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In this paper, a sol-spray pyrolysis route was employed to fabricate (Cs, Ba)-hollandite ceramic waste forms. The high-phase purity (Cs0.8−xBa0.4+x)(Al1.6+xTi6.4−x)O16 (0 ≤ x ≤ 0.4) ceramics were synthesized at 1050 °C using the produced powders by sol-spray pyrolysis. The results show that all samples show tetragonal hollandite with rod morphology. Additionally, the sintered (Cs, Ba)-hollandite ceramics exhibit a good chemical durability. The normalized release rates of Cs and Ba were < 10−2 g m−2 d−1 after 14 days. These results indicate that hollandite ceramics are promising candidate for immobilizing radioactive cesium. [ABSTRACT FROM AUTHOR]

Sebacic acid, an important chemical intermediate, is usually prepared by fermentation. However, the composition of the fermentation broth is complex, which causes significant difficulties in the purification of the product and is still a key problem in the industry. In this study, the application of ceramic membranes for the separation and purification of simulated fermentation broth was studied. Ceramic microfiltration (MF) and ultrafiltration (UF) membranes with average pore sizes of 100 and 6 nm, respectively, were systematically compared by analyzing their separation effects on different components in the fermentation broth and their permeation flux during filtration. Both ceramic MF and UF membranes can be used to clarify the fermentation broth with turbidity less than 0.01 NTU by the effective removal of emulsified oil and bacteria while allowing sodium sebacate to pass through freely. However, the ceramic UF membrane showed a higher protein rejection of more than 95%, whereas the removal rate of the MF membrane was only approximately 20%. In addition, the fouling process of ceramic UF membrane was analyzed. In the suitable operating conditions when the pH was 9.2, the temperature was 60 ℃, the pressure was 0.1 MPa and the cross-flow velocity was 1.8 m·s−1, the membrane fouling process was dominated by the reversible cake formation. A ceramic UF membrane with a smaller pore size can effectively avoid pollution in pore channels, and thus exhibits a higher permeation flux in the filtration of the fermentation broth. • Ceramic MF and UF membranes were compared for the clarification of fermentation broth. • The turbidity can be reduced below 0.01 NTU by both ceramic MF and UF membranes. • Sebacic acid permeated through the ceramic UF membrane freely in its salt form. • Ceramic UF membrane effectively avoided fouling in pores and exhibited a higher flux. [ABSTRACT FROM AUTHOR]

Hollandite ceramics are considered as a promising host matrix for cesium immobilization. In the paper, [Cs x Ba y [Fe3+ 2 y + x Ti4+ 8-2 y - x O 16 (0.3 ​≤ ​ x , y ​≤ ​0.75) ceramics were synthesized by solid-state reaction method using 133Cs and 133Ba as the substitutes for radioactive Cs and its daughter product Ba. It was found that the as-prepared (Cs,Ba)-hollandite solid solution shows a tetragonal structure (I 4/m) with >90% crystallinity and good Cs retention at 1250 ​°C. Moreover, the normalized release rates of Cs and Ba are in the order of 10−3 ​g ​m−2 ​d−1 for 28 days, exhibiting excellent aqueous durability. The Fe-substituted hollandite provides a large enough space to accommodate Cs+ and Ba2+ cations and forms a solid solution with excellent structural stability and aqueous durability. Image 1 • The high purity (Cs,Ba)(Fe,Ti) 8 O 16 hollandite ceramics with above 90% crystallinity were fabricated at 1250 ​°C for 4 ​h. • The effects of substitutions of Ba2+ for Cs+ and Fe3+ for Ti4+ on the phase structure, chemical compositions and microstructure were investigated. • The (Cs,Ba)(Fe,Ti) 8 O 16 hollandite exhibits an excellent capacity to accommodate Cs and its daughter Ba in its crystal structure. • The normalized release rates of Cs and Ba are in the order of 10−3 ​g ​m−2 ​d−1 for 28 days, exhibiting excellent aqueous durability. [ABSTRACT FROM AUTHOR]

It is rather necessary to find a simple and rapid way to immobilize complex nuclear waste into stable ceramic matrix. In this work, complicated lattice occupation design was avoided through introducing complex waste into as-prepared host matrix. Two types of simulated TRPO (trialkyl phosphine oxides) wastes were introduced into as-prepared Gd 2 Zr 2 O 7 matrix by spark plasma sintering (SPS) in 3 min. It is assumed that the waste composition, especially the contents of oxides with relatively low melting point (MoO 3 , RuO 2 and PdO) and raw material for Gd 2 Zr 2 O 7 (ZrO 2), determines the final solubility. Moreover, the obtained compounds exhibit highly densified microtopography. Mo, Ru and Pd show more obvious enrichment with increased dopant while other doped elements show unobservable enrichment to the highest dopant. These results express a rapid and efficient way to immobilize oxides of high melting point into as-prepared host matrix without lattice occupation consideration. [ABSTRACT FROM AUTHOR]