Work

Green Recycling of Waste Tire Rubber Crumb: Characterization and Water Treatment Applications

Year: 2026

Type: article

Abstract: Discarded tires are adding to the waste problem that exists worldwide and requires proper recycling methods. Rather than employing chemicals or energy-intensive thermal treatments, which leads to an increase in environmental pollution, in this work, the discarded tires are subjected to mechanical grinding into a fine powder form, resulting in recycled Waste Tire Rubber Crumb (WTRC), then used as an adsorbent for the removal of methylene blue (MB) dye from the polluted water. The use of the adsorbent is eco-friendly and cost-effective, which is beneficial for water treatment. The structural, thermal, and morphological characteristics of WTRC were studied with the use of X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential analysis. It was found that there was an elastic polymer matrix with inorganic additions of ZnO and CaCO3. Zeta potential measurements provided the value −32.5 mV at pH 7.0, demonstrating electrostatic repulsion of the particles and providing solid colloidal stability in aqueous media. In batch tests, WTRC proved to be a good adsorbent of MB, with up to 92.7% removal efficiency within 30 min. under the basic medium (pH 11.0, 1.2 g/50 mL dosage, and initial MB concentration of 5 mg/L ppm). The Langmuir model gave the best fit, with R2 = 0.982, which is more than Freundlich model, R2 = 0.957. The good fit of the Langmuir model indicates that adsorption predominantly occurred as a monolayer on relatively homogeneous adsorption sites on the surface of WTRC. The theoretical monolayer capacity (qmax) is calculated as 0.95 mg/g. It is proved by the surface changes after the adsorption of MB, shown in FTIR and SEM pictures. In general, the raw WTRC can serve as a simple and economic adsorbent for dyes from industry.

Source: Polymers

DOI: 10.3390/polym18202492