THE MECHANOCHEMISTRY STUDY OF CAO AND KH2PO4 TO MAKE SLOW RELEASE MATERIAL TO CONTROL POTASSIUM DISSOLUTION IN WATER

• Main Author: Melanthony Pasaribu, Amos
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/47270
• Institution: Institut Teknologi Bandung

Increasing world population is the main cause of demand for agricultural products. This is related to the increased demand for fertilizer to replenish nutrients in the soil. The use of conventional fertilizers is ineffective because the ability to absorp the nutrients by root plants is not balanced with the release of nutrients by fertilizer so that this can have a negative impact on the environment. To overcome this problem, it needs slow release material that can release the nutrients slower in the water so that it can be more balanced with the ability to absorp the nutrients by root plants. One of the methods of making slow release material is mechanochemistry. In this study, a mixture of calcite minerals as CaO and KH2PO4 was used. The solubility tests of K in water at room temperature and pressure were conducted to study the effect of the grinding speed, grinding time, and ball to powder ratio (BPR). CaO and KH2PO4 samples were mixed by 1: 1.32 mole ratio in a planetary mill with a weight of a grinding ball of 280 grams. The effect of speed is studied with the rotational speed of 150, 200, and 250 rpm. The effect of grinding time is studied at 4, 6, 8, 12, 16, and 24 hours. While the influence of BPR was studied at a ratio of 14: 1, 28: 1, and 56: 1. All grind samples are heated to a temperature of 600oC. Grinding products are analyzed using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscope (SEM). Atomic Absorption Spectroscopy (AAS) analysis was carried out to find out the percent solubility of K in water with a dissolving time of 4 days. The grinding product observed in the XRD is K2CaP2O7. From the SEM analysis, it can be seen that grinding in planetary mill changes the morphological shape of the sample to be smoother than the initial one and give even distribution of the elements which indicate that the grinded sample is homogeneous, whereas the heating of the sample causes the grinded particles to undergo agglomeration where the resulting agglomerate is getting bigger with higher heating temperatures. FTIR analysis showed that there was a P-O-P group bond in each of the crushing samples from K2CaP2O7. For samples with variations in the grinding speed of 250 rpm, grinding time 24 hours, and BPR 56: 1 has the smallest solubility value, which is 44.09%.