Utilization of Petroleum Sludge Waste as an Al-Fe Oxide/C Catalyst and Its Characterization
Department of Chemistry, Faculty of Mathematics and Natural Science, Universitas Sriwijaya, Jl. Palembang-Prabumulih Km. 35., 30662 Indralaya, Sumatra Selatan, Indonesia
Abstract
This research addresses the utilization of petroleum oil sludge, which is classified as hazardous and toxic waste (B3), into an Al-Fe/C oxide adsorbent through sulfuric acid (H2SO4) activation using the hydrothermal method. The adsorbent leverages the significant content of C (51.7%), Al (1.6%), and Fe (10.8%) present in the waste. The primary goal is to synthesize the Al-Fe/C oxide into an effective adsorbent for the removal of methylene blue (MB) and eriochrome black T (EBT) dyes. Morphological and metal component characterization was performed using Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDX), while the Bronsted and Lewis acid sites were analyzed using Fourier-Transform Infrared Spectroscopy (FTIR). The adsorbents performance was evaluated by determining the optimum conditions for pH, contact time, and dye concentration, and then analyzed using adsorption isotherm and kinetic models. The initial oil sludge powder exhibited surface acidity of 0.646 mmol/g, internal acidity of 4.9878 mmol/g, and total acidity of 5.6338 mmol/g. The optimum conditions for the Al-Fe/C oxide adsorbent in adsorbing MB were found at pH 7 with a contact time of 20 minutes and a dye concentration of 90 mg/L. For EBT, the optimum conditions were at pH 3 with a contact time of 180 minutes and a dye concentration of 70 mg/L. The adsorption kinetics for both dyes followed the pseudo-second-order model, with rate constants of 0.0712 g/mg.min (MB) and 0.0028 g/mg.min (EBT). The adsorption isotherm for MB fit the Freundlich model (R2= 0.9491), while EBT followed the Langmuir model (R2= 0.9325). These results indicate that the Al-Fe/C oxide hydrothermally synthesized from oil sludge is effective and potentially useful as a functional adsorbent for dye wastewater treatment.
