Numerous studies have demonstrated the efficacy of biochar in enhancing soil physical and chemical properties. The nitrogen content in biochar varies significantly based on the pyrolytic temperature, growth stage of the plant used and plant type (nitrogen fixer and non-nitrogen fixer). Nevertheless, biochar generally possesses an inherently low nitrogen content. This research sought to investigate the potential for elevating the nitrogen content of biochar through intercalation with Urea, employing chemical methods. Urea intercalated municipal biochar (UMB) fertilizer was created by blending a urea solution with the original municipal biochar at a 1:1 ratio (20 ml: 20 g). Subsequently, it underwent an oven drying process at 65°C for 8 hours to eliminate moisture content. One gram of adhesive polymer (starch) was introduced into the mixture and allowed to air dry. The final product was subjected to characterization through Fourier Transform Infrared Spectroscopy (FTIR) within the range of 400 to 4000 cm-1, utilizing Attenuated Total Reflectance techniques. Selected chemical properties of municipal biochar, urea, and urea intercalated biochar, such as pH and total nitrogen (N), were determined. Notably, the nitrogen content of municipal biochar was substantially lower (3.36 %) than that of urea-intercalated biochar (24.5 %). FTIR analysis of the intercalated biochar was compared with the original biochar, revealing the emergence of numerous absorption sites in regions corresponding to amides (3600 - 3300 cm-1), carboxylic acid groups (1750 - 1700 cm-1), nitrile groups (2260 - 2210 cm-1), and hydroxyl groups (OH) at 2950 cm-1. These features were absent in the FTIR results of the original municipal biochar. The predominant peak in the municipal biochar spectra was attributed to the COOH group at a wavelength peak of 1630 cm-1. The outcomes of this study validate the feasibility of enhancing the nitrogen content of biochar through intercalation. Furthermore, the presence of numerous functional groups in urea-intercalated municipal biochar fertilizer suggests its potential as a slow-release nitrogen fertilizer. Nonetheless, additional research is warranted to confirm its efficacy.

Keywords: FTIR; Municipal biochar; Urea intercalated biochar; Functional group