Adsorption of dyes onto candle soot: Equilibrium, kinetics and thermodynamics

Candle soot was collected and successfully applied as an adsorbent for the removal of two basic dyes (methylene blue and rhodamine B). A batch study of adsorption experiments was done and the effects of parameters like time of contact, adsorbent and adsorbate dosage, temperature and pH of solution were studied. The optimum soot quantity for both dyes removal was found to be 0.2g/30 ml. The time taken to reach the quasi-equilibrium was 150 minutes. The effective pH for removal of methylene blue and rhodamine B was 12 and 6, respectively. A thermodynamic study suggests that the adsorption process for both dyes is spontaneous. A kinetic study suggests that both pseudo first- and second-order equations best fit adsorption kinetic data and the Langmuir isotherm fits best equilibrium data. Ethanol was used as the desorption media for desorption of rhodamine B from candle soot. The adsorbent was also found recyclable up to certain cycles.