Analysis of Sulfur-Containing Gases in the Ambient Air Using Selective Pre-Filters and a Micro-coulometric Detector

Adams, Donald F.; Bamesberger, W. L.; Robertson, Taryn

doi:10.1080/00022470.1968.10469104

Cited by 19 publications

(11 citation statements)

References 9 publications

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“…Os filtros foram selecionados de acordo com a recomendaçã o de Adams et al (1968). Foram utilizados os filtros de membrana modelo AAWP02500, constituídos de ésteres mistos de celulose (nitrato e acetato), de 25 mm de diâmetro e porosidade de 0,8µm.…”

Section: Elementos De Filtraçã Ounclassified

“…Cada membrana sofreu a impregnaçã o de uma determinada soluçã o, conforme recomendado por Adams et al (1968), durante 30 minutos. Apó s esse período, foi removido o excesso de reagente e estas secaram ao ar em suportes de vidro.…”

Section: Preparaçã O Das Membranasunclassified

“…As soluções químicas, que foram preparadas com concentraçã o de 5%, indicadas por Adams et al (1968), são as seguintes: a) Bicarbonato de só dio, pH 7,0 -11,0; b) mistura de cloreto de zinco e ácido bó rico, pH 4,0 -5,0; c) mistura de nitrato de mercúrio e ácido tartárico, pH 1,0; d) mistura de nitrato de prata, ácido bó rico e ácido tartárico, pH 2,0.…”

Section: Preparo Das Soluçõ Es Químicasunclassified

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Caracterização de compostos reduzidos de enxofre gerados na produção de celulose kraft e pré-hidrólise kraft.

Moura

Foelkel²,

Frizzo³

2002

Ciênc. Florest.

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RESUMOUm problema ambiental da indústria de celulose kraft é o odor causado pela emissão dos compostos reduzidos de enxofre gerados pela deslignifica çã o de madeiras de um modo em geral. Para monitorar essas emissões, existem equipamentos simples, desenvolvidos para a mediçã o contínua do "total reduced sulphur" (TRS), tal como o analisador coulométrico. Neste trabalho, foram analisados sulfeto de hidrogê nio (H 2 S), metil mercaptana (CH 3 SH), dimetil sulfeto [(CH 3 ) 2 S)] e dimetil dissulfeto [(CH 3 ) 2 S 2 ], gerados em deslignificações laboratoriais kraft e pré-hidró lise kraft de dois grupos de madeiras de folhosas. Um dos grupos de madeiras continha 25% e o outro 20% de lignina, base peso seco. Foi observado que as madeiras com menores teores de lignina geraram significativamente menores quantidades de compostos reduzidos de enxofre de TRS. Nã o foram notadas diferenç as significativas nas quantidades totais geradas entre os processos de deslignificaçã o estudados. O processo pré-hidró lise kraft foi mais sensível aos teores de lignina da madeira que o processo kraft. Recomenda-se, por isso, trabalhar com madeiras com menores teores de lignina quando do uso do processo pré-hidró lise kraft para produçã o de celulose. As principais formas geradas de TRS foram dimetil sulfeto e metil mercaptana.Palavras-chave: processo kraft, processo pré-hidró lise kraft, TRS, enxofre reduzido, gases, lignina. ABSTRACTAn environmental concern in the kraft pulping is the odor caused by the reduced sulphur compounds.There are many simple equipments to detect on-line the total reduced sulphur (TRS), like the coulometric titrator. This study had as aim to measure the components of the total reduced sulphur compounds generated in kraft and pre-hydrolysis kraft laboratory cooking. Two types of hardwood chips were used in the cookings: one with 25% of lignin (on dry wood), the other with 20% lignin. The wood containing less lignin generated less total reduced sulphur compounds. Considering the gases formed i n the two types of cooking processes, no significant differences could be detected in terms of generated amounts of reduced sulphur compounds. However, the lignin content of the woods under evaluation had important role in generating TRS. The pre-hydrolysis kraft process was proved to be more sensitive to the higher lignin content in the wood. It is recomended to work with low lignin content wood when cooking by this process. Dimethyl sulphide and methyl mercaptan were the dominant TRS compounds in the reli ef gases from the digester.Key words: kraft process, pre-hydrolysis kraft, TRS, gases, lignin. INTRODUÇÃONo processo de polpaçã o kraft, utiliza-se uma soluçã o quente (cerca de 170 º C), denominada de licor branco, rica em hidró xido de só dio (NaOH) e sulfeto de só dio (Na 2 S), para a deslignificaçã o da madeira. Como resultado do cozimento da madeira, tem-se a celulose e um licor preto, rico em álcali e matéria orgânica dissolvida da madeira. Esse licor deve passar por um processo de recupera çã o, em que, ao final, ...

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Section: Elementos De Filtraçã Ounclassified

Section: Preparaçã O Das Membranasunclassified

Section: Preparo Das Soluçõ Es Químicasunclassified

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Caracterização de compostos reduzidos de enxofre gerados na produção de celulose kraft e pré-hidrólise kraft.

Moura

Foelkel²,

Frizzo³

2002

Ciênc. Florest.

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“…CH3SH is known to collect efficiently on Ag-impregnated filters 20 and the bisulfide group is apparently responsible for the fluorimetric quenching interaction with FMA. Nevertheless, the method's discrimination toward CH3SH agrees with previous results showing that n-butyl mercaptan 8 and S-carboxymethyl-L-cysteine 4 do not quench the 520 nm fluorescence of FMA.…”

Section: Interferencesmentioning

confidence: 99%

Performance Characterization and Optimization of the AgNO₃-Filter/FMA Fluorimetric Method for Atmospheric H₂S Measurements

Farwell¹,

Chatham²,

Barinaga³

1987

JAPCA

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This sensitive, albeit precarious, method for measuring ppb-ppt (V/V) concentrations of H 2 S was examined for various sources of potential error within the procedure. Filter preparation, filter storage, filter extraction, fluorimetric reagent stabilities, matrix differences between standards and samples, and possible interferences from other sulfur-containing compounds were separately studied for their effects on the analytical performance of the method. The overall method showed no Interference from SO 2 , CS 2 , COS, CH 3 SH, CH3SCH3, and SO 4~2 . To minimize bias and obtain a reliable estimate of precision, the method should be calibrated with H 2 S standards rather than liquid bisulfide standards. The measurement precision is a function of the quantity of H 2 S collected as Ag 2 S and/or AgSH on the impregnated filters. Because of the method's linear dynamic range, sufficient air should be sampled to achieve filter loadings of 15 to 35 ng S/filter. A quality control method based on fluoresceln mercuric acetate (FMA) is presented that ensures data quality while reducing the otherwise frequent need for fluorimetric calibration.A sensitive method for measuring low and sub-parts-perbillion (ppb V/V) concentrations of atmospheric hydrogen sulfide has been described by Natusch et al. 1 and modified by Jaeschke et al. 2 for automated field sampling. The method employs the collection of H2S on a AgNCVimpregnated filter. The filter is then leached with a basic cyanide solution to liberate the sulfide collected as Ag2S and/or AgSH on the filter. Quantification is achieved by the selective quenching effects of sulfide [S"~2] (or more correctly bisulfide [HS~] since pK2 = 19 ± 2 for H2S( aq ) 3 ) on the fluorescence of fluorescein mercuric acetate (FMA). This fluorimetric procedure was initially described by Karush et al.,4 Grunert et al., 5 and Axelrod et al. 6The work described in this paper was performed as a portion of a more comprehensive evaluation of potential analytical techniques to measure natural emissions of volatile sulfur compounds. 7 The major objectives for the specific evaluation of the AgNCVfilter/FMA fluorimetric method were to: a) compare the responses of liquid sodium sulfide standards, which are normally used to calibrate the method, with gaseous H2S standards, which better simulate actual analyte and sample matrix components; b) clarify previous conflicting reports 1 ' 2 ' 8 concerning potential positive interferences from CH3SCH3 and CH3SH; c) assess the sources and magnitudes for both indeterminate and systematic errors in the sampling and fluorimetric procedures; and d) suggest modifications to the basic method and/or operational procedures that improve both analytical ruggedness and data quality. Experimental Methods ApparatusAn Aminco-Bowman spectrophotofluorometer with an analog readout was used for the fluorimetric determinations. The excitation and emission wavelengths were 499 nm and 520 nm, respectively. Conventional fused silica cuvettes were used for the fluorimetric measurements. A...

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“…The most widely used fundamental tech-niques for H 2 S determination have been compared by Bethea [1]. The chemical methods include collection of gas in liquid [2 -4], collection on impregnated solid substrates [5 -7], coulometry [8,9], gas chromatography [10 -13] and ion chromatography [14].…”

Section: Introductionmentioning

confidence: 99%

A novel sorbent tube for ambient hydrogen sulfide determination

Volkan

Eroglu

et al. 1998

Talanta

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A novel tubular device has been developed for hydrogen sulfide determination in air. Several substrates such as commercial silica gel and alumina TLC plates, silica gel powder, alumina, CaSO 4 , CaCO 3 , BaSO 4 , MgO, chalk, h-cellulose and ethyl cellulose were tested as solid substrates. 30 -70-mesh silica gel was finally employed in glass tubes of 4.0 mm internal diameter. Silica gel is treated with 0.5 M aqueous CdCl 2 solution, dried, filled into the glass tube and sample gas is passed through the device using nitrogen as the carrier gas where 70% relative humidity is employed. The analyte reacts with the solid substrate to form a luminescent spot whose length in the tube is measured and correlated to concentration. The flow rate was 68 ml min − 1 . The analytical system is linear in the range of 0.2-1.3 ppm H 2 S for the specified conditions. The prepared devices are stable at least for 3 months prior to sampling; and after sampling, the luminescing spot is stable also at least for 3 months.

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Analysis of Sulfur-Containing Gases in the Ambient Air Using Selective Pre-Filters and a Micro-coulometric Detector

Cited by 19 publications

References 9 publications

Caracterização de compostos reduzidos de enxofre gerados na produção de celulose kraft e pré-hidrólise kraft.

Caracterização de compostos reduzidos de enxofre gerados na produção de celulose kraft e pré-hidrólise kraft.

Performance Characterization and Optimization of the AgNO₃-Filter/FMA Fluorimetric Method for Atmospheric H₂S Measurements

A novel sorbent tube for ambient hydrogen sulfide determination

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Analysis of Sulfur-Containing Gases in the Ambient Air Using Selective Pre-Filters and a Micro-coulometric Detector

Cited by 19 publications

References 9 publications

Caracterização de compostos reduzidos de enxofre gerados na produção de celulose kraft e pré-hidrólise kraft.

Caracterização de compostos reduzidos de enxofre gerados na produção de celulose kraft e pré-hidrólise kraft.

Performance Characterization and Optimization of the AgNO3-Filter/FMA Fluorimetric Method for Atmospheric H2S Measurements

A novel sorbent tube for ambient hydrogen sulfide determination

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Performance Characterization and Optimization of the AgNO₃-Filter/FMA Fluorimetric Method for Atmospheric H₂S Measurements