Preparation of mordenite and its composite material with nano-sized magnetite from diatomites for radioactive Cs decontamination

Abstract

Mordenite was artificially synthesized using various diatomites for radioactive Cs decontamination. A high CEC (Cation Exchange Capacity) value was obtained when the diatomite had a high Al/Si elemental ratio. The Cs + adsorption rate from 100 ppm Cs solution for the synthesized mordenite (1.0 g) was ca. 100% and ca. 83% in 100 mL of water and seawater, respectively. The composite powder material consisting of mordenite and nano-sized magnetite was synthesized from a mixed slurry of the diatomite and nano-sized magnetite. Magnetic collection rate for the composite material using a neodymium magnet was larger than 90% for the 20 and 30 wt % magnetite-containing composite materials. The total Cs decontamination rates using magnetic collection after the Cs + adsorption in water were 92.7% and 97.2% for the 20 and 30 wt % magnetite-containing composite material, respectively.

Synthesis of mordenite and its composite material using chemical reagents for Cs decontamination

“…The non-reacted Si 4+ ions would remain in the solution after the reaction in the autoclave and were removed by the washing process. Figure 8 shows a comparison of the XRD patterns for the artificial mordenite from the reagents in this study (Al/Si = 0.085, 180°C, 24 h), artificial mordenite from diatomites, 18) and a natural mordenite. The mordenite synthesized from the reagents showed high intensity for the XRD peaks compared to those of the artificial mordenite from diatomites and the natural mordenite.…”

“…In our previous study, we synthesized the mordenites from diatomite. 18) Figure 16 shows a comparison of Cs + the adsorption ability for the mordenites prepared from reagents and diatomite. Although the Cs + adsorption ability in water was greater than 99% for both mordenites, the ability in seawater was also higher for the mordenites prepared from the reagents.…”

“…The selectivity in seawater for the mordenite prepared from diatomite was almost the same as that for the natural mordenite. 18) These abilities for the mordenite from reagents are the highest values because of the low impurities.…”

Cs+ decontamination properties of mordenites and composite materials synthesized from coal fly ash and rice husk ash

“…Although the synthesis of mordenite has been reported by a hydrothermal method using the reagents of Na, Al, and Si sources without the template and the seed, the conditions for the preparation have not been established in detail [18,19]. We established the preparation method for the mordenite or the composite materials of mordenite and nanosized magnetite from the diatomite or chemical reagents [20,21]. The most suitable Al/Si ratio of the raw materials was determined for the preparation of the mordenite.…”

Adsorption characteristics of Cs⁺ onto artificial zeolites synthesized from coal fly ash and diatomite

“…6) An artificial Na-P1 from coal fly ash and an artificial mordenite from diatomite were hybridized with magnetite for the purpose of the decontamination of Cs + from waters and soils. 17), 18) Both hybrid materials performed high Cs + adsorption capacity where more than 99% of Cs + was adsorbed from 100 mL of 100 ppm Cs + solution by one gram of those materials. However, detailed Cs + adsorption study has not been carried out.…”