Surface modified polythiophene nanocomposite using HPC and DBSNa for heavy metal ion removal

In the present work, surface modified nanocomposite adsorbents polythiophene (PTh)/rice husk ash (RHA) have successfully been synthesized in the presence of hydroxyl propyl cellulose (HPC) and sodium dodecyl benzene sulfonate (DBSNa) as surfactants. The synthesized nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR), and the synthesized nanocomposite adsorbents were applied as an efficient sorbent for Pb(II) ion removal from contaminated water and the removal efficiency was compared to pure PTh/RHA composite. Several variables affecting the extraction efficiency of the nanoadsorbent i.e., adsorbent dosage, metal ion concentration, extraction time, and adsorption conditions were investigated. The highest efficiency of adsorption (98.12%) was achieved with 0.05 g of PTh/RHA/HPC nanocomposite adsorbent in 50 mL of 10 mg/L Pb(II) solution. Equilibrium studies were also performed with known linear and non-linear adsorption isotherms including Langmuir, Freundlich and Sips from which the best result was achieved with Freundlich and Sips isotherms representing multilayer adsorption on heterogeneous structure of the adsorbent. The pseudo-first-order model and the pseudo-second-order model were adopted to analyze the adsorption kinetics of Pb(II) on PTh/RHA/HPC and PTh/RHA/DBSNa. The consistency of the experimental adsorption capacity with the ones calculated from the pseudo-second-order kinetic model illustrated that the adsorption of Pb(II) onto both adsorbents at initial concentration of 50 mg/L was probably controlled by chemical adsorption.