Hydrothermal Synthesis of Na-P₁ Zeolite from Pumice to Enhance Moisture Content and Water Retention Capacity of Sandy Soil

In this study, pumice as a precursor from Semen Shoa, Minjar Shenkora Woreda was used in synthesis of Na-P₁ zeolite. Hydrothermal treatment was performed with sodium hydroxide at different ratio of pumice to NaOH pellets (1:1.2, 1:1.5 and 1:1.8) at varying temperatures of 60, 80 and 100 °C and reaction time of 70,100 and 130 min. Effect of pumice to NaOH ratio, reaction temperature and reaction time on Si/Al ratio of synthesized zeolite was studied. Optimal silica to alumna ratio of 2.5 was obtained at temperature of 100 °C, reaction time of 100 min and pumice to NaOH ratio of 1:1.5. Na-P₁ zeolite obtained at optimum operating conditions was used for other characterizations such as FTIR, XRD and surface area analysis and for the moisture testing & pressure plate extractor testing. The surface area for this zeolite was found to be 56.04 m²/g. The XRD patterns of the synthesized material after formation of zeolite Na-P₁ was observed through reflections on 2θ = 19.31°, 23.44°, 28.32°, 32.43°, 33.5° and 49.10^o. The synthesized zeolite showed the most prominent reflection peak at 32.43°. Effects of different dozes of the synthesized zeolite on sandy soil moisture content and water retention capacity were studied. As the dose of zeolite increased from 0 g/kg to 20 g/kg, the rate of moisture loss from sandy soil decreased. The results showed that application of zeolite to the sandy soil significantly increased the moisture content in the mixtures of soil-zeolite. The water holding capacity of the amended soil was tested using pressure plate extractor at 1, 3, 5 and 15 bars. At 0 bars, all soil samples were observed to have the same water content since at the beginning all soil samples had been moistened with water (70% by weight. Then at 1 bar sandy soil without zeolite had a moisture content about 12% whereas sandy soil with 10 g/kg had 15.65%. As the amount of zeolite added increased from 10 g/kg to 15 g/kg and to 20 g/kg, it was observed that adding zeolite on the sandy soil increases the water retention capacity of the soil.