Removal of Crystal Violet Dye by Adsorption onto Picrilima Nitida Stem Bark Powder: Kinetics and Isotherm Studies

Abstract

The removal of Crystal Violet (CV) dye with the powder of picrilima nitida stem bark (PNSBP) has been demonstrated based on adsorption parameters like contact time, initial dye concentration, adsorbent dose, pH, and temperature. The adsorbent was characterized by FTIR and SEM analysis. Equilibrium amount of CV dye adsorbed per unit mass of PNSBP adsorbent, qe (mg/g), occurred after 60 min. contact time. The q e values increased with increasing initial CV dye concentration from 25 mg/L to 125 mg/L, and with pH increasing from 2 to 10. However, the qe value continuously decreased as temperature increased from 30 o C to 70 o C and PNSBP adsorbent dosage from 0.5 g to 4 g. Based on values of correlation coefficient (R 2 ), the Freundlich isotherm was more appropriate in explaining the mechanism of the CV adsorption onto PNSB. Kinetic studies showed that the CV dye adsorption onto PNSB adsorbent followed the pseudo second order reaction kinetics. Thermodynamic quantities were evaluated and the negative G 0 values obtained indicated spontaneous adsorption process. The negative H 0 and S 0 values obtained indicate the exothermic nature and decrease in