Attachment behaviour of inorganic particles on fibrous media: combined effects of dissolved organics and divalent cations

Abstract

A systematic study was carried out to investigate the attachment of inorganic particles to fabric media in the presence of divalent cations and the dissolved organics in water, on filter media, or on both. The presence of organics (humic acid, HA) reduced the attachment of inorganic particles on the fabric. Specific attachment trends were observed for the inorganic particles–fibre system. For [CaCl₂] < 500 ppm, the particle attachment was lower in the presence of 10 ppm of HA compared to its absence. At [CaCl₂] ≥ 500 ppm, the attachment in the presence or absence of HA was similar, suggesting that the attachment was independent of the presence of HA. It was also found that the particle attachment to the fabric was lower when HA was present in water compared to when present on the fabric, suggesting that the attachment behaviour of inorganic particles was dependent on water chemistry (i.e. presence of calcium ions and organics in water), which also altered the surface properties of filter media. The removal trends were explained on the basis of particle aggregation, surface charge and Derjaguin–Landau–Verwey–Overbeek (DLVO) theory.