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Studies on photocatalytic degradation of lignin are scarce, even though it is an effective method for treatment of industrial effluents. In the present work, an advanced oxidation process (AOPs), leading to the photodegradation of lignin aqueous solutions, is proposed by using microstructured (T-MT) and nanostructured (T-NT) titanium dioxide compounds. Hydrothermal synthesis, in accordance with an experimental factorial design considering time of synthesis, NaOH concentration and synthesis temperature, was used to produce tunable TiO₂ photocatalysts for further study of its effects on the degradation of lignin. Photocatalytic reactions were conducted in a micro reactor batch system under UV irradiation. The catalysts were analyzed by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), surface area and porosity analyzer (BET), energy-dispersive X-ray spectroscopy (EDS) and UV-Vis diffuse reflectance spectroscopy. In order to optimize the yield reaction, an experimental factorial design was performed. According to our results, nanostructured TiO₂ consisting in different structural features and light absorption properties were produced using this method. It is shown that T-MT and T-NT compounds exhibit a wide range of values, for the kinetic parameters, in photoinduced degradation of methylene blue (MB) and lignin.

A novel heterogeneous Fenton catalyst was prepared by immobilizing iron(II) phthalocyanine (FePc) onto the amidoximated Polyacrylonitrile (PAN) fiber through axial coordination bonds. The obtained catalyst was characterized using XRD and DRS technique, and then used for the degradation of Rhodamine B under visible irradiation. The results indicated that optimum FePc concentration in the dispersion solution is 7.5 g/L, and the amidoxime groups having great coordination ability significantly facilitate anchoring FePc onto the catalyst. FePc immobilization led to the catalyst with decreased crystallinity region and obvious absorption feature in the visible region. In addition, the catalyst was found to be an efficient catalyst for oxidation elimination of RhB by activating H₂O₂ under visible irradiation.