High Molecular Weight Organic Material Research Articles

Refractory organic pollutants and toxicity in pulp and paper mill wastewaters.

This review describes medium and high molecular weight organic material found in wastewaters from pulp and paper industry. The aim is to review the versatile pollutants and the analysis methods for their determination. Among other pollutants, biocides, extractives, and lignin-derived compounds are major contributors to harmful effects, such as toxicity, of industrial wastewaters. Toxicity of wastewaters from pulp and paper mills is briefly evaluated including the methods for toxicity analyses. Traditionally, wastewater purification includes mechanical treatment followed by chemical and/or biological treatment processes. A variety of methods are available for the purification of industrial wastewaters, including aerobic and anaerobic processes. However, some fractions of organic material, such as lignin and its derivatives, are difficult to degrade. Therefore, novel chemical methods, including electrochemical and oxidation processes, have been developed for separate use or in combination with biological treatment processes.

Low-pressure membrane filtration of secondary effluent in water reuse: Pre-treatment for fouling reduction

Fouling in the low-pressure membrane filtration of secondary effluent for water reuse can be severe due to the complex nature of the components in the water. Pre-filtration, coagulation and anion exchange resin were investigated as pre-treatments for reducing fouling of microfiltration (MF) and ultrafiltration (UF) membranes in the treatment of activated sludge-lagoon effluent. The key fouling components were determined using several analytical techniques to detect differences in the organic components between the feed and permeate. Pre-filtration (1.5 μm) enhanced the permeate flux for MF by removing particulates, but had little effect for UF. Marked flux improvement was obtained by coagulation pre-treatment at 5 mg L −1 Al 3+ with internal membrane fouling being substantially alleviated. Anion exchange resin removed >50% of effluent organic matter but did not improve the flux or reduce irreversible membrane fouling. These results, together with detailed organic compositional analyses, showed that the very high-molecular weight organic materials (40–70 kDa) comprised of hydrophilic components such as soluble microbial products, and protein-like extracellular matter were the major cause of membrane fouling.

Water adsorption and cloud condensation nuclei activity of calcite and calcite coated with model humic and fulvic acids

Recent studies have shown that organics can alter the water adsorption and cloud condensation nuclei (CCN) activity of common deliquescent species in the Earth's atmosphere. However, very little is known about the effect of organics on water adsorption and CCN activity of insoluble nuclei, such as mineral dust aerosol. A large fraction of unidentified organic material in aerosol particles is composed of poly-acidic compounds resembling humic substances. The presence of these humic-like substances (HULIS) can alter the water adsorption and CCN activity of mineral dust aerosol. We have measured the CCN activity of model humic and fulvic acids and of mineral dust particles coated with these substances in the laboratory. We find that coatings of humic and fulvic acids on calcite particles significantly increases water adsorption compared to uncoated particles. CCN measurements indicate that humic- or fulvic acid-coated calcite particles are more CCN active than uncoated calcite particles. Additionally, thicker coatings of humic or fulvic acids appear to result in more efficient CCN activity. Thus, mineral dust particles coated with high molecular weight organic materials will take up more water and become more efficient CCN in the atmosphere than uncoated mineral dust particles, potentially altering the effect of mineral dust on the Earth's climate. In addition to the experimental results, we have explored a newly modified Köhler theory for predicting the CCN activity of insoluble, wettable particles based on multi layer water adsorption measurements of calcite.

Lead- and copper-complexing extracellular ligands released by Kirchneriella aperta (Chloroccocales, Chlorophyta)

The freshwater planktonic alga Kirchneriella aperta was grown in batch cultures to stationary growth phase. Copper and lead complexation properties of the exudate from stationary and exponential growth phases were determined by titrations monitored by ion-selective electrodes. Molecular weight fractionation (dialysis) and analysis of the titration data (Scatchard Plot) revealed that K. aperta releases metal-complexing ligands. Copper is associated with low and high molecular weight compounds, whereas lead forms complexes with only high molecular weight compounds. Gas–liquid chromatography showed that mannose and rhamnose make up 74% of the total high molecular weight organic material, with uronic acids present at 19%.

δ 13C of free and macromolecular aromatic structures in the murchison meteorite

Analyses of the organic compounds in the Murchison meteorite have led to a greater understanding of the nature of extraterrestrial organic materials. However, the relationship between low and high molecular weight material remains poorly understood. To investigate this relationship, untreated Murchison was subjected to supercritical fluid extraction (SFE) to obtain the free organic components in the meteorite. Toluene and other volatile aromatic hydrocarbons dominated the extract, and the carbon isotopic composition of these molecules was determined by gas chromatography-isotope ratio-mass spectrometry (GCIRMS). δ 13C values of the aromatic hydrocarbons ranged from −28.8 to −5.8‰. These compounds displayed a 13C-enrichment with increasing carbon number suggesting an origin by cracking. The high molecular weight organic material in the meteorite was isolated and subjected to hydrous pyrolysis. This procedure produced a number of aromatic products, the majority of which were volatile aromatic hydrocarbons, particularly toluene. SFE was used to extract and successfully retain them. This enabled the first carbon isotopic analysis of this poorly understood material to be performed at the molecular level by GCIRMS. δ 13C values for aromatic pyrolysis products occupied a range from −24.6 to −5.6‰. The trend of 13C-enrichment with increasing carbon number, observed in the free compounds, was also evident in the macromolecular fragments. Furthermore, the organic fragments of the macromolecular material were consistently 13C-enriched when compared to structurally identical free molecules. This suggested that the free aromatic hydrocarbons in Murchison were produced by the preterrestrial degradation of the organic macromolecular material. This natural degradation event was extended by the hydrous pyrolysis experiment.

95/00006 Carbon Isotopic composition of individual hydrocarbons and associated gases evolved from micro-scale sealed vessel (MSSV) pyrolysis of high molecular weight organic material

95/00006 Carbon Isotopic composition of individual hydrocarbons and associated gases evolved from micro-scale sealed vessel (MSSV) pyrolysis of high molecular weight organic material

Carbon isotopic composition of individual hydrocarbons and associated gases evolved from micro-scale sealed vessel (MSSV) pyrolysis of high molecular weight organic material

The molecular carbon isotopic composition of pyrolytically generated gaseous and non-gaseous compounds was monitored by compound specific isotopic ratio mass spectrometry. The instrument used for this study was a modified commercial GC-C-IRMS system onto which a micro-scale sealed vessel (MSSV) injection assembly has been mounted. The use of two different GC columns (Poraplot Q for gases and SE 54 for liquids) permitted analysis of the δ 13C of the pyrolysates for their C 1−C 30 + n-alkane content. In addition, CO 2 could be analysed together with the methane to hexane content in a single GC-C-IRMS run. Data obtained from the analysis of asphaltenes were contrasted with those obtained from the molecular isotopic analyses of their parent oils. Additional materials including sediments, coals, and humic matter were amenable to the MSSV pyrolysis procedure and provided isotopic information that could be exploited in terms of kerogen type but failed to show any maturity relationships. A relationship between the isotopic composition of pyrolytically generated carbon dioxide and the depositional paleoenvironments of candidate source rocks was found.

Characterization of Chlorinated Aromatic Structures in High Molecular Weight BKME-Materials and in Fulvic Acids from Industrially Unpolluted Waters

This paper presents the results of a comprehensive characterization of chlorinated aromatic structures in high molecular weight organic material from bleached kraft mill effluents (BKME) and industrially unpolluted surface waters and groundwaters. After oxidative degradation (permanganate) of the organic materials and derivatization (diazomethane) of the degradation products obtained, the occurrence of chlorinated aromatic degradation products was investigated using gas chromatography/mass spectrometry. About twenty chlorinated methyl esters of aromatic carboxylic acids were identified in degraded samples of both industrial and natural origin. The identified compounds originated from chlorinated 4-hydroxyphenyl, 3,4-dihydroxyphenyl, guaiacyl, “condensed” guaiacyl, syringyl and veratryl units present as structural elements in the high molecular weight organic materials studied. Degradation products originating from mono- and dichlorinated 4-hydroxyphenyl units dominated in the degraded samples from unpolluted environments, whereas degradation products originating from chlorinated guaiacyl and syringyl units were most abundant in the degraded softwood and hardwood BKME samples. A special study of the monochlorinated isomers of 4-ethoxy-3-methoxybenzoic acid methyl ester showed that the 6-chloro isomer dominated in the degraded BKME samples whereas about equal amounts of the 5-chloro and 6-chloro isomers were found in degraded fulvic acids isolated from unpolluted waters.

Assessment of trophic structure of Cretaceous communities based on stable nitrogen isotope analyses

New δ 15 N data suggest the retention of an indigenous signal in ancient high molecular weight organic material. These data open the possibility of obtaining new paleoecological information, based on isotopic analyses, on ancient, well-preserved fossil communities. Stable carbon and nitrogen isotope analyses were performed on high molecular weight organic material isolated from 22 taxa of Late Cretaceous vertebrates (Judith River Formation, Alberta,Canada). The majority of δ 13 C and δ 15 N values (-27‰ to -23‰ and 4‰ to 12‰, for δ 13 C and δ 15 N, respectively) are similar to those reported for modern consumers. An assessment of trophic levels based on δ 15 N is consistent with previous interpretations of food web structure derived from paleoecological interpretations. Among terrestrial consumers, carnivorous theropods (tyrannosaurids and dromaeosaurids) have high δ 15 N values (6.6‰ ±0.4‰ and 7.9‰, respectively) relative to those of the dominant megaherbivore (hadrosaurids, 4.7‰ ±0.5‰). Within aquatic environments, the values of δ 15 N of the bowfin Amia (11.6‰) and plesiosaur (11.0‰),distinguish the piscivorous tendencies of these organisms from those of tower trophic level consumers such as the benthic feeding sturgeon Acipenser and the turtle Aspideretes (δ 15 N = 5.1‰ and 4.5‰, respectively). The correlation in trophic position between δ 15 N values and paleoecological evidence is unlikely to be coincidental.

Geochemical characterization of high molecular weight material isolated from late cretaceous fossils

The appraisal of geochemical analyses obtained from the organic component isolated from fossils is often limited by the ability to assess the origins of this material. This study reports the first carbon and nitrogen isotope and amino acid analyses of high molecular weight organic material isolated from bones and teeth of reptiles from the Judith River Formation, Alberta. Amino acid analysis of the HC1 hydrolyzates of these samples show an abundance of glutamic acid and aspartic acid which suggests good preservation. Evidence of a remnant of the original organic material is indicated by the apparent presence of hydroxyproline, a common amino acid in bone collagen. Amino acid d/l values are less than 0.25. This may result from incorporation of the amino acids into a high molecular weight organic materials. Stable carbon and nitrogen isotope values range between − 26.0 and −24.0% 0 and 2 and 12% 0, respectively. Reptiles of terrestrial and aquatic habitats have δ 15N values which increase in the order of panoplosaur < hadrosaur < ceratopsid < tyrannosaur and aspideretes < champsosaur <crocodile < plesiosaur, respectively. These isotope signatures and trends in nitrogen values are typical of large modern herbivores and carnivores. The geochemical data suggest that a biochemical signal may be maintained throughout diagenesis. Such a signal could provide exciting new information pertaining to the comparative biochemistry, metabolism and ecology of fossil assemblages.

Characterization of a Scottish dopplerite

A dopplerite found in a sand quarry near Strathaven, Strathclyde comprises mainly high molecular weight organic materials about 2850 years old. It superficially resembles humic acid in its acid and alkali solubility characteristics and in its elemental C, H, N and O composition. Its ash contains substantial amounts of Ca, Fe and Al. In these respects it resembles earlier data for dopplerite found in Europe and America. Infrared spectroscopy and acid hydrolysis, however, showed that the sample, which is poorly humified, more closely resembles sphagnol, a lignin-like polymer from Sphagnum, than a conventional humic acid. Its most likely origin is therefore from Sphagnum moss and the low N content is consistent with this interpretation.

High molecular weight organic matter in seawater

The presence and nature of high molecular weight organic matter in seawater was critically reviewed and its biogeochemical cycle was discussed. Organic matter that passes through a filter of 0.5–1 μm pore size is called dissolved and that which does not pass through such a filter is defined as particulate. The size of colloidal particles ranges from 0.001 to 1 μm, and therefore, they are included in the dissolved fraction having high molecular weight. High molecular weight organic matter greater than 100,000 molecular weight was found in the seawater of Tokyo Bay. The values ranged from 0.1 to 1.5 mgC/l, and accounted for 8–45% of the total dissolved organic matter. Decomposition experiments on dissolved organic matter showed that macromolecular organic matter is refractory to bacterial attack. However, macromolecular organic materials tend to aggregate or adsorb on small particles to a sufficient size for precipitation. Organic aggregates thus formed sink to the bottom of the sea and bioelements included in them are removed from water column. High molecular weight organic materials are, therefore, considered to play an important role in transportation and distribution of matter in seawater. In order to elucidate the chemical and biological properties of macromolecular organic matter, concentration and isolation of this material are important, using methods such as adsorption on organic adsorbents or ultrafiltration.

Optical and dielectric properties of water solutions of some high-molecular weight organic materials

Optical and dielectric properties of water solutions of some high-molecular weight organic materials