Efficacy of Soybean Extracted Using Different Method in Calcite Precipitation for Soil Improvement

This study aims to evaluate the extraction method of soybean as a plant-derived urease enzyme. The use of soybeans as a source of urease offers several advantages. Soybeans are a renewable and sustainable resource that is readily available in many regions. Moreover, they contain high levels of urease enzyme, which accelerates the carbonate precipitation process, leading to faster soil improvement. By focusing on this research aspect, the development of an efficient and sustainable extraction process is necessary to obtain the urease enzyme from soybeans, thereby increasing the effectiveness and practicality of the EICP method for soil improvement. Furthermore, the soybean powder was prepared in a suspension and extracted using two methods, namely filtration and centrifugation, to separate the particle and solution and obtain a purified solution. Its efficacy as a biocatalyst was evaluated using a test-tube experiment to determine the hydrolysis rate of urea as well as the production of precipitated materials. Unconfined compression strength (UCS) tests were used to assess its effect on soil strength at different curing times. The highest hydrolysis rate was obtained using 50 g/L of soybean extract in the two extraction methods, centrifugation and filtration, with speeds of 1,100 u/g and 500 u/g, respectively. A maximum precipitation ratio of 100% was achieved using a concentration of 20 g/L, which later increased constantly. This study showed that the extraction methods had similar UCS values, ranging from 300 to 400 kPa. In conclusion, a soybean concentration of 20 g/L prepared using filtration has great potential for use in the calcite precipitation technique for soil improvement.