STUDY OF ZEOLITE GEOPOLYMERIZATION UTILIZED FOR POTASSIUM SLOW RELEASE IN WATER

• Main Author: Alexius Sitompul, Johannes
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/43818
• Institution: Institut Teknologi Bandung

Indonesia is a country which is the fourth largest human population in the world with 268 million people in 2019. This has an impact of rapidly increasing food demand so that the use of fertilizer increases. However, uncontrolled use of fertilizer can cause environmental problems. High solubility of fertilizer causes the fertilizer elements to be improperly absorbed by soil. This problem can be solved by developing a material for slow releasing fertilizer elements. One of the material suitable for this purpose is geopolymer. In this research work, mixture of zeolite, K2HPO4.3H2O and (Na2SiO3) is used to form geopolymer. Zeolite being used was obtained from the region of Tasikmalaya, West Java. Series of tests at atmospheric pressure and room temperature have been carried out to study the effect of geopolymer composition, geopolymerization temperature and briquetting pressure on the potassium dissolution percentage. The effect of geopolymer composition was studied at various ratio of zeolite mass (gram) and waterglass 2,5M volume (ml) 3,5:1, 4,0:1 and 4,5:1. The effect of geopolymerization temperature was studied at various temperature of 110, 120, 130 and 140°C. Meanwhile the effect of briquetting pressure was studied at various pressure of 0 (hand press), 20, 30 and 40 kg/cm2. The percentages of dissolved potassium as a function of time at various conditions were determined by analysis of AAS. In the variation of geopolymer composition, geopolymer with a composition of 3.5:1 has the lowest percent potassium release. In the geopolymerization temperature variations, geopolymers with 140°C geopolymerization temperature has the lowest percent potassium release. In the variation of geopolymer briquetting pressure, the geopolymer with a pressure of 40 kg/cm2 has the lowest percent potassium release. In this research, the lowest percentage of dissolved potassium was obtained at combined condition of 3.5:1 geopolymer composition, 140°C geopolymerization temperature and 40 kg/cm2 briquetting pressure. The percentages of dissolved potassium obtained at that condition is 19,29%. SEM and FTIR analysis were carried out to determine the geopolymer structure.