Phenol degradation and HPLC identification of products generated using red mud as a catalyst in solar advanced oxidation processes

The work is based on the degradation of phenol using red mud as a catalyst for solar advanced oxidation processes (AOP). A factorial experiment design 23 was applied with two points at the center; the COD measurement was performed using the HACH DR2010 method and the phenol concentration by the 4-aminoantipyrine method. AOP achieved degradations in the COD of 94;1% and of the phenol concentration of 99;7 %. Secondary standards were analyzed for HPLC, where the spectral coincidence of the compounds was guaranteed by mass coupled gas chromatography (CG-MS). The identification of the species of the phenol degradation was performed through High Performance Liquid Chromatography (HPLC) coupled to a UV-HP DAD detector. The optimal separation of the studied standards was with a mobile phase: water / methanol (7:3), pH 4,0 adjusted with 0,1 M H3PO4, with a flow of 0.5 mL/min, lambda = 220 nm. After the separation conditions were obtained, the samples were identified as degradation products oxalic, formic, acetic acid and hydroquinone. Demonstrating that the red mud was appropriate to decrease the COD and phenol concentration by means of solar AOP.