Impact of Nanoparticles and Natural Organic Matter on the Removal of Organic Pollutants by Activated Carbon Adsorption

摘要

Isotherm experiments evaluating trichloroethylene (TCE) adsorption onto powdered-activated carbon (PAC)nwere conducted in the presence and absence of three commercially available nanomaterials: iron oxide (Fe2O3),ntitanium dioxide (TiO2), and silicon dioxide (SiO2). Isotherm experiments were also conducted in the presencenand absence of natural organic matter (NOM), in the form of humic acid, to more closely model natural waternconditions. Nanoparticles at two concentration levels (0.5 and 1.0mg=L for Fe2O3 and TiO2, and 5.0 and 10mg=Lnfor SiO2) were considered. Zeta potential and pH of point of zero charge (pHpzc) of the nanoparticles and thenPAC were measured. Particle size distribution (PSD) of the nanoparticle dispersions was analyzed as a functionnof time to determine the nanoparticle size range of each dispersion. Aggregation of Fe2O3 and TiO2 nanoparticlesnwas observed but not for SiO2 nanoparticles. Adsorption isotherm experiments were conducted at three initialnTCE concentrations, two nanoparticle concentrations, and with varying amounts of PAC. Isotherm data showedna higher degree of adsorption in the presence of Fe2O3 and TiO2 nanoparticles, regardless of concentration. Innactivated carbon-free experiments both Fe2O3 and TiO2 nanoparticles alone were observed to act as adsorptionnsites for TCE by removing up to 60% of TCE from the aqueous phase. Silica appeared to have no impact on TCEnadsorption at either of the concentrations evaluated, except in the presence of humic acid. This study providesnimportant information related to the use of nanoparticles in water treatment and their impact on the perfor-nmance of a commonly used adsorbent used to remove organic pollutants. No studies to date have attemptednto quantitatively describe the adsorption behavior of TCE to PAC in the presence of TiO2, SiO2, and Fe2O3nnanoparticles.