Size, number and chemical composition of nanosized particles in drinking water determined by analytical microscopy and LIBD

• Published in: Water research (Oxford) Vol. 42; no. 10-11; pp. 2778 - 2786
• Main Authors: Kaegi, R., Wagner, T., Hetzer, B., Sinnet, B., Tzvetkov, G., Boller, M.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.2008; Elsevier Science
• Subjects: AFM; analytical methods; Applied sciences; atomic force microscopy; carbon; chemical composition; dissolved organic matter; Drinking water; Exact sciences and technology; laser-induced breakdown method; Lasers; LIBD; Microscopy; Microscopy, Atomic Force; Microscopy, Electron, Transmission; Nanoparticles - analysis; Nanoparticles - chemistry; Nanoparticles - ultrastructure; nanotechnology; Other industrial wastes. Sewage sludge; Particle Size; particulates; Pollution; scanning transmission X-ray microscopy; shape; STXM; TEM; transmission electron microscopy; Ultrafiltration; Wastes; water pollution; Water Purification - methods; Water Supply; Water treatment and pollution; AFM; STXM; Drinking water; Microscopy; LIBD; TEM; Atomic force microscopy; Water treatment; Organic matter; X ray microscopy; Dissolved matter; Membrane separation; Image analysis; Particle size distribution; Transmission electron microscopy; Ultrafiltration; Detection limit; Morphology; Surface water; Lakes; Chemical composition; Spherical particle; Concentration distribution; Particle number
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2008.02.009

In this paper we comprehensively characterized particles in drinking water originating from a lake water source. We focused on particles smaller than a few hundred nm. Several analytical techniques were applied to obtain information on number concentration, size distribution, morphology and chemical composition of the particles. Morphological information was obtained by atomic force microscopy (AFM) analysis. Two types of particles, spherical aggregates up to a few tens of nm and elongated fibers were identified. Similar structures were also observed in transmission electron microscope (TEM) images. A size distribution of the particles was obtained by applying image analysis (IA) tools on the TEM images. IA results showed an exponential increase of the particle number concentration down to 40nm, which is the lower detection limit of our setup. The total number of particles down to 10nm and the average particle diameter were determined with the laser-induced breakdown detection (LIBD) method. The results were in good agreement with the TEM-IA data and showed a total number concentration of roughly 108particles/mL in the purified water. The carbon of the particles was investigated with scanning transmission X-ray microscopy (STXM), which revealed that most particles were organic matter; the C-1s spectra were typical for dissolved organic matter. The methods were applied to characterize the particles from two different drinking waters treated with different methods (conventional vs. ultrafiltration (cut-off 100kDa)). The results showed that the particle number density following ultrafiltration was lower by a factor of 5–10, compared to conventional treatment. However, the average particle diameter in the finished water of both treatment trains was roughly the same.