Olalla Iglesias

Decolourisation of dyes under electro-Fenton process using Fe alginate gel beads.

This study focuses on the application of electro-Fenton technique by use of catalytic activity of Fe alginate gel beads for the remediation of wastewater contaminated with synthetic dyes. The Fe alginate gel beads were evaluated for decolourisation of two typical dyes, Lissamine Green B and Azure B under electro-Fenton process. After characterization of Fe alginate gel beads, the pH effect on the process with Fe alginate beads and a comparative study of the electro-Fenton process with free Fe and Fe alginate bead was done. The results showed that the use of Fe alginate beads increases the efficiency of the process; moreover the developed particles show a physical integrity in a wide range of pH (2-8). Around 98-100% of dye decolourisation was obtained for both dyes by electro-Fenton process in successive batches. Therefore, the process was performed with Fe alginate beads in a bubble continuous reactor. High color removal (87-98%) was attained for both dyes operating at a residence time of 30 min, without operational problems and maintaining particle shapes throughout the oxidation process. Consequently, the stable performance of Fe alginate beads opens promising perspectives for fast and economical treatment of wastewater polluted by dyes or similar organic contaminants.

Effective heterogeneous electro-Fenton process of m-cresol with iron loaded actived carbon

The degradation of m-cresol (MC) has been investigated by a heterogeneous electro-Fenton process using iron loaded activated carbon (Fe-AC) as the heterogeneous electro-Fenton catalyst. Experimental results demonstrated that MC was effectively removed through an electro-Fenton process. Calculated TOC removal and overall energy consumption showed that the use of a low iron concentration (28 mg L−1) increases the efficiency of the process. The reactions followed a pseudo-first order kinetic equation and kinetic coefficients confirm that the MC reduction, when it is alone, is faster than in the presence of a similar compound, tert-butylhydroquinone (TBHQ) (from 0.0935 to 0.0692 min−1); therefore TBHQ exerts an antioxidative protection effect. In all cases, it is concluded that heterogeneous electro-Fenton treatment with Fe-AC follows a two-step process: adsorption and oxidation; allowing removal rates higher than in the literature. In addition, the reusability of this catalyst was demonstrated by operating it in continuous mode. Finally, LC-MS analysis allowed the development of a plausible degradation route.

Environmental application of an industrial waste as catalyst for the electro-Fenton-like treatment of organic pollutants

The application of acid mine drainage sludge (AMDS), an industrial waste with high metal content, as catalyst for the electro-Fenton-like technology on the treatment of organic polluted effluents has been investigated. The study has demonstrated the potential use of this waste using dye Lissamine Green B as a model contaminant, which allowed the optimization of sludge dosage and pH. AMDS proved to perform a high decoloration rate at pH 2, however, acidic conditions favored metal leaching. Alginate gel beads were selected to immobilize AMDS and to avoid metal release and the wash out of the reactor operating in continuous mode. This developed catalyst showed high reliability and efficiency in successive batches. The efficacy of the established treatment was also verified on the degradation of pesticide pirimicarb and a degradation pathway was determined by LC-MS studies.