Activated Hydrochar Prepared from Longan Fruit (Dimocarpus longan Lour.) Peel via Hydrothermal Carbonization-NaOH Activation for Cationic Dyes Removal

Neza Rahayu Palapa (Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Sriwijaya, Ogan Ilir, South Sumatra, 30862, Indonesia)
Alfan Wijaya (Research Centre of Inorganic Materials and Coordination Complexes, Graduate School of Universitas Sriwijaya, Palembang, South Sumatra, 30139, Indonesia)
Nur Ahmad (Research Centre of Inorganic Materials and Coordination Complexes, Graduate School of Universitas Sriwijaya, Palembang, South Sumatra, 30139, Indonesia)
Amri Amri (Research Centre of Inorganic Materials and Coordination Complexes, Graduate School of Universitas Sriwijaya, Palembang, South Sumatra, 30139, Indonesia)
Risfidian Mohadi (Magister Program of Materials Science, Graduate School of Universitas Sriwijaya, Palembang, South Sumatra, 30139, Indonesia)
Aldes Lesbani (Magister Program of Materials Science, Graduate School of Universitas Sriwijaya, Palembang, South Sumatra, 30139, Indonesia)

Science and Technology Indonesia
Vol. 8 No. 3 (2023): July

Hydrothermal carbonization is recognized as a method of processing biomass into carbon-rich products due to its energy-saving and environmental-friendly advantages. In this study, two types of hydrochar were prepared from Longan Fruit (Dimocarpus longan Lour.) Peel via hydrothermal carbonization at temperatures of 190°C and 250°C and activated using NaOH (HC-ACT 190 and HC-ACT 250) for removal of malachite green (MG) and rhodamine B (RhB) dyes. The maximum capacity for MG dye removal using HC-ACT 190 and HC-ACT 250 materials was 172.414 mg/g and 250 mg/g, while for RhB dye was 111.111 mg/g and 151.515 mg/g, respectively. The optimum pH was obtained at pH 6 for MG and pH 3 for RhB with adsorption equilibrium time occurring at 90 minutes. The kinetic study shows that the adsorption process follows pseudo-second-order kinetics, while the isotherm model was determined by the Langmuir isotherm model. Materials can be reused effectively for at least 3 cycles with an adsorption percentage of MG dye removal using HC-ACT 190 and HC-ACT 250 materials was 69.91% and 83.15% respectively, while for RhB dye was 35.79% and 55.6% respectively. The material is more selective on MG dye compared to RhB dye based on the selectivity test on the adsorption of the dye mixture.