In this work, a SiO2-TiO2 coating, composed of different numbers of TiO2 and SiO2 layers, was fabricated by a spray-coating technique. The films were deposited onto ignimbrite rock and divided into two groups according to the number of SiO2 layers applied, 10 and 15 layers of SiO2 and 5 layers of TiO2 for each group. The morphology and chemical composition of the synthesized samples were characterized by field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectrometer (EDS), which reveal the successful SiO2-TiO2 coating on ignimbrite. The photocatalytic activities of samples obtained were evaluated toward the decomposition of 3 ppm of methyl orange (MO). Finally, NOx gas degradation was studied. The obtained results evidenced that the SiO2 and TiO2 coating improved the photocatalytic activity of ignimbrite.

No abstract

Geopolymeric mortars derived from residues of the Peruvian formal mining industry were manufactured and mechanically evaluated under normal conditions of temperature and atmosphere. The mechanical results found in geopolymeric mortars were compared with those found in conventional Portland cement mortars (control). The values of maximum uniaxial compressive strengths for geopolymeric mortars were between 15.5 and 31.5 MPa, finding the best results when considering a ratio binder:fine sand of 1:2, hardener solution molarity of 20M and a ratio hardener solution:binder of 0.6. The microstructure found for both types of mortars studied (control and geopolymeric) consisted of an interconnected continuous phase of binder (cement or geopolymerized mining tailings) and another discontinuous one of fine sand particles, located within the binder phase.