Adsorption studies of a direct dye using polyaniline coated activated carbon prepared from Prosopis juliflora

An attempt was made to prepare an activated carbon from Prosopis juliflora seeds and it was coated in a polyaniline matrix. The prepared adsorbent has a BET surface area of 1028 m2/g. The adsorbent was analyzed for its ability to remove Direct Red 23 in its aqueous solution. Effect of pH proves that maximum uptake of DR23 by PPAC was obtained at pH 3.0. The adsorption of DR23 by PPAC follows pseudo second-order kinetics with a very high correlation coefficient of 0.9968 < r2 < 0.9996. The intra particle model proves that pore diffusion plays a major role for the adsorption DR23 on to PPAC. The Langmuir monolayer adsorption capacity (Q0) increases from 90.91 to 109.89 mg/g while increasing the temperature from 30 to 45 °C. Column model analysis was also carried out to evaluate the adsorbent performance for continuous operation. Thomas, Yoon–Nelson and Bohart–Adams mathematical models were applied to evaluate the column performance. YN model provides excellent fit with very high r2 (0.9844–0.9953) and low Sd (0.09–0.37).