Colin D. Chriswell

Analytical investigation of the properties and uses of a new hydrophobic molecular sieve.

Distribution coefficients and capacities have been determined for many different organic compounds on a new molecular sieve called silicalite, which does not adsorb water but does adsorb small organic molecules with diameters up to 6 A, from both liquid and gaseous streams. The characteristics of silicalite have been examined closely and new applications for it are briefly described.

Chemical cleaning of coal by molten caustic leaching after pretreatment by low-temperature devolatilization

Pretreatment of coal by devolatization at temperatures ranging from about 420° C. to about 450° C. for from about 10 minutes to about 30 minutes before leaching with molten caustic leads to a significant reduction in carbonate formation, greatly reducing the cost of cleaning coal on a per ton basis.

Applications of resins for extracting organic components from water

ZusammenfassungDie verwendeten Harze, die Extraktionsvorrichtungen, einige Leistungstests sowie die allgemeine Methodik werden kurz beschrieben. Neue Entwicklungen von einfachen und wirtschaftlichen Verfahren zur Überwachung interessierender Verschmutzungsstoffe werden besonders erwähnt. Als Beispiele werden Wasserverunreinigungen durch PVC-Röhren, durch Pesticide, Amine, halogenierte Kohlenwasserstoffe sowie Modellverbindungen diskutiert. Das Verfahren der Sorption an Harz wird mit der Sorption an Aktivkohle sowie mit der Lösungsmittelextraktion verglichen. Ein neu entwickeltes Kleingerät zur Probenahme wird beschrieben.SummaryThe discussion of the applications is prefaced by very brief descriptions of: 1) the resin characteristics, 2) the extraction device, 3) some efficiency tests, and 4) the general methodology. Recent developments of simple and inexpensive procedures for the monitoring of selected contaminants of concern are stressed. Examples are given of the contamination of water by PVC tubes and of the measurements of pesticides, amines, halocarbons, and model compounds in water. Practical comparisons of the resin sorption method to carbon sorption and solvent extraction procedures are presented and recently developed mini-samplers are discussed.

The partitioning of elements during physical cleaning of coals

Abstract The fate of 75 different elements was determined in coal samples before and after physical cleaning; in coarse coal wastes removed during cleaning; in process waters before and after the cleaning of coal; and in leachates of coal wastes. The results showed that the concentration of most elements simply followed the ash content of coal before and after cleaning. Germanium was significantly enriched and beryllium, molybdenum, uranium, iodine, cobalt and antimony were slightly enriched in cleaned coals. Sodium, sulfur, chlorine, calcium, iron, magnesium and potassium were observed in the process waters at concentrations above 100 mg/l with sodium at 860 mg/l being the highest concentration observed.

Selective concentration of amines from aqueous solutions by a gas purging technique.

Amines are removed from heated, basic solutions saturated with salt by inert gas stripping and selectively trapped as coordination complexes on columns containing copper(II) salts coated on an inert support. An estimate of the amine concentrations at ppm levels can be made by measuring the length of the trapping column colored by the complexes. Concentrations of amines in ppb can be determined by eluting this column with potassium hydroxide and determining the amines in the effluent directly by gas chromatography. The procedure allows amines to be concentrated by a factor of 200 and removes potentially interfering substances from the sample.

Determination of forms of organic sulfur in coal by step-wise oxidation with perchloric acid-ferric perchlorate mixture

Abstract Differentiation of organic sulfur forms in coal by step-wise oxidation with a mixture of perchloric acid (HClO 4 ) and ferric perchlorate (Fe(ClO 4 ) 3 ) was studied. Various organic sulfur compounds were oxidized with HClO 4 solution containing Fe(ClO 4 ) 3 , and the amounts of sulfate formed during reaction were measured. The compounds can be grouped into three categories according to their reactivities as follows: (1) easily oxidized ones, i.e. disulfides, for which almost all of the sulfur was converted to sulfate after oxidation, (2) less reactive ones including aliphatic sulfides, aliphatic and aromatic thiols (20–30% of sulfur in these compounds was oxidized to sulfate), and (3) relatively stable ones, i.e. thiophenes and aromatic sulfides, from which no sulfate was formed. Samples of Illinois No. 6 and Bevier coals were also reacted with HClO 4 solutions containing increasing concentration of Fe(ClO 4 ) 3 . The organic sulfur in these coals could be differentiated into various groups according to their reactivities.

Effect of hydrofluoric or hydrochloric acid pretreatment on the ultrasonic extraction of organic materials from fly ash for chromatographic analysis.

H In order to increase the amounts of organic material extracted ultrasonically from fly ash for chromatographic analyses, the effects of acid pretreatment were investigated. Fly ash samples were extracted without pretreatment, after pretreatment with hydrofluoric acid (HF), and after pretreatment with hydrochloric acid (HC1). Gas and liquid chromatographic profiles of the extracted materials revealed that both HF and HC1 pretreatments led to the recovery of greater amounts of organic material than without pretreatment, and pretreatment with HF increased the recovery of organic material significantly more than pretreatment with HCl. The effectiveness of HF pretreatment is believed to be due to dissolution of sorbing matter, such as silica and metal salts, originally present in the fly ash. Chromatograms of the extracts of HC1pretreated fly ash samples did contain some more intense peaks than those found in chromatograms of HF-pretreated fly ash. These findings indicate that pretreatment with HF alone is not effective in releasing all of the organic components from fly ash.

Improved caustic coal desulfurization by a float-sink/leaching process employing 50% aqueous NaOH solutions

Abstract The lowest residual sulfur levels ever attained by caustic leaching of Illinois No. 6 coal samples have resulted from the application of a combined float-sink/leaching (FL) process in which 50% aqueous NaOH solutions serve as the heavy medium during the float-sink step and as the reagent during subsequent atmospheric pressure leaching. In addition to yielding coal with extremely low residual sulfur levels, this process also requires significantly less energy and less caustic for cleaning coal than molten caustic leaching (MCL) procedures from which it was derived. In one variation of the FL process, coal samples are pretreated by a float-sink procedure using 50% aqueous NaOH as the heavy medium. The floated coal plus a portion of the 50% aqueous caustic used during float-sink are then heated at 390°C at atmospheric pressure for 30 minutes. The resulting coal-caustic cake is then washed to remove solubilized materials, and a clean coal product is recovered. When applied to Illinois No. 6 coal samples initially containing 3.8% sulfur and 11% ash, this variation of the FL process led to recovery of a cleaned coal containing only 0.2% sulfur and 0.3% ash. In other variations of the FL procedure, the amount of caustic, the leaching temperature, and leaching durations have been reduced. Even under these milder conditions, use of the FL process resulted in cleaned coals at least as low in sulfur as can be attained by MCL. An important advantage of the FL process compared with MCL is the reuse of recovered caustic solutions without need for drying. It is estimated that 90% of the energy consumed during MCL is required for evaporation of water from regenerated caustic process streams to produce a dry caustic for reuse. With the FL process, unreacted caustic is recovered as a 50% solution that has been reused without drying and without loss of cleaning effectiveness. The effectiveness of the FL process may result from the removal of a sulfur-containing species during the float-sink step that is unreactive with caustic during the subsequent leaching step.

Separation by Countercurrent Washing of Coal-Caustic Mixtures during Chemical Coal Cleaning

Abstract Leaching coal with molten sodium hydroxide at 370–390°C converts most of the sulfur and mineral components of the coal into soluble species. The unreacted caustic and soluble components are then separated from the cleaned coal by a series of washing and filtration steps. A laboratory-scale simulation of a 6-stage countercurrent washing and filtration procedure was performed on Illinois No. 6 and Kentucky No. 11 coal samples that had been leached with molten sodium hydroxide. The mass of filter cakes and filtrates during each wash cycle and the concentrations of all major components of the caustic solutions were determined in each process stream. The countercurrent washing procedure resulted in a relatively clean coal and a final filtrate with a caustic concentration close to the desired 50%. However, after several coals had been processed, filtration rates decreased markedly and the mass of filtrate recovered also decreased. This was due to a build-up of a precipitate, consisting predominantly of...

Mutagenic Analysis of Drinking Water

As recently as ten years ago relatively little was known about organic contaminants in drinking water. The carbon absorption methods (3,12) and other techniques were used to provide an indication of the amount of organic matter in water. However, only a handful of the individual compounds had ever been identified. During the past ten years it has become possible to separate and identify many organic substances in drinking water using techniques such as gas chromatography-mass spectrometry (GC-MS). Nearly 500 compounds have now been positively identified (9,10) and the list of identifications is continuing to grow.