Fluorescence-based method for fast quantification of active aluminums in natural and treated water

Delimiting conditions under which natural organic matter can control Fe speciation and size in freshwaters

Nanoparticle stability in lake water shaped by natural organic matter properties and presence of particulate matter

Ferrate(VI) decomposition in water in the absence and presence of natural organic matter (NOM)

Total luminescence spectra of IHSS standard and reference fulvic acids, humic acids and natural organic matter: comparison of aquatic and terrestrial source terms

Removal of endocrine disrupters in water under artificial light: the effect of organic matter

Stability studies for titanium dioxide nanoparticles upon adsorption of Suwannee River humic and fulvic acids and natural organic matter

Adsorption of natural organic matter and divalent cations onto / inside loose nanofiltration membranes: Implications for drinking water treatment from rejection selectivity perspective.

The composition and physiochemical properties of aquatic-phase natural organic matter (NOM) are most important problems for both environmental studies and water industry. Laser desorption/ionization (LDI) mass spectrometry facilitated successful examinations of NOM, as humic and fulvic acids in NOM are readily ionized by the nitrogen laser. In this study, hydrophobic NOMs (HPO NOMs) from river, reservoir and waste water were characterized by this technique. The effect of analytical variables like concentration, solvent composition and laser energy was investigated. The exact masses of small molecular NOM moieties in the range of 200-1200 m/z were determined in reflectron mode. In addition, spectra of post-source-decay experiments in this range showed that some compounds from different natural NOMs had the same fragmental ions. In the large mass range of 1200-15,000 Da, macromolecules and their aggregates were found in HPO NOMs from natural waters. Highly humic HPO exhibited mass peaks larger than 8000 Da. On the other hand, the waste water and reservoir water mainly had relatively smaller molecules of about 2000 Da. The LDI-MS measurements indicated that highly humic river waters were able to form large aggregates and membrane foulants, while the HPO NOMs from waste water and reservoir water were unlikely to form large aggregates.

Natural organic matter (NOM) can be defined as a mixture of complex organic compounds that universally present in natural waters. High NOM content in water strongly impact the water quality and treatment in several ways (e.g. causing colour and odour, filter fouling and increase coagulant dose). Besides that, NOM also acts as the main precursor to disinfectant by products (DBPs) produce from the reaction of NOM and disinfectant during water treatment. DBPs are known to be carcinogenic to human and animals. The formation of DBPs is depending on NOM characteristics. Generally, NOM characteristics are differ according to the water sources. In order to understand NOM properties, NOM fractionation is required and therefore different approaches have been proposed for its characterization. Meanwhile several methods of treatment have been developed to remove or reduce the amount of NOM in drinking water sources to prevent DBPs formation. The aim of this paper is to review and discuss the properties and available treatment techniques for NOM.

Removal of fluoride and natural organic matter from natural tropical brackish waters by nanofiltration/reverse osmosis with varying water chemistry

Sorption of natural organic matter fractions to goethite (α-FeOOH): effect of chemical composition as revealed by liquid-state 13C NMR and wet-chemical analysis

Speciation of rare earth elements in natural terrestrial waters: assessing the role of dissolved organic matter from the modeling approach

The binding capacity of fulvic and alginic acids towards trimethyl tin(IV) cation was quantitatively determined in order to evaluate the sequestering ability of toxic organometallic compounds by natural organic matter. Investigations were performed in the pH range of natural waters (5–8.5) where the carboxylate groups, largely present in both sequestering agents, are the main binding sites. A chemical interaction model, according to which both the protonation of polyelectrolyte ligands and the hydrolysis of the organotin cation in NaCl aqueous solution were considered, was used to define the speciation of the systems under investigation. Measurements performed at different ionic strength values (0.1, 0.25, 0.5 and 0.7 mol L−1, NaCl) allowed us to consider the dependence of stability constants on the ionic strength, and to calculate the formation constants at infinite dilution. Results obtained show the formation of the complex species TMT(L), TMT(L)2 and TMT(L)(OH) for L = fulvic acid and TMT(L) for L = alginic acid, respectively. In order to compare the strength of interaction of these natural poly electrolytes with other analogous synthetic polyelectrolytes, measurements were also carried out on the trimethyltin(IV)–polyacrylate (5.1 kDa) system, and in this case the formation of TMT(L), TMT(L)2 and TMT(L)(OH) species was found. Results show the following trend of stability for the species TMT(L) in the systems investigated: TMT–fulvate ≈ TMT–polyacrylate > TMT–alginate. On the basis of the stability data obtained, the lowest concentration of fulvic and alginic acids, able to act as sequestering agents towards triorganotin(IV) cation in the conditions of natural waters, was also calculated. Copyright © 2006 John Wiley & Sons, Ltd.

Experiments were performed to assess the effects of treating the fulvic acid fractions of background natural organic matter (NOM) by catalyst-induced oxidative coupling reactions. Changes in the molecular characteristics of the fulvic acids and related disinfection byproduct formation potentials of these important NOM constituents were investigated. The coupling reactions were induced by addition of horseradish peroxidase (HRP) and hydrogen peroxide to aqueous solutions of the fulvic acids (FAs) in semicontinuous flow reactors. Subsequent removal of organic matter by ultrafiltration was found to be markedly enhanced for FA solutions subjected to oxidative coupling treatment. Uniform formation condition tests further indicated that the disinfection byproducts formed upon chlorination of FAs treated via induced oxidative coupling were reduced significantly on a unit carbon basis relative to those formed upon chlorination of their untreated counterparts. Spectroscopic examinations revealed thatthe FA molecules were effectively reconfigured in the oxidative coupling reactions. Substantial conversion of aromatic hydroxyl groups into ether-bonded moieties is evident, and a loss of primary amine groups, probably through conversion into secondary or tertiary amines, was also observed. These conversions apparently result in cross-linking of the natural FA moieties to form stable species of larger sizes, thus rendering them more readily removable by ultrafiltration and less reactive with chlorine. The results of the study may be interpreted as indicating that catalytically induced oxidative coupling reactions of the type conducted in this work can be combined with ultrafiltration to provide an effective scheme for removal of disinfection byproduct precursors.

NOM mitigates the phytotoxicity of AgNPs by regulating rice physiology, root cell wall components and root morphology