Effect of ultrasound intensity on the size and morphology of synthesized scorodite particles

Disposal of high-arsenic waste acid by the stepwise formation of gypsum and scorodite

“…24,38,48 On the basis of Fujita's method, ultrasonic was introduced to the atmospheric synthesis method to produce high-crystallinity scorodite with large particle size (>10 mm). 49 An As(III)-bearing copper renery process solution was also treated by biomineralization of scorodite. 50 Therefore, the scorodite method for the arsenic xing and treatment of high-arsenic waste acid might be a green process.…”

“…This morphology is slight different from those of scorodite prepared by using pure As and Fe sources. 47,49 It might be associated with the complex composition of waste acid used in this experiment ( Table 1). The As content for the spot (Fig.…”

Utilization of carbon dioxide to synthesize large scorodite particles under ultrasound irradiation

“…In a previous work, we reported that oxidant radicals generated under 200 kHz ultrasound irradiation and O 2 gas flow contribute to the oxidation reaction to synthesize scorodite. 11,12) Thus, when the gas mixture contains more than 50 vol % of CO 2 , the oxidation reaction during the ultrasound agglomeration process is inhibited because of the reduction in O 2 gas and oxidant radicals, which are responsible for oxidation. Therefore, a large proportion of CO 2 gas (≥50 vol %) prevented nuclei formation by oxidation of radicals and O 2 gas during ultrasound irradiation (10 min) at the early reaction stage.…”

“…[33][34][35] The oxidants promoted the oxidation of scorodite precursor. 11,12) However, we consider that the dispersion effect ( jet flow, shock wave) resulting from cavitation during ultrasound irradiation led to the potential for the inhibition of the precursor agglomeration by ultrasound vibration.…”

“…11,[36][37][38][39] The cavitation effect decreases with decreasing ultrasound power 11) because as power decreases, the amplitude of the resulting standing wave also decreases, reducing the likelihood that the standing wave will exceed the cavitation threshold necessary to generate bubbles. A lower ultrasound power also results in a smaller agglomeration effect because the frequency of particle collision decreases with decreasing power.…”