Effect of HNO₃ and H₃PO₄ on Ion Exchange of Natural Zeolite for Making Agricultural Cultivation Solution from Seawater

Abstract

Effects of HNO 3 and H 3 PO 4 on ion exchange of natural zeolite in a new-simple process, which is a twostep process using calcined hydrotalcite and natural zeolite, for making agricultural cultivation solution were examined. The anion-reduced solution obtained by the treatment of seawater with calcined hydrotalcite (CHT-solution) was neutralized with phosphoric (CHT-solution-H 3 PO 4) or nitric acids (CHT-solution-HNO 3), and each four solutions (seawater, CHT-solution, CHT-solution-H 3 PO 4 and CHT-solution-HNO 3) was treated with natural zeolite to compare the ion exchange behaviors among these solutions. The pH of the all solutions can be neutralized to 5.5 by zeolite treatment, and the Na + content can be removed from the all solution. The tendencies of Na + removal in all solutions are almost same, and percentages of Na + removal from all solutions are above 95% over 8 times zeolite treatment. The amounts of supplies for K + , Mg 2+ and Ca 2+ to the CHT-solution-HNO 3 is higher than those of other solutions up to 6 times treatment. While almost PO 4 3was removed, NO 3 was remained in the solution, over 6 times treatment with natural zeolite. Therefore, NO 3is possible to be supplied to the solution as nutrient in the two-step process, but PO 4 3isn't possible.

Desalination Behaviors From Seawater Using Natural Zeolite and Calcined Ca-Fe Layered Double Hydroxide for Cultivation

“…In previous studies, desalination behaviors of natural zeolite and synthetic zeolite in seawater were examined [4][5][6][7], and seawater was treated with calcined Mg-Al layered double hydroxide (LDH) and natural zeolite in two steps to obtain a solution that can be used for germination of radish sprouts from seawater [8][9][10][11][12]. Furthermore, we have succeeded in cultivating radish sprouts using seawater treated with a mixture of mordenite-type natural zeolite and calcined Ca-Fe LDH (calcination at 500 o C) (mixing ratio of zeolite to LDH =5: 4), which are cheap materials [13][14][15][16].…”

Desalination Behavior of Calcined Hydrotalcite From Seawater for Preparation of Agricultural Cultivation Solution Using Natural Zeolite

“…This process can be applied to seawater after its use as a coolant in electric power plants and chemical plants, and to high salinity water in some areas; accordingly, we expect this process to be useful for vegetation in arid areas. Therefore, we investigated the ion exchange properties of natural zeolite in a two-step process (Shimizu et al, 2007;Wajima et al, 2013). However, little information regarding the treatment of seawater using CHT is available.…”