Abstract
The present study deals with the removal of Cr (VI) from aqueous solution by polypyrrole (PPy). Response surface methodology
(RSM) was applied for the design and analysis of experiments in the optimization of pH, temperature, initial concentration,
contact time and adsorbent dose during the removal of the Cr (VI). The optimum adsorbent dose, temperature, initial
concentration of Cr (VI), pH and contact time were found to be 0.8 g, 46.5 oC, 187.5 mg/L, 5.3 and 15.4 min respectively. Under
optimal values of process parameters, high removal efficiency (>90%) was obtained for Cr (VI). Analysis of variance (ANOVA)
of central composite design showed a high coefficient of determination value (R2 = 0.96) and satisfactory prediction second-order
regression model was derived. Maximum chromium removal efficiency was predicted and experimentally validated. The
Langmuir, Freundlich and Dubinin–Radushkevick isotherms are subjected to sorption data to estimate sorption capacity. The
results gained from this study were well described by the theoretical Freundlich. Three equations, i.e. Morris–Weber, Lagergren
and pseudo - second order have been tested to track the kinetics of adsorption process. The results gained from this study were
well described by the theoretical pseudo - second order. The removal of Cr (VI) by PPy was also investigated in a fixed bed
column. Experiments were conducted to study the effect of important parameters such as bed depth (5–20 cm), flow rate (5–15
ml min−1) and initial concentration (50-300 mg/L). Also the PPy was used for the Cr (VI) removal from industrial wastewater and
showed a high potential for the wastewater treatment.