IntroductionRecently, engineered nanoparticles have been widely used in numerous industrial products, resulting in an increasing discharge of nanoparticles into aquatic systems [1][2]. Engineered nanoparticles have been observed to be toxic to microbes, plants, animals, and ecosystems [3]. As a result, engineered nanoparticles represent an emerging category of foulants. More attention has been paid to how engineered nanoparticles will be removed by -and impact the performance of -wastewater treatment systems [4]. Ultrafiltration (UF) has been acknowledged as a promising technology for removing nanoparticles due to its high-quality effluent, reliability in operation, Pol. J. Environ. Stud. Vol. 26, No. 5 (2017), 2259-2266
AbstractThis research attempts to elucidate the effect of humic acid (HA) on TiO 2 nanoparticle ultrafiltration (UF) membrane fouling, and quantitatively analyze the synergistic membrane fouling mechanisms using interaction energies. The extended Derjaguin-Landau-Verwey-Overbeek (xDLVO) theory was employed to analyze the interaction energies and predict UF membrane fouling. Membrane fouling effects were studied during the dead-end filtration of individual TiO 2 and HA-TiO 2 mixtures using two kinds of polymeric UF membranes. It was found that HA-TiO 2 mixtures lead to greater flux declines than individual TiO 2 . For specific foulant, the hydrophobic PVDF membrane showed relative severe membrane fouling than hydrophilic PES membrane. As for the HA-TiO 2 mixture, much higher irreversible fouling was observed compared with that of individual TiO 2 . Moreover, this study highlights the importance of HA concentration in synergistic fouling effects of the HA-TiO 2 mixture. The increase of HA concentration caused an increase of contact angle and lower interaction energy, thus aggravating membrane fouling. Results illustrated that synergistic membrane fouling by TiO 2 and HA could be successfully explained using the xDLVO analysis. The extent of membrane fouling turned out to be dominated by Lewis acid-base interaction.