Polymer supported inorganic nanoparticles: characterization and environmental applications

Abstract

Nanoscale Inorganic Particles (NIPs) and their agglomerates offer excellent opportunities conducive to selective removal of a wide array of target compounds from contaminated water bodies. For example, (i) hydrated Fe(III) oxides or HFO particles can selectively sorb dissolved heavy metals like zinc, copper or metalloids like arsenic oxyacids or oxyanions; (ii) Mn(IV) oxides are fairly strong solid phase oxidizing agents; (iii) magnetite (Fe 3O 4) crystals are capable of imparting magnetic activity; (iv) elemental Zn o or Fe o are excellent reducing agents for both inorganic and organic contaminants. Very high surface area to volume ratio of these nanoscale particles offers favorable sorption and/or reaction kinetics. However, applications of NIPs in fixed-bed columns, in-situ reactive barriers and in similar flow-through applications are not possible due to extremely high pressure drops. Also, these NIPs are not durable and lack mechanical strength. Harnessing these inorganic nanoparticles and their aggregates appropriately within polymeric beads offers new opportunities that are amenable to rapid implementation in the area of environmental separation and control. While the NIPs retain their intrinsic sorption/desorption, redox, acid–base or magnetic properties, the robust polymeric support offers excellent mechanical strength, durability and favorable hydraulic properties in the flow-through systems. This paper discusses at length the preparation, characterization and environmental applications of two classes of polymer supported nanoparticles: (i) Hydrated Fe(III) Oxide (HFO) dispersed polymeric exchanger and their As(III), As(V), and heavy metals removal properties; (ii) Magnetically Active Polymeric Particles (MAPPs). The polymer supported nanoparticles are reusable and can be easily reprocessed over many cycles of operation.