INVESTIGATION OF CAVITATIONAL EXPANSION OF SODIUM HYPOCHLORITE UNDER ISOTHERMAL CONDITIONS

Liquid waste and wastewater, that contain hypochlorites, are formed during the production of chlorine and caustic soda; electrolytic production of magnesium and chlorine; in the production of pulp and paper products etc. Such wastewaters belongs to sub-standard, therefore they are not reused in corresponding technological processes. In accordance with the current normative documents, hypochlorite wastewaters must be disposed of at the local treatment facilities of the enterprises where they are produced.

The performed researches have established that cavitation treatment of hypochlorite sewage is a promising method of their purification. The aim of the work was to investigate the destruction of sodium hypochlorite under the action of cavitation, excited by acoustic radiation of the ultrasound range.

In the control study, the thermal catalytic process of the NaClO decomposition was investigated under conditions that correspond to the production.

The hydrodynamic and chemical processes that occur in the zone of cavitation excited by ultrasound radiation are analyzed. In particular, it has been found that under the hydrodynamic conditions the reactor is approaching perfect mixing. On their basis, the results of studies of the decomposition of NaClO, depending on the temperature of the process and the specific power of ultrasound radiation, were interpreted. It is established that the order of the reaction of the cavitational decomposition of NaClO, as well as the thermal, is close to one. However, it is noted that simultaneously with the cavitational destruction of NaClO, its reduction to NaCl occurs due to interaction with products of water sonolysis. Due to this, the process length is much smaller than the ideal mixing ratio for the characteristic equation.

With the increase in the temperature of the reaction medium, the efficiency of energy input, in particular acoustic and thermal, in the reaction medium decreases. This is due to an increase in the partial pressure of water vapor, which reduces the effectiveness of the cavitation bubbles, and the formation of relatively stable babuston microbubbles due to cavitation.

The obtained results confirm the significantly higher efficiency of the cavitational expansion of hypochlorites compared to the cavitational thermal method of their neutralization, which was estimated by the values of the speed constants and the duration of the processes, at least 1.5 times.