Effect Of Ethanol And The Host Cross-linking Degree On The Structure And Properties Of Hydrous Ferric Oxide-Resin Nanocomposites

Hydrated ferric oxide (HFO) nanoparticles exhibit preferable sorption to arsenate and phosphate. However, their self-aggregation into bulky particles and poor mechanical strength greatly hinder their direct application in water treatment. Immobilization of HFO particles inside porous polymer beads is an effective approach respond to the above puzzles, where HFO nanoparticles could be well dispersed and the resultant composite has inherent outstanding mechanical strength. Also, the charged groups of the resin would favor sorption of anionic pollutants through the potential Donnan membrane principle. Currently, the available studies mainly focused on preparation and characterization of the resultant composite sorbents, as well as the evaluation of their properties for arsenic sequestration. Little is known concerning how to control the basic structure of the composite material, such as HFO dispersion in the host polymer. In this study, we examined the effect of ethanol rinsing and the cross-linking of polymer on the structure and properties of the HFO-oriented composite.First, we figured out the role of ethanol washing, that is, it would increase the pore size, pore volume, and specific surface area of the composite, as well as to improve HFO dispersion inside D201.However, the mechanical strength of the composite and the morphology of the immobilized HFO was the same as water rinsing. Also, the ethanol washing influenced the arsenate adsorption isotherm slightly, whereas little effect was observed on the sorption tendency dependent upon solution pH and other co-anions. Furthermore, the ethanol washing posed insignifcant influence on the fix-bed adsorption and recyclability of the composite adsorbent.Second, two polystyrene hosts of the same host and functional groups but different crosslinking degre e, named D201 and N201,were employed to fabricate two HFO-oriented composites. With the increasing cross-linking degree, the pore volume, pore size, and specific surface area of the resultant polymer nanocomposites increased. Consequently, HFO particle size decreased and HFO dispersion was improved. Additionally, the composite sorbent of higher crosslinking degree exerted higher arsenate capacity and preference over other competing ions. Column adsorption further demonstrated that the composite sorbent of higher crosslinking degree could be used for efficient arsenate removal in a much higher water flow rate, i.e., arsenate adsorption occurred much faster.In summary, the results available in this study may provide some guidance to improve the preparation and potential application of the new HFO-oriented nanocomposites in water remediation.