Study on the adsorption of different types of phenolic dyes using raw sugarcane bagasse as biosorbent

Coloured textile wastewater is one of the main contributions to water pollution. This wastewater is not properly managed before being discharged and thus affect to the environment. Adsorption is one of the important strategies to remove coloured wastewater. This study highlighted the use of more economical adsorbent, untreated sugarcane bagasse to remove the batik textile dyes, bromocresol green (BCG), bromophenol blue (BPB) and reactive red 120 (RR120). The biosorbent was selected due to its high content of cellulosic materials, microporous structure, wide surface area and surface acidity. The dye removal efficiency was evaluated by a few adsorption parameters such as contact time (1, 3, 5, 10, 15, 30, 45 and 60 minute), pH (1-6), initial dye concentration (5-25 mg/L), particle sizes (125-500 μm) and biosorbent dosage (0.01-0.2 g). The biosorbent was analysed and characterized by Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The result shows that dyes removal process needed 15 minutes of contact time and operated in optimum conditions (pH 1, 5 mg/L dye concentration, ≤125 μm of particle size and 0.1-0.15 g biosorbent dosage) to adsorb 96.68%, 98.73% and 94.44% of BCG, BPB and RR120, respectively. The kinetic data showed pseudo-second order kinetic model most fitted for the BCG, BPB and RR120 adsorption with the R2 were 1, 0.9996 and 0.9976 respectively. Adsorption isotherms were tested with Langmuir and Freundlich isotherms. Langmuir isotherm was indicated as the best isotherm that fitted BCG while Freundlich isotherm fitted better for BPB and RR120 as the R2 obtained were 0.9808, 0.9942 and 0.9832 for BCG, BPB and RR120, respectively. The adsorption capacity of dyes on sugarcane bagasse increased in the order RR120<BCG<BPB which were 2.84, 17.08 and 38.48 mg/g respectively. Sugarcane bagasse is highly recommended as an effective biosorbent for dye adsorption.