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In recent years, it has been considered to secure water and food using seawater desalination technology, and a new simple desalination material for reducing the high concentration of sodium chloride in seawater is required. In this study, desalting agents were prepared from natural zeolite, obtained from Kagoshima prefecture, Japan, with the addition of calcined Ca-Fe type layered double hydroxide (LDH), to desalinate seawater for cultivation. By treating with the mixture of natural zeolite and calcined Ca-Fe LDH at a mixing ratio of 5: 4, the salinity could be reduced from 3.61% in seawater to 0.97% by cation exchange reaction of natural zeolite and reconstruction reaction of calcined Ca-Fe LDH, and the pH of the obtained solution is 8.4-9.0. The desalination reaction using this mixture was almost the same regardless of temperature. Radish sprouts, bean sprouts, and mung beans could be harvested using seawater treated with a mixture of natural zeolite and calcined Ca-Fe LDH, while it was not possible to harvest using seawater. [ABSTRACT FROM AUTHOR]

The desalination technology of seawater is considered to secure water and food in recent years, and a new simple desalting material to decrease the high concentration of sodium chloride in seawater is desired. In this study, preparation of the desalting agent from two Ca-type clay minerals, natural zeolite and Ca-Fe type layered double hydroxide (LDH), attempted to desalinate seawater for agricultural water[1][2][5]. Natural zeolites used in this study were mordenite-type zeolite from Fukushima prefecture, Japan and clinoptilolite-type zeolite from Kagoshima prefecture, Japan, and raw and Ca-substituted zeolites were used for seawater desalination[1][2][3][4][5]. Regardless of zeolite type, desalination behaviors of Ca-substituted zeolite were almost same as those of raw zeolite. The salinity and pH of seawater were 3.46% and 8.0, respectively, while clinoptilolite decreased the salinity to 3.20%, mordenite decreased to 2.09%, above 5.0 g/L zeolite addition. As increasing the Calcined Ca-Fe LDH addition to seawater, the salinity decreased to 3.3%, and pH of the solution increased to pH 11.5, and then became almost constant above 2.0 g/L addition of Calcined Ca-Fe LDH. As increasing the mixing ratio of Calcined Ca-Fe LDH to raw mordenite, the salinity decreased to 0.8% (79.2% reduction) while pH of the solution was neutral (about 7.6~8.0). Radish sprouts could be harvested using the seawater treated with a mixture of raw mordenite-type natural zeolite and Calcined Ca-Fe LDH, although those could not be harvested using seawater, the seawater treated with natural zeolite or Calcined Ca-Fe LDH. [ABSTRACT FROM AUTHOR]