Removal of Congo Red Dye from Aqueous Solutions using Steam Activated Pigmented Rice Husk Carbon as an Adsorbent: A Thermodynamic Study

Abstract

Dyes are very hazardous pollutant discharged in the environment in the effluents of textile industries during dyeing and rinsing processes causing detrimental effects on the workers. It is therefore fundamental to remove the dyes by using various techniques. In
the present paper adsorption technique was employed for removal of Congo red dye. Congo red dye is a carcinogenic dye, which comes in the effluents of textile industries during dyeing and rinsing processes. In the present work, thermodynamic study of adsorption of Congo red dye on to steam activated pigmented carbon prepared from rice husk (B.N. ORYZA SATIVA) was investigated The adsorbent was investigated under variable system parameters, such as temperature. The results of the present study have indicated the value of ΔH were in the range of = - 14.18 to -14.36 k J mol-1. This suggests the adsorption of Congo red dye on SAPRHC as an exothermic process. The (ΔS) values were in the range -47.77 to -53.91 Jmol-1K-1, which is attributed to the higher degree of ordering of the small number of the dye molecules on the solid phase compared to their ordering in the aqueous phase. The adsorbent–dye interactions are spontaneous in all the cases supported by decrease in Gibbs energy.The results obtained indicate a
potential use of SAPRHC for removing dyes like Congo red dye from water.