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

- Various composites were prepared using biological moieties and peanut hull waste biomass.
- Composites have been used for crystal violet dye adsorption.
- Composites showed promising efficiency for CV adsorption versus native biomass.
- Composites showed stability at high temperature.
- The prepared composites are potential candidate for preparation of new class of adsorbents.

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 100.6 mg/g was achieved (onto chitosan aniline composite) using 150 mg/L dye initial concentration, 50 °C temperature, 60 min contact time, 0.05 g adsorbent dose and > 7 pH. 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.