Oxyanion-Binding in a Bioinspired Nanoparticle-Assembled Hybrid Microsphere Structure: Effective Removal of Arsenate/Chromate From Water

Abstract

We demonstrate a bioinspired assembly wherein the specific interaction of polyamines with multivalent anions allows the assembly of silica nanoparticles to generate hybrid microsphere structures while this very phenomenon further provides ways for the microspheres to adsorb oxyanions like arsenate and chromate. In a typical method based on the biomineralization of diatomaceous biosilica structure, thus produced nanoparticle-assembled microspheres with a porous structure and hybrid functionalities exhibit efficient adsorption and separation of these toxic anions from water. The adsorption follows Freundlich isotherm with an inference for stronger interaction between adsorbate and adsorbent with nonuniform distribution of adsorption affinities. The opportunities to tune the composition with respect to the multivalent anion and their interaction with the polyamine, charge ratio, and so forth, illustrate the design of bioinspired robust structures with efficient oxyanion-binding property and recyclability. The consequence of competing anions shows that the binding selectivity follows the Hofmeister series of counterion interaction. Interestingly, in accordance with a molecular imprinting mechanism, the silica nanoparticle-assembled structure stabilizes and preserves the polyamine-anion nanostructure creating cavities/voids complementary to the adsorbing ions in shape, size, and functional groups. As a result, the polyamine with phosphate as the multivalent anion exhibits efficient binding and removal of these toxic contaminants, which is better than most of the other reported adsorbents.

Heterogenization of Phosphotungstate Clusters into Magnetic Microspheres: Catalyst for Selective Oxidation of Alcohol in Water

“…These changes in the magnitude of surface charge and particle size are the preliminary indications that the PTA clusters are assembled around the aggregates. The change in the average size seen in the DLS measurements after addition of PTA clusters to PAH–citrate–Fe 3 O 4 aggregates could be due to various factors, as has been reported earlier. − One is due the assembly or inclusion of the inorganic components (PTA clusters in the present case). The other one is because of the dynamic nature of the above PAH aggregates, which can lead to an increase in their size with time as a result of coalescence among themselves.…”

Deciphering Structure–Functionality Relationship of Polycarbonate-Based Polyelectrolytes by AIE Technology

“…For polyelectrolytes with M n < 5600 g mol −1 , the short hydrophilic chains inclined to extend along the radial direction with a loose space, so that Zn 2+ can diffuse into the loose space between the polymer chains. 53 The fluorescence signal enhancement resulted from the shrinkage of the nanoparticle because of the coordination of Zn 2+ with carboxyl units in a single nanoparticle. However, for M n > 7600 g mol −1 , the possible entanglement and wrapping of long chains played the role of a steric barrier and hindered the diffusion of Zn 2+ , triggering the coordination of Zn 2+ between different nano- particles to enlarge the particle size.…”

“…Upon addition of Zn 2+ , an M n -dependent fluorescence intensity enhancement mechanism is observed. For polyelectrolytes with M n < 5600 g mol –1 , the short hydrophilic chains inclined to extend along the radial direction with a loose space, so that Zn 2+ can diffuse into the loose space between the polymer chains . The fluorescence signal enhancement resulted from the shrinkage of the nanoparticle because of the coordination of Zn 2+ with carboxyl units in a single nanoparticle.…”

Design, characterization and application of layered double hydroxide-based colloidal systems

“…121 Dichromate ion was also studied to assess contaminant removal and adsorption capacity of the obtained materials. Dichromate is a well-known carcinogenic polluttant 142 and Cr2O7 2was the predominant species under the conditions applied. The adsorption capacities showed dependency on the specific surface area and the pore size distribution (Table 4 and 5).…”