The evaluation of kinetic adsorption process of sulfonated carbon-derived from Eichhornia crassipes in the adsorption of methylene blue dye from aqueous solution has been carried out. The sulfonated carbon-derived from E. crassipes (EGS-600) was prepared by carbonation of E. crassipes powder at 600 °C for 1 h, followed by sulfonation with concentrated sulfuric acid for 3 h. The physical properties of the adsorbents were characterized by using Fourier transform infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and nitrogen adsorption-desorption studies. Adsorption study using methylene blue dye was carried out by varying the contact time and initial dye concentration for investigated kinetics adsorption models. The effect of varying temperature was used to determine the thermodynamic parameter value of ΔG, ΔH, and ΔS. The results showed that the equilibrium adsorption capacity was 98% when EGS-600 is used as an adsorbent. The methylene blue dye adsorption onto adsorbent takes place spontaneity and follows a pseudo-second-order adsorption kinetic model.

The carbon-containing hydroxyapatite has been synthesized using the fish bone obtained from East Kalimantan, Indonesia. The synthesis was conducted at varying calcination temperature (300-700 °C) and duration time (1-5 h). The carbon-containing hydroxyapatite were characterized by using Nitrogen adsorption-desorption, Fourier transform infrared spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Thermogravimetric analysis (TGA) and Differential thermal analysis (DTA). The carbon-containing hydroxyapatite nanoparticles consisted of the mesoporous structure with a specific surface area of 159 m2.g-1 and pore size of 44 Å. The carbon-containing hydroxyapatite nanoparticles were utilized as the adsorbent for the removal of methylene blue by varying the contact time, initial dye concentration, pH, adsorbent dosage and temperature. The maximum amount of adsorption capacity was 56.49 mg.g-1. The adsorption was well fitted with the Langmuir adsorption model (R2 ~ 0.998) and the pseudo-second-order model. This indicated that the dye molecules were adsorbed on the surface-active site of carbon-containing hydroxyapatite via chemical binding, forming an adsorbate monolayer. Hence, the adsorption capability corresponds to the physical properties such as the surface area and pore volume of hydroxyapatite because the larger surface area consists of higher binding sites for the adsorption. Thermodynamic parameters, including the Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS), indicated that the adsorption of methylene blue onto the carbon-containing hydroxyapatite nanoparticles was spontaneous. Thus, carbon-containing hydroxyapatite nanoparticles can be applied as a low-cost adsorbent for the treatment of industrial effluents that are contaminated with the methylene blue. Copyright © 2019 BCREC Group. All rights reserved