Nexus between polymer support and metal oxide nanoparticles in hybrid nanosorbent materials (HNMs) for sorption/desorption of target ligands

Abstract

Metal oxide nanoparticles like hydrated ferric oxide (HFO) or hydrated zirconium oxide (HZrO) are excellent sorbents for environmentally significant ligands like phosphate, arsenic, or fluoride, present at trace concentrations. Since the sorption capacity is surface dependent for HFO and HZrO, nanoscale sizes offer significant enhancement in performance. However, due to their miniscule sizes, low attrition resistance, and poor durability they are unable to be used in typical plug-flow column setups. Meanwhile ion exchange resins, which have no specific affinity toward anionic ligands, are durable and chemically stable. By impregnating metal oxide nanoparticles inside a polymer support, with or without functional groups, a hybrid nanosorbent material (HNM) can be prepared. A HNM is durable, mechanically strong, and chemically stable. The functional groups of the polymeric support will affect the overall removal efficiency of the ligands exerted by the Donnan Membrane Effect. For example, the removal of arsenic by HFO or the removal of fluoride by HZrO is enhanced by using anion exchange resins. The HNM can be precisely tuned to remove one type of contaminant over another type. Also, the physical morphology of the support material, spherical bead versus ion exchange fiber, has a significant effect on kinetics of sorption and desorption. HNMs also possess dual sorption sites and are capable of removing multiple contaminants, namely, arsenate and perchlorate, concurrently.

Arsenic and fluoride removal from contaminated drinking water with Haix-Fe-Zr and Haix-Zr resin beads

“…and 7a-c), especially where the HZrO nano-precipitates are present compared to the HFO nano-precipitates (Figure 6c) which occur in more concentric orientation Smith et al (2015). reports in the instances when anion exchange resin beads are used as host materials for HFOs and HZrO anions in the groundwater such as F -, As(V)increasingly drawn inside the bead allowing sorption onto the HFO and HZrO nanoparticles.…”

“…These beads are durable as no physical or chemical degradation of the Haix-Zr resin beads have been observed after regeneration (Padungthon et al, 2015). By combining these metal oxide nano-particles of hydrated iron oxides with the chemically and mechanically stable polymeric ion exchange resins, a synergistic effect is created from enhancing the ligand sorption affinity of HFO and HZrO which is assisted by the Donnan membrane effect (Smith et al, 2015). Additional batch tests should be carried-out to validate this point.…”

Optimization of hybrid polymer preparation by ex situ embedding of waste Fe/Mn oxides into chitosan matrix as an effective As(III) and As(V) sorbent

“…Embedding of the waste sludge in the porous matrix of organic polymers leads to obtaining hybrid materials composed of a macromolecular skeleton and inorganic deposit. Due to the combination of the properties of both constituents, it is possible to obtain a sorbent exhibiting high mechanical strength and advantageous hydraulic properties ensured by a porous polymeric matrix, simultaneously showing high adsorptive properties characteristic for inorganic oxides (Cumbal et al 2003; Sarkar et al 2012; Samiey et al 2014; Smith et al 2015). However, the majority of hybrid polymers was synthesized by in situ methods based on sol–gel processes starting with the introduction of precursors (metal salts) into the preformed polymer matrix containing functional groups enabling even distribution of the metal precursor and followed by hydrolysis occurring within the polymeric matrix.…”

CuO-Loaded Macroreticular Anion Exchange Hybrid Polymers Obtained via Tetrachlorocuprate(II) Ionic Form

“…They are obtained from synthetic ion exchangers into the structure of which an inorganic deposit is introduced. The presence of proper inorganic constituent results in excellent and selective adsorption properties of HIX for removal of target pollutants from contaminated water and wastewater, while same-sign functional groups of polymer matrix greatly enhance the permeation of the pollutant ion and its preconcentration prior to effective sorption by inorganic particles (the Donnan membrane effect) [1][2][3]. Due to their physical form (spherical beads), HIX can be used, as a bed in a column, in dynamic conditions.…”