The results for the extraction of arsenic in complex mining waste by employing a CCD design for the use of an ultrasonic bath for energy proved to be quite satisfactory. Optimum conditions for extraction of arsenic were obtained by evaluating operational parameters of the ultrasonic bath and conditions of analysis with the experimental design.
In assessing the influence of temperature on the extraction of arsenic in ultrasound, it was noted that there is no significant influence up to 40 °C. However, it was noted that the position of the sample in the ultrasonic bath tub is significant in that a greater proximity between the samples and the source of ultrasonic waves allows the intensification of the phenomenon of cavitation in the vicinity of the sample and thus, extraction of arsenic.
The concentration of arsenic obtained using the method optimized for ultrasound (HNO3, 2.7 mol L− 1 and 136 minutes of sonication) was superior to that obtained by the standard method performed in the microwave, which indicates that the method developed contributes significantly to the establishment of a more accurate assessment of the real environmental impact caused by mining waste deposits.