Abstract:
This study explored the fabrication of Polypyrrole (PPy) and Granular
Activated Carbon (GAC) composites (PPy-GAC) for effective removal of toxic
hexavalent chromium (Cr(VI)) from aqueous solutions. Two synthesis
methods are employed: (1) electrostatic deposition of PPy onto pre-charged
GAC paper and (2) in-situ chemical polymerization of pyrrole monomer with
GAC particles. Batch adsorption experiments investigated the impact of
various operational parameters on Cr(VI) removal. Compared to pristine GAC
(54.64 mg g−1), the PPy-GAC composite exhibited a remarkable 3-fold
increase in equilibrium adsorption capacity, reaching 175.44 mg g−1.
Pseudo-second-order kinetic model (R2 > 0.999) accurately described the
adsorption kinetics, while the Langmuir isotherm model (R2 > 0.99) provided
a good fit for the equilibrium data. Maximum adsorption capacity (qmax)
increased with temperature, reaching 204.08, 243.90, and 270.27 mg g−1 at
298, 308, and 318 K, respectively. Furthermore, a fixed-bed column
experiment examined the composite’s effectiveness in continuous Cr(VI)
removal, demonstrating its suitability for practical applications. Notably, the
PPy-GAC composite successfully removed Cr(VI) from a real wastewater
sample containing 68 μg L−1 Cr(VI) obtained from a ferrochrome industry,
highlighting its potential for real-world remediation.
