This work reveals a modified method for the preparation of activated carbon (P-ACA) using low-cost materials (mix natural asphalt: polypropylene waste). The P-ACA was prepared at 600 °C by assisting KOH and HF. The morphological variations and chemical species of the P-ACA were characterized using SEM–EDX and FTIR. The active surface area, density and ash content of the P-ACA were also investigated. Adsorption properties of P-ACA were used for the thermodynamic and kinetic study of 4-((2-hydroxy naphthalenyl) diazenyl) antipyrine (HNDA), which was prepared as a novel azo dye in this work. The optimal conditions (initial concentration, adsorbent dose, contact time and temperature) of the adsorption process were determined. Adsorption isotherms (Freundlich and Langmuir) were applied to the experimental data. These isothermal constants were used to describe the nature of the adsorption system, and the type of interaction between the dye and the P-ACA surface. The results have indicated that the mixture (Natural asphalt-polypropylene waste) is efficient for the synthesis of P-ACA. The synthesized P-ACA demonstrates the presence of pores on the surface with various diameter ranges (from 1.4 to 4.5 μm). Furthermore, P-ACA exhibits an active surface area of 1230 m2 g−1, and shows a high adsorption capacity for HNDA.

The study aims to use asphaltene particles (As) extracted from natural bitumen to synthesize activated carbon (ACAs). The asphaltene particles were mixed with a fixed weight of potassium hydroxide (KOH) as an activating agent, preheated to 600 °C, and then treated with 15% hydrofluoric acid (HF). The methylene blue (MB) 20 mg/l was used to determine the adsorption capacity of ACAs and reactivated carbon (RACAs). The morphology of ACAs and its components were characterized using scanning electron microscopy–energy dispersive X-ray (SEM–EDX) and Fourier-transform infrared spectroscopy (FTIR). The study included the application of adsorption isotherms Freundlich and Langmuir on the experimental data of the studied systems. The yield of ACAs was 92% of the raw material. The activated carbon displayed high adsorption capacity and can be reprocessed after reactivation using microwave radiation. The active surface area of ACAs is found to be 970 m2/g. The effectiveness and adsorption ability of ACAs and RACAs, as proven by its adsorption capacity (218.15 and 217.907 mg/g) for MB, demonstrate that ACAs and RACAs have a large external surface area and an extensive array of pores. The ACAs are most sensitive at 30 °C and neutral pH. The results also showed that the isotherms have a good fit to the experimented data.