In this study, results are presented concerning the development of alternative materials based on titanium dioxide (TiO2) and agro-industrial waste for use in the treatment of effluent contaminated with dyes. The photocatalytic activity of a composite formed by the association of activated carbon, obtained from pit residue of mango, with modified titanium dioxide was evaluated by the degradation of crystal violet dye. From the analysis of X-rays diffratograms, it was observed that the modification introduced in the TiO2, as well as the formation of the composite with activated carbon, lead to wider peaks with lesser intensity, suggesting the formation of small particles. The composite presented the best photocatalytic performance, attributed to the significantly large specific area of this material when compared to pure TiO2, reaching 99% degradation of the organic matter after 60 minutes of reaction time. This is, therefore, a promising material for environmental photocatalysis.