Study on the regeneration of activated carbon adsorbed with radon by using a deep depressurization method

In order to develop a non-heating, fast, and efficient method for activated carbon regeneration, the deep depressurization method was proposed. A validation experimental setup was designed to systematically study the impact of desorption methods, desorption duration, and desorption conditions on the desorption effectiveness of activated carbon adsorbed with radon and water. Continuous repetitive experiments and expanded experiments were conducted. The experimental research results indicate that the combination of continuous ventilation and deep depressurization is the most effective desorption method. Considering factors such as overall energy consumption and time, the optimal desorption time for activated carbon is 2 hours. Reducing the relative humidity of radon-laden air and elevating the desorption environmental temperature significantly enhances the desorption rate. Under environmental conditions featuring a temperature of 24-25 °C, a relative humidity ranging from 5% to 15%, and a flow rate of 0.3 L/min, 122.5 g of activated carbon can achieve a desorption rate of 85% after 2 hours of desorption. Moreover, the desorption results remain stable through 10 consecutive repetitions. Further experiments on a kilogram-scale activated carbon bed demonstrate that under conditions featuring a vacuum level higher than that corresponding to the environmental temperature's water evaporation point and an appropriate flow rate, the desorption rate of the activated carbon can reach the efficiency of a smaller carbon bed and is independent of the shape of the activated carbon bed. The deep depressurization method for the regeneration of the activated carbon adsorbed with radon and water holds promise as a rapid and efficient online regeneration method.