The role of zeolites in the nuclear leak crisis(2)

In response to this measure, TEPCO said: When discharging nuclear wastewater, the tritium contained in the water will be diluted to less than one-fortieth of the Japanese national standard for tritium discharge from nuclear power plant wastewater, which is 60,000 becquerels of tritium activity per liter of water, and will also meet one-seventh of the World Health Organization drinking water standard.

The principle of why zeolite can adsorb radioactive substances is revealed.

The release of nuclear wastewater in Japan is bound to cause certain health and safety problems, but we cannot ignore the role of zeolites in adsorbing radioactive substances. For radioactive substances such as tritium, cesium, cobalt, strontium, etc., adsorption or ion exchange techniques are most commonly used. Zeolite is widely used in the adsorption of radioactive materials in the nuclear industry because of its unique structure, its strong irradiation stability, and its huge adsorption capacity, which makes it particularly suitable for long-term storage of radioactive waste and does not produce secondary waste, and has a strong purification capacity. The specific applications are focused on 2 areas: removal of highly radioactive waste; and long-term storage of radioactive waste.

According to the report on the discharge records and seawater monitoring results of the Fukushima Daiichi nuclear power plant in February, which Japan provided to the International Atomic Energy Agency on March 25, the amount of tritium contained in each liter of seawater was about 1100, which exceeded the limit measurement value.

Zeolite, as an inorganic material, has high affinity for polymer polarities such as H2O, NH3, H2S, CO2, etc. It still has high adsorption capacity and high adsorption rate especially for water, under very harsh conditions such as low partial pressure (even below 133 Pa) or low concentration, high temperature or even above 100°C). 

Luo De Li and others from the Chinese Academy of Engineering Physics have demonstrated that zeolite can effectively adsorb and remove tritium from nuclear wastewater, and the modified zeolite molecular sieve can make its adsorption rate reach 99%. In addition, researcher Li Wei confirmed through experimental data that the filtration efficiency of zeolite for tritium water gas will be enhanced with the increase of temperature, and its average filtration efficiency is basically more than 90%.

It is worth mentioning that in addition to its ability to effectively adsorb radioactive materials, zeolite is also currently used in protective equipment as a protective filter material in the nuclear industry.

The porous structure and strong stability of zeolite enable it to adsorb and remove radioactive elements such as cobalt and strontium. Compared with organic materials, zeolites are more resistant to resin degradation caused by ionizing radiation. Also, zeolite can be used for long-term storage of long-lived radioisotopes such as cobalt and strontium.

Despite the progress in scientific research, the treatment and disposal of radioactive waste is still a major problem in the world. As an excellent inorganic adsorbent material, zeolite has been used in the world's serious nuclear accidents, and has done a good job in wastewater treatment and environmental remediation, so that the world has witnessed its "magic". At present, zeolite has been widely used in nuclear industry treatment technology at home and abroad, and we believe that if we continue to strengthen the development and application of zeolite, we will be able to play a stronger role in adsorption and purification, so as to better solve the world's nuclear pollution problems.