Particulate Sorbents Research Articles

Environmentally-stable eco-friendly pectin-silica bio-hybrid foams for soil remediation

Here we present a new class of hybrid material composed of a polysaccharide macroporous core surrounded by a thin silica layer as new adsorption platforms for the retention of organic pollutants in soil media. The core-shell hybrid foams were fabricated by ice-templating to create highly anisotropic pectin foams, followed by vapor phase silica deposition. The structural stability of the hybrid foams was tested in compression, reaching a Young's Modulus up to 5 MPa, but also, and more importantly, in direct contact with wet soils over more than one month. Hybrid foams showed a sorption capacity for a toxic dye nearly two orders of magnitude higher than the surrounding soils. Altogether, these hybrid foams combine all chemical, structural and functional properties required to be effective materials for soil depollution and, thanks to their easy-recovery, should compete with common particulate sorbents.

Novel chemically cross-linked self-molding particulate sorbents as solid-phase extraction media.

Here, we describe novel, chemically cross-linked, self-molding particulate polymer sorbents that are utilized as a molding-type solid-phase extraction medium (M-SPEM), which exhibits high permeability and rigidness. To fabricate such M-SPEM, first, polyethyleneimine (PEI)-modified reversed-phase (RP)-type particulate sorbents were synthesized, thereafter, they were chemically cross-linked by a polymer having many epoxy groups together with additional PEI. By optimizing the binding conditions of the particulate sorbents, the resultant M-SPEM has almost the same adsorption properties as the corresponding unmolded particulate sorbent for some polar (e.g., uracil and adenine) compounds. The binding technique proposed here is expected to facilitate the fabrication of molding-type sorbents and improve the performance of the SPE procedure.

Preparation and evaluation of molding-type solid-phase extraction media binding with commercially available adhesives.

A fabrication method of molding-type solid-phase extraction media (M-SPEM) bound with commercially available adhesive is presented. Six pieces of M-SPEM were prepared by heating each kneaded product of a particulate sorbent and an adhesive inserted into a six-hole cylindrical mold for hardening under an open system and normal pressure. The particulate sorbent contained in M-SPEM was divinylbenzene-based reversed-phase mode solid-phase extractants that we have reported. An examination of several adhesives showed that the moldability of M-SPEM depended on the composition and properties of the adhesive. The optimized procedure can be used to prepare an M-SPEM containing an 85 wt% particulate sorbent (particulate sorbent/adhesive, 100mg/17mg; particle diameter, 90-150µm), and the M-SPEM has a specific surface area of about 500m2/g. The established procedure in this study can bind particulate sorbents together, which showed almost no reductions in the adsorption property and liquid permeability compared with those of the particulate sorbent.

Novel Self-Molding Particulate Sorbents as Solid-Phase Extraction Media

Novel Self-Molding Particulate Sorbents as Solid-Phase Extraction Media

Molding-type Solid-phase Extraction Media Glued with Commercially Available Adhesives.

The handling of a particulate sorbent for solid-phase extraction is often troublesome because it causes static clinging and scattering. To overcome this problem, a production method for a simple molding-type solid-phase extraction medium (M-SPEM) was developed in this study by using commercially available adhesives. The content of a particulate sorbent can increase to as much as 85 wt% in the M-SPEM. Because of the high content, the proposed M-SPEMs have a higher specific surface area than previous monolithic media.

粒状収着剤を用いた気流式二槽循環流動層による気流間水分移動 -第1 報：システムの試作と基礎的水分移動特性-

粒状収着剤を用いた気流式二槽循環流動層による気流間水分移動 -第1 報：システムの試作と基礎的水分移動特性-

Sorbent material characterization using in-tube extraction needles as inverse gas chromatography column.

In-tube extraction is a full automated enrichment technique that consists of a stainless-steel needle, packed with sorbent material for the extraction of volatile and semivolatile compounds. In principle, all particulate sorbents used for enrichment in air or headspace analysis can be used. However, the selection of the sorbents is merely based on empirical considerations rather than on experimental data, which is caused by a lack of knowledge about the relevant physicochemical properties of the sorbent. Especially, the knowledge of hydrostatic, advective, diffusive, and dispersion mechanisms in addition to sorption enthalpies are important for combined transport and sorption models. To provide these missing parameters, we developed and evaluated a method in which an ordinary in-tube extraction needle was employed directly as column for sorbent characterization by inverse gas chromatography. As probe compounds, benzene, ethyl acetate, and 3-methyl-1-butanol were used to determine thermodynamic parameters such as sorption enthalpy, partitioning constant between the solid and gas phase, and kinetic parameters such as the diffusion coefficient, dispersion coefficient, and apparent permeability, exemplarily. As sorbent, three commercially available phases were characterized to demonstrate the applicability of the method.

Limitations on the Use of Spill Treating Agents at Low Temperature

ABSTRACT 2017-367 Selecting appropriate countermeasures for spill response requires access to reliable information on the utility and limitations of available countermeasures for the oil type and environmental conditions encountered. The scope of use for four classes of oil spill treating agent was assessed using laboratory tests to provide insight to the functional limitations relative to low temperature. Dispersant effectiveness is found to be relatively unaffected by temperature, however the rheological properties of oil that physically limit dispersibility are temperature-dependent. A limiting threshold value for effective dispersion is established at which rheological properties dominate, while remaining highly dispersible below the threshold. Surface washing agent effectiveness is shown to be impacted by both the increased viscosity of the oil at low temperatures, as well as reduced penetration of the product into the oil. Greater benefit may be achieved through SWA use as an enhancement to warm water flushing, ensuring selection of a product with favorable cold-weather qualities to penetrate heavy oil residue. Herder effectiveness was not examined, however an assessment of physical properties found that product density may limit the scope of use in fresh water. Both products assessed had density values very near that of water. At low temperatures one of the assessed products became negatively buoyant in fresh water, with implications to marine applications where salinity at the surface is reduced. Solidifier effectiveness was found to modestly improve with decreasing temperature, reaching a limit at the point that the solidifier-treated oil lost cohesiveness as a gel. At a temperature of −10 °C, the solidifier is merely a rigid particulate sorbent; however, functionality is restored when the temperature is raised.

EFFECT OF NOVEL OINTMENT COMPOSITION AG/TAGA: CHITOSAN-GEL ON HEALING OF EXPERIMENTAL WOUNDS WITH DIFFERENT ORIGINS

The purpose of the study – evaluation of the regenerating activity of two-component paste, consisting of silver containing finely particulate sorbent: chitosan gel. Material and methodologies. For the study we used novel excipient, consisting of two components: silver containing finely particulate sorbent: chitosan gel in ratio one-to-one. Novel sorbent agent, taken for study, consists of thermally activated silica containing aluminum hydroxide in the form of its modification silver. Experiment was conducted on 48 Wistar models in case of scalp (degloving) wound (abscission of skin area 30–40 mm2 in size on depilated side surface) and chemical burn (applying 1–2 drops of 70% sulfuric acid on the depilated surface side. Regenerating activity was evaluated based on morphometry area of the wound surface, fixing the rate of scarring. Evaluation was made histologically on 4th - micrometers paraffin sections, stained with hematoxylin and eosin, and semithin sections, stained with toluidine blue. The results of study. Composition (paste) developed from silver containing finely particulate sorbent: chitosan gel sped up (for 3 days) the process of reparative regeneration of tissue on the model of chemical burns, helped to structuring formations in skin by the type of granuloma, at the same time there were no signs of perifocal inflammation. In case of scalp wound ointment composition wasn’t conducive to raising the rate of regeneration. Conclusion . Developed excipient (paste) is effective at the first phase of wound healing process, which was showed on scalped and burn wounds, as hydrophilic base had a large sorption capacity. Traumatic effect of dry sorbent powder (powder) on the surface of the wound was offset by connecting the sorption component and a hydrophilic ointment base.

Narrow Bore Packed Column Designed for Capillary Gas Chromatograph

A narrow-bore packed column (packed-capillary column) that designed for a direct installation in conventional capillary gas chromatographic (GC) system had been developed. In this column, particulate sorbents that employed in typical GC packed columns were packed into a stainless-steel capillary of 1.0 mm i.d. By attaching a pair of stainless-steel capillaries of 1.27 mm o.d. at both ends of the column, the packed-capillary column can be directly installed into the conventional capillary GC system. In this article, fundamental of the packed-capillary column developed by our research group is mainly reviewed, along with the various applications, such as column switching analysis and evaluation of catalytic property based on the determinations of CO and CO2.

Novel sample preparation technique with needle-type micro-extraction device for volatile organic compounds in indoor air samples

A novel needle-type sample preparation device was developed for the effective preconcentration of volatile organic compounds (VOCs) in indoor air before gas chromatography–mass spectrometry (GC–MS) analysis. To develop a device for extracting a wide range of VOCs typically found in indoor air, several types of particulate sorbents were tested as the extraction medium in the needle-type extraction device. To determine the content of these VOCs, air samples were collected for 30min with the packed sorbent(s) in the extraction needle, and the extracted VOCs were thermally desorbed in a GC injection port by the direct insertion of the needle. A double-bed sorbent consisting of a needle packed with divinylbenzene and activated carbon particles exhibited excellent extraction and desorption performance and adequate extraction capacity for all the investigated VOCs. The results also clearly demonstrated that the proposed sample preparation method is a more rapid, simpler extraction/desorption technique than traditional sample preparation methods.

Transfer Kinetics of Polar Organic Compounds over Polyethersulfone Membranes in the Passive Samplers Pocis and Chemcatcher

Passive samplers for polar organic compounds often use a polyethersulfone (PES) membrane to retain the particulate sorbent material (e.g., in a POCIS; polar organic chemical integrative sampler) or to reduce the sampling rate and thus extend the kinetic regime (e.g., in a Chemcatcher). The transport kinetics over the PES membrane are evaluated here in a short-term (6 days) and a long-term (32 days) experiment with POCIS and Chemcatchers. Passive samplers were placed in a channel with flowing river water that was spiked with 22 organic chemicals including pharmaceuticals, pesticides and biocides; with logK(ow) (logarithmic octanol-water partitioning coefficient) values between -2.6 and 3.8. Samplers were removed at intervals and membranes and sorbent material were extracted and analyzed with LC-MS/MS. Uptake kinetics of the compounds fell between two extremes: (1) charged chemicals and chemicals of low hydrophobicity did not accumulate in PES and rapidly transferred to the sorbent (e.g., diclofenac) and (2) more hydrophobic chemicals accumulated strongly in the PES and appeared in the sorbent after a lag-phase (e.g., diazinon and diuron). Sorption kinetics were modeled with a three-compartment first-order kinetic model to determine uptake and elimination rate constants and partitioning coefficients. Water PES partitioning coefficients fitted with the model correlated well with experimentally determined values and logK(ow). Sampling rates of Chemcatcher (0.02-0.10 L/d) and POCIS (0.02-0.30 L/d) showed similar patterns and correlated well. Thus the samplers are interchangeable in practical applications. Longer lag-phases may pose problems when calculating time-weighted average aqueous concentrations for short passive sampling windows and for a correct integrative sampling of fluctuating concentrations.

Carbon dioxide capture with dolomite: A model for gas–solid reaction within the grains of a particulate sorbent

This work describes a mathematical model for a gas–solid reaction taking place within reactant particles made up of very small spherical grains, which grow during the reaction process due to solid product formation around the grain inner core, so that the particle void-fraction is reduced as the reaction proceeds. The structural changes in the spherical grains are taken into account in the proposed model by the inclusion of a variable diffusion coefficient of the gaseous reactant through the developing product layer. This progressively increasing transport resistance leads to a marked reduction in both reaction rate and sorbent capacity, as observed in practice in the carbonation of calcined dolomite, a process of importance in hydrogen production by means of coal or biomass gasification.

Bioavailability and detoxification of cationics: I. Algal toxicity of alkyltrimethyl ammonium salts in the presence of suspended sediment and humic acid

We investigated the role of sorption in reducing bioavailability and consequently the measured toxicity of monoalkyl trimethyl ammonium salts (MAQ) under environmental conditions. The observed toxicity of MAQ in the presence of various types of sorbents was tested on algae. Decreased toxicity was found in the presence of all particulate sorbents tested, i.e. montmorillonite, silica, different sediments and for dissolved humic acid. Silica had a minor effect on the observed toxicity, whereas the clay mineral montmorillonite detoxified very effectively. The detoxification by several real-world sediments being mixtures of sand and clay was in-between silica and montmorillonite. Humic acid detoxified most effectively on weight basis. Polynomial relationships (‘QSARs’) were established for algal toxicity of MAQ in the presence of montmorillonite, silica and humic acid with carbon chain length as descriptor. Freundlich sorption isotherms for MAQ C16 for a clay sediment, montmorillonite, silica and for algae confirmed their relative detoxification in toxicity tests. Humic acid significantly reduced bioavailability and observed toxicity of quaternary ammonium salts. Sorption of positively charged amines to suspended sediment is effectively controlled by its silt/clay fraction, not by the organic fraction. Purchased defined quality montmorillonite can serve as model sorbent in standard tests mimicking the clay fraction of natural suspended matter. It enables to study the effect of bioavailability on toxicity in a standardised way. The QSARs developed for ecotoxicity of MAQ in the presence of suspended matter and humic acid enable quantitative incorporation of bioavailability in effect assessment. This increases realism in risk assessments of these fatty amine derivatives.

燃料ガス精製用ハロゲン化物吸収剤の開発

A halide removal sorbent for hot gas clean-up system was investigated by reactivity tests with a simulated gasification fuel gas. The particulate sorbent containing sodium aluminate (NaAlO2) reacts with hydrogen chloride (HCl) under diffusion-controlling mechanism in the solid product layer. The sorbent can reduce HCl and hydrogen fluoride (HF) to less than 1 ppm at 573K. The superior performance was brought by the reaction of NaAlO2 in sorbent with HCl and HF to form sodium chloride (NaCl) and Chiolite (Na5Al3F14), respectively.

Addition of Carbon Sorbents to Reduce PCB and PAH Bioavailability in Marine Sediments: Physicochemical Tests

The addition of activated carbon as particulate sorbent to the biologically active layer of contaminated sediment is proposed as an in-situ treatment method to reduce the chemical and biological availability of hydrophobic organic contaminants (HOCs) such as polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). We report results from physicochemical experiments that assess this concept. PCB- and PAH-contaminated sediment from Hunters Point Naval Shipyard, San Francisco Bay, CA, was contacted with coke and activated carbon for periods of 1 and 6 months. Sediment treated with 3.4 wt % activated carbon showed 92% and 84% reductions in aqueous equilibrium PCB and PAH concentrations, 77% and 83% reductions in PCB and PAH uptake by semipermeable membrane devices (SPMD), respectively, and reductions in PCB flux to overlying water in quiescent systems up to 89%. Adding coke to contaminated sediment did not significantly decrease aqueous equilibrium PCB concentrations nor PCB or PAH availability in SPMD measurements. Coke decreased PAH aqueous equilibrium concentrations by 38-64% depending on coke dose and particle size. The greater effectiveness of activated carbon as compared to coke is attributed to its much greater specific surface area and a pore structure favorable for binding contaminants. The results from the physicochemical tests suggest that adding activated carbon to contaminated field sediment reduces HOC availability to the aqueous phase. The benefit is manifested relatively quickly under optimum contact conditions and improves in effectiveness with contact time from 1 to 6 months. Activated carbon application is a potentially attractive method for in-situ, nonremoval treatment of marine sediment contaminated with HOCs.

Selective adsorption of endotoxin inside a polycationic network of flat-sheet microfiltration membranes.

For the removal of remaining amounts of endotoxin, sorbents with high selectivity for endotoxin are required. Typically, particulate sorbents with positively charged ligands, such as histidine, polymyxin B poly-L-lysine and poly(ethyleneimine) (PEI), display moderate to high removal efficiencies in an environment of low ionic strength. It was found that polycationic ligands are most suitable to meet an endotoxin concentration which is below the threshold level required for parenteralia. Furthermore, protein recoveries close to 100% are obtained if the decontamination is performed at a pH close to the pI of acidic proteins. The high selectivity is probably caused by complexation of the polycationic ligand with the polyanionic endotoxin, leading to interactions with KD < 10(-9) M using PEI and assuming M(r) = 10 kDa for monomeric endotoxin; with BSA the same ligand reveals only KD = 4 x 10(-6) M. Using polymer-coated microfiltration membranes, immobilization of positively charged ligands leads to membrane adsorbers which are generally superior to chromatographic adsorbers and allow faster processing. Since immobilization takes place at polymer chains, low-molecular-weight ligands mainly add positive charges to the hydrophilic polymer. Consequently, membrane adsorbers with low-molecular-weight ligands, even DEAE, demonstrate similar selectivity to PEI or poly-L-lysine.

Removal of Gaseous Alkali Metal Compounds from Hot Flue Gas by Particulate Sorbents

Six commercially available materials have been tested as granular sorbents to be used in granular-bed filters for the removal of gaseous alkali metal compounds from the hot (1073 to 1153 K) flue gas of pressurized fluidized-bed combustors (PFBC) for proposed combined-cycle power generation. Tests were performed using a simulated dry flue gas of PFBC in a laboratory-scale, fixed-bed combustor. Diatomaceous earth and activated bauxite were found to be the two most promising sorbents. The experimental results of screening tests are presented, along with the effects of temperature and superficial velocity and space velocity of the flue gas on the sorption performance for the two sorbents. Possible sorption mechanisms, applications of the sorbents and preliminary cost evaluations are discussed.