Preparation and application of a new Fenton-like catalyst from red mud for degradation of sulfamethoxazole.

In this work, using molasses wastewater as a partial acidifying agent and bagasse pith as a pore-enlarging agent, a new low-cost Fenton-like catalyst (ACRM) used for degradation of sulfamethoxazole was prepared through a simple process of acidification and calcination using red mud (RM) as the main material. The optimum preparation conditions of ACRM were acquired, and the optimum preparation conditions of ACRM were as follows: mass ratio of bagasse pith to RM (:) 0.033:1, particle size of bagasse pith 0.10-0.20 mm, calcination temperature 773 K, and calcination time 2 h. The ACRM catalyst was characterized by XRD, SEM, EDS, and BET. According to the results of characterizations, it was found that the iron phase of ACRM had completely transformed into α-FeO after the process of acidification and calcination, and the addition of bagasse pith significantly improved the surface area of the prepared ACRM. Furthermore, under the reaction conditions of catalyst dosage of 2 g/L, initial pH 3 and reaction time 90 min, the ACRM has showed the highest catalytic activity. ACRM had significantly higher activity than red mud, and exhibited a remarkable settleability. Besides, ACRM retained good recyclability and stability during use. Kinetic studies showed the degradation process could be described with the first-order model. Overall, the prepared ACRM was an effective and excellent catalyst in the Fenton-like process.