Low-cost iron-doped catalyst for phenol degradation by heterogeneous Fenton.

The aim of this work was to study the feasibility of textile sludge as a precursor to prepare catalysts for catalytic wet peroxide oxidation (CWPO) by chemical and thermal treatments. Textile sludge was characterized by physical-chemical and metal composition analyses. The chemical activation was evaluated using iron sulfate and the thermal treatment was carried out at 720 °C in a vacuum pyrolysis reactor. Two catalysts with iron contents of 1.5% and 5.6% were selected. Process parameters influence on CWPO of phenol were evaluated and a maximum removal of phenol and TOC was observed at pH 3 and 60 °C, using 3 g L-1 of the catalyst containing 5.6% of iron and 11.8 mmol L-1 of H2O2. Metal analysis indicated that the textile sludge is suitable to be employed as both iron catalyst and adsorbent. The catalysts characterization indicated a reasonable surface area with a well-developed microporosity and the presence of Hematite structures in the carbonaceous matrix. The degradation process achieved 98.2% of phenol conversion, 68.2% of mineralization and 2.11 mg L-1 of iron leaching in 150 min of reaction. The catalyst presented activity for up to 5 cycles of use, but with loss of efficiency.