ZnO/bentonite Hybrids Obtained by a Simple Method of Synthesis and Applied as Catalyst for Biodiesel Production Ana Flávia Félix Farias, Sandro Marden Torres, Elson Longo, Maguy Jaber, Maria Gardennia Fonseca, Liliana Fátima Bezerra Lira Pontes, and Ieda Maria Garcia dos Santos Abstract ZnO/bentonite hybrids were obtained by the microwave-assisted hydrothermal method, in order to change the bentonite surface and improve its activity for biodiesel production. No previous treatment of the clay was used and in situ crystallization of ZnO was done by a fast single step method. A factorial design was used to optimize synthesis conditions (e.g., reaction time, solution pH, and ZnO amount). The hybrids were fully characterized to determine its structural, chemical, and morphological properties. The results demonstrated the positive contribution of the microwave-assisted hydrothermal method to the formation of ZnO/bentonite hybrids, in addition to showing that the pH was the most important parameter influ- encing the formation of ZnO. A pH value of 8 favored the incorporation of approx- imately 19.6% of ZnO onto the smectite particles even after 5 min of microwave irradiation. The ZnO/bentonite hybrid with the biggest amount of ZnO was applied as a catalyst in the transesterification reaction of soybean oil. As such, our results A. F. F. Farias · M. G. Fonseca · I. M. G. Santos (B ) Núcleo de Pesquisa e Extensão—Laboratório de Combustíveis e Materiais (NPE/LACOM), Universidade Federal da Paraíba, João Pessoa, PB, Brazil e-mail: ieda@quimica.ufpb.br A. F. F. Farias Laboratório de Síntese de Materiais Cerâmicos (LabSMaC), Universidade Federal de Campina Grande, Campina Grande, PB, Brazil S. M. Torres Depto de Engenharia de Materiais (DEMAT), Laboratório de Tecnologia de Novos Materiais (TECNOMAT), Universidade Federal da Paraíba, João Pessoa, PB, Brazil E. Longo Laboratório Interdisciplinar de Eletroquímica e Cerâmica (LIEC)/Center for Development of Functional Materials (CDFM), Universidade Federal de São Carlos, São Carlos, SP, Brazil M. Jaber Sorbonne Universités, Laboratoire d’Archéologie Moléculaire et Structurale, Paris, France L. F. B. L. Pontes Depto de Química, Universidade Federal da Paraíba, João Pessoa, PB, Brazil © The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 F. A. La Porta and C. A. Taft (eds.), Functional Properties of Advanced Engineering Materials and Biomolecules, Engineering Materials, https://doi.org/10.1007/978-3-030-62226-8_1 1