Prospects for sonochemical treatment of wastewater containing synthetic surfactants
Experimental studies have been carried out to study the effect of low-frequency ultrasound on the destruction of nonionic synthetic surfactants, which have different molecular weights. Model solutions of two nonionic surfactants: polyethylene oxide and oxanol were chosen as the objects of study. The studies were carried out in order to confirm the prospects of using low-frequency ultrasound in the process of local treatment of wastewater containing nonionic synthetic surfactants. The level of disintegration of polyethylene oxide and oxanol was evaluated by two methods in a comparative aspect: viscometry and photocolorimetry. A similar nature of the dependences of the destruction efficiency of nonionic surfactants obtained on the basis of photocolorimetric and viscometric measurements was revealed. The possibility of using the viscometric method for express determination of the most effective mode of ultrasonic exposure has been confirmed.A more significant effect of the intensity of ultrasonic action on the degree of decomposition of nonionic surfactants was found in comparison with the duration of ultrasonic treatment. The possibility of manifestation of surface-active properties in the decay products of the studied pollutants is shown. Prospective modes of ultrasonic treatment of industrial effluents are proposed. As a result of the research, the most promising from the point of view of economics and purification efficiency mode of preliminary ultrasonic treatment of industrial effluents was established: 6 W/cm2 intensity and 1 min duration. This mode provides a sufficiently high efficiency of decomposition of nonionic surfactants. At significant initial concentrations of nonionic surfactants in wastewater (above 50 mg/dm3), it is recommended to increase the intensity of ultrasonic action.