Influence of natural organic matter on the transport and deposition of zinc oxide nanoparticles in saturated porous media

Transport and retention behaviors of titanium dioxide nanoparticles in iron oxide-coated quartz sand: Effects of pH, ionic strength, and humic acid

“…However, the colloidal particles employed in the aforementioned studies were negatively charged due to their low IEP values, so that the above prediction (i.e., enhanced colloid retention) could be acknowledged over the pH range of natural environment. On the other hand, nanoparticles are very diverse and they have various IEP values depending on their surface properties [4,14,22,23,28,39,40]. For example, nTiO 2 particles used in our previous study had a neutral IEP value (∼6) [28], indicating that the surface charge of nTiO 2 particles could be positive or negative depending on surrounding pH conditions.…”

Influence of soil pH on the toxicity of zinc oxide nanoparticles to the terrestrial isopod Porcellionides pruinosus

“…The processes of dissolution and aggregation or agglomeration have been shown to be dependent on characteristics of both the exposure media and the NPs. The stability of ZnO NPs is affected by environmental conditions such as pH [5], organic matter content [6], and ionic strength [7]. In soils, pH is one of the most important factors to consider in toxicity tests, because it can change the NP surface charge and zeta potential [4].…”

Influence of Humic Acid on the Transport and Deposition of Colloidal Silica under Different Hydrogeochemical Conditions

“…This behavior may be attributed to the HA macromolecules undergoing non-adsorbing complex formation with calcium ions and adsorption onto the colloidal silica (colloidal silica-HA-calcium), which reduces the charge and steric influences of the adsorbed macromolecular layers [20,33]. The finding that the addition of humic acid in salt solution retarded colloids' deposition has been observed in many previous studies [22,31]. strands becomes more compact; therefore, the adsorbed layer became more dense with increasing IS.…”

“…KCl (aq) and CaCl 2 (aq) were used to control cation types, and HA, a primary component of NOM in freshwater systems [19,20], was used to study the role of natural organic matter on colloidal silica transport. Suwannee River HA (SRHA) standard II from the International Humic Substance Society that has been widely employed in many previous studies as a kind of natural organic matter [20][21][22], was used in this study. A 20 mg dry HA was introduced to 100 mL of deionized water and sonicated for 30 min to disperse the particles, after which it was stored at 10 • C. The concentration in the experiment was 10 mg/L according to research by Liu et al [23].…”