Application of natural and modified sugar cane bagasse for the removal of dye from aqueous solution

In the present study waste product of sugar mill (bagasse) was used as low-cost adsorbent in its natural, and modified forms for the removal of malachite green (MG) dye. Chemical treatment of sugar cane bagasse (SB) was carried out with formaldehyde and sulfuric acid which produced carbonaceous bagasse (C-SB). The sugar cane bagasse (SB), carbonaceous bagasse (C-SB) and fly ash bagasse (FA-SB) were tested as adsorbents for the removal of malachite green (MG) dye from aqueous solutions. The removal of dye was carried out by the adsorption process under the optimized conditions of concentration of dye, amount of adsorbent, temperature and contact time. The spectrophotometric technique was adopted for the estimation of concentration of dye before and after the adsorption. The equilibrium data were applied on Langmuir, Freundlich and Dubinin-Radushkevich isotherm models and the values of their corresponding constants were evaluated from the slopes and intercepts of their respective plots. The isotherm data can be best described by the Langmuir equation in the concentration range of 1 × 10−5-1 × 10−4 M. From the results it was observed that C-SB shows better adsorption capacity as compared to other adsorbents due to increase in the surface area of adsorbent by the chemical treatment.Thermodynamic parameters ΔG°, ΔH° and ΔS° were also evaluated. The values of ΔG° show spontaneous behavior of the system. The modified bagasse C-SB shows about 89% removal, due to the formation of new modified surface and enhancement in its surface area. It could be employed as a low-cost alternative method for the removal of dyes and purification of textile effluents.