Arsenic removal from acidic industrial wastewater by ultrasonic activated phosphorus pentasulfide

Abstract

Arsenic is one of the main harmful elements in industrial wastewater. How to remove arsenic has always been one of the research hotspots in academic circles. In the process of arsenic removal by traditional sulfuration, the use of traditional sulfurizing agent will introduce new metal cations, which will affect the recycling of acid. In this study, phosphorus pentasulfide (P2S5) was used as sulfurizing agent, which hydrolyzed to produce H3PO4 and H2S without introducing new metal cations. The effect of ultrasound on arsenic removal by P2S5 was studied. Under the action of ultrasound, the utilization of P2S5 was improved and the reaction time was shortened. The effects of S/As molar ratio and reaction time on arsenic removal rate were investigated under ultrasonic conditions. Ultrasonic enhanced heat and mass transfer so that the arsenic removal rate of 94.5% could be achieved under the conditions of S/As molar ratio of 2.1:1 and reaction time of 20 min. In the first 60 min, under the same S/As molar ratio and reaction time, the ultrasonic hydrolysis efficiency of P2S5 was higher. This is because P2S5 forms ([(P2S4)])2+ under the ultrasonic action, and the structure is damaged, which is easier to be hydrolyzed. In addition, the precipitation after arsenic removal was characterized and analyzed by X-ray diffraction, scanning electron microscope-energy dispersive spectrometer, X-ray fluorescence spectrometer and X-ray photoelectron spectroscopy. Our research avoids the introduction of metal cations in the arsenic removal process, and shortens the reaction time.