Application of zero valent iron (ZVI) immobilized in Ca-Alginate beads for CI Reactive Red 195 catalytic degradation in an air lift reactor operated with ozone

The efficiency of nanoscale zero-valent iron (nZVI) for the recalcitrant organic pollutants degradation has been frequently reported. However, some disadvantages such as low hydraulic conductivity, rapid passivation and consequent loss of reactivity have motivated researchers to study immobilized forms. In this work, calcium alginate beads incorporated with nZVI were prepared, characterized and applied in a catalytic ozonation system of Reactive Red 195 dye (RR195). In order to avoid shearing the calcium alginate beads, an Air lift reactor operated with Air/03 cycles in an 8 mg L-1 concentration was used. The RR195 treatability tests conducted with a dye concentration of 25 mg L-1, 50 g L-1 of nZVI-Alg beads and an Air/O-3 feed flow of 1 L min(-1), revealed significant process efficiency, which was not limited only to the dye discoloration. Total discoloration levels were observed in 30 min of treatment and reductions in 97 % of organic matter in 90 min of treatment, measured through the chemical oxygen demand. The typical absorptions of aromatic compounds reduction (lambda(max) = 290 nm) and the acute toxicity reduction (Anemia Saline bioassay), contribute to the Alg-nZVI/O-3 system potential for the application in the treatment of liquid effluents contaminated with dyes.