POLYMER-SUPPORTED SUBCOLLOIDAL PARTICLES: CHARACTERIZATION AND ENVIRONMENTAL APPLICATION

摘要

In the field of environmental separation and remediation, many submicron inorganic particles offer favorable properties in regard to selective separation and/or chemical transformation of target contaminants. 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° or Fe° are excellent reducing agents for both inorganic and organic contaminants (1-6). Extremely high surface area to volume ratio of these tiny particles offers very favorable kinetics for selective sorption and oxidation-reduction reactions. Nevertheless, these particles cannot be used in fixed-bed columns, in underground reactive barriers or in any plug flow type configuration due to excessive pressure drops and poor durability. On the contrary, many commercially available porous polymeric beads are very durable and offer excellent hydraulic properties in regard to pressure drops. The prices of these polymeric particles are quite competitive and the trend around the globe indicates that they will further decrease in the future. Ideally, it would be very desirable to develop a new class of polymeric/inorganic materials that combine the excellent hydraulic characteristics of spherical polymer beads with favorable sorption/redox/magnetic properties of inorganic nanoparticles. There remain many possibilities and new opportunities to effectively apply these hybrid particles for environmental separation and control. To this effect, we will confine our discussion in this paper to two specific classes of polymer supported nanoscale particles: ⅰ) Hydrated Fe(Ⅲ) Oxide (HFO) dispersed polymeric exchanger and their As(Ⅲ) and As(Ⅴ) removal properties; ⅱ) Preparation and characterization of Magnetically Active Polymeric Particles (MAPPs).