Chitosan Encapsulation of FerrateVI for Controlled Release to Water:Mechanistic Insights and Degradation of Organic Contaminant

Abstract

Tetraoxy-anion of iron in +6 oxidation state (FeVIO42−, FeVI), commonly called ferrate, has shown tremendous potential as a green oxidative agent for decontaminating water and air. Encapsulation of solid potassium salt of ferrate (K2FeO4) circumvents the inherent drawbacks of the instability of ferrate under humid conditions. In the encapsulated strategy, controlled release without exposing the solid ferrate to the humid environment avoids self-decomposition of the oxidant by water in the air, and the ferrate is mostly used to decontaminate water efficiently. This study demonstrated the formulation of oxidative microcapsules with natural materials present in chitosan, whose release rate of the core material can be controlled by the type of intermediate hydrocarbon layer and the pH-dependent swelling of chitosan shell. The pH played a pivotal role in swelling chitosan shell and releasing the core oxidant. In a strong acidic solution, chitosan tended to swell quickly and release FeVI at a faster rate than under neutral conditions. Additionally, among the several long-chain hydrocarbon compounds, oleic acid exhibited the strongest “locking” effect when applied as the intermediate layer, giving rise to the slow release of FeVI. Coconut oil and mineral oil, in comparison, allowed FeVI to penetrate the layer within shorter lengths of time and showed comparable degrees of degradation of target contaminant, methylene orange, under ambient temperature and near-neutral conditions. These findings have practical ramifications for remediating environmental and industrial processes.

Smart nanocomposites of chitosan/alginate nanoparticles loaded with copper oxide as alternative nanofertilizers

“…In addition, copper ions were linked to chitosan functional groups, characterized by their chelating capacity, which contributed to slow the Cu diffusion and release into the medium, as observed 57 for copper ions encapsulated in a CS porous network and for iron in iron oxide nanoparticles coated with CS. 58 Therefore, in the case of the CuO/PEC NPs, two main mechanisms can be hypothesized to describe the Cu release, Cu diffusion out of the polymeric nanoparticles, driven by the concentration gradient, and polymer swelling and degradation, 59,60 which took place over several days, as schematized in Fig. 6(b).…”

Compositionally Anisotropic Colloidal Surfactant Decorated with Dual Metallic Nanoparticles as a Pickering Emulsion Stabilizer and Their Application in Catalysis

“…Interestingly, GNP-immobilized brush-modified particles loaded with or without iron(0) nanoparticles were found to rapidly decolorize MO in pure water and in emulsion (within 2 and 1 min, respectively), whereas iron(0) nanoparticle-loaded, brush-modified P 50 particles (without GNPs) did not reduce the dye in emulsion as well as in pure water within this time period (Figure S17), indicating the role of GNPs in catalyzing the reaction. However, iron(0) nanoparticle-loaded, brush-modified P 50 particles (devoid of gold) did show partial reduction of dye after 180 min in water and in the emulsion system (Figure S18), implying its ability to reduce the dye but at a slower rate as compared to GNPs probably due to free accessibility of the latter . The increase in the catalytic activity in the emulsion phase as compared to the aqueous phase can be attributed to the accessibility of more active sites and increased effective contact area between microparticles and the dye arising from the predominant positioning of the GNPs toward the water phase .…”

Application of Fe(VI) in abating contaminants in water: State of art and knowledge gaps

“…Consequently, the encapsulated K 2 FeO 4 is effective in degrading various TrOCs and reducing the COD value of the contaminated water even under extreme pH conditions (Yuan et al, 2008b;Wang et al, 2009). Chen et al (2019a) modified the encapsulated K 2 FeO 4 samples by replacing paraffin wax with chitosan and a buffer layer between the wall material and the oxidant was added to prevent Fe(VI) from reacting with the wall material.…”