SAWDUST-BASED ACTIVATED CARBON FOR MALACHITE GREEN REMOVAL:KINETIC AND THERMODYNAMIC STUDY

摘要

Sawdust as a lignocellulosic solid waste, has been valorized and used as an adsorbent for the removal of Malachite green (MG) from aqueous solution. Impregnation in 20% KOH (SDK), and (NH4)2S2O8 (SDP) solutions then pyrolysis at 600°C for 3 hours were found to enhance the adsorption capacity of malachite green (MG) as a pollutant significantly relative to its inactivated state (SDU). The batch adsorption experiments resulted in a maximum adsorption capacity determined from Langmuir models of up to 434.78 mg/g, 238.10 and 200.0 for SDK, SDP and Merck respectively. Parameters influencing adsorption capacity such as contact time, adsorbent dosage, pH and temperature were studied. FT-IR analyses and iodine number determination were also performed to characterize the prepared adsorbents. Adsorption kinetics was found to comply with the pseudo second order with a good correlation factor (R2 = 0.99) with intraparticle diffusion as the rate determining steps. Thermodynamic analysis and temperature effects of the process confirm that the adsorption reaction was spontaneous (ΔGo 0). This study showed that sawdust as a waste could prove to be a very useful in removing toxic substances from the environment.