Removal of Heavy Metals and Cationic Dye Simultaneously From Polluted Water by Polypyrrole/<scp>TiO₂</scp> Nanocomposite

ABSTRACT In the present study for simultaneous removal of both the contaminations from the water, Polypyrrole (PPY), TiO 2 nanoparticles, and PPY/TiO 2 composite have been synthesized by oxidative polymerization, sol–gel method, and in situ polymerization, respectively. X‐ray diffraction and FTIR results showed the formation of a PPY/TiO 2 composite. A significant decrease in the energy band gap is found in the PPY/TiO 2 composite compared to TiO 2 from 3.82 eV to 1.75 eV. The decrement in band gap resulted in the maximum photodegradation of crystal violet dye in 20 min being 99.6%, which is higher than the degradation rate of individual PPY (74.2%) and TiO 2 (83.8%) in 100 min. PPY demonstrated adsorption efficiencies of 76% for Pb(II) and 72.6% for Cd(II); TiO 2 exhibited 99.8% for Pb(II) and 0.2% for Cd(II) in 100 min, while in only 40 min, the PPY/TiO 2 composite has shown 94.1% and 97.2% adsorption efficiencies for Pb(II) and Cd(II) respectively. The optimum concentration and pH for PPY/TiO 2 in the solution are 1 g/L and 7, respectively. The kinetic study revealed that the adsorption of heavy metals and photodegradation of dye both followed the Pseudo‐second‐order kinetic model emphasizing the chemisorption nature of adsorption.