Adsorption of Congo Red Dye from Aqueous Solution Using Agricultural Waste

Abstract

The potential of Breadfruit seed shell powder, for the removal of congo red (CR) dye from aqueous solution was investigated. The adsorbent was characterized by FTIR and SEM analysis. Batch adsorption studies were conducted and various parameters such as contact time, adsorbent dosage, initial dye concentration, pH and temperature were studied to observe their effects in the dye adsorption process. The optimum conditions for the adsorption of CR onto the adsorbent (BFSSP) was found to be: contact time (60mins), pH (2.0) and temperature (303K) for an initial CR dye concentration of 500mg/L and adsorbent dose 1.0g. The experimental equilibrium adsorption data fitted best and well to the Freundlich isotherm model. The maximum adsorption capacity was found to be 16.00mg/g. The kinetic data conformed to the pseudo-second-order kinetic model, suggesting that the rate limiting step may be chemisorptions. Thermodynamic quantities such as Gibbs free energy (G 0), enthalpy (H 0) and entropy (S 0) were evaluated. The negative values of G 0 and the negative value of H 0 obtained indicated the spontaneous and exothermic nature of the adsorption process while the negative S 0 value obtained indicated decreased randomness during the adsorption process.