Adsorption and desorption studies on hazardous dye Naphthol Yellow S

In the present study, the batch technique was adopted under a variety of conditions, viz., amount of adsorbent, contact time, concentration, temperature and pH. By using UV spectrophotometer, concentration of dye was measured before and after adsorption. Dye removal data were fitted into the Langmuir and Freundlich adsorption isotherm equations. The values of their corresponding constants were determined. Thermodynamic parameters like free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) of the systems were calculated by using Langmuir constant. The estimated values for (ΔG) were -8.027×10³ and -28.46×10³kJmol^-1 over activated carbon and activated de-oiled mustard at 303K (30°C), indicate toward a spontaneous process. The adsorption process followed pseudo-first-order model. The values of % removal and k_ad for dye systems were calculated at different temperatures ranging (303-323K). Desorption studies indicate that elution by dilute NaOH through the fixed bed of the adsorbents columns could be regenerated and a quantitative recovery of Naphthol Yellow S can be achieved.