Polypyrole, polyaniline and sodium alginate biocomposites and adsorption-desorption efficiency for imidacloprid insecticide.

In view of promising adsorption efficiency of biocomposites, the removal of imidacloprid was studied using biocomposites of polypyrole (PPY), polyaniline (PAN) and sodium alginate (Na-Alginate) with peanut husk (PH). The affecting variables such as pH, insecticide concentration, composite dose, contact time, temperature were optimized for efficient removal of imidacloprid. The biocomposites showed promising efficiency for the removal of imidacloprid. Among all composites polypyrole composite exhibited maximum efficiency at pH 3, 0.05 g adsorbent dose, 90 min contact time, 25 mg/L initial concentration at 35 °C. Langmuir, Freundlich, Harkins-Jura and Temkin isotherms models were applied on the experimental data. The best fitted were Langmuir and Freundlich isotherms with R2 value > 0.904 and >0.97, respectively. Insecticide adsorption followed the pseudo first order kinetics model. Thermodynamics (free energy, enthalpy and entropy) study revealed that the insecticide adsorption process on to biocomposites was spontaneous and exothermic in nature. This study revealed that the polypyrole, polyaniline and sodium alginate composites with peanut husk have promising adsorption potential and this class of adsorbent could be used for the remediation of wastewater contains imidacloprid insecticide.