Biopolymers composites with peanut hull waste biomass and application for Crystal Violet adsorption

Composites of polyaniline, starch, polypyrrole, chitosan aniline and chitosan pyrrole using peanut waste were prepared and employed for the adsorption of Crystal Violet (CV) dye from aqueous media. The process variables i.e., composite doses, pH, contact time, CV initial concentration and temperature were optimized. Thermodynamic, equilibrium modelling and kinetics models were fitted to the CV adsorption data in order to understand the mechanism and nature of CV adsorption onto native and composite adsorbents. Maximum CV adsorption of 100.6mg/g was achieved (onto chitosan aniline composite) using 150mg/L dye initial concentration, 50°C temperature, 60min contact time, 0.05g adsorbent dose and>7pH. Effect of composites pre-treatments with salts, surfactants and co-metals ions were also studied. The CV adsorption efficiencies of adsorbents were found in following order; chitosan aniline composite>starch composite>chitosan pyrrole composite>polyaniline composite>polypyrrole composite>native peanut biomass. The pseudo-second-order kinetic model and Freundlich isotherm fitted well to the CV equilibrium adsorption data and intraparticle diffusion was the rate limiting step. Composites showed endothermic and energetically stable nature for CV adsorption. Composites also showed good desorption properties, which revealed the recycling ability of prepared composites.