Hyman D. Gesser

Chelating polymers and related supports for separation and preconcentration of trace metals.

This review is concerned mainly with the applications of chelating polymeric resins for the separation and concentration of trace metals from oceans, rivers, streams and other natural systems. Commercially available resins, specially prepared polymers and a selection of other sorbents are described and their uses outlined. Special emphasis is placed on the preconcentration of uranium from sea-water.

Microextraction of volatile organic compounds using the inside needle capillary adsorption trap (INCAT) device

A novel method of solventless extraction has been developed based on a combination of solid phase micro extraction and purge and trap methods. In this technique, a hollow needle with either a short length of GC capillary column placed inside it, or an internal coating of carbon, is used as the preconcentration device. Sampling may be performed on ambient air, on solution, or the solution headspace, by passing the gas or liquid through the device either actively with a syringe, or passively via diffusion. The VOC are sorbed and concentrated onto either the carbon layer, or the liquid stationary phase of the capillary column, within the needle. Placing the needle into a heated GC injection port thermally desorbs the organic compounds directly into the GC without the need for solvent extraction. Results suggest that this procedure provides a rapid and sensitive alternative method to those currently available.

Recovery of gallium from coal fly ash

A study has been made on the extraction of gallium from coal fly ash. A process which includes acid leaching, impurity removal, foam extraction of gallium and its purification has been suggested. The relatively moderate conditions of temperature, acid strength and time should be chosen in acid leaching to obtain the most efficient extraction of gallium. The experiments showed that the major elements in fly ash, such as aluminum, iron, silicon and calcium, can be recovered efficiently via the proposed flowsheet and that secondary environmental pollution can be avoided.

The active and passive sampling of benzene, toluene, ethyl benzene and xylenes compounds using the inside needle capillary adsorption trap device

A new and simple method of solventless extraction of volatile organic compounds (VOCs) from air is presented. The sampling device has an adsorbing carbon coating on the interior surface of a hollow needle, and is called the inside needle capillary adsorption trap (INCAT). This paper describes a study of the reproducibility in the preparation and sampling of the INCAT device. In addition, this paper examines the effects of sample volume in active sampling and exposure time in passive sampling on the analyte adsorption. Analysis was achieved by sampling the air from an environmental chamber doped with benzene, toluene, ethyl benzene and xylenes (BTEX) compounds. Initial rates of adsorption were found to vary among the different compounds, but ranged from 0.0099 to 0.016 nmol h(-1) for passive sampling and from 2.2 to 10 nmol h(-1) for active sampling. Analysis was done by thermal desorption of the adsorbed compounds directly into a gas chromatograph injection port. Quantification of the analysis was done by comparison to actively sampled activated carbon solid phase extraction (SPE) measurements.

Autoxidation and yellowing of methyl linolenate

The autoxidation of fatty esters of linseed oil is studied extensively, and the products formed from these reactions are identified. The mechanism suggested for autoxidation, helps to understand fat deterioration resulting in offensive odours and flavours, and to develop new antioxidants to prevent this decomposition. The oxidation following oxidative copolymerization should be investigated in order to understand and to develop new methodology to prevent yellowing. Although the yellowing of indoor oil paints could be prevented to an extent, no compound is known to completely inhibit this process nor has the cause for this yellow colouration been isolated, leaving the doors wide open for further investigation.

The extraction of uranium by amidoximated orlon

The nitrile groups in polyacrylonitrile (Orlontrade mark) fabric were converted to amidoxime groups to produce an amidoximated orlon fabric. The amidoximated fabric was evaluated for its ability to extract uranium from aqueous solution with a wide range of temperature and pH values. The conversion of nitrile groups to amidoxime groups was simple and relatively inexpensive. In general, the modified orlon fabric showed superior extractability of uranium at all temperatures and pH values tested when compared to untreated Orlontrade mark fabric.

Extraction of uranium from aqueous solution by phosphonic acid-imbedded polyurethane foam

Phenylphosphonic acid was imbedded into the matrix of the polyurethane foam during the fabrication process of the polymer. The extraction of uranium by phosphonic acid-imbedded polyurethane foam and blank polyurethane (i.e., foam without phosphonic acid functional groups) was investigated. Phosphonic acid-imbedded foam showed superior extractability of uranium from solutions with pH=7.0+/-1.5 over a wide range of temperature.

The extraction and recovery of phthalate esters from water using porous polyurethane foam

Abstract Porous polyurethane foam has been successfully used to remove some phthalate esters from water at the parts per million level. A variety of foams was tested, as well as coated foams, under flow and under static conditions. The mechanism of absorption was investigated.

Evaluation of a β-diketone-imbedded polyurethane foam

Abstract A β-diketone-imbedded polyurethane foam was made for the sorption of uranium from aqueous solutions. The incorporation of the β-diketone functional group into the polyurethane foam was simple, and relatively inexpensive. The β-diketone foam was ground to facilitate the evaluation of its ability to extract uranium from aqueous solutions with a wide range of temperature and pH values. The β-diketone material showed superior extractability of uranium from solutions with pH 7 ± 3. In general, the β-diketone material showed greater extractability of uranium at all temperatures and pH values tested when compared to a blank polyurethane foam without the β-diketone functional group.

Analysis of trace metals in water by in-situ sample pre-concentration combined with wavelength dispersive X-ray fluorescence spectroscopy and inductively coupled plasma-optical emission spectroscopy.

In this paper an earlier work on the use of poly(acrylamidoxime) cloth for use as a passive monitor for trace metals in water by characterizing the sorption of several metals onto the cloth using a continuous flow chamber is extended. The monitors consists of amidoxime chelating groups covalently bound to the surface of a textile encased in a common 35 mm slide holder. Placement of this device in the water to be sampled resulted in the uptake of heavy metals by the chelating groups. After removal of the monitor from water, the metals were analyzed using wavelength dispersive X-ray fluorescence spectroscopy (WDXRF) as well as by acid extraction followed by inductively coupled plasma-optical emission spectroscopy (ICP-OES). Correlation between the two methods of analysis varied with maximum correlation of 0.99897 observed for Pb and a minimum correlation of 0.16512 for Mg. The order of the distribution coefficients for the seven metals tested was: Pb> or =Cu>Zn>Cd>Mn>Fe>Mg, in agreement with the order of the stability constants for the amidoxime/hydroxamic acid group for the chelation of the same metals at a pH of 5, with the exception of Fe. Field testing of the monitors was also carried out and a comparison made between active sampling of river water and sampling with the monitors. Results indicated that semiquantitative analysis of trace metals in water may be performed using the passive monitors.