Abstract:
The use of low-cost, locally available, highly efficient, and eco-friendly adsorbents has been investigated as an ideal alternative to the current expensive methods of removing dyes from waste water. This study investigates the potential use of 1 M HCl treated clay, 0.5 M HCl treated clay and untreated clay for the removal of Reactive Red 43 and Reactive Blue 49 dyes from simulated waste-water. The effect of pH, contact time, temperature, initial dye concentration and adsorbent dosage were investigated and optimal experimental conditions were ascertained. The maximum removal of Reactive Red dye was obtained at acidic pH of pH 3 for 1 M HCl treated clay, pH 2 for 0.5 M HCl treated and untreated clays with percentage removal of 85.33 %, 91.33 % and 91.33 % respectively while for Reactive Blue dye, the maximum removal was obtained at pH 2 for 1 M HCl and 0.5 M HCl treated clays, pH 3 for untreated clay with percentage removal of 91.36 %, 97.73 % and 97.27 % respectively for maximum adsorbent dose of 0.5 g of 25 ml at 100 mgl-1 initial dye concentration at room temperature. The results showed that as the amount of the adsorbents increased, the percentage of dye removal increased accordingly. The adsorption kinetics of dye removed was studied and the rate of adsorption was found to conform to pseudo-second-order kinetics with a good correlation (R2 > 0.99). The equilibrium data were analysed and fitted best to the Freundlich isotherm. The adsorption thermodynamics of the adsorbents were also studied and the results showed that ΔH0 and ΔS0 had negative values indicating an exothermic and non-sponstaneous reaction, while positive values of ΔG0 indicated the decrease in feasibility of the adsorption process. The FT-IR analysis was also carried out, the results indicates that both treated and untreated clays could be employed as a low-cost alternative for the removal of reactive dyes from wastewater since test analysis carried out on simulated dyeing wastewater showed better dye removal.
