Copper hexacyanoferrate (Cu-HCF), which is a type of Prussian Blue analogue (PBA), possesses a specific lattice structure that allows it to selectively and effectively adsorb cesium with a high capacity. However, its powdery form presents difficulties in terms of recovery when introduced into aqueous environments, and its dispersion in water has the potential to impede sunlight penetration, possibly affecting aquatic ecosystems. To address this, sponge-type aluminum oxide, referred to as alumina foam (AF), was employed as a supporting material. The synthesis was achieved through a dip-coating method, involving the coating of aluminum oxide foam with copper oxide, followed by a reaction with potassium hexacyanoferrate (KHCF), resulting in the in-situ formation of Cu-HCF. Notably, Copper oxide remained chemically stable, which led to the application of 1, 3, 5-benzenetricarboxylic acid (H3BTC) to facilitate its conversion into Cu-HCF. This was necessary to ensure the proper transformation of copper oxide into Cu-HCF on the AF in the presence of KHCF. The synthesis of Cu-HCF from copper oxide using H3BTC was verified through X-ray diffraction (XRD) analysis. The manufactured adsorbent material, referred to as AF@CuHCF, was characterized using Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). These analyses revealed the presence of the characteristic C≡N bond at 2,100 cm-1, confirming the existence of Cu-HCF within the AF@CuHCF, accounting for approximately 3.24% of its composition. AF@CuHCF exhibited a maximum adsorption capacity of 34.74 mg/g and demonstrated selective cesium adsorption even in the presence of competing ions such as Na+, K+, Mg2+, and Ca2+. Consequently, AF@CuHCF effectively validated its capabilities to selectively and efficiently adsorb cesium from Cs-contaminating wastewater.

Ms. Hee Choon Oh was a Jeju Haenyeo(woman diver) and one of the few surviving victims of the Jeju 4.3 (1948). As a Haenyeo: Jeju society was very poor at the time during the Japanese colonial period and the division of the two Korea, especially after the Korean War, so she had to work regardless of gender. It was hard to go into the sea, but it was the only thing to support my family. In retrospect, Going out to work in the sea was like a life-threatening adventure every day. While there were many emergency moments, She becomes one with the sea and forgot all the pain. After having spent a lot of time together with the sea, I had to stop working as a Haenyeo because it was hard to take care of nine children after having heart surgery. I was able to receive Honorary Haenyeo through continuous exchanges and dedication to the society. As a victim of the Jeju 4.3: I had no choice but to explain it why I had to do work as a Haenyeo and to understand my life. I am a woman who chose the job of Haenyeo, but I have lived through the pain of the dark modern and contemporary history of Korea. The unfair one-year prison life that I wanted to hide even from my children hurt me all my life. Over the past 70 years, sharing pain with the sea, neighbors, and family, serving the region, and hopefully waiting for a better society and justice to come. and finally It was not until 2019, 70 years after 1948, that I was officially acquitted by a Korean court. I regained my honor as a Haenyeo and was able to get rid of my deep sadness.