Abstract
Natural iron oxide (TIO) was prepared and investigated as an adsorbent for diazo dye (Congo Red, CR) removal. Characterization, adsorption capacity, and photochemical regeneration of the adsorbent were studied. Results show that the optimal adsorption condition are [CR] = 10(-4) M, adsorbent dose = 0.1 g, pH = 7, and contact time = 60 min. 60 min was sufficient to reach adsorption equilibrium with 80% of Congo red removal. Adsorption process obeyed Langmuir type and pseudo-secondorder kinetic suggested monolayer adsorption and physisorption process. Results show that advanced oxidation process via photo-Fenton reaction, carried out at neutral pH under UV light irradiations allowed the restitution of the used catalyst (TIO). Ninety minutes is required for photochemical regeneration of saturated adsorbent, the regeneration efficiency can reach 96% under the optimal proposed conditions (25 degrees C, [H2O2] =10 mmol L-1, [CR] =10(-4) mol L-1) at neutral pH and under UV irradiations. After 3 consecutive adsorption-regeneration cycles, the regeneration efficiency was still achieved (96%) and the adsorbent has a good stability with the increase of experimental runs.