Investigation of the adsorption characteristics of natural organic matter from typical Chinese surface waters onto alumina using quartz crystal microbalance with dissipation

Abstract

The adsorption of natural organic matter (NOM) from eight typical Chinese surface waters onto alumina was investigated using quartz crystal microbalance with dissipation monitoring (QCM-D). The adsorbed masses of NOM varied between 25ngcm−2 and 64ngcm−2, and these showed significant correlation with geographical location, and NOM character and concentrations. Adsorbed mass correlated with DOC concentration (slope k=0.0676, R2=0.61) and hydrophobic acid (HoA) and weakly hydrophobic acid (WHoA) (k=0.0342 and 0.0183; R2=0.49 and 0.52 for HoA and WHoA, respectively) constituents present in the water samples. The process of adsorbed layer formation was investigated from changes in the ΔD/Δf ratio and viscosity of adsorbed layer with injected time. The adsorbed layer viscosity increased exponentially with injected time (R2>0.99) for most samples. Samples with low DOC concentration (k=−1091.8, R2=0.55) and low content of HoA and WHoA (k=−524.33 and −322.76; R2=0.41 and 0.64 for HoA and WHoA, respectively), the slope of logarithm viscosity value is steeper, the property of adsorbed layer and NOM is more inconsistent. The QCM-D technique provides a method to view the process of complexation between NOM and coagulant, and can provide useful information to establish a quantitative calculation model of the coagulation process.