Characterization of Spent Bleaching Earth as an Adsorbent Material for Dye Removal

Initial research has been carried out to determine the potential of SBE as an adsorbent material through chemical and surface area characterization. Several analyses were performed, including oil content, BET, SEM-EDS, XRD, FTIR, and adsorption capacity. The oil content of the SBE samples were 0.05–0.09%, well below the standard (3%) of hazardous material classification according to the Indonesian government regulation. The chemical composition of SBE, measured by EDS, was dominated by Si and Al elements. XRD analysis revealed two 2-theta diffraction peaks indicated the presence of crystalline SiO2 and Al₂O₃ phases. Additionally, the results of the FTIR test also showed the dominance of Si-O and Al-O-H functional groups. The SBE morphology, as observed in SEM image, exhibited irregular shape and porous surface covered by impurities. These results supported by the BET data which showed SBE surface area of 10.86 m²g^-1 and a mesopore volume of 2.49 cm3(STP)g-1. Batch adsorption study conducted using low and high range concentration of methylene blue produced a maximum adsorption capacity of 7.993 mg/g and 40.485 mg/g, respectively. The adsorption isotherm analysis showed that the adsorption mechanism was in accordance with the Langmuir isotherm model. Considering its chemical characteristic, SBE has met the criteria for adsorbent material. Nevertheless, the small surface area requires SBE to be activated prior to use.