Deposition Kinetics of Colloidal Manganese Dioxide onto Representative Surfaces in Aquatic Environments: The Role of Humic Acid and Biomacromolecules

Abstract

The initial deposition kinetics of colloidal MnO2 on three representative surfaces in aquatic systems (i.e., silica, magnetite, and alumina) in NaNO3 solution were investigated in the presence of model constituents, including humic acid (HA), a polysaccharide (alginate), and a protein (bovine serum albumin (BSA), using laboratory quartz crystal microbalance with dissipation monitoring equipment (QCM-D). The results indicated that the deposition behaviors of MnO2 colloids on three surfaces were in good agreement with classical Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. Critical deposition concentrations (CDC) were determined to be 15.5 mM NaNO3 and 9.0 mM NaNO3 when colloidal MnO2 was deposited onto silica and magnetite, respectively. Both HA and alginate could largely retard the deposition of MnO2 colloids onto three selected surfaces due to steric repulsion, and HA was more effective in decreasing the deposition rate relative to alginate. However, the presence of BSA can provide more attractive deposition site and thus lead to greater deposition behavior of MnO2 colloids onto surfaces. The dissipative properties of the deposited layer were also influenced by surface type, electrolyte concentration, and organic matter characteristics. Overall, these results provide insights into the deposition behavior of MnO2 colloids on environmental surfaces and have significant implications for predicting the transport potential of common MnO2 colloids in natural environments and engineered systems.

Transport Behaviors of Colloidal Manganese Dioxide in Aqueous Media: Effects of Ionic Specificity of Monovalent Cations

“…11 −13 For deposition kinetics, the deposition of colloidal MnO 2 onto three representative interfaces (i.e., SiO 2 , Fe 3 O 4 , and Al 2 O 3 ) in a sodium nitrate solution and the effects of HA, alginate, and BSA have also been investigated. 14 We found that in the absence of macromolecules, the aggregation and deposition behaviors of colloidal MnO 2 were greatly consistent with the classical Derjaguin−Landau−Verwey−Overbeek (DLVO) theory, which involves van der Waals forces (vdW) and electrical double layer forces (EDL) to interpret the interaction forces among the particles or between the particles and interfaces. In the presence of macromolecules, the DLVO theory was expanded as the EDLVO theory by modifying the interaction energy calculations through the introduction of a steric repulsive energy that was generated by the absorbed macromolecule layers around the MnO 2 colloids and onto the interfaces, according to the Flory−Krigbaum theory.…”

“…For alginate, the deposition was hindered mainly due to the steric repulsion generated by the adsorbed alginate layers, which was also observed in our previous study. 46 In the presence of BSA, some positively charged parts (e.g., Arg and Lys residues) could attach to the NPs and surfaces and generate mutual attractive sites to the exposed negatively charged regions of colloids and surfaces. 47,48 Furthermore, the promotive effect of BSA on the deposition of colloidal MnO 2 onto the tested surfaces was observed.…”

“…Similar observations were also reported in previous studies. 14 In addition, ion-specific effects were also obvious when comparing the α D values under the influence of one single macromolecule.…”

“…Aggregation and deposition behaviors are the major reasons for the transport of colloids and nanoparticles in an aqueous environment . For aggregation behaviors, the influence of environmental conditions, such as monovalent and divalent cations, various natural organic matters (i.e., Suwannee River fulvic acid (SRFA), Suwannee River humic acid (SRHA), alginate, and bovine serum albumin (BSA)), and redox processes have been reported in our previous studies. − For deposition kinetics, the deposition of colloidal MnO 2 onto three representative interfaces (i.e., SiO 2 , Fe 3 O 4 , and Al 2 O 3 ) in a sodium nitrate solution and the effects of HA, alginate, and BSA have also been investigated . We found that in the absence of macromolecules, the aggregation and deposition behaviors of colloidal MnO 2 were greatly consistent with the classical Derjaguin–Landau–Verwey–Overbeek (DLVO) theory, which involves van der Waals forces (vdW) and electrical double layer forces (EDL) to interpret the interaction forces among the particles or between the particles and interfaces.…”

Density Functional Theory Investigation into the Effects of Dissolved Organic Matter on H2O2 Activation over α-Fe2O3 (001) Surfaces

“…When dealing with actual wastewater, the iron-based catalysts readily interact with dissolved organic matter (DOM). Ubiquitously existing in both natural and engineered aquatic environments, DOM plays significant roles in various environmental-related processes. − DOM exhibits high heterogeneity with different functional groups including hydroxyl, phenol, carboxyl, aldehyde, amide, quinone, and other groups, facilitating it to interact with metal ions, organic contaminants, inorganic colloids, and nanoparticles. − The fundamental interaction mechanisms between the solid catalysts and DOM include hydrogen bonding, hydrophobic interactions, electrostatic and van der Waals interactions, ligand bonding, chelation, and cation bridge, , which are affected by different factors such as the DOM molecular properties and the solution chemical environment. , The inevitable roles of DOM also attract our attention to its effects on the Fenton process.…”