Abstract:
using the hydrothermal method and its application as adsorption for methylene blue dye. This study
aims to determine the effect of the addition of oxalic acid on the characteristics and adsorption ability
of hydrochar from nypa frond to adsorption of methylene blue. The hydrothermal process was carried
out at 170˚C for 2 hours with the addition of oxalic acid at a concentration of 0; 1.5; 3.0; and 4.5%
(w/v). Substrates resulting from the hydrothermal process were characterized using FTIR spectroscopy
to determine the functional group changes of the nypa frond. The results showed that the nypa fronds
decreased in mass and shifted in functional groups after the hydrothermal process with oxalic acid
addition. The adsorption capacity of methylene blue increased after the hydrothermal process with the
addition of oxalic acid concentrations 1.5; 3.0; and 4.5% (w/v), which were 44.33; 45.10; 45.98; and
46.62 mg/g. The highest adsorption capacity results were obtained for hydrochar with the addition of
4.5% oxalic acid, which was 46.62 mg/g
Keywords: hydrochar, nypa frond, hydrothermal, adsorption, methylene blue
