Abstract:
This research aims to develop 3-composite bead adsorbents from waste gelatin (GE), activated carbon (AC-Powders), and bentonite (BE-Powders) for methylene blue adsorption. The AC-Powders were synthesized from spent coffee grounds via carbonization at 400°C for 2 h followed by chemical activation using KOH and calcination at 600°C for 3 h under a nitrogen atmosphere. Various properties of the adsorbents were determined using N2 physisorption, Field emission scanning electron microscope (FESEM), Energy dispersive xray spectrometer (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermal gravimetric analysis (TGA), Zeta Potential, and swelling measurement. The effect of contact time, initial concentration, adsorbent dosage, and pH were investigated. It was found that the adsorption capacity of only GE-Beads was 44.66 mg/g after 24 h using an amount of adsorbent of 0.05 g, a pH of 5.7, and a methylene blue initial concentration of 500 mg/L. Additions of AC-Powders and BE-Powders could further improve the adsorption capacities significantly to attain the maximum values of 77.28, 78.71, 81.29, 87.01, 104.75, 111.90, and 132.79 mg/g for GE/100AC-Beads, GE/90AC-10BE-Beads, GE/70AC-30BE-Beads, GE/50AC50BE-Beads, GE/30AC-70BE-Beads, GE/10AC-90BE-Beads, and GE/100BE-Beads, respectively. In addition, the adsorption of methylene blue on these adsorbents could be well explained with the pseudo-second-order adsorption kinetics and Langmuir model. The adsorption capacities of 68.28 and 73.56 mg/g for GE/10AC-90BE-Beads and GE/100BE-Beads, respectively, were observed after repeated use in the 4th cycle.