How feasible is packing oxidants for their use in treatment of contaminated sites

Abstract

Protection of different active ingredients is recognized as quite an old practice (in 1931 gelatine microspheres were obtained by coacervation process) and it quickly developed, with applications in pharmaceutical, textile and food industries, and lately for products applied in agriculture. Coating or encapsulating different chemicals implies placing an external “shell”, with protective role, on a core of active ingredient. The final product is a micro-particle, under the form of individual core-shell micro-capsule or a matrix, with more active particulates embodied in. Many physical and chemical techniques have been used for packing ingredients, which were, in most of the cases, chemical substances amenable to be consumed / selfdepleted before being active for a specific role. For application in environmental technologies a major challenge is raised by the high chemical reactivity of reagents, especially oxidants, often used for the synthesis or chemical transformation of the potential shell materials. Still, some oxidants were reported to have been packed (Sodium Persulfate or Percarbonate, Potassium Permanganate, too), and the final products were particles in the range of hundreds ìm – cm, which released the oxidant in interval of hours - days. Obtaining microcapsules in the range of micrometric size (< 100 ìm), with slow regent release is an additional challenge. More preparation methods were experimentally developed (e.g. in-situ polymerization, coacervation or double layer coating) for Potassium Permanganate coating. Better results are obtained when using physical methods, although the economical feasibility is questionable even when using the most cost-efficient methods.