Adsorption of acid and basic dye from the simulated wastewater using carbonized microplastic particles synthesized from recycled polyethylene terephthalate plastic waste bottles: an integrated approach for experimental and practical applications

Abstract

Abstract This study emphasizes the possible utilization of carbonized microplastic particles (CMPs) prepared from polyethylene terephthalate (PET) plastic bottle waste for dye adsorption. Methylene blue (MB) and methyl orange (MO) are adsorbed in a batch experiment to determine the effects of various experimental factors, including contact time (1–210 min), solution pH (3–11), adsorbent dosage (1–20 g/L), temperature (25–600 °C), and initial dye concentration (5–70 mg/L). The variance analysis (ANOVA) results of response surface methodology (RSM) indicated that the second-order model was statistically significant and had a high coefficient value (R2 = 0.99 for MO and R2 = 0.92 for MB). The RSM results stated that solution pH and adsorbent dose significantly influence MO and MB dyes removal, where the maximum adsorption removal was 99.95 and 99.04% for MO and MB dye at high acidic (pH 3) and alkaline (pH 11) conditions, respectively, with high adsorbent doses. Furthermore, trained neural networks demonstrated a strong correlation between the experimental and projected colour removal efficiencies. The adsorption data for MO and MB were well explained by pseudo-second-order kinetics and Langmuir isotherm models. A thermodynamic study shows that dyes adsorptions are favourable, exothermic, and spontaneous. Finally, real wastewater and desorption studies indicate the effectiveness and environmentally friendly properties of CMPs.