Concentration In Aqueous Phase Research Articles

Microbial kinetic model for the degradation of poorly soluble organic materials

A novel mechanistic model is presented that describes the aerobic biodegradation kinetics of soybean biodiesel and petroleum diesel in batch experiments. The model was built on the assumptions that biodegradation takes place in the aqueous phase according to Monod kinetics, and that the substrate dissolution kinetics at the oil/water interface is intrinsically fast compared to biodegradation kinetics. Further, due to the very low aqueous solubility of these compounds, the change in the substrate aqueous-phase concentration over time was assumed to approaches zero, and that substrate aqueous concentration remains close to the saturation level while the non-aqueous phase liquid (NAPL) is still significant. No former knowledge of the saturation substrate concentration (Ssat) and the Monod half-saturation constant (Ks) was required, as the term Ssat/(Ks + Ssat) in the Monod equation remained constant during this phase. The n-alkanes C10–C24 of petroleum diesel were all utilized at a relatively constant actual specific utilization rate of 0.01–0.02 mg-alkane/mg-biomass-hr, while the fatty acid methyl esters (FAMEs) of biodiesel were utilized at actual specific rates significantly higher with increasing carbon chain length and lower with increasing number of double bonds. The results were found to be in agreement with kinetic, genetic, and metabolic evidence reported in the literature pertaining to microbial decay rates, uptake mechanisms, and the metabolic pathway by which these compounds are assimilated into microorganisms. The presented model can be applied, without major modifications, to estimate meaningful kinetic parameters from batch experiments, as well as near source zone field application. We suggest the estimated actual microbial specific utilization rate (kC) of such materials to be a better measure of the degradation rate when compared to the maximum specific utilization rate (k), which might be orders of magnitude higher than kC and might never be observed in reality.

Effective sorption of perfluorooctane sulfonate (PFOS) on hexadecyltrimethylammonium bromide immobilized mesoporous SiO2 hollow sphere

The hexadecyltrimethylammonium bromide (HDTMAB) immobilized hollow mesoporous silica spheres were prepared for the efficient removal of perfluorooctane sulfonate (PFOS) from aqueous solution. Besides the traditional sorption behavior including sorption kinetics as well as effect of solution pH and temperature, the effect of increasing volume which simulated the natural river where the rate of solute and solvent was relatively constant and solution volume was always changing was investigated. The result indicated that the residual PFOS concentrations in aqueous phase decreased with increasing solution pH and ionic strength, whereas they increased with increasing temperature. The HDTMAB immobilized material still maintained high efficiency after increasing volume, that is, the removal kept more than 99% after the treatment when the initial PFOS concentration was 1mgL−1. The uptake behavior and morphology of spheres which was characterized by transmission electron microscopy (TEM) revealed that the additional HDTMAB and mesoporous shell were responsible for the enhanced sorption of PFOS. It was concluded that electrostatic interaction and Ca-bridge role played an important role in the sorption of PFOS on the mesoporous SiO2 hollow spheres, whereas, hydrophobic interaction contributed to the nice sorption performance of PFOS on the HDTMAB immobilized sorbent.

Stable emulsions with thermally responsive microstructure and rheology using poly(ethylene oxide) star polymers as emulsifiers

Poly(ethylene oxide) star polymers (PEO stars) were prepared by atom transfer radical polymerization of 2000 molecular weight PEO methacrylate macromonomer with divinylbenzene as a crosslinking co-monomer. With an average of 460arms per star, these PEO stars had a 12nm radius of gyration that is consistent with a dense polymer core surrounded by an extended PEO corona. The PEO stars were extremely efficient emulsifiers, stabilizing cyclohexane-in-water or xylene-in-water emulsions against coalescence for several months at aqueous phase concentrations as low as 0.008wt% or 0.01wt%, respectively. Consistent with their emulsifying performance, PEO star adsorption decreased interfacial tension by approximately 22mN/m and imparted significant dilatational elasticity to the xylene/water interface. PEO stars were thermally responsive, displaying a cloud point upon heating in water that was tuned by addition of kosmotropic electrolytes, and they in turn produced xylene-in-water emulsions that were thermally responsive in terms of the dispersion state of the emulsion droplets and the emulsion rheology. Emulsions prepared at room temperature mainly had non-flocculated droplets. Heating such an emulsion above the cloud point temperature triggered droplet flocculation, but not coalescence, that in turn was associated with increased viscous and elastic moduli of the emulsion measured after cooling back to room temperature. Emulsions that initially were homogenized above the cloud point temperature and then cooled showed neither droplet flocculation nor rheological thickening relative to emulsions that were prepared and held at room temperature. A mechanism based on the bridging behavior of PEO stars adsorbed at the droplet/water interface is postulated to explain this thermal response of the emulsion microstructure.

Effects of Carbon Nanotubes, Chars, and Ash on Bioaccumulation of Perfluorochemicals by Chironomus plumosus Larvae in Sediment

This study examined the effect of five types of carbonaceous materials (CMs) in sediment on bioaccumulation of perfluorochemicals (PFCs) by Chironomus plumosus larvae. The CMs included two multiwalled carbon nanotubes (MWCNT10 and MWCNT50), maize straw- and willow-derived chars, and maize straw-origin ash. The PFCs included perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnA), and perfluorododecanoic acid (PFDoA). The CMs with different concentrations (0-1.5% dry weight) were amended into sediments spiked with PFCs and aged for 60 d. The uptake rate constants (k(s)) for each PFC to larvae differed with different CM amendments (p < 0.05), while elimination rate did not change significantly (p > 0.05). Decreasing PFC concentration in larvae (C(B)) was found with increasing CM concentration (f(CM)) in the sediments, and a linear positive correlation existed between 1/C(B) and f(CM) (p < 0.05). The effect of CMs on PFC bioaccumulation agreed well with the CM properties; MWCNT10 with the highest specific surface area resulted in the lowest k(s) values and biota-sediment accumulation factors (BSAF), with a BSAF reduction of 66%-97% by a 1.5% amendment. The mechanism was explored by analyzing the aqueous phase concentrations of PFCs and the sorption of PFCs on sediments amended with CMs. The results suggested that the decreasing trend of PFCs in larvae was caused by the decreasing aqueous phase concentration with increasing CM concentration. In the studied conditions with low PFC concentrations, the bioaccumulation of PFCs was a linear partitioning between pore water and biota, and the sorption of PFCs to the sediment/CM mixtures was a two domain linear distribution. This study suggests that both the type and concentration of carbonaceous materials in sediment can affect the bioaccumulation of PFCs to benthic organisms through changing their aqueous phase concentrations.

Sugaring-out assisted liquid/liquid extraction with acetonitrile for bioanalysis using liquid chromatography–mass spectrometry

Recent research demonstrated that sugar at a high concentration can induce the mixture of acetonitrile and water to form phase separation. As a result of phase separation, more acetonitrile and low polarity solutes tend to go to the upper layer and more water and high polarity components tend to stay at the bottom. This sugaring-out assisted liquid/liquid extraction (SULLE) has been successfully demonstrated in the determination of eight compounds in human plasma. SULLE for lopinavir and ritonavir from human plasma has been validated with reference to good laboratory practice guidance, and cross-validated against a previously reported method. Achieved method performance of SULLE–LC–MS/MS is similar to that of the reported method using salting-out assisted liquid/liquid extraction (SALLE). SULLE can be used to enrich low polarity analyte by varying the volume ratios of acetonitrile, aqueous phase and sugar concentration. SULLE extract is compatible with reversed phase liquid chromatography and can be directly injected into an LC–MS/MS system with an optional dilution with water when needed. All liquid transfers can be handled easily with multichannel pipettes and the high throughput extraction can be achieved without difficulty in most bioanalytical laboratories.

Reverse micelles‐mediated transport of lipase in liquid emulsion membrane for downstream processing

This work deals with the downstream processing of lipase (EC 3.1.1.3, from Aspergillus niger) using liquid emulsion membrane (LEM) containing reverse micelles for the first time. The membrane phase consisted of surfactants [cetyltrimethylammonium bromide (CTAB) and Span 80] and cosolvents (isooctane and paraffin light oil). The various process parameters for the extraction of lipase from aqueous feed were optimized to maximize activity recovery and purification fold. The mechanism of lipase transport through LEM consisted of three steps namely solubilization of lipase in reverse micelles, transportation of reverse micelles loaded with lipase through the liquid membrane, and release of the lipase into internal aqueous phase. The results showed that the optimum conditions for activity recovery (78.6%) and purification (3.14-fold) were feed phase ionic strength 0.10 M NaCl and pH 9.0, surfactants concentration (Span 80 0.18 M and CTAB 0.1 M), volume ratio of organic phase to internal aqueous phase 0.9, ratio of membrane emulsion to feed volume 1.0, internal aqueous phase concentration 1.0 M KCl and pH 7.0, stirring speed 450 rpm, and contact time 15 min. This work indicated the feasibility of LEM for the downstream processing of lipase.

Optimization, characterization and nanofiltration properties test of MWNTs/polyester thin film nanocomposite membrane

MWNTs/polyester thin film nanocomposite (TFN) membranes were prepared through an improved process by interfacial polymerization of triethanolamine (TEOA) and trimesoyl chloride (TMC) on the polysulfone (PSf) supporting membrane in the presence of multi-walled carbon nanotubes (MWNTs). The effect of MWNTs concentration and surfactant species in the aqueous phase as well as the reaction time of interfacial polymerization on the membrane properties were investigated. The water permeability increased as the MWNTs concentration in aqueous phase increased up to 0.5mg/mL, reaching a maximum which was nearly double that of the thin film membrane without MWNTs, while the membrane rejection kept increasing dramatically. Compared with cationic (CTAB) and non-ionic (Triton X-100) surfactants, anionic (SDS) surfactant was more suitable for the preparation of TFN membrane. The reaction time determined the extent of interfacial polymerization and the integrality of surface skin layer. Furthermore, the nanofiltration properties of the MWNTs/polyester TFN membrane were tested by examining the separation performance of different feed solutions, feed concentrations, feed pHs at 0.6MPa operating pressure. Additionally, the MWNTs/polyester TFN membrane exhibited a good long-term stability.

Structuring lipids by aggregation of acidic protein microspheres in W/O emulsions

This study shows that controlled aggregation of acidic whey protein microspheres in water-in-oil (W/O) emulsions can be used to create semi-solid lipids. An acidic aqueous phase (10 g/100 g whey protein isolate, 100 mmol/L NaCl, pH 3.5) was homogenized with an oil phase (8 g/100 g polyglycerol polyricinoleate in soybean oil) to form a W/O emulsion. These emulsions were then heated (90 °C, 30 min) to induce thermal denaturation and gelation of the globular proteins in the internal aqueous phase, which promoted irreversible gelation of the overall W/O emulsion. Rheology measurements indicated that the resulting materials had paste-like properties: they were solid-like below a critical yield stress and fluid-like (shear-thinning) above this value. The apparent shear viscosity of the W/O emulsions increased with thermal treatment, aqueous phase content, and decreasing shear rate. W/O emulsion gels containing acidic aqueous phases were considerably weaker than those containing neutral aqueous phases due to the pH dependence of whey protein gelation. Controlled aggregation of whey protein microspheres within W/O emulsions may be a useful means of producing highly viscous or semi-solid lipids with low saturated and trans-fat contents for use in the food and other industries.

A Two-Component Mass Balance Model for Calibration of Solid-Phase Microextraction Fibers for Pyrethroids in Seawater

Determination of the analyte-specific distribution coefficient between the aqueous and sorbing phases is required for estimation of the aqueous-phase concentration of the analyte of interest using polymeric materials. Poly(dimethylsiloxane)-coated solid-phase microextration (PDMS-SPME) fiber-water partition coefficient (K(f)) values for eight common-use pyrethroids were determined using a two-compartment mass balance model and parameters determined in experimental seawater microcosms. Mass balance, epimerization, and aqueous-phase degradation (i.e., hydrolysis) were characterized using gas chromatography-negative chemical ionization mass spectrometry to facilitate K(f) estimation. Of the eight pyrethroids, only bifenthrin exhibited increasing sorption on the SPME fiber over the entire time-series exposure, indicating that its K(f) value could be estimated through a stable-compound model. The remaining pyrethroids were found to be unstable (half-life of <22 days), underscoring the importance of accounting for degradation in estimating K(f). The two-compartment model explained the experimental time-series data for bifenthrin (R(2) > 0.98) and the remaining unstable pyrethroids (R(2) > 0.7), leading to estimated values of log K(f) between 5.7 and 6.4, after correcting for residual dissolved organic carbon (DOC) in the experimental seawater. These K(f) values can be used to determine freely dissolved pyrethroid concentrations in the pg/L range using PDMS-SPME in fresh or seawater matrices under equilibrium conditions in laboratory or field applications.

Optimization of Formulation Variables to Increase Antigen Entrapment in PLGA Particles

Efficient antigen entrapment is a key factor in preparation of poly (lactide-co-glycolide) acid (PLGA) vaccine formulations when the antigen is of short supply. This study presents a systematic approach in the testing of formulation variables with the objective to increase antigen entrapment in particles when the antigen stock concentration was low. Some of the experimental variables tested were poly (vinyl) alcohol (PVA) concentration in the inner (W1) and outer (W2) aqueous phase, W1/oil (O) phase ratio and choice of organic solvent. The double emulsion solvent evaporation technique was applied to prepare PLGA particles with sonication as the emulsifying force. To measure antigen entrapment efficiency, the antigen (bovine serum albumin, BSA) was isotope labeled with 125iodine (125I). Our results demonstrated that a low PVA concentration in the inner aqueous (W1) phase was beneficial to achieve a high encapsulation efficiency of antigen. On the contrary, in the outer aqueous (W2) phase, a high PVA concentration favored antigen entrapment. We also demonstrated that decreasing the W1 to O/polymer ratio contributed to increased entrapment efficiency. Testing different organic solvents (ethyl acetate, dichloromethane and chloroform), either alone or in combination, revealed that using chloroform as solvent resulted in the highest encapsulation of antigen and the highest production yield. Some of the results presented in this work are in disagreement with well-established formulation variables from previous studies.

Bioaccumulation and uptake routes of perfluoroalkyl acids in Daphnia magna

Perfluoroalkyl acids (PFAs), one kind of emerging contaminants, have attracted great attentions in recent years. However, the study about their bioaccumulation mechanism remains scarce. In this research, the bioaccumulation of six kinds of PFAs in water flea Daphnia magna was studied. The uptake rates of PFAs in D. magna ranged from 178 to 1338Lkg−1d−1, and they increased with increasing perfluoroalkyl chain length; the elimination rates ranged from 0.98 to 2.82d−1. The bioaccumulation factors (BAFs) of PFAs ranged from 91 to 380Lkg−1 in wet weight after 25d exposure; they increased with increasing perfluoroalkyl chain length and had a significant positive correlation with the n-octanol/water partition coefficients (logKow) of PFAs (p<0.05). This indicated that the hydrophobicity of PFAs plays an important role in their bioaccumulation. The BAFs almost kept constant when the PFA concentrations in aqueous phase increased from 1 to 10μgL−1. Scenedesmus subspicatus, as the food of D. magna, did not significantly affect the bioaccumulation of PFAs by D. magna. Furthermore, the body burden of PFAs in the dead D. magna was 1.08–2.52 times higher than that in the living ones, inferring that the body surface sorption is a main uptake route of PFAs in D. magna. This study suggested that the bioaccumulation of PFAs in D. magna is mainly controlled by their partition between organisms and water; further research should be conducted to study the intrinsic mechanisms, especially the roles of protein and lipid in organisms.

Multicomponent NAPL Source Dissolution: Evaluation of Mass-Transfer Coefficients

Mass transfer rate coefficients were quantified by employing an inverse modeling technique to high-resolution aqueous phase concentration data observed following an experimental release of a multicomponent nonaqueous phase liquid (NAPL) at a field site. A solute transport model (SEAM3D) was employed to simulate advective-dispersive transport over time coupled to NAPL dissolution. Model calibration was demonstrated by accurately reproducing the observed breakthrough times and peak concentrations at multiple observation points, observed mass discharge at pumping wells, and the reported mass depletions for three soluble NAPL constituents. Vertically variable NAPL mass transfer coefficients were derived for each constituent using an optimized numerical solute transport model, ranging from 0.082 to 2.0 day(-1) across all constituents. Constituent-specific coefficients showed a positive correlation with liquid-phase diffusion coefficients. Application of a time-varying mass transfer coefficient as NAPL mass depleted showed limited sensitivity during which over 80% of the most soluble NAPL constituent dissolved from the source. Long-term simulation results, calibrated to the experimental data and rendered in terms of mass discharge versus source mass depletion, exhibited multistage behavior.

Extraction of lactoferrin with hydrophobic ionic liquids

Lactoferrin is a high-added value protein that is contained in bovine whey. This work presents the study of lactoferrin extraction with imidazolium-based ionic liquids as a novel separation process that can overcome constraints associated with conventional techniques used to separate and purify this protein (e.g. chromatography). A bulk membrane configuration based on U-shaped tubes is used as an experimental set-up. Lactoferrin extraction efficiencies of up to 20% are achieved. Despite the lower efficiencies obtained with 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (BmimNTf2), this ionic liquid is preferred to 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6) because the former is more stable and less soluble in water. Low protein concentration (100mgL−1), neutral pH (6.4–8.2) and low ionic strength (0.03M) are the experimental conditions with highest extraction efficiencies. BmimNTf2 is selective towards lactoferrin with respect to bovine serum albumin (BSA), since the amount of BSA extracted is almost one order of magnitude lower. However, back-extraction of protein from the ionic liquid was not observed. In conclusion, hydrophobic, imidazolium-based ionic liquids are able to extract lactoferrin selectively, which may be due to their interaction with iron atoms of this protein. The distribution coefficient between the organic and aqueous phase depends mainly on the concentration of protein in the organic phase (exponent −2.8), showing a slight influence on the aqueous phase concentration.

Formation–structure–performance correlation of thin film composite membranes prepared by interfacial polymerization for gas separation

Thin film composite (TFC) membranes for CO2/N2 separation were prepared by interfacial polymerization from N-Methyldiethanolamine (MEDA) and Trimesoyl chloride (TMC) on crosslinked polydimethylsiloxane (PDMS) coating polysulfone (PS) support membrane. The structural properties of TFC membrane surfaces were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffractometer (XRD). The relationships among the skin layer formation conditions, skin layer structure, and membrane separation performance were investigated. Results show that membranes with higher CO2 permeance and good CO2/N2 selectivity appeared to consist of thinner, more crosslinked, and less crystalline skin layer structures. Such high performance gas separation membranes were obtained by (1) increasing MEDA diffusivity and decreasing MEDA solubility in the organic solvent, and (2) reducing TMC concentration in organic phase and raising MEDA concentration in aqueous phase under the circumstances of forming an integrated skin layer. Furthermore, our results also indicate that crosslinking could enhance the CO2-induced plasticization resistance of the membranes. These findings have great theoretical significance for the controlled preparation of gas separation membranes.

Equilibrium study on the reactive liquid–liquid extraction of 4-cyanopyridine with 4-nonylphenol

A liquid–liquid extraction equilibrium model was developed describing the extraction of aqueous 4-cyanopyridine with the reactive solvent 4-nonylphenol. The model describes the capacity of the solvent up to an equilibrium aqueous phase concentration of 20g/L within a temperature interval of 25 to 80°C. This model describes the transfer of 4-cyanopyridine from the aqueous to the 4-nonylphenol phase and takes into consideration the complexation in the solvent phase through hydrogen bonding of 4-nonylphenol with both functional groups of 4-cyanopyridine, as well as the oligomerization of 4-nonylphenol. The thermodynamic equilibrium parameters were regressed to the experimental data with good accuracy, the largest error at the confidence limit of the estimated parameters being 4%. The obtained results were in good agreement with the literature on the complexation of pyridines with phenols. The mean relative error between the model and the experimental data obtained in this work was 3.8%.

Laboratory-scale analysis of transportation and natural attenuation of diesel fuel in aquifer

Processes that control the distribution and natural attenuation (NA) of petroleum hydrocarbons dissolved from the released diesel fuel in a bench-scale model aquifer were evaluated. The experimental results obtained in two-dimensional aqueous-phase petroleum hydrocarbon concentrations indicated that the total petroleum hydrocarbon (TPH) in the aquifer migrated in longitudinal and lateral directions. The TPH plume of 2 mg L−1 spread to the entire area of the aquifer, and the maximum concentration at the center of the plume was 44.15 mg L−1 after 90 days of release. After diesel fuel release, the NA of TPH was evaluated and quantified. Experimental data indicated that the NA of TPH was immediately implemented to prevent migration of the plume into the downgradient of the aquifer, but controlling the TPH plumes using NA mechanisms requires a long time.

Reverse Micelle Liquid-Liquid Extraction of a Pharmaceutical Product

Reverse micelle extraction has received considerable attention in recent years due to its ability to selectively solubilise solutes from an aqueous phase, and in the case of biomolecules to maintain their biological activities. The apparent success of research on protein extraction from the aqueous phase using reverse micelle provides motivation to study the solubilisation of antibiotic. The objective of this study is to investigate the extraction of antibiotic (penicillin G is chosen as model antibiotic) from aqueous solution (forward extraction) and from the reverse micelle to a new aqueous solution (backward extraction). Sodium di(2-ethylhexyl)sulfosuccinate (AOT) is chosen as the surfactant and isooctane as the organic solvent. The UV-Vis spectrophotometer is used to determine the mass of penicillin G in solution after the extraction process. The extraction is expected to be influenced by the initial penicillin G concentration, the salt type and concentration in the aqueous phase, pH, and surfactant concentration. It is expected that as penicillin is an interfacially active compound that will interacts with AOT surfactant, the interfacial association will be dependent on both pH and surfactant concentration.

Influence of Formulation Factors on the Preparation of Zein Nanoparticles

The main objective of the present study was to investigate the influence of various formulation parameters on the preparation of zein nanoparticles. 6,7-dihydroxycoumarin (DHC) was used as a model hydrophobic compound. The influence of pH of the aqueous phase, buffer type, ionic strength, surfactant, and zein concentration on particle size, polydispersity index, and zeta potential of DHC-loaded zein nanoparticles were studied. Smaller nanoparticles were formed when the pH was close to the isoelectric point of zein. DHC-loaded zein nanoparticles prepared using citrate buffer (pH 7.4) was better than phosphate buffer in preventing particle aggregation during lyophilization. The ionic strength did not have a significant influence on the particle size of DHC-loaded zein nanoparticles. A combination of Pluronic F68 and lecithin in 2:1 ratio stabilized the zein nanoparticles. An increase in zein concentration led to increase in particle size of DHC-loaded zein nanoparticles. The use of optimal conditions produced DHC-loaded nanoparticles of 256 ± 30 nm and an encapsulation efficiency of 78 ± 7%. Overall, the study demonstrated the optimal conditions to prepare zein nanoparticles for drug encapsulation.

Predicting the concentration range of unmonitored chemicals in wastewater-dominated streams and in run-off from biosolids-amended soils

Organic compounds such as sterols and hormones have been detected in surface waters at ecologically relevant concentrations with sources including effluent discharged from publicly owned treatment works (POTWs) as well as leachate and runoff from land amended with municipal sludge (biosolids). Greater than 20% of regulated effluents discharged into U.S. surface waters experience in-stream dilution of <10-fold and potential impacts are particularly likely in receiving waters dominated by POTW effluents. The increasing use of biosolids on agricultural land exerts additional stress, thereby necessitating environmental monitoring for potential ecological and human health effects. Alternatively or in addition to monitoring efforts, screening for potentially hazardous chemicals can be performed using empirical models that are scalable and can deliver results rapidly. The present study makes use of data from U.S. EPA's Targeted National Sewage Sludge Survey (TNSSS) to predict the aqueous-phase concentrations and removal efficiencies of 10 sterols (campesterol, β-sitosterol, stigmasterol, β-stigmastanol, cholesterol, desmosterol, cholestanol, coprostanol, epicoprostanol, and ergosterol) as well as the putative toxicity posed by four specific hormones based on their reported biosolids concentrations using published empirical models. Model predictions indicate that removal efficiencies for sterols are uniformly high (~99%) and closely match removal rates calculated from chemical monitoring at POTWs (paired t-test; p=0.01). Results from toxicity modeling indicate that the hormones estrone, estradiol and estriol had the highest leaching potentials amongst the compounds considered here and that 17 β-ethinylestradiol was found to pose a potentially significant threat to fathead minnows (Pimephales promelas) via run-off or leaching from biosolids-amended fields. This study exemplifies the use of in silico analysis to (i) identify potentially problematic organic compounds in biosolids, (ii) predict influent and effluent levels for hydrophobic organic compounds (HOCs) of emerging concern, and (iii) provide initial estimates of runoff concentrations, in this case for four prominent hormones known to act as endocrine disruptors.

Development of novel in situ nickel-doped, phenolic resin-based micro–nano-activated carbon adsorbents for the removal of vitamin B-12

Activated carbon spheres (ACSs) and carbon micro–nanoparticles derived from nickel (Ni)-doped phenolic beads (∼0.8mm) were synthesized as efficient adsorbents for vitamin B-12 (VB12). Ni was incorporated in an intermediate step during a suspension polymerization. ACSs were synthesized by the carbonization and activation of Ni-doped polymeric beads. Carbon micro–nanoparticles (average size ∼200nm) were synthesized by milling polymeric beads followed by carbonization and activation. Adsorption tests were carried out under both batch and dynamic (flow) conditions. The latter tests were carried out in a specially designed and fabricated micro-column packed with carbon micro–nanoparticles. The adsorption loading of VB12 on the adsorbents was determined to be ∼300mg/g, corresponding to an aqueous phase concentration of 500ppm, which is comparable to or larger than the literature data. The method of in situ synthesis of metal incorporated carbon micro–nanoadsorbents and their use in a micro-column under the flow conditions has much potential for bio- and pharmaceutical separation and purification applications.