Robert Helleur

Characterization and potential applications of pyrolytic char from ablative pyrolysis of used tires

Pyrolysis has the potential of transforming used tires into useful recyclable products. Pyrolytic char is one of the most important products of tire pyrolysis. The process economy depends strongly on its commercial value. A 2-year study was undertaken to examine the chemistry and commercial applications of pyrolytic char obtained from the commercialized process called Continuous Ablative Regenerator (CAR) system (Enervision Inc., Halifax, Canada). The pyrolysis temperature was 550°C, residence time 0.6 s, under N2 flow and using ∼1 cm tire shreds. A small-scale unit, 0.25 ton day−1, was used in the study. The process is unique in design and features several operating parameters, which favor optimum tire pyrolysis (e.g. no heat transfer medium, fast pyrolysis and rapid product quenching). The physical properties (porosity, particle and aggregate size, surface area), chemical properties (elemental analysis, ash content and composition) and aqueous adsorption properties (for metals, phenols and methylene blue) of the pyrolytic char were examined. As well, laboratory-scale production of activated carbon from tire pyrolysis char was examined as a means of upgrading. The activated carbon was characterized in the same manner as the char. Results revealed that the char must be post- carbonized (600°C) to remove unwanted odor and trace oils. The resulting carbonized char has excellent adsorption capacity for phenol and metals (i.e. lead) from solution. It is believed that the high sulfur content in the char (2%) and the inherent composition of tire char is responsible for these properties. Activation using steam (900°C, 3 h) produced an activated carbon with good surface area (302 m2 g−1), excellent adsorption for phenol and methylene blue, but showed no improvement for metal removal. Norit SA3 and commercial charcoal were used for comparison. Further studies will be conducted to examine the char performance for Hg removal from air and water and its use in wastewater treatment and as a stack gas scrubber medium.

Lipid and Phenolic Biomarkers in Marine Ecosystems: Analysis and Applications

Biomarkers are compounds or groups of compounds that can be used as signatures of individual organisms or groups of organisms, or of certain environmental processes. Lipid and phenolic biomarkers can be used to assess the health of an ecosystem and the degree to which it has been influenced by terrestrial and anthropogenic inputs. Lipid classes and fatty acids can be used to determine production of marine biogenic material of dietary value to pelagic and benthic organisms. Polycyclic aromatic hydrocarbons and 5β-stanols such as coprostanol can be used to determine pollutant loading from oil spillage or sewage and the phenanthrene/methylphenanthrene ratio can be used specifically as an indicator of wood burning. N-alkanes and thermochemolysis products in cores can show the sensitivity of sediments to changes in land use patterns near the land margin. The relationship between marine and terrestrially derived products in sediment cores can be used to indicate the degree to which land use changes have impacted the pattern of marine biogenic productivity in the area. Stable isotope and multivariate analyses are particularly useful for biomarker validation.

Characterization of the tetramethylammonium hydroxide thermochemolysis products of carbohydrates

Abstract The identification of the thermochemolysis products (in the presence of tetramethylammonium hydroxide, TMAH) of carbohydrates is presented. Analysis was carried out using on-line flash pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and off-line flash (vacuum) pyrolysis followed by GC/MS. Standard samples of hexoses, pentoses, deoxyhexoses, lactose, cellulose and starch were treated with 25% aqueous TMAH (100 times excess by weight). Approximately 50 μg (for on-line analysis) or 250 μg (for off-line analysis) of the carbohydrate/TMAH mixture was heated to 700°C (10 s) using a quartz holder and a CDS pyroprobe. From electron and chemical impact mass spectral data, and, from literature on alkaline decomposition of carbohydrates, tentative structures of unique products and the mechanisms of their formation are proposed. A series of permethylated deoxy aldonic acids are tentatively identified as key products. It is postulated that these ‘saccharinic acids’ are initially formed from the action of alkali on reducing sugars which are then subsequently methylated. In addition, thermochemolytic analysis of lactose, cellulose and starch afforded their own unique permethylated deoxy aldonic acids as well producing methoxy benzene products, i.e. 1,2,4-trimethoxybenzene, 2,4-dimethoxyphenol. It is believed that glycosidically-linked saccharides initially degrade under alkaline conditions similar to the so-called ‘peeling reaction’ observed for cellulose under alkaline pulping conditions and then are finally methylated. An algal sample has been analyzed for its carbohydrate composition. The observation of hexose, pentose and polysaccharide thermochemolysis products illustrate the potential of the method to characterize the saccharide composition of more complex biomaterials.

Biogeochemistry of sterols in plankton, settling particles and recent sediments in a cold ocean ecosystem (Trinity Bay, Newfoundland)

Abstract In the context of a multidisciplinary study to determine current and past ecosystem health and the relative contributions of sources of organic matter (marine vs. terrestrial and natural vs. anthropogenic input), sterols were determined in plankton, settling particles and sediments from Trinity Bay, Newfoundland, a sub-polar Atlantic Ocean ecosystem. The centric diatoms Chaetoceros spp., Thalassiosira spp. and Leptocylindrus danicus were all prominent in the plankton samples, and centric diatoms predominated in the settling particles. Plankton samples contained 0.4±0.4 mg/g dw (1995) or 1.4±1.3 mg/g dw (1996) total sterols, with cholesta-5,24-dien-3β-ol (mean 26% of total sterols), cholest-5-en-3β-ol (24%) and cholesta-5,22( E )-dien-3β-ol (13%) chief among these, denoting diatom and zooplankton sources. In settling particles, the prominence of cholesta-5,24-dien-3β-ol (24%), cholest-5-en-3β-ol (24%), cholesta-5,22( E )-dien-3β-ol (13%) and 24-methylcholesta-5,22( E )-dien-3β-ol (9%) again suggested mainly marine sources. The sterol composition of plankton and settling particles from different sampling periods showed a high degree of consistency. Higher plant C 29 sterols (notably 24-ethylcholest-5-en-3β-ol, 9–26%) were prominent in sediments from both inshore and offshore sites. No decreasing trend in total or individual sterols was observed down the 30-cm sediment cores, suggesting good overall preservation. No 5β-stanols such as 5β-cholestan-3β-ol (coprostanol) were detected in offshore sediments, plankton or settling particles, with only low levels (5β-cholestan-3β-ol max. 4.4%, 5β-cholestan-3α-ol max. 5.1%) in certain inshore sediments. This suggests that raw sewage discharges in rural Newfoundland are being efficiently degraded or dispersed, or that inputs are highly localized. Source apportionation of organic matter in the sediment samples based on sterol composition was attempted. This highlighted the large terrestrial contribution to the sterols in marine sediments (up to 58% of sterols inshore, 24% offshore) and suggests either degradation or effective recycling of marine sterols.

Biomolecular characterization of allergenic proteins in snow crab (Chionoecetes opilio) and de novo sequencing of the second allergen arginine kinase using tandem mass spectrometry

Snow crab (Chionoecetes opilio) proteins have been recognized as an important source of both food and occupational allergens. While snow crab causes a significant occupational allergy, only one novel allergen has recently been fully characterized. The muscle proteins from snow crab legs were profiled by SDS-PAGE. Several of these proteins were characterized using tandem mass spectrometry. Five proteins were identified; sarcoplasmic Ca-binding (20kDa), arginine kinase (40), troponin (23kDa) and α-actine (42kDa) and smooth endoplasmic reticulum Ca(2+)ATPase (113kDa). Immunoblotting using serum of sixteen allergic patients resulted in strong reactivity with the 40-kDa protein in seven patients (43%). This protein was purified by chromatography and subsequently de novo sequenced using matrix assisted laser desorption ionization and electrospray tandem mass spectrometry. We identified a second important allergen, arginine kinase, in snow crab, designated Chi o 3. Based on identity and homology analysis, using bioinformatics tools, a signature peptide was identified as a chemical surrogate for arginine kinase. The suitability of this signature peptide was tested for analytically representing the arginine kinase, by performing a multi-reaction monitoring tandem mass spectrometry approach on actual air filter samples collected from a simulated crab processing plant.

Characterization of the saccharide composition of heteropolysaccharides by pyrolysis-capillary gas chromatography-mass spectrometry

Abstract The saccharide composition of a number of heteropolysaccharides has been successfully characterized by pyrolysis-gas chromatography. In addition, small residues of carbohydrate impurities in samples can be easily identified. The success of pyrolysis-gas chromatography to differentiate among carbohydrates was established by previous studies which found that rapid pyrolysis initiates glycosidic cleavage of saccharide units through transglycosidation thereby forming intact fragments which retain the stereoconfiguration of the saccharide, i.e., anhydro sugars. The high molecular weight product mixtures are resolved on a proper capillary column and the individual anhydro sugars identified by mass spectrometry. Bacterial and plant polysaccharides were selected having various compositions, consisting of hexoses, pentoses, deoxy sugars and uronic acids. The composition of a highly sulfated polysaccharide was also examined. It was found that uronic acid-containing polysaccharides require that the carboxylate functional group be protonated in order to obtain structurally-significant pyrolysis products.

Lipid class and carbohydrate concentrations in marine colloids

Cross-flow filtration (CFF) was used to concentrate marine colloids from microalgal cultures and surface seawater. Lipid classes in different size fractions were determined using the Chromarod-Iatroscan thin-layer chromatography with the flame ionization detection method. Total carbohydrate concentrations were determined colorimetrically using methyl benzothiazolinone hydrazone reagent. Extensive determinations of CFF blanks and recoveries were conducted for each lipid class to optimize CFF operating procedures. The total lipid blank in the CFF system was approximately 6-7 μg (~0.5 μM C). Recoveries for the major lipid classes in marine samples varied from 80% to 120%. -- Both colloidal lipid and carbohydrate concentrations in microalgal cultures were found to be 120-140 μg/L. Triacylglycerol (TAG) and polar lipids were the major lipid classes in colloids from microalgal cultures. Concentrations of colloidal (> 10,000 dalton) lipids and carbohydrates in Newfoundland seawater ranged from 0.9 μg/L to 8.7 μg/L and from 21 μg/L to 30 μg/L, respectively. The major lipid classes present in coastal seawater colloids were TAG, free fatty acids, and phospholipids. -- Data from both algal cultures and actual seawater samples showed that marine colloids are characterized by having high proportions of free fatty acids, phospholipids and hydrocarbons by comparison with truly dissolved material. The free fatty acids may be produced by microbial degradation, the phospholipids are probably derived from biological membranes, and the hydrocarbons are likely preferentially adsorbed from the surrounding water onto the colloids.

Characterization of tetramethylammonium hydroxide thermochemolysis products of near-shore marine sediments using gas chromatography/mass spectrometry and gas chromatography/combustion/isotope ratio mass spectrometry

Abstract The study describes the application of gas chromatography/mass spectrometry (GC/MS) and gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) to characterize the molecular and compound-specific stable carbon isotope composition, respectively, of tetramethylammonium hydroxide (TMAH) thermochemolysis products of organic matter present in marine sediments. The objective of the study was to examine the usefulness of TMAH thermochemolysis products in identifying organic markers of terrestrial-derived sources in marine sediments. ‘Batch-wise’ thermochemolysis conditions (excess TMAH. 250 °C, sealed glass tube, 30 min) were used on sediments and standards. Compound-specific isotope analysis (CSIA) of standards showed no evidence of isotopic fractionation at methyl carbon during methylation of a number of phenolic acid and fatty acid compounds. It was also shown that no appreciable isotopic affect occurs during bond cleavage and methylation of fatty acid groups of the standard triglyceride, tricaprin. These preliminary tests indicate that the initial δ 13 C composition of chemical markers containing acidic functional groups can be obtained by measuring the δ 13 C of the corresponding methyl esters and/or ethers after TMAH methylation. In order to confirm the number of methoxy groups in lignin-derived markers, tetraethylammonium hydroxide was employed. Useful chemical markers found in near-shore sediments in reasonable abundance were a range of fatty acids, vanillin, vanillic acid and P -coumaric acid. Preliminary results of CSIA of these phenolic markers and selected saturated fatty acids in three different marine sediment cores are reported.

Absolute quantification method and validation of airborne snow crab allergen tropomyosin using tandem mass spectrometry.

Measuring the levels of the major airborne allergens of snow crab in the workplace is very important in studying the prevalence of crab asthma in workers. Previously, snow crab tropomyosin (SCTM) was identified as the major aeroallergen in crab plants and a unique signature peptide was identified for this protein. The present study advances our knowledge on aeroallergens by developing a method of quantification of airborne SCTM by using isotope dilution mass spectrometry. Liquid chromatography tandem mass spectrometry was developed for separation and analysis of the signature peptides. The tryptic digestion conditions were optimized to accomplish complete digestion. The validity of the method was studied using international conference on harmonization protocol, Where 2-9% for CV (precision) and 101-110% for accuracy, at three different levels of quality control. Recovery of the spiked protein from PTFE and TopTip filters was measured to be 99% and 96%, respectively. To further demonstrate the applicability and the validity of the method for real samples, 45 kg of whole snow crab were processed in an enclosed (simulated) crab processing line and air samples were collected. The levels of SCTM ranged between 0.36-3.92 μg m(-3) and 1.70-2.31 μg m(-3) for butchering and cooking stations, respectively.

GC-MS/MS measurement of natural and synthetic estrogens in receiving waters and mussels close to a raw sewage ocean outfall.

In recent times, there has been an increased concern over the appearance of human estrogens in marine ecosystem and their effects on the marine habitat. Discharge of raw sewage has been identified as one of the most important sources of human estrogens in the marine environment. Therefore, we have developed a gas chromatography-(ion-trap) mass spectrometry/mass spectrometry method for the analysis of natural estrogens estrone (E1), and 17beta-estradiol (E2) and synthetic estrogens 17alpha-ethynylestradiol (EE2) and diethylstilbestrol (DES) in sewage effluents, seawater and mussels. Recovery of target analytes from mussels (n=3) was above 60% with RSD ranging from 8% to 13%. For aqueous samples (n=3) recoveries were above 80% with RSD ranging from 3% to 7%. Method detection limits for the target analytes ranged from 0.1ngg(-1) to 1.0ng/g for mussel sample analysis and from 0.5ngL(-1) to 1.2ngL(-1) for water sample analysis. The usefulness of the method was demonstrated by analyzing environmental samples from St. Johns and Halifax, Canada, where raw sewage is directly discharged into the harbors. Estrone and 17 beta-estradiol were found at 1.5ngL(-1) and 1.8ngL(-1) in seawater samples collected from St. Johns harbor, while trace amounts of estrone was measured in some mussels collected from Halifax harbor.