Photocatalytic and sonophotocatalytic degradation of rhodamine B by nano-sized La2Ti2O7 oxides synthesized with sol-gel method

•Study of the Rhodamine B photodegradation on the nano-sized La2Ti2O7 photocatalyst synthesized by sol-gel route.•The influence of crystallite size, dye concentration, catalyst loading and temperature on photocatalytic properties.•Determination of the Point of Zero Charge (PZC) by zeta potential measurements.•The pH influence on the degradation of cationic or anionic pollutants has been highlighted.•The sonophotocatalysis study shows an improvement in the photodegradation of Rhodamine B (synergistic effect of 23 %).