Preparation of Hydrochar from Salacca zalacca Peels by Hydrothermal Carbonization: Study of Adsorption on Congo Red Dyes and Regeneration Ability

Abstract

Hydrochar ofSalacca zalaccapeels (HC-SP) is prepared by hydrothermal carbonization treatment ofSalacca zalaccapeels (SP)obtained from local fruits at Palembang, South Sumatera, Indonesia, with the resulting yield weight reaching 90%. Materials arecharacterized using the XRD diffraction, FTIR spectrum, and SEM-EDX. The XRD pattern shows the characteristics of the formation ofamorphous compounds. The FTIR spectrum confirms the presence of functional groups O-H, C-H, C=C, and C-O. Data of SEM-EDXshow that materials have heterogeneous morphologies, form aggregates, and in HC-SP materials there is an increase in carboncontent from the initial material. The capacity of SP in the congo red (CR) adsorption process is 33.003 mg/g and increases to 133.333mg/g in HC-SP. The maximum dye adsorbed was achieved at pH 4. The adsorption kinetics followed PSO with the equilibriumadsorption occurring at 90 minutes, and the adsorption isotherm followed the Langmuir isotherm with the value of R2closer to thevalue of 1. A positive4H value indicated that the adsorption is an endothermic process. In contrast, an4S value suggested that thedegree of irregularity in the adsorption process is small in large concentrations. Based on data regeneration ability, materials of SPand HC-SP can be used in the three cycles regeneration process of the CR adsorption process. The adsorption process of CR occursphysically and chemically based on enthalpy values and FT-IR data after being adsorbed with CR.

Keywords

• hydrochar
• salacca zalaccapeels
• adsorption
• congo red
• regeneration