Capacity And Efficiency Of Bagasse Adsorbents At Different Experimental Conditions For De-contamination Of Spiked Water

Bagasse, a fibrous residue from Sugar mills, is not easily biodegradable posing disposal challenges. Given its abundance in the sugar producing regions of Kenya, there is continued need to find other alternative uses. The objective of this study was to investigate the potential use of sugarcane bagasse-based adsorbents for removing Cd2+, Pb2+, methylene blue and turbidity from water spiked with the contaminants. Four bagasse-based adsorbents were prepared and used in batch experiments. Sugarcane bagasse activated charcoal was obtained by carbonizing bagasse at 800oC in low oxygen followed by activation by phosphoric acid. Non-activated bagasse was obtained by grinding dried bagasse while activated bagasse was prepared by soaking ground dried bagasse in 1M NaOH for 18 hours. Bagasse ash was obtained through burning bagasse at 600oC. The percentage removal of the contaminants by the prepared adsorbents under different conditions of temperature, pH, contact times, initial concentration, adsorbent dose and agitation speeds were determined by batch experiments and found to be dependent on the prevailing physical conditions under investigation. Adsorption data obtained was fitted against Freundlich and Langmuir isotherm models. It was found that  the adsorption data for Pb2+on ash, non-activated bagasse, activated bagasse and activated charcoal best fitted Freundlich isotherm model with R2 values of 0.736, 0.958, 0.978 and 0.951, respectively with adsorption capacities of 62.7±0.01, 6.6±0.09, 18.4±0.01 and 3.7±0.01 mg/g in the same order. Ash was the best in removal of Pb2+ with capacity of 62.7±0.01 mg/g. Adsorption data for Cd2+ on ash, non-activated bagasse, activated bagasse and activated charcoal best fitted Langmuir isotherm model with R2 values of 0.914, 0.995, 0.975 and 0.989, respectively and adsorption capacities of 40.9±0.1, 43.9±0.01, 52.9±0.01 and 45.4±0.03 mg/g in that order. Activated bagasse was the best in removal of Cd2+ with capacity of 52.9±0.01 mg/g. The data on methylene blue removal by ash and non activated bagasse best fitted Freundlich model with R2 values of 0.975 and 0.973 and capacities of 71.4±0.01 and 50.0±0.01 mg/g respectively. Data on methylene blue removal by activated charcoal and activated bagasse fitted Langmuir model with R2 values of 0.979 and 0.980 and capacities of 45.5±0.03 and 200.0±0.05 mg/g respectively.