In this work, pure bismuth ferrite (BiFeO3) as a visible-light photocatalyst has successfully synthesized via ultrasonic method in a short time and low temperature. The product was characterized by different techniques. Then, the degradation of Rhodamine B (RhB) was investigated under sunlight irradiation by bismuth ferrites synthesized with ultrasound. The RhB in solution was completely degraded in 35 min under applied conditions in acidic medium. The nanocatalyst did not exhibit significant loss of activity even after four cycles of successive uses. The total organic carbon (TOC) measurements displayed a complete mineralization in 90 min. To determine the mechanism of photocatalytic degradation of RhB, different methods were used. Based on the results, two possible competitive photodegradation pathways proposed: chromophores cleavage and N-deethylation. The hole as a reactive species had a key role in the degradation process. The BiFeO3 (BFO) nanoparticles synthesized with ultrasound exhibited higher crystallization, smaller crystallite size and a higher photocatalytic activity than the sample synthesized with sol–gel method in stricter conditions.

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