EXAMINATION OF CALCITE PRECIPITATION USING PLANT-DERIVED UREASE ENZYME FOR SOIL IMPROVEMENT

Abstract

The enzyme-mediated calcite precipitation (EMCP) method was established as a soil-improvement technique. This study discussed the possibility of using a plant-derived urease enzyme as a bio-catalyst. The urease enzyme was utilized for the hydrolysis of urea, which causes the supply of calcium ions to precipitate calcium carbonate. Several sources that may contain the urease enzyme were examined. Extracts from cabbage and soy pulp, without purification, were utilized as substitutes for commercial urease enzyme products. Initially, the solution was composed of 15 g/L of crude extract and 1 mol/L each of urea and calcium chloride. The precipitation results using commercial products and crude extracts were compared under the same concentration of reagent solution. A mineralogical analysis of the precipitated materials was also conducted. The mineralogy and morphology of the precipitated materials were examined by Fourier-Transformed Infra-Red (FTIR) spectroscopy, X-Ray Diffraction (XRD), and Scanning Electromagnetic (SEM) tests. The precipitation ratios using the crude extracts as replacements for the urease enzyme were found to be more than 60% of the maximum theoretical value. From the mineralogical and morphological analyses, the calcite mineral was confirmed as the precipitated material. The results of this study indicated that crude extracts from cabbage and soy pulp are potential materials for sources of the urease enzyme