Concentration In Aqueous Phase Research Articles

Partitioning of surfactant into drug-rich nanodroplets and its impact on drug thermodynamic activity and droplet size

The excipients present in an amorphous solid dispersion (ASD) are essential functional additives that ultimately influence the drug release performance and absorption. Herein, the effect of a polymer, hypromellose (HPMC), and three chemically diverse surfactants, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and polyoxyethylene sorbitan monooleate (Tween 80, Tween), on the size and stability of the colloidal ketoprofen (KTP)-rich phase generated by liquid-liquid phase separation was evaluated. In addition, the impact of the excipients on the thermodynamic activity of KTP at concentrations in excess of the amorphous solubility was evaluated. Dynamic light scattering measurements showed that using surfactant alone did not effectively suppress coarsening of the KTP-rich phase. In contrast, the combined use of surfactant and HPMC maintained the KTP-rich droplet size at around 200 nm, which was smaller than in HPMC solutions without surfactant. Solution nuclear magnetic resonance spectroscopy revealed that HPMC distributed into the KTP-rich phase, leading to a reduced thermodynamic activity of KTP, and a consequent decrease in the maximum achievable aqueous phase concentration. Moreover, substantial amounts of both CTAB and Tween distributed into the KTP-rich phase from the aqueous phase, while SDS remained predominantly in the aqueous phase. The combined use of HPMC with CTAB or Tween resulted in a further decrease in the thermodynamic activity of KTP relative to in the presence of HPMC alone, due to the mixing of both HPMC and surfactant with the KTP-rich phase. In contrast, the addition of SDS did not reduce the thermodynamic activity of KTP because of the limited distribution of SDS into the KTP-rich phase. A reduction in KTP thermodynamic activity translated to a decreased supersaturation and hence a reduction in the maximum achievable membrane flux. The present study illustrates the complex effects of surfactant and polymer on drug thermodynamic activity, factors which should be considered when optimizing ASD formulations to maximize oral drug absorption. Ideally, excipients that do not substantially impact drug thermodynamic activity should be selected, in particular for drugs where achieving high supersaturation is critical to drive their absorption.

Chemical speciation of mercury, sulfur and iron in a dystrophic boreal lake sediment, as controlled by the formation of mackinawite and framboidal pyrite

The chemical speciation of mercury (Hg), methyl mercury (MeHg), sulfur and iron was investigated in the sediment and porewater of Lake Ängessjön, a boreal, shallow (maximum depth 2.5 m), oligo-/dystrophic lake in northern Sweden. The lake receives terrestrial stream runoff from surrounding coniferous forest soils and peatlands having a low pH (4.6) and high concentrations of dissolved organic matter (DOM, annual average: 45 mg L−1), Fe (60 µM), sulfate (105 µM), inorganic Hg (1200 pM) and MeHg (250 pM). Sulfur K-edge XANES and Hg LIII-edge EXAFS spectroscopic measurements were used to characterize and quantify the sulfur speciation in the lake sediment at nine occasions, covering different seasons in the years of 2007 and 2009. In the surface sediment (0–3 cm) sulfate is reduced to zero-valent S and inorganic sulfide, that in turn reacts with Fe to form FeSm (mackinawite) and FeS2 (framboidal pyrite). The latter mineral becomes increasingly dominant by depth in the sediment. Thermodynamic modeling successfully predicted measured porewater concentrations of Hg in the sediment. Metacinnabar (β-HgS) and Hg(NOM-RS)2 complexes (the latter formed as a reaction between Hg(II) and thiol groups associated with natural organic matter, NOM-RSH) were the dominant forms of Hg(II) in the solid phase of sediments and Hg(II)-polysulfides (aq) dominated in the porewater. We argue that FeSm is a key component that indirectly controlled the Hg(II) speciation in the sediment by keeping the aqueous phase concentration of inorganic sulfide in the 0.5–2 µM range throughout the year. Besides providing a pool of readily soluble inorganic sulfide for formation of β-HgS(s), as demonstrated by previously reported EXAFS experiments, we further suggest FeSm may serve as a precursor for the formation of a more crystalline (less soluble) β-HgS(s) phase than present in environments devoid of FeSm. Support for this was provided by comparing our results with previously reported thermodynamic modelling results of Hg(II) and MeHg solubility in organic soils devoid of FeSm. In more general terms, we suggest the presence or absence of FeSm, through its influence on the chemical speciation of Hg and MeHg, may be a key factor behind the variability in rates of Hg(II) and MeHg transformation processes, such as methylation, reduction and demethylation, reported for different environmental settings.

Rheology and Catastrophic Phase Inversion of Emulsions in the Presence of Starch Nanoparticles

Emulsions stabilized by solid nanoparticles, referred to as Pickering emulsions, are becoming increasingly important in applications as they are free of surfactants. However, the bulk properties and stability of Pickering emulsions are far from being well understood. In this work, the rheological behavior and catastrophic phase inversion of emulsions in the presence of starch nanoparticles were studied using in-situ measurements of viscosity and electrical conductivity. The aqueous phase consisting of starch nanoparticles was added sequentially in increments of 5% vol. to the oil phase under agitation condition to prepare the emulsions. The emulsions were water-in-oil (W/O) type at low to moderate concentrations of aqueous phase. At a certain critical volume fraction of aqueous phase, catastrophic phase inversion of W/O emulsion to oil-in-water (O/W) emulsion took place accompanied a sharp jump in the electrical conductivity and a sharp drop in the emulsion viscosity. The W/O emulsions were nearly Newtonian at low concentrations of aqueous phase. At high concentrations of aqueous phase, prior to phase inversion, the W/O emulsions exhibited a shear-thickening behavior. The O/W emulsions produced after phase inversion were shear-thinning in nature. The comparison of the experimental viscosity data with the predictions of emulsion viscosity model revealed only partial coverage of droplet surfaces with nanoparticles. With the increase in the concentration of starch nanoparticles (SNPs) in the aqueous phase of the emulsions, the phase inversion of W/O emulsion to O/W emulsion was delayed to higher volume fraction of aqueous phase. Thus SNPs imparted some stability to W/O emulsions against coalescence and phase inversion.

Increasing Efficiency of Copper-Molybdenum Ore Flotation using Measurement of Pulp Absorption Capacity

A promising line in development of reagent consumption automatic control systems is applying data on measuring collector concentration in the pulp aqueous phase. For effective using data on the concentration of the nonionic collector – allyl ester of amylxanthogenic acid – in the process of flotation, the studies were carried out and the method for analyzing its residual concentration in the flotation pulp liquid phase was developed. The developed spectral technique for measuring the concentration of amylxanthogenic acid allyl ester in the pulp aqueous phase showed stable results in the temperature range of 10 to 25 °С, pH range of 8.5 to 11.0. This allowed applying the technique to measuring residual concentration of AeroMX- 5140 collector in the operation of bulk sulphide flotation in copper-molybdenum ore beneficiation. The laboratory tests allowed determining connection between the indicators of residual concentration with the main indicators of copper-molybdenum flotation. The studies showed that increasing the residual concentration of the non-ionic collector occurs with increasing its consumption and pH of the pulp aqueous phase. It is shown that significant increase in metal recoveries is observed at similar residual collector concentrations: for copper, in the range of 0.25 to 0.5 mg/l, and for molybdenum and pyrite iron, at the concentrations from 0.25 to 1 mg/l. The possibility of using the nonionic collector residual concentration as the informational indicator of the flotation process has been substantiated. It is proposed to use the ore absorption capacity in relation to the collector applied as an indicator of the ore grade. It is shown that using this indicator reduces relative variance for the dependences of the yields of individual ore types and increases the accuracy of determining the composition of the processed ore as a mixture of typical ore grades. An algorithm for automated control of the consumption of flotation reagents based on the advanced control of the processed ore elemental and mineral composition was developed and tested at Erdenet GOK processing plant, with the calculation of the pulp absorption capacity in relation to the nonionic collector, including the beneficiation process indicators determination using an economically-oriented optimization criterion. The expected economic effect from the reduction of metal losses amounted to USD 145 thous.

Sorption and desorption of pendimethalin alone and mixed with adjuvant in soil and sugarcane straw

Sugarcane straw may work as a physical barrier for pre-emergent herbicides and interact with their molecules, increasing sorption process. Adjuvants may change herbicides dynamics in the environment and improve their efficiency for weed control. The objective of this work was to evaluate sorption and desorption of pendimethalin alone and in mixture with adjuvant in soil and sugarcane straw. Sorption experiments were performed using pendimethalin alone and in mixture with vegetable oil with herbicide solution concentrations ranging between 2.5 and 40 μg mL−1 for both conditions. Sorption distribution coefficient (Kd) for soil was 18.48 mL g−1 using pendimethalin alone. Kd value was not determined when pendimethalin was in mixture with adjuvant due to the complete retention of the herbicide in the soil regardless of the initial aqueous phase concentration. Sugarcane straw sorption experiment had Kd values corresponding to 355.52 and 27.24 mL g−1 for pendimethalin alone and in mixture with adjuvant, respectively, indicating the addition of vegetable oil may significantly decrease pendimethalin retention in the straw and could improve weed control. Besides all desorption coefficients were higher than the respective sorption coefficients, which means that the sorption process may be considered irreversible.

Bioaccumulation of estrogenic hormones and UV-filters in red swamp crayfish (Procambarus clarkii)

Estrogenic hormones and organic ultraviolet-filters (UV-filters) have attracted increased attention as endocrine disrupting chemicals (EDCs) due to their potent estrogenicity and widespread occurrence in the environment. This study investigated the accumulation of three estrogenic hormones and five UV-filters in red swamp crayfish (Procambarus clarkii). Exposure experiments were conducted for 42 days with a mixture of EDCs at two environmentally-relevant design concentrations (i.e., 500 and 5000 ng L−1). The aqueous-phase EDC concentrations decreased over time and were re-established every two days. Within 14 days of exposure, the five UV-filters were measured at 2.2 to 265 ng g−1 (dry weight) in crayfish tail tissue. Only one estrogenic hormone, 17β-estradiol, was detected in the crayfish at 10.4–13.5 ng g−1. No apparent changes were observed for EDC concentrations in the tail tissue over the next four weeks of exposure. The apparent bioaccumulation factors for the EDCs ranged from 23 L (kg tail tissue, dry weight)−1 for 4-methylbenzylidene camphor to 1050 L (kg tail tissue, dry weight)−1 for 2-ethylhexyl-4-methoxycinnamate. EDC input was stopped after 42 days, and the more hydrophobic UV-filters (i.e., octocrylene, 2-ethylhexyl-4-methoxycinnamate, homosalate) were found to be persistent throughout a 14-d elimination period. A lyticase-assisted yeast estrogen screen demonstrated that the residual estrogenic activity of water samples aligned with (or was lower than) predictions from targeted chemical analysis. These results suggest that the transformation products did not contribute significant estrogenicity, although further analysis of endocrine disruption outcomes in crayfish is recommended.

Analysis of Freeze-Thaw Behavior of Double (W1/O/W2) Emulsions by Differential Scanning Calorimetry: Effects of Inner Salt Concentration and Solid Fat Content

This work is focused on the study of freeze-thaw behavior of double (W1/O/W2) emulsions by the application of a cooling-heating-cooling cycle by differential scanning calorimetry. Emulsions were prepared with sodium caseinate as hydrophilic emulsifier in outer aqueous (W2) phase and sunflower oil (SO) and/or interesterified vegetable fat (VF) plus polyglycerol polyricinoleate as lipophilic emulsifier in lipid phase. The effects of sodium chloride concentration in inner aqueous (W1) phase and solid fat content in lipid phase were analyzed. In all cases, W1 phase froze at lower temperature than W2 phase because higher undercooling was required for the crystallization of inner water droplets. In the absence of VF, the system with low salt concentration showed water diffusion from undercooled W1 phase to frozen W2 phase at the first cooling stage, due to the lower vapor pressure of ice. However, at the second cooling stage, this phenomenon was not observed and partial recovery of inner water was detected, probably because of an osmotic effect. The increase of salt concentration allowed a higher retention of inner water after freezing of W2 phase, attributed to the lowered vapor pressure of W1 phase. The loss of inner water was also restrained or prevented by the presence of VF in lipid phase due to the immobilization of water droplets within a fat crystal network. The crystallization behavior of SO was related to inner water quantity and VF content. This study could be useful for the formulation of W1/O/W2 emulsions with enhanced freeze-thaw stability.

Oxacillin antibiotic removal from aqueous solution using nonionic micellar system or ionic liquid: a comparative study based upon experimental optimization and response surface methodology

Oxacillin antibiotic was removed from aqueous effluents using the biodegradable nonionic surfactant Triton X-114 (TX-114) and the ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([C4C1im]PF6). The experimental results of oxacillin extraction from aqueous solution according to the surfactant (Xt) or ionic liquid (XIL) concentration and temperature (T) were expressed by the following parameters: antibiotic extraction extent (E%), remaining antibiotic concentration (Xs,w), residual surfactant (Xt,w) or ionic liquid (XIL,w) concentration in aqueous phase after extraction, and volume fraction of coacervate at equilibrium (ϕc). High extraction yields were reached under optimal conditions: 99% for TX-114 and 89% using [C4C1im]PF6. The concentration of antibiotic in effluent was reduced by about 7-fold and 6-fold using TX-114 and [C4C1im]PF6, respectively. Sodium sulfate addition (3 wt%) increased E% from 20% to 88% at only 2 wt% of TX-114. Finally, solute stripping from the micellar phase using Winsor II microemulsion extraction was investigated. Thereby, 90% of the TX-114 in the micelle-rich phase was separated into the organic phase (Om).

A mechanism study on effects of bromide ion on mercury re-emission in WFGD slurry

The application of bromide-blended coal combustion technology can effectively improve the total mercury removal efficiency in coal-fired power plants. However, the effects of bromine introduced into WFGD slurry on the mercury re-emission process were still unclear. In this paper, the effects of Br- on mercury re-emission were studied in a bench-scale simulated WFGD system. The results indicated that Br- had an inhibitory effect on Hg0 re-emission. The mercury re-emission could be promoted with higher temperature, lower pH and moderate sulfite concentration in aqueous phase in the presence of Br-. The underlying mechanism of the inhibitory effect of Br- on Hg0 re-emission was proposed by combining experimental UV–visible spectra analyses with theoretical quantum chemistry calculations. It was found that the formation of BrnHgSO3n- (n = 1–3) complex and HgBr2 suppressed the reduction of Hg2+. The reason was that the BrnHgSO3n- complex and HgBr2 were more stable than HgSO3, whose decomposition is the main cause of mercury re-emission in WFGD in the solvent. Since the bromide-blended coal combustion technology can both oxidize elemental mercury and inhibit mercury re-emission, it has a good performance on mercury removal.

Treatment of non-ideality in the SPACCIM multiphase model – Part 2: Impacts on the multiphase chemical processing in deliquesced aerosol particles

Abstract. Tropospheric deliquesced particles are characterised by concentrated non-ideal solutions (“aerosol liquid water” or ALW) that can affect the occurring multiphase chemistry. However, such non-ideal solution effects have generally not yet been considered in and investigated by current complex multiphase chemistry models in an adequate way. Therefore, the present study aims at accessing the impact of non-ideality on multiphase chemical processing in concentrated aqueous aerosols. Simulations with the multiphase chemistry model (SPACCIM-SpactMod) are performed under different environmental and microphysical conditions with and without a treatment of non-ideal solutions in order to assess its impact on aqueous-phase chemical processing. The present study shows that activity coefficients of inorganic ions are often below unity under 90 % RH-deliquesced aerosol conditions and that most uncharged organic compounds exhibit activity coefficient values of around or even above unity. Due to this behaviour, model studies have revealed that the inclusion of non-ideality considerably affects the multiphase chemical processing of transition metal ions (TMIs), oxidants, and related chemical subsystems such as organic chemistry. In detail, both the chemical formation and oxidation rates of Fe(II) are substantially lowered by a factor of 2.8 in the non-ideal base case compared to the ideal case. The reduced Fe(II) processing in the non-ideal base case, including lowered chemical rates of the Fenton reaction (−70 %), leads to a reduced processing of HOx∕HOy under deliquesced aerosol conditions. Consequently, higher multiphase H2O2 concentrations (larger by a factor of 3.1) and lower aqueous-phase OH concentrations (lower by a factor of ≈4) are modelled during non-cloud periods. For H2O2, a comparison of the chemical reaction rates reveals that the most important sink, the reaction with HSO3-, contributes with a 40 % higher rate in the non-ideal base case than in the ideal case, leading to more efficient sulfate formation. On the other hand, the chemical formation rates of the OH radical are about 50 % lower in the non-ideal base case than in the ideal case, leading to lower degradation rates of organic aerosol components. Thus, considering non-ideality influences the chemical processing and the concentrations of organic compounds under deliquesced particle conditions in a compound-specific manner. For example, the reduced oxidation budget under deliquesced particle conditions leads to both increased and decreased concentration levels, e.g. of important C2∕C3 carboxylic acids. For oxalic acid, the present study demonstrates that the non-ideality treatment enables more realistic predictions of high oxalate concentrations than observed under ambient highly polluted conditions. Furthermore, the simulations imply that lower humidity conditions, i.e. more concentrated solutions, might promote higher oxalic acid concentration levels in aqueous aerosols due to differently affected formation and degradation processes.

Towards nanoformulations for skin delivery of poorly soluble API: What does indeed matter?

Loading sparingly soluble active pharmaceutical ingredients (API) and overcoming biological barriers are two challenging issues in the drug delivery and technology fields. In this work, we assessed the influence of composition on the ability of nanosized ethosomes to increase the apparent solubility and drug incorporation, as well as the skin penetration of two hydrophobic drugs, celecoxib and paclitaxel. Ethosomes were produced through the bottom-up method using ethanol injection, and APIs were added in supersaturated ethanolic solution. Variations in the composition of the aqueous phase (containing or not Tween 80 micelles) and phospholipid content (2 or 4%, w/v) were included to assess their effect on ethosomes characteristics and drug apparent solubility. Dynamic light scattering enabled monitoring the non-soluble API precipitation and indicated an increase in size (up to 500–1000 nm) and polydispersity (above 0.3). Soft and fast centrifugation at 5000g for 5 min enabled removal of non-soluble APIs, decreasing size and PDI to ~300–400 nm and 0.2–0.3, respectively. The nanoformulation incorporated ~60–90% of the API added, but short-term stability assays suggested precipitation of paclitaxel at 24–72 h. These results were evaluated by two factorial designs 22, and a significant effect of lecithin concentration on celecoxib solubilization was observed. A tendency of interaction between Tween 80 micelles presence and increased solubilization was observed for celecoxib but not paclitaxel. Higher amounts of celecoxib (~5-fold) were quantified in the stratum corneum and epidermis (minus stratum corneum) + dermis after treatment with ethosomes containing Tween 80 compared to those without the surfactant, but not in the receptor phase. For paclitaxel, presence of Tween 80 micelles did not affect delivery. This work evidenced the feasibility of the ethosomes developed to load poorly water soluble APIs and to deliver them to skin but suggest that this effect vary with composition and the API physicochemical characteristics. Nanocarrier composition and level of molecular complexity and characteristics of APIs are factors that can interact and generate distinctive effects on both API solubilization and delivery to/across the skin.

Solving the Nonalignment of Methods and Approaches Used in Microplastic Research to Consistently Characterize Risk.

The lack of standard approaches in microplastic research limits progress in the abatement of plastic pollution. Here, we propose and test rescaling methods that are able to improve the alignment of methods used in microplastic research. We describe a method to correct for the differences in size ranges as used by studies reporting microplastic concentrations and demonstrate how this reduces the variation in aqueous-phase concentrations caused by method differences. We provide a method to interchange between number, volume, and mass concentrations using probability density functions that represent environmental microplastic. Finally, we use this method to correct for the incompatibility of data as used in current species sensitivity distributions (SSDs), caused by differences in the microplastic types used in effect studies and those in nature. We derived threshold effect concentrations from such a corrected SSD for freshwater species. Comparison of the rescaled exposure concentrations and threshold effect concentrations reveals that the latter would be exceeded for 1.5% of the known surface water exposure concentrations worldwide. Altogether, this toolset allows us to correct for the diversity of microplastic, to address it in a common language, and to assess its risks as one environmental material.

Solvent extraction of lithium ions using benzoyltrifluoroacetone in new solvents

This work studies the solvent extraction of lithium ions from alkaline aqueous solutions by chelating agent 3-benzoyl-1,1,1-trifluoroacetone (HBTA). To develop a more eco-friendly extraction system for lithium than currently used, various hydrophobic room-temperature ionic liquids were investigated as diluents. The influence of several experimental parameters on lithium extraction was examined, including aqueous phase pH, the nature of lithium counter-ion, extractant concentration, the addition of electrically neutral co-extractant.It was found that contrary to the traditional extraction systems with molecular diluents, HBTA alone dissolved in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid extracts efficiently lithium ions from the aqueous solution. The addition of co-extractant, tri(n-octyl)phosphine oxide (TOPO) to HBTA did not result in a synergetic effect. To confirm the mechanism of lithium extraction by HBTA dissolved in ionic liquid (IL), the measurements of IL constituent ions and deprotonated HBTA concentrations in the equilibrium aqueous phase were carried out. Analysis of the results suggests that an electrically neutral lithium-HBTA extractant complex is extracted into the IL phase.The system combining HBTA extractant and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid has high selectivity for lithium over sodium but poor selectivity over calcium. We have shown also that a high stripping ratio can be obtained using relatively concentrated aqueous solutions of hydrochloric acid. Finally, it was found that the use of some deep eutectic solvents as diluents is much less efficient compared with ILs.

Life cycle assessment of the Fischer-Tropsch biofuels production by supercritical water reforming of the bio-oil aqueous phase

This paper is aimed at performing an environmental evaluation regarding biofuel production. The process combines four sections: biomass fast pyrolysis to bio-oil with two phases, oil-phase upgrading by hydrotreating, using H2 obtained by steam reforming, and a new process to produce Fischer-Tropsch biofuels from supercritical water reforming of the aqueous phase. This phase can be valorised in the latter process entirely so natural gas is reformed to H2 (case-study 1), or partially so a fraction of this aqueous phase is reformed (case-study 2), or all this phase is reformed to H2 (case-study 3). The two former can include CO2 storage and aqueous phase concentrations were 15, 25 and 35 wt% organic compounds. At 25 wt%, the global warming potential is 11 g CO2-eq/MJ-biofuel for the case 2 with CO2 storage, while it was 11.3, 12.6, 27.7 and 34 g CO2-eq/MJ-biofuel for the cases 3, 2 without CO2 storage, 1 with and without CO2 storage, respectively. Thus, the case-study 2 with CO2 storage gives the minimum global warming potential, allowing significant reductions with respect to the use of fossil fuels. For the other categories, the case-study1 presents the lowest impacts. Similar trends are found at 15 and 35 wt%.

Extraction of Rare Earth Elements(III) from Nitric Acid Solutions with Binary Extractants Based on Dialkylamino Derivatives of Carbamoylmethylphosphine Oxides and Dinonylnaphthalenesulfonic Acid

Interphase distribution of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y between aqueous HNO3 solutions and solutions of binary extractants obtained by reaction of equimolar amounts of dialkylamino derivatives of carbamoylmethylphosphine oxides and dinonylnaphthalenesulfonic acid in organic solvents has been studied. Stoichiometry of extracted complexes has been determined, effect of HNO3 concentration in aqueous phase and organic solvent nature on the efficiency of metal ion recovery into organic phase has been considered. On the formation of extractable REE(III) complexes, the cationic moiety of binary extractant provides coordination solvation of REE(III) ions, while anionic moiety offers their high hydrophobicity, which favors to the efficient transition of metal ions into organic phase.

Fouling mitigation and carbon recovery in nanofiltration processing of hydrothermal liquefaction aqueous waste stream

A significant fraction of the embedded energy, carbon, and nutrients in biomass is lost to the aqueous phase during the hydrothermal liquefaction of biomass to bio-oil. The feasibility of concentrating the aqueous phase to recover and recycle the organics back to the hydrothermal liquefaction reactor using nanofiltration was investigated. The dissolved organic carbon content (~ 1 wt%) of the hydrothermal liquefaction aqueous phase was mostly comprised of carboxylic acids, phenolics, and ketones. Several pretreatments, including pH adjustment, thermal treatment, ultrafiltration, and adsorption, were conducted prior to the nanofiltration process to mitigate membrane fouling. Adjustment of pH to 8 and higher was observed to improve the permeate flux. Minor amounts of humic-like organic materials were determined to be the major contributor to membrane fouling. Adsorption using coal was especially effective at selectively removing organic foulants and enabled the volume reduction of the hydrothermal liquefaction aqueous phase by a factor of ~8. The dissolved organic carbon concentration in the retentate increased fourfold and an organic carbon mass recovery of ~50% was achieved. The results show promise as a cost-effective way to the recovery of dissolved organic carbon in the hydrothermal liquefaction aqueous phase. Further integrated process development is needed to maximize valorization.

Polyarylate membrane with special circular microporous structure by interfacial polymerization for gas separation

Microporous polymer membranes have received extensive attention in the membrane separation field based on the advantage of high gas permeance and low cost. However, there are a few reports of microporous polyacrylate membranes fabricated by interfacial polymerization (IP), and the formation mechanism and influence factor of the microporous structure is rarely illuminated. In this work, thin-film polyacrylate membrane with circular microporous morphology were prepared by IP method with cyclodextrin and acyl chloride as the aqueous and oil phase monomer respectively for effective gas separation. The effects of the aqueous and organic phase monomer structure and concentration, the concentration and type of alkali in the aqueous solution on the membrane morphology and gas separation performance were investigated in detail. As a result, the polyacrylate membrane fabricated by β-cyclodextrin (β-CD) and trimesoyl chloride (TMC) with optimal content of NaOH in the aqueous phase formed the special circular microporous structure by the scanning electronic microscope (SEM) characterization. The resulting membrane showed CO2 permeance of 200 GPU with CO2/N2 ideal separation selectivity of 10.53. This work provides an effective strategy to fabricate high performance polyacrylate membrane by regulating the monomer structure and the alkali concentration in the aqueous phenol solution with IP method, which would inspire the exploration of other phenolic monomer for the assembly of microporous polymer membranes for gas separation or seawater desalination.

Evaluation of pharmaceuticals and personal care products (PPCPs) in drinking water originating from Lake Erie

This project evaluated pharmaceuticals and personal care products (PPCPs) concentrations in drinking water originating from Lake Erie. Raw and treated water samples were collected from the local water treatment plant in Erie, Pennsylvania over a 10 month period. Along with grab samples, long-term samples were collected using Polar Organic Chemical Integrative Samplers (POCIS). The samples were analyzed for 17 PPCPs (acetaminophen, ampicillin, atrazine, bisphenol-A, caffeine, carbamazepine, cimetidine, ciprofloxacin, digoxin, gemfibrozil, ibuprofen, metformin, naproxen, simazine, sulfamethoxazole, sulfathiazole, trimethoprim) in raw and treated drinking water. For grab samples, six of the 17 PPCPs were found at detectable levels in raw or treated drinking water including atrazine, bisphenol-A, caffeine, ibuprofen, metformin, and simazine. Detectable PPCP levels in treated water samples were usually lower than those in raw water. For long-term samples, an additional four PPCPs (ten total) were found at detectable levels including gemfibrozil, naproxen, sulfamethoxazole, and trimethoprim. Aqueous phase concentrations of PPCPs were estimated using sampling rates, deployment periods, and analytical results of POCIS samplers.

Parametric Study of Rupture Analysis for the Optimization of Stable Emulsion Liquid Membrane using DOE Approach

Rupture of the membrane is considered as one of the most critical characteristics while working on wastewater treatment via emulsion liquid membrane. This paper presents a decisive study of different parameters affecting the rupture of membrane. The potential parameters which are investigated in this study include, surfactant dosage, surfactant concentration, concentration of aqueous phase, emulsification velocity, ratio of organic to aqueous phases and ratio of membrane to feed phases. The Design of Experiment (DOE) approach was used to design the experiments and the results were analyzed statistically through a software Minitab-18. The study revealed that amongst all these parameters, two are the highly significant playing a crucial role in rupture of the membrane. These significant parameters are emulsification velocity and ratio of the organic to aqueous phase. Pareto chart being used as an effective statistical tool implied that the emulsification velocity and ratio of the organic to aqueous phase have negative and positive effects on the response respectively. Using the Response Optimizer tool, the optimum levels of all the potential parameters were statistically calculated followed by an experimental verification resulting a least minimum rupture of 36%. A statistical model was developed in this study and the values of predicted rupture were compared with the experimental results. The calculated correlation coefficient R2 of the developed model was 0.998 and the accuracy of correlation coefficient deduced that the developed model of rupture will precisely calculate the rupture over the range of values.

Single- and multi-component adsorption of selected contaminants of emerging concern from water and some of their metabolites onto hierarchical porous copper(II)-zeolite -activated carbon composite

A copper(II) functionalized hierarchical faujasite zeolite/activated carbon composite adsorbent (Cu-CFAU) was prepared in an attempt to develop a platform for the effective removal of contaminants of emerging concern (CECs: caffeine, carbamazepine, naproxen, and metabolites clofibric acid, 10,11-epoxy-carbamazepine, o-desmethyl-naproxen, paraxanthine, salicylic acid) from water at ambient conditions. CFAU was prepared hydrothermally via seeded in situ growth of zeolite crystals within the pores of an activated carbon (AC, Darco-KB-G) and subsequently exchanged with copper(II). The materials were characterized using XRD, TEM, TGA, porosimetry, and elemental analysis. TEM, TGA and textural properties showed direct evidence of the in situ growth of the zeolite phase. Performance of the CFAU composite for CECs equilibrium adsorption was addressed in both single- and multi-component fashion and for CECs aqueous phase concentrations covering the μg L−1 – mg L−1 range. Cu-CFAU displayed the best overall adsorption working capacities, probably due to greater affinity for all CECs by relying on complexation interaction with the transition metal sites along with an enhancement of electrostatic and hydrophobic-hydrophilic interactions. Compared to AC, the composite excelled in adsorbing ionic CECs and was able to offer at least equal capacity toward neutral CECs. Compared to other adsorbents reported so far in the literature, the Cu-CFAU offers adsorption capacities that are larger by an order of magnitude in many cases. Preliminary tests for the reusability of the composite after various adsorption/desorption cycles suggest that Cu-CFAU might be regenerated via thermal treatment under inert atmosphere when the adsorbed CEC possesses a relative low melting point.