Hydrophilic Organic Compounds Research Articles

Modelling passive sampling of hydrophilic compounds under time-variable aqueous concentrations

Passive sampling is a crucial method for evaluating concentrations of hydrophilic organic compounds in the aquatic environment, but it is insufficiently understood to what extent passive samplers capture the intermittent emissions that frequently occur for this group of compounds. In the present study, silicone sheets and styrene-divinyl benzene-reversed phase sulfonated extraction disks with and without a polyethersulfone membrane were exposed under semi-field conditions in a 31 m3 flume at three different flow velocities. Natural processes and spiking/dilution measures caused aqueous concentrations to vary strongly with time. The data were analyzed using two analytical models that account for these time-variable concentrations: a sampling rate model and a diffusion model. The diffusion model generally gave a better fit of the data than the sampling rate model, but the difference in residual errors was quite small (median errors of 19 vs. 25% for silicone and 22 vs. 25% for SDB-RPS samplers). The sampling rate model was therefore adequate enough to evaluate the time-integrative capabilities of the samplers. Sampler performance was best for SDB-RPS samplers with a polyethersulfone membrane, despite the occurrence of lag times for some compounds (0.1 to 0.4 days). Sampling rates for this design also spanned a narrower range (80 to 110 mL/day) than SDB-RPS samplers without a membrane (100 to 660 mL/day). The effect of biofouling was similar for all compounds and was consistent with a biofouling layer thickness of 150 µm.

Microfluidically Produced Microcapsules with Amphiphilic Polymer Conetwork Shells

AbstractMicrocapsules with an aqueous core can be conveniently prepared by water‐in‐oil‐in‐water double emulsion microfluidics. However, conventional shell materials are based on hydrophobic polymers or colloidal particles. Thus, these microcapsules feature a hydrophobic shell impermeable to water‐soluble compounds. Capsules with semipermeable hydrogel shells have been demonstrated but may exhibit poor mechanical properties. Here, amphiphilic polymer conetworks (APCNs) based on poly(2‐hydroxyethyl acrylate)‐linked by‐polydimethylsiloxane (PHEA‐l‐PDMS) are introduced as a new class of wall materials in double emulsion microcapsules. These APCNs are mechanically robust silicone hydrogels that are swellable and permeable to water and are soft and elastic when dry or swollen. Therefore, the microcapsules can be dried and rehydrated multiple times or shrunken in sodium chloride salt solutions without getting damaged. Moreover, the APCNs are permeable for hydrophilic organic compounds and impermeable for macromolecules. Thus, they can be loaded with macromolecules or nanoparticles during microfluidic formation and with organic molecules after capsule synthesis. The microcapsules serve as microreactors for catalytically active platinum nanoparticles that decompose hydrogen peroxide. Finally, the surface of the APCN microcapsules can be selectively functionalized with a cholesterol‐based linker. Concluding, APCN microcapsules could find applications for the controlled delivery of drugs, as microreactors for synthesis, or as scaffolds for synthetic cells.

Hydrotrope dynamics: unraveling solubility pattern and correlation of benzimidazole using response surface methodology expert system

Solubilizing drugs in liquid and semisolid environments typically involves the use of cosolvents or surfactants. In contrast, the utilization of hydrotropic agents, which are small hydrophilic organic compounds like sodium salicylate or sodium benzoate, has been less explored in the field of pharmaceutical formulations. However, particularly in the context of topical dosage forms, hydrotropic solubilization can present valuable alternatives for enhancing solubility. One challenge in employing hydrotropic solubilization has been the unpredictability of its effectiveness with different drug molecules. In the current study, three different hydrotropes namely sodium salicylate, sodium benzoate, and pyrogallol were chosen to test the solubility enhancement of benzimidazole drug. Optimization of solubility was proceeded with Central Composite Design obtained from RSM expert system. It was noticed from the results that sodium salicylate had performed the best compared to the other two chosen hydrotropes. This was also reexamined using two models namely modified Apelblat model and polynomial model. The thermodynamic studies were assessed and it had reconfirmed the acquired solubility study results. The minimum and maximum hydrotrope concentrations of sodium salicylate required were 0.4 and 2.25 mol/L, respectively. The solubility enhancement factor was also remarkably high for sodium salicylate with 36.91 ± 0.07. With careful selection of the appropriate hydrotropic agent, the solubility of poorly soluble drug, benzimidazole has been significantly improved.

Effects of Hovenia dulcis fruit and peduncle extract on alcohol metabolism

Ethnopharmacological relevanceThe dried fruit and peduncle of Hovenia dulcis Thunberg (Rhamnaceae) (HD) has been used as a folk medicine to treat liver disease, detoxify alcoholism, and prevent and cure hangovers. Aim of the studyWe investigated the pharmacology of HD on the kinetics of EtOH and on the enzymes related to alcohol metabolism to seek the scientific evidence of HD to prevent hangover, the effectiveness as a folk medicine. Materials and methodsEtOH was orally administered 30 min after oral administration of HD boiling water extract in rats. Then, the profiles of blood EtOH concentrations were measured. Mice were reared with food containing powdered HD for 7 days, and the activities of alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) in liver were measured. Hepa1c1c7 cells were cultured with the medium containing HD extract, and the activities of ADH and ALDH were measured. ResultsHD extract reduced the blood EtOH concentrations in rats and induced the activities of ADH and ALDH and mRNA and protein expressions of ADH1B, ALDH1A1, and ALDH2 in the liver of mice and Hepa1c1c7 cells. Dihydromyricetin, one of the ingredients of HD, significantly induced the activities of ADH and ALDH in Hepa1c1c7 cells, however, the fractions containing hydrophilic organic compounds with small molecular weight contributed the most of the activities of HD extract. ConclusionsWe clarified the experimental pharmacological evidences of HD as a folk medicine to detoxify alcoholism and prevent hangovers.

Genotoxicity of chlorinated hydrophobic organic compounds extracted from a source of drinking water

As precursors of disinfection by-products (DBPs), sediment hydrophobic organic compounds (HPOCs) derived from six reservoirs along the Dongjiang River were chlorinated (Cl-WS) and then fractionated into two polar components (hydrophobic organic compounds (Cl-HOCs) and hydrophilic organic compounds (Cl-HICs)) by solid phase extraction. Based on Caco-2 cell exposure study, the genotoxicity of Cl-WS, Cl-HOCs and Cl-HICs was analyzed by reactive oxygen species (ROS) analysis, comet assay and ethoxyresorufin-O-deethylase assay. Protective effects of antioxidants (catalase, vitamin C and epigallocatechin 3-gallate (EGCG)) on genotoxicity of the chlorinated samples were investigated. The results showed that Cl-WS and its two fractions (Cl-HOCs and Cl-HICs) induced ROS, DNA damage and dioxin-like toxicity (TEQbio), and Cl-HICs were a major contributor to oxidative damage and TEQbio compared with Cl-HOCs. Antioxidants significantly reduced Cl-HOCs- and Cl-HICs-induced ROS, but had insignificant effect on DNA oxidative damage and TEQbio. In addition, EGCG showed higher efficacy in reducing DNA damage induced by Cl-HICs than by Cl-HOCs. To our knowledge, this is the first study to investigate the genotoxicity of Cl-WS and its two polar components in Caco-2 cells, as well as the protective effects of antioxidants on Cl-HOCs and Cl-HICs-induced ROS, DNA damage, and TEQbio. This study provides important toxicity information for water treatment industries in differentiating DBPs of different polarity.

Surface-bubble-modulated liquid chromatography: an experimental strategy for identification of molecular processes of solute retention in reversed-phase separation systems.

Molecular level understanding of the chemistry at the aqueous/hydrophobe interface is crucial to separation processes in aqueous media, such as reversed-phase liquid chromatography (RPLC) and solid-phase extraction (SPE). Despite significant advances in our knowledge of the solute retention mechanism in these reversed-phase systems, direct observation of the behavior of molecules and ions at the interface in reversed-phase systems still remains a major challenge and experimental probing techniques that provide the spatial information of the distribution of molecules and ions are required. This review addresses surface-bubble-modulated liquid chromatography (SBMLC), which has a stationary gas phase in a column packed with hydrophobic porous materials and enables one to observe the molecular distribution in the heterogeneous reversed-phase systems consisting of the bulk liquid phase, the interfacial liquid layer, and the hydrophobic materials. The distribution coefficients of organic compounds referring to their accumulations onto the interface of alkyl- and phenyl-hexyl-bonded silica particles exposed to water or acetonitrile-water and into the bonded layers from the bulk liquid phase are determined by SBMLC. The experimental data obtained by SBMLC show that the water/hydrophobe interface exhibits an accumulation selectivity for organic compounds, which is quite different from that of the interior of the bonded chain layer, and the overall separation selectivity of the reversed-phase systems is determined by the relative sizes of the aqueous/hydrophobe interface and the hydrophobe. The solvent composition and the thickness of the interfacial liquid layer formed on octadecyl-bonded (C18) silica surfaces are also estimated from the bulk liquid phase volume determined by the ion partition method employing small inorganic ions as probes. It is clarified that various hydrophilic organic compounds as well as inorganic ions recognize the interfacial liquid layer formed on the C18-bonded silica surfaces as being different from the bulk liquid phase. The behavior of some solute compounds exhibiting substantially weak retention in RPLC or the so-called negative adsorption, such as urea, sugars, and inorganic ions, can rationally be interpreted with a partition between the bulk liquid phase and the interfacial liquid layer. The spatial distribution of solute molecules and the structural properties of the solvent layer on the C18-bonded layer determined by the liquid chromatographic methods are discussed in comparison to the results obtained by other research groups using molecular simulation methods.

Removal effect of trihalomethanes (THMs) and halogenated acetic acids (HAAs) precursors in reclaimed water by polyaluminum chloride (PACl) coagulation.

This study analyzed the removal effect of various doses of polyaluminum chloride (PACI) on wastewater treatment plants at pH 7. The sewage plant's secondary effluent organic matter (EfOM) separates into four components: hydrophobic base (HOB), hydrophilic (HI), hydrophobic acid (HOA), and hydrophobic neutral (HON). The removal effect for various forms of organic waste is optimum at 16 mg/L and that halogenated acetic acids (HAAs) and trihalomethanes (THMs) are formed simultaneously. After PACI treatment, hydrophobic organic compounds were converted to humic acid (HA), fulvic acid (FA), soluble microbial products (SMPs), and other HI organic compounds, increasing the amount of HAAs produced by HI fractions. Removal rate of hydrophobic organic compounds, particularly HON, is 92.8% when using PAC. Moreover, after EfOM coagulation, most HAAs are trichloroacetic acid (TCAA), followed by bromochloroacetic acid (BCAA) and bromodichloroacetic acid (BDCAA). Only HOB can produce monochloroacetic acid (MCAA), whereas HA and SMPs with HOA are primary components of dichloroacetic acid (DCAA). The toughest removable byproduct of THMs is CHBr3, and after condensation of each THM component, only HOA and HON produce CHBr3, while HI produces only a minimal quantity of CHBrCl2 and CHCl3.This finding is critical for understanding how disinfection byproducts are produced after chlorinating EfOM.

Coulometric method with titratable impurity analysis and mass balance method: convert acidimetric purity to chemical purity for SI-traceable highest standard of qNMR (potassium hydrogen phthalate), and verified by qNMR.

In this study, the coulometric method with titratable impurity analysis and the mass balance method were successfully applied in the quantification of the certified reference material of potassium hydrogen phthalate (KHP) with accurate metrological traceability of chemical purity value (99.983% with an expanded uncertainty of 0.024%, k = 2). In contrast to the general coulometric titration method, the coulometric method with titratable impurity analysis enables the conversion of acidimetric purity to chemical purity: The acidimetric purity was determined by coulometric titration method, and then the impurities that may be titrated as principal components were found as far as possible using various methods and the result of deducting these impurities from the acidimetric purity can be considered as chemical purity. The mass balance method also accounted for all possible types of impurities as much as possible to improve the accuracy of the determined result. The accuracy and reliability of the purity results were subsequently verified by a two-step quantitative nuclear magnetic resonance (qNMR) method. This KHP certified reference material was the first hydrophilic internal standard of qNMR (applied in polar solvents) with an expanded uncertainty lower than 0.03%, which will become a major reference standard in the organic chemistry traceable calibration chain, especially when evaluating hydrophilic organic compounds to obtain purity values with very low uncertainty.

Development of a New Polar Organic Chemical Integrative Sampler for 1,4-dioxane Using Silicone Membrane as a Diffusion Barrier.

Efficient monitoring methods must be developed for 1,4-dioxane, which is suspected to be carcinogenic to humans and is highly mobile in aquatic environments. In this regard, polar organic chemical integrative samplers (POCIS) have been utilized extensively as passive samplers for determining time-weighted average concentrations of hydrophilic organic compounds. However, POCIS are difficult to apply to extremely hydrophilic known organic compounds with negative log octanol-water partition coefficient (Kow ) values due to their limited kinetic sampling time. Using an activated carbon-based sorbent with a high adsorption capacity and a bilayer of silicone and polyethersulfone membranes that inhibit mass transfer to the sorbent, we developed a POCIS device to measure 1,4-dioxane (log Kow -0.27) in the present study. Permeation and field calibration tests demonstrated that the use of silicone membranes effectively reduces the water-to-sorbent mass transfer rate. The sampling rate and kinetic sampling period determined by field calibration tests were 1.4 ml day-1 and >14 days, respectively. Finally, the developed POCIS device was applied to a landfill treatment plant to determine the 1,4-dioxane concentrations. Environ Toxicol Chem 2023;42:296-302. © 2022 SETAC.

New insights into adsorption mechanism of pristine and weathered polyamide microplastics towards hydrophilic organic compounds

The widespread coexistence of hydrophilic organic compounds and microplastics (MPs) in the environment has greatly increased their associated environmental problems. To evaluate the potential carrier effect of oxygen-containing MPs on coexisting pollutants, adsorption behaviors of four hydrophilic organic compounds (benzoic acid, sulfamethoxazole, sulfamerazine and ciprofloxacin) on MPs (pristine and weathered polyamide (PA)) were studied in the aquatic environment. The results showed that the surface morphology, size, oxygen content, molecular structure, surface charge and crystallinity of PA were changed after weathering, and the weathering degree of PA treated with heat-activated potassium persulfate was the highest. The main adsorption mechanisms included hydrogen bonding, hydrophobic interaction, charge-assisted hydrogen bonding, and electrostatic interaction. Hydrogen bonding and hydrophobic interaction contributed to the adsorption, while electrostatic interaction weakened the adsorption under the specific pH conditions. The formation of charge-assisted hydrogen bonding (CAHB) was also verified through pH influence experiments, and this force can overcome the electrostatic repulsion. The high adsorption of KPA (PA weathered by K2S2O8) under alkaline conditions was well explained by the formation of homonuclear CAHB due to the increase of oxygen-containing functional groups compared to the other three PA. Additionally, weathering did not always enhance the adsorption of hydrophilic organic compounds on PA, which was related to the changes in surface charge, crystallinity and hydrophilicity of PA. Overall, the physical and chemical properties (e.g., specific surface area, oxygen content, molecular structure) of PA after weathering and its trend of adsorption were different from other oxygen-free MPs in this study. This work can provide basic data for environmental risk of MPs and contribute to clarify and understand the processes of oxygenated MPs in the aquatic environment.

Understanding soil selenium accumulation and bioavailability through size resolved and elemental characterization of soil extracts

Dietary deficiency of selenium is a global health threat related to low selenium concentrations in crops. Despite the chemical similarity of selenium to the two more abundantly studied elements sulfur and arsenic, the understanding of its accumulation in soils and availability for plants is limited. The lack of understanding of soil selenium cycling is largely due to the unavailability of methods to characterize selenium species in soils, especially the organic ones. Here we develop a size-resolved multi-elemental method using liquid chromatography and elemental mass spectrometry, which enables an advanced characterization of selenium, sulfur, and arsenic species in soil extracts. We apply the analytical approach to soils sampled along the Kohala rainfall gradient on Big Island (Hawaii), which cover a large range of organic carbon and (oxy)hydroxides contents. Similarly to sulfur but contrarily to arsenic, a large fraction of selenium is found associated with organic matter in these soils. However, while sulfur and arsenic are predominantly found as oxyanions in water extracts, selenium mainly exists as small hydrophilic organic compounds. Combining Kohala soil speciation data with concentrations in parent rock and plants further suggests that selenium association with organic matter limits its mobility in soils and availability for plants.

Content of adsorbed film water and density of oxygen-containing functional groups on surface of ageing biochar in sandy spodosol

Abstract Application of different types of feedstocks and conditions of their pyrolysis can result in different properties and sustainability of biochar during changes (aging) of its properties in soils. The aim of the studies was to assess the consequences of aging of biochar in soil for a content of adsorbed film water and a density of oxygen-containing functional groups on its surface. Sampling of soil and biochar was conducted in May and July of 2021 in a plot experiment with an applied rate of biochar of 20 t.ha−1 in 2016. WP4-T dew point potentiometer was used for measurements of relationships of potentials of adsorbed film water and its content in soil and biochar. Infrared Fourier FSM 2201/2202 spectrometer was applied for determination of densities of oxygen-containing functional groups on surface of biochar in a mid-infrared spectrum. Results showed that retention capacity of adsorbed film water by soil increased from May to July, possibly because of increasing content of hydrophilic organic compounds of plant origin. Aging of biochar in soil also resulted in an increase of retention capacity of adsorbed film water on its surface. The results of infrared Fourier spectroscopy confirmed that densities of oxygen-containing functional groups on the surface of biochar increased from May to July at spectra of wavenumbers of 1,600–1,400 cm−1 and 1,400–1,100 cm−1.

Characterization of the Interfacial Liquid Layer Formed on Hydrophobic Packing Material Surfaces by Liquid Chromatographic Analysis of the Distribution of Ions and Molecules.

We determine the bulk liquid phase volumes in octadecyl-bonded silica (C18 silica) columns equilibrated with acetonitrile–water and methanol–water (0–19%(v/v)) binary mixed solvents by a liquid chromatographic method with inorganic ions used as probes. The solvent composition and the thickness of the interfacial liquid layer formed on the C18-bonded silica surface are then determined from the bulk liquid phase volume, the total liquid phase volume, the surface area of the C18 silica packing material, and the retention volumes of the isotopically labeled eluent components for the columns. We used two C18 silica packing materials having identical bonding structures but different pore sizes and surface areas. Our results show that various hydrophilic organic compounds as well as inorganic ions recognize the interfacial liquid layer as being different from the bulk phase. The behavior of the solute compounds exhibiting substantially weak retention in reversed-phase liquid chromatography or the so-called negative adsorption, such as urea, sugars, and inorganic ions, can rationally be interpreted with a partition between the bulk liquid phase and the interfacial solvation liquid layer. The structural properties of the solvent layer on the C18-bonded layer determined by liquid chromatography are consistent with the molecular dynamics simulation results that have been obtained by other researchers.

New Insights into Adsorption Mechanism of the Pristine and Weathered Polyamide Microplastics Towards the Hydrophilic Organic Compounds

New Insights into Adsorption Mechanism of the Pristine and Weathered Polyamide Microplastics Towards the Hydrophilic Organic Compounds

Effect of superfine pulverization of powdered activated carbon on adsorption of carbamazepine in natural source waters

The purpose of this study is to investigate adsorptive removal of carbamazepine from natural source waters by superfine pulverized powdered activated carbon. Superfine pulverization is becoming an increasingly attractive approach to decrease the diffusion path of a target adsorbate molecule and improve the overall the kinetics of activated carbon adsorption. Here we report the impact of pulverization on powdered activated carbon characteristics, and carbamazepine adsorption behavior in distilled and deionized water and natural organic matter solutions. The superfine pulverization decreased the particle size of activated carbon by 50 folds and the specific surface area by 24%. In addition, the micropore volume of the activated carbon decreased from 0.23 cm3/g to 0.14 cm3/g, while mesopore and macropore volumes increased from 0.15 cm3/g and 0.11 cm3/g to 0.18 cm3/g and 0.48 cm3/g, respectively. In terms of surface chemistry, the oxygen and iron contents of the activated carbon increased notably after pulverization. Despite the decrease in surface area and increase in surface polarity, the pulverization improved the adsorption kinetics especially for short contact times i.e., < 6-h. In general, the dissolved organic carbon concentration negatively influenced the kinetic advantage of superfine pulverized activated carbon. Isotherm results indicated that the parent adsorbent has a higher adsorption capacity than superfine activated carbon in distilled and deionized water and in natural waters. This was attributed to the losses in specific surface area and favorable sorption sites inside micropores. Our literature analysis indicated that unlike the small molecular weight hydrophilic organic compounds, the pseudo-equilibrium adsorption capacity could be increased or at least not deteriorated for hydrophobic molecules (Kow > 3). Therefore, superfine pulverization of PAC can serve as a promising approach to remove micropollutants from natural source waters with a kinetic advantage.

Cell-Penetrating Peptides Derived from Animal Venoms and Toxins.

Cell-penetrating peptides (CPPs) comprise a class of short polypeptides that possess the ability to selectively interact with the cytoplasmic membrane of certain cell types, translocate across plasma membranes and accumulate in the cell cytoplasm, organelles (e.g., the nucleus and mitochondria) and other subcellular compartments. CPPs are either of natural origin or de novo designed and synthesized from segments and patches of larger proteins or designed by algorithms. With such intrinsic properties, along with membrane permeation, translocation and cellular uptake properties, CPPs can intracellularly convey diverse substances and nanomaterials, such as hydrophilic organic compounds and drugs, macromolecules (nucleic acids and proteins), nanoparticles (nanocrystals and polyplexes), metals and radionuclides, which can be covalently attached via CPP N- and C-terminals or through preparation of CPP complexes. A cumulative number of studies on animal toxins, primarily isolated from the venom of arthropods and snakes, have revealed the cell-penetrating activities of venom peptides and toxins, which can be harnessed for application in biomedicine and pharmaceutical biotechnology. In this review, I aimed to collate examples of peptides from animal venoms and toxic secretions that possess the ability to penetrate diverse types of cells. These venom CPPs have been chemically or structurally modified to enhance cell selectivity, bioavailability and a range of target applications. Herein, examples are listed and discussed, including cysteine-stabilized and linear, α-helical peptides, with cationic and amphipathic character, from the venom of insects (e.g., melittin, anoplin, mastoparans), arachnids (latarcin, lycosin, chlorotoxin, maurocalcine/imperatoxin homologs and wasabi receptor toxin), fish (pardaxins), amphibian (bombesin) and snakes (crotamine and cathelicidins).

Determination of mononitrophenols in water by gas-chromatography

Nitrophenols are highly toxic hydrophilic organic compounds. Nitrophenols prevalence in the biosphere is associated with both human industrial activity and with natural processes in the atmosphere and hydrosphere. Nitrophenols determination using gas chromatography requires chemical modification in order to reduce the hydrophilicity and polarity of the analytes. The derivatization must be carried out before the extraction concentration stage, but in most methods of the nitrophenols determination in water this approach is not implemented. The method of determination of mononitrophenols (2-, 3-, and 4-nitrophenols) in water was developed. It involved the nitrophenols bromination directly in the water, bromoderivatives liquid extraction with toluene, silylation by N-tert-Butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA) extract and gas chromatographic determination with the electron-capture detector ( GC-ECD ). The nitrophenols bromination conditions in aqueous solutions were optimized (pH value, bromination duration, bromide-ions concentration). In order to reduce the oxidizing activity of bromine, the nitrophenols bromination was recommended in the presence of bromide anions. The extraction (degree of extraction) and gas chromatographic (retention indices, ECD relative molar responses) properties and nitrophenols bromoderivatives properties were studied. It was shown that the degree of extraction of brominated nitrophenols in the toluene/water system exceeded 80% and the subsequent silylation of the bromoderivatives significantly improved their chromatographic properties. The analytical range of nitrophenols in water was 0.02-10 µg/dm 3 with an error of 10-35%, the detection limits were 0.05-0.07 μg/dm 3 , the sample volume for analysis was 50 cm 3 , the analysis duration was 90 min. Key words : mononitrophenols, chemical modification, gas-chromatography, electron-capture detector DOI: http://dx.doi.org/10.15826/analitika.2020.24.2.006 I.V. Gruzdev, B.M. Kondratenok, E.I. Lyu-Lyan-Min Institute of Biology of Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences (IB FRC Komi SC UB RAS), Kommunisticheskaya st., 28, Syktyvkar, 167982, Russian Federation

An Efficient Operational Matrix Method for a Few Nonlinear Differential Equations Using Wavelets

In this paper, a theoretical model of biofiltration of mixture of hydrophilic (methanol) and hydrophobic (α-pinene) volatile organic compounds is discussed. An efficient wavelet-based operational matrix method is developed for the analytical expressions pertaining to the concentration profiles of methanol and α-pinene in the air stream and bio-film stream. The convergence and supporting analysis of the proposed method is discussed. The operational matrix of derivatives contains many zero entries, which lead to the high efficiency of the method and reasonable accuracy is achieved even with less number of collocation points. Our results are in good agreement with the Bernstein polynomial method and Adomian decomposition method. The efficiency of the proposed method is confirmed by using computational CPU runtime.

Pre-coagulation coupled with sponge-membrane filtration for organic matter removal and membrane fouling control during drinking water treatment

A new hybrid system was developed in this study for the treatment of drinking water consisting of pre-coagulation using polyaluminium chloride (PACl) and membrane filtration (MF) with sponge cubes acting as biomass carriers (P-SMF). When compared to a conventional MF (CMF) and a MF after coagulation by utilizing PACl (P-MF), better removal of nutrients, UV254 and dissolved organic carbon (DOC) (>65%) was obtained from the P-SMF. The accumulation of biopolymers (including polysaccharides and proteins), humic substances, hydrophilic organics, and other small molecular weight (MW) organic matter in the CMF led to the most severe membrane fouling coupled with the highest pore blocking and cake resistance. Pre-coagulation was ineffective in eliminating small MW and hydrophilic organic matter. Conversely, the larger MW organics (i.e. biopolymers and humic substances), small MW organics and hydrophilic organic compounds could be removed in significantly larger quantities in the P-SMF by PACl coagulation. This was achieved via adsorption and the biodegradation by attached biomass on these sponges and by the suspended sludge. Further analyses of the microbial community indicated that the combined addition of PACl and sponges generated a high enrichment of Zoolgloea, Amaricoccus and Reyranella leading to the reduction of biopolymers, and Flexibacter and Sphingobium were linked to the degradation of humic substances. Moreover, some members of Alphaproteobacteria in the P-SMF may be responsible for the removal of low MW organics. These results suggest that the pre-coagulation process coupled with adding sponge in the MF system is a promising technology for mitigating membrane fouling.

Complexation of Iron and Copper in Ambient Particulate Matter and Its Effect on the Oxidative Potential Measured in a Surrogate Lung Fluid.

We investigated the complexation state of atmospheric iron and copper and its impact on the oxidative potential (OP) of ambient PM2.5 (PM, particulate matter). A novel fractionation scheme was developed to segregate three different fractions of Fe and Cu present in ambient PM2.5: (i) complexed with hydrophobic organic compounds, (ii) complexed with hydrophilic organic compounds, and (iii) free or inorganic metal fraction. A solid phase extraction (C-18) column was used to separate these fractions. The fractionation scheme applied to the ambient PM2.5 samples collected from an urban site showed that up to 70-90% of water-soluble Fe and Cu were complexed with the organic compounds. The capability of the complexes of Fe(II) and Cu(II) with Suwanee river fulvic acid (SRFA), a proxy for the atmospheric organic compounds, to generate reactive oxygen species (ROS) (·OH and H2O2) in a surrogate lung fluid (SLF) was measured. The complex of Fe-SRFA showed a strong synergistic effect in the generation of ·OH in SLF, while that of Cu-SRFA showed an additive effect. Overall, our results indicate that organic complexation of the metals in ambient PM could significantly alter their OP and needs to be considered while assessing their health impacts.