust the properties of the prepared emulsion, but the mechanisms are proved to be different when considering the influence of pH and metal ions. Besides, to the best of our knowledge, humic acid based surfactant is proposed as a Pickering emulsifier for the first time, known as solid surfactant. This work promises the great potential of humic acid as a natural environment-responsive surfactant and has important implications for the application of humic acid based surfactant in industry and understanding of the role of humic acid in the natural environment.

Emulsifying Properties of an Homologous Series of Medium- and Long-Chain d-Maltotriose Esters and their Impacts on the Viabilities of Selected Cell Lines

The development of functional as well as nutritional surfactants for the food industry remains a matter of great interest. In the present study, a series of 6″-O-acylmaltotriose monoesters bearing alkyl side chains of 10-18 carbons was prepared by enzymatic means. The emulsions derived from those monoesters incorporating palmitoyl, stearoyl, and oleoyl side chains generally displayed advantageous shelf-lives, superior resistance to environmental variations, and more favorable droplet size distributions as well as stronger cytotoxic effects against various cancer cell lines. Ester 6 was shown to significantly inhibit the proliferation of MCF-7 breast cancer cells by inducing G1 phase arrest. Specifically, the levels of the G1 phase-related markers cyclin D1 and cyclin E as well as the cycle-dependent kinase 4 were suppressed by this particular ester. This study thus reveals that maltotriose esters can not only serve as novel functional food emulsifiers but also act, in vitro, as notable cytotoxic agents through a well-defined mechanism-of-action.

PFAS (per- and polyfluoroalkyl substances) and asthma in young children: NHANES 2013–2014

Per- and polyfluoroalkyl substances (PFAS) are a class of persistent chemicals used as industrial surfactants, fire-fighting foams, and textile treatments. Early childhood exposure to perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS) may affect the immune system to increase the risk of allergic and respiratory diseases. However, there are substantial gaps in our knowledge about the relationship between PFAS and immune-mediated outcomes such as asthma in children. Thus, we examined the cross-sectional associations of serum PFOA, PFOS, PFNA, and PFHxS concentrations with childhood asthma. We used data from children aged 3-11 years who participated in the National Health and Nutrition Examination Survey (2013-2014). Serum PFAS concentrations were measured in serum using analytical chemistry methods. Asthma was assessed by parent-reported, doctor-diagnosed, asthma using a standardized questionnaire. Controlling for covariates, we estimated odds ratios for asthma per standard deviation increase in ln-transformed serum PFAS concentrations (n=607). We also examined effect measure modification by child age, sex, and race/ethnicity. PFOA (1.1; 95% CI: 0.8, 1.4), PFOS (1.2; 95% CI: 0.8, 1.7), PFNA (1.1; 95% CI: 0.8, 1.6), and PFHxS (1.1; 95% CI: 0.9, 1.6) were weakly associated with an increased odds of asthma. Age modified associations between serum PFOS, but not other serum PFAS concentrations, and odds of asthma (age x PFOS interaction term p-value=0.03). Sex and race/ethnicity did not modify these associations. We observed some evidence that serum PFAS concentrations are weakly associated with increased asthma prevalence in US children.

Interaction of Stabilized Alkylbenzene Sulfonate Surfactants on the Nanoscale with Water-Wet and Oil-Wet Carbonate Surfaces under High-Salinity and High-Temperature Conditions: A QCM-D Study.

Understanding the interactions of surfactants and wettability alteration of surfaces is important for many fields, including oil and gas recovery. This work utilizes the quartz crystal microbalance with dissipation to study the interaction of stabilized linear and branched alkylbenzene sulfonates (ABSs), among the most cost-efficient industrial surfactants, with water- and oil-wet calcite surfaces under high-salinity and high-temperature conditions. Confocal laser scanning microscopy is also used to study the effect of the type of ABS on their interaction with oil-wet calcite surfaces. Experiments demonstrate that vesicles made of linear and branched ABSs interact differently with both water- and oil-wet surfaces. Therefore, surfactant formulations made of ABSs for high-salinity applications can further be improved for advantageous wettability properties by varying the hydrophobic chain of the surfactants. When interacting with a water-wet surface, both types of vesicles adsorb onto the surface as is. Upon dilution, however, vesicles made of linear ABS stay adsorbed as is, and vesicles made of branched ABSs disassemble and produce a layered structure with altered wettability. Linear ABSs show greater efficiency in desorbing oil from the oil-wet calcite. The results of this study demonstrate an improved method for studying and understanding the interaction of surfactant formulations with water- and oil-wet surfaces. This approach could significantly benefit applications in which wettability alteration of surfaces is of great interest and facilitate the implementation of low-cost surfactants based on petroleum sulfonates.

Application of microbial extracellular carbohydrate polymeric substances in food and allied industries.

Extracellular polymeric substances (EPS) are biopolymers, composed of polysaccharides, nucleic acids, proteins and lipids, which possess unique functional properties. Despite significant strides made in chemical production processes for polymers, the niche occupied by exopolysaccharides produced by bacteria, yeast or algae is steadily growing in its importance. With the availability of modern tools, a lot of information has been generated on the physico-chemical and biological properties using spectrometric tools, while advanced microscopic techniques have provided valuable insights into the structural-functional aspects. The size of EPS generally ranges between 10 and 10,000kDa. The wide spectra of applications of EPS as adhesives, stabilizer, gelling, suspending, thickening agent, and surfactants in food and pharmaceutical industries are observed. The health benefits of these EPS enable the improvement of dual function, added value, and green products. This review summarizes previous work on the structural composition, rheological and thermal behaviour, and biosynthetic pathways of EPS and bioprocesses developed for their production. This review also considers each of the above factors and presents the current knowledge on the importance and refinement of available downstream protocols and genetic engineering towards specific food applications, which can help to diversify their prospects in different food and allied industries.

Insights into nonylphenol degradation by UV-activated persulfate and persulfate/hydrogen peroxide systems in aqueous matrices: a comparative study.

Nonylphenol ethoxylates are widely used industrial surfactants. Once released into environment compartments, these chemicals undergo degradation and generate more toxic short chain artificial compound nonylphenol (NP). The latter is a known endocrine disrupting compound and persistent micropollutant. In the present study, the performance of NP degradation in UV-induced PS, PS/Fe2+, PS/H2O2, and PS/H2O2/Fe2+ systems was examined. The effect of concentration of oxidant and activators on the efficiency of target compound decomposition was studied. The trials were conducted in ultrapure water and groundwater to assess the influence of matrix composition. The obtained results indicated that NP degradation by all the systems studied followed a pseudo-first-order kinetics. The application of UV-activated PS at lower concentrations of the oxidant improved NP oxidation in both water matrices. The addition of iron activator at a cost-effective concentration showed slight improvement in the studied PS-based systems. The application of UV-induced dual oxidant PS/H2O2 system demonstrated promising results in NP oxidation. In turn, the addition of Fe2+ to the UV/PS/H2O2 system accelerated the target compound oxidation at an optimized dose of iron activator. The radicals scavenging studies indicated that HO• was the predominant radical in all UV-induced PS-based systems. The results of this research could provide significant information for the removal of NP from different water matrices by means of UV-induced persulfate-based oxidation processes.

Determination of equivalent alkane carbon number for West Siberian oils as a stage of optimisation in surfactant-polymer compositions for chemical flooding

The hydrophobicity of and products can be characterised in terms of its equivalent alkane carbon number (EACN). This characteristic can be determined on the basis of the correlation between the interfacial tension data and other characteristics for homologous oils and a number of alkanes having subsequent interpretation for and products. The EACN is a useful metric for selecting an effective surfactant for the emulsification of and products. The research is aimed at determining the equivalent alkane car-bon number of various crude samples obtained in the fields of Western Siberia using standard high-performance compositions of imported and domestic industrial sulphonate surfactants. In order to determine the EACN of and products, the S* characteristic was applied representing the optimal NaCl concentration (optimum salinity) in the aqueous surfactant phase, as well as providing the minimum surface tension and formation of the maximum microemulsion volume during the phase experiment at the interface with the hydro-carbon phase. Direct determination of the interfacial tension at the oil / surfactant solution interface was car-ried out with a tensiometer using the spinning drop method at a temperature of 87 ° С . Linear dependencies are identified in accordance to the empirical correlation equations between the EACN, surfactant parameters and phase behaviour parameters of aqueous surfactant solutions and or a mixture of hydrocarbons. The K characteristic parameter of the proposed three standard surfactant compositions is determined to be consistent with the literature data for individual surfactants. The composition of industrial surfactants for determining the EACN of and products is proposed. The equations of linear regression for the logS* ~ EACN dependency with high correlation coefficients (R² = 0.9444-0.9999) are obtained, resulting in the determination of the EACN for kerosene and seven samples from Western Siberian fields. Promising surfactants can be selected on the basis of this indicator for reducing interfacial tension in the hydrocarbon / water solution system, as well as for predicting the most effective composition for obtaining emulsions.

Per- and Polyfluoroalkyl Substances Differentially Inhibit Placental Trophoblast Migration and Invasion InVitro.

Per- and polyfluoroalkyl substances (PFAS) are used as industrial surfactants and chemical coatings for household goods such as Teflon. Despite regulatory efforts to phase out legacy PFAS, they remain detectable in drinking water throughout the United States. This is due to the stability of legacy PFAS and the continued use of replacement compounds. In humans, PFAS have been detected in placenta and cord blood and are associated with low birth weight and preeclampsia risk. Preeclampsia is a leading cause of maternal mortality and is driven by insufficient endometrial trophoblast invasion, resulting in poor placental blood flow. PFAS alter invasion of other cell types, but their impact on trophoblasts is not understood. We therefore assessed the effects of PFAS on trophoblast migration, invasion, and gene expression in vitro. Trophoblast migration and invasion were assessed using a modified scratch assay in the absence or presence of Matrigel, respectively. Treatment with perfluorooctanoic sulfate (PFOS), perfluorooctanoic acid (PFOA), and GenX (1000 ng/ml) each decreased trophoblast migration over 24 h. However, only GenX (1000 ng/ml) significantly inhibited trophoblast invasion. Treatment with PFOS, PFOA, and GenX also decreased trophoblast expression of chemokines (eg, CCL2), chemokine receptors (eg, CCR4), and inflammatory enzymes (eg, ALOX15) involved in migration. Inhibition of chemokine receptors with pertussis toxin (10 ng/ml), a G-protein inhibitor, inhibited trophoblast migration similar to the PFAS. Taken together, PFAS decrease trophoblast migration, invasion, and inflammatory signaling. By understanding the mechanisms involved, it may be possible to identify the biological and exposure factors that contribute to preeclampsia.

Corn Oil-Water Separation: Interactions of Proteins and Surfactants at Corn Oil/Water Interfaces.

Purification and collection of industrial products from oil-water mixtures are commonly implemented processes. However, the efficiencies of such processes can be severely influenced by the presence of emulsifiers that induce the formation of small oil droplets dispersed in the mixtures. Understanding of this emulsifying effect and its counteractions which occur at the oil/water interface is therefore necessary for the improvement of designs of these processes. In this paper, we investigated the interfacial mechanisms of protein-induced emulsification and the opposing surfactant-induced demulsification related to corn oil refinement. At corn oil/water interfaces, the pH-dependent emulsifying function of zein protein, which is the major storage protein of corn, was elucidated by the surface/interface-sensitive sum frequency generation (SFG) vibrational spectroscopy technique. The effective stabilization of corn oil droplets by zein protein was illustrated and correlated to its ordered amide I group at the oil/water interface. Substantial decrease of this ordering with the addition of three industrial surfactants to corn oil-zein solution mixtures was also observed using SFG, which explains the surfactant-induced destabilization and coalescence of small oil droplets. Surfactant-protein interaction was then demonstrated to be the driving force for the disordering of interfacial proteins, either by disrupting protein layers or partially excluding protein molecules from the interface. The ordered zein proteins at the interface were therefore revealed to be the critical factor for the formation of corn oil-water emulsion.

Effects of synthesized nanoparticles and Henna-Tragacanth solutions on oil/water interfacial tension: Nanofluids stability considerations

Rising global energy demand has encouraged engineers to create and design new methods to improve oil recovery from reservoirs. In this study, feasibility of using Henna extract as a natural surfactant and synthesized nanoparticles (Titanium dioxide (TiO2), Silicon dioxide (SiO2), Graphene and composite of TiO2-Graphene) for reduction of oil-water interfacial tension has been experimentally investigated. Nanoparticles were synthesized via sol-gel method and XRD, FESEM, EDAX and FTIR tests were conducted to confirm the authenticity of this synthesizing materials. Nano-surfactants were stabled with a natural water-based suspending surfactant called Tragacanth extract, which could be introduced as a practical substitute for industrial nanoparticles' stabilizers in oil industry. After CMC determination of Henna extract surfactant, the optimal concentration of Tragacanth extract surfactant, with the purpose of nano-surfactants’ stabilization, was determined through particle size and zeta potential tests. Results of interfacial tension (IFT) measurements showed that the increase of Henna extract concentration from 0 wt% to 10 wt% reduced IFT between kerosene and water from 37.23 to 15.24 mN/m. Furthermore, adding 1 wt% of synthesized TiO2 nanoparticle to the Henna extract surfactant at its CMC value reduced IFT from 18.43 to 14.57 mN/m. As an impact of this significant reduction in IFT value, oil recovery factor could be improved drastically during EOR operations. Results proved that TiO2 nano-surfactant was as effective as industrial surfactants, which put human's and environment's health at risk and impose heavy economic strain on governments.

Direct and selective enzymatic synthesis of trehalose unsaturated fatty acid diesters and evaluation of foaming and emulsifying properties

Trehalose diesters are Gemini-type surfactants that might have better surface activity than conventional surfactants. A one-step method for the preparation of trehalose unsaturated fatty acid diesters has been successfully developed. The yield of trehalose diester of different unsaturated fatty acids was between 78 % and 88 % under optimal conditions: 25 mmol/L trehalose, 100 mmol/L unsaturated fatty acid, 60 g/L 3 Å molecular sieves and 20 g/L lipase at 150 rpm and 50 °C for 42 h in 15 mL of acetone. Additionally, trehalose diester was the sole product obtained with Novozym 435 in acetone. The chemical structures of 6,6′-di-O-oleoyltrehalose, 6,6′-di-O-linoleoyltrehalose, 6,6′-di-O-eicosenoyltrehalose and 6,6′-di-O-erucoyltrehalose were confirmed by FTIR, MS and NMR. Moreover, the hydrophile-lipophile balance (HLB) values, foaming properties and emulsifying properties of trehalose diesters were assessed, showing the potentials of these diesters as naturally derived surfactants for the food industry.

A comprehensive micro scale study of poly-ionic liquid for application in enhanced oil recovery: Synthesis, characterization and evaluation of physicochemical properties

Ionic liquids (ILs) have found their application as novel green surfactants in different chemical industries. These ILs are emerging as a substitute for the surfactants employed in petroleum industries. The quest for a reliable surface-active agent for enhanced oil recovery application has led to the investigation of polymeric ionic liquid as chemical agents. Poly-ionic liquids (PILs) are unique compounds that possess distinctive properties of ILs such as, thermal stability and salt tolerance, along with the specific property of polymers such as flexibility and durability of the polymeric backbone. In present work, poly [1-hexadecyl-3-vinyl-imidazolium bromide] (poly [C16VIm+][Br−]) was synthesized and investigated as a chemical agent for enhanced oil recovery. The interaction of PIL with aqueous injection fluids and crude oil has been analyzed by different properties such as interfacial tension, wettability alteration, dynamic light scattering (DLS), and rheological parameters, which help in understanding the performance of PIL flooding. Surface tensiometry studies revealed the critical micellar concentration (CMC) of PIL to be much lower (200 ppm) in comparison to analogous ILs. The synthesized poly-ionic liquid showed good salt tolerance behavior (>10%) and long-term thermal stability (90 °C) in the presence of monovalent and divalent ions, thus confirming its applicability in the high saline reservoir. Highly beneficial low interfacial tension (IFT) values were obtained at crude oil-aqueous interfaces, which further decreased with an increase in salinity and temperature. DLS studies revealed that hydrodynamic particle size of PIL at CMC to be ~180 nm and it increased with concentration due to aggregation of molecules. PIL showed pseudoplastic or shear-thinning behavior, and viscosity increased with concentration due to the formation of transient network and entanglement of molecules. Contact angle studies showed that poly [C16VIm+][Br−] aqueous solution alters the wetting characteristics of rock from intermediate-wet to water-wet condition (below 20°). Analyzing the above properties, core-flooding experiments were conducted, and additional oil recovery of 31.25% of the original oil in place was obtained after the conventional water flooding.

Adsorptive removal of surfactant using dolochar: A kinetic and statistical modeling approach.

Disturbingly high rates of consumption of surfactants in household and industries have led to mark them as emerging contaminants in the environment. In the present work, removal of sodium dodecyl sulfate (SDS), an anionic surfactant, using an industrial waste (dolochar) was explored. The adsorbent material was characterized with the help of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Kinetic evaluation was performed using first, pseudo-first, second, and pseudo-second order models. Adsorption of SDS over dolochar was expressed best by pseudo-second order kinetic model with regression coefficient (R2 ) of .99. Three input parameters including adsorbent dose (20-10g/L), initial concentration (30-100mg/L) of the surfactant, and contact time (2-60min) were chosen for optimization using response surface methodology based on Box-Behnken design (BBD) approach. A total of 15 experiments were run to examine the effect of these variables on removal of SDS by dolochar in a multivariate system. A regression analysis indicated the experimental data fitted well to a quadratic polynomial model with coefficient of regression (R2 ) as .99. ANOVA and lack-of-fit test depicted the precision and efficiency of the model. The optimized conditions for SDS removal were found to be adsorbent dose 16.62g/L, contact time 40min, and initial concentration 47mg/L with removal efficiency as 98.91%. PRACTITIONER POINTS: Daily ablutions and use of personal care products introduce a number of surfactants and recalcitrant compounds into the environment. Adsorption is a handy and easy to operate treatment technique to remove graywater pollutants. Kinetic and statistical modeling may be recommended as one of the most prominent tools to understand the removal mechanism. Decentralized treatment of graywater using industrial wastes is recommended as sustainable solution in the developing nations.

Derivation of a chronic reference dose for perfluorohexane sulfonate (PFHxS) for reproductive toxicity in mice

Perfluorohexane sulfonate (PFHxS) is a six-carbon perfluoroalkyl sulfonic acid that was used as an industrial surfactant, but is now found as an environmental contaminant worldwide. In addition to its use as an industrial surfactant, it is a legacy contaminant from the use of aqueous film-forming foams. Despite its widespread occurrence in the environment and evidence of biological activity associated with PFHxS and similar perfluoroalkyl sulfonic acids in rodents, there is no oral toxicity value currently available from the IRIS Database. To derive an oral reference dose (RfD) for PFHxS, available toxicity studies were reviewed using a weight-of-evidence approach. A 42-day mouse reproductive study was chosen as the critical study for the derivation of the oral RfD. Benchmark dose modeling was utilized to derive a point of departure (POD) for a reduction in litter size. A 95% lower confidence limit on the benchmark dose (BMDL) of 13,900 ng/mL (serum PFHxS) was modeled for a reduction in litter size. An oral RfD for PFHxS of 4.0 ng/kg/d was calculated by conversion of the BMDL to a human equivalent oral dose using a human half-life adjusted dosimetric conversion factor and the application of a total uncertainty factor of 300. Additional research is needed to better characterize the toxicity associated with oral exposure to PFHxS and refine the development of toxicity values.