Improved Adsorption of Organic Dyes onto a Polypyrrole/Tannic Acid Nanocomposite

Methyl orange (MO) and methylene blue (MB) dyes are toxic and carcinogenic; thus, their presence in water bodies has been a major concern. Designing an efficient adsorbent for removal of these dyes is a scientific challenge for researchers. In this work, a polypyrrole–tannic acid nanocomposite was prepared via a chemical oxidation method and used as a novel adsorbent for removing these toxic dyes. The synthesized nanocomposite was characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Brunauer–Emmett–Teller methods. The effect of different parameters on adsorption such as adsorbent doses, temperature, pH, initial dye concentration, and contact time was studied. The adsorption was in line with pseudo-second-order kinetics and the Langmuir isotherm model. ΔG°, ΔH°, and ΔS° were calculated to ascertain the feasibility of adsorption. The maximum adsorption capacities attained for this adsorbent were found to be 204.08 mg/g toward the MO dye and 217.39 mg/g toward the MB dye.