Vol.:(0123456789) 1 3 Journal of Materials Science: Materials in Electronics https://doi.org/10.1007/s10854-020-03764-2 Semiconducting polypyrrole@TiO 2 pure anatase nanoparticles for photodegradation of reactive red 120 azo dye E. G. Villabona‑Leal 1,2  · Alondra G. Escobar‑Villanueva 2  · Víctor M. Ovando‑Medina 2  · Erick Balam Pérez‑Pérez 2  · Paola E. Díaz‑Flores 3  · Adolfo Romero‑Galarza 4  · Alfredo Marquez‑Herrera 1 Received: 20 April 2020 / Accepted: 7 June 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020 Abstract In the recent years, the development of new and efcient materials for photocatalytic processes has been of growing inter- est for applications in wastewater treatment. In this sense, TiCl 4 stabilized with H 2 SO 4 was precipitated with ammonium hydroxide in the presence of sodium dodecyl sulfate and calcined to obtain thermally stable TiO 2 nanoparticles, which were subsequently coated with semiconducting polypyrrole (PPy) by chemical oxidation resulting in a composite of TiO 2 @PPy. TiO 2 and TiO 2 @PPy composite were characterized by SEM, Raman, XRD, UV/Vis–NIR, FTIR and TGA. It was observed that TiO 2 consisted of spherical nanoparticles with number-average particle diameter of 19.2 nm and polydispersity index in sizes of 1.2, whereas TiO 2 @PPy composite consisted of agglomerated spherical PPy nanoparticles of number-average diam- eter of 182.4 nm coating TiO 2 nanoparticles. The calculated optical bandgap of TiO 2 was 3.07 eV, and it was demonstrated by the Rietveld refnement method of the XRD spectrum and from the Raman analysis that synthesized TiO 2 corresponds to highly pure rhombic anatase crystal structure. TiO 2 @PPy composite was tested in the photodegradation of the reactive red 120 azo dye in aqueous solutions under visible light irradiation. It was observed that photodegradation rate increased with decreasing the initial dye concentration and increasing the composite load. Almost 100% of dye removal was achieved after 45 min of reaction for 20 mg L −1 of initial dye concentration and 1.0 g L −1 of composite load. 1 Introduction Water availability is considered a global problem due to scarcity, global warming, and pollution [1, 2]. In fact, textile industry consumes approximately 200 L of water to produce 1 kg of product from washing to bleaching of fbers, and from dyeing to washing of products [3], from which a high amount is discarded either without or with minimum or inad- equate treatment so that wastewater can contains between 10 and 50 mg L −1 of dyes in solution, which are enough to afect considerably the receiving water bodies where are discharged [4]. Therefore, new highly efcient approaches and of low cost are being studied by researchers around the world. These technologies must be based on materials meet- ing at least the following requisites: raw materials availabil- ity, easy and practical synthesis/preparation, environmen- tally friendly and of low cost without efciency decrease. In this regard, photocatalytic degradation of organic matter pre- sent in aqueous solution has emerged as an excellent option for textile wastewater treatment [5]. Photocatalysis is based on the radicals generated when a photon of enough energy collides the material surface, promoting electrons from the * Víctor M. Ovando-Medina ovandomedina@yahoo.com.mx * Adolfo Romero-Galarza a_romero@uadec.edu.mx 1 Departamento de Ingeniería Agrícola, DICIVA, Universidad de Guanajuato, Campus Irapuato-Salamanca, Ex Hacienda el Copal km 9, Carretera Irapuato-Silao, 36500 Irapuato, GTO, Mexico 2 Ingeniería Química, Coordinación Académica Región Altiplano (COARA), Universidad Autónoma de San Luis Potosí, Carretera a Cedral KM 5+600, San José de Las Trojes, 78700 Matehuala, SLP, Mexico 3 Facultad de Agronomía y Veterinaria, Universidad Autónoma de San Luis Potosí, Km. 14.5, Carretera Matehuala-San Luis Potosí, C.P. 78321 Soledad de Graciano Sánchez, SLP, Mexico 4 Departamento de Ingeniería Química, Facultad de Ciencias Químicas, Universidad Autónoma de Coahuila, Blvd. V. Carranza e Ing. José Cárdenas V. S/N, 25280 Saltillo, COAH, Mexico