Removal of turbidity, cadmium (II) and lead (II) ions using zeolitic materials derived from rice husk and sugarcane bagasse
Njagi, Margaret Wambui Gicheru
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The Kenya's increasing population coupled with astronomical industrial expansion witnessed in the recent past is. a key concern on increased presence of heavy metals in water bodies. The . present work aimed at synthesizing zeolitic material from agricultural waste and determining their adsorption efficiency and capacity in removing cadmium and lead ions from wastewater. A hydrothermal reaction on ash mixtures of different ratio of sugarcane bagasse and rice husk ashes gave three zeolitic materials, Zeolitic Sample A (ZSA),Zeolitic Sample B( ZSB) and Zeolitic Sample C (ZSC). The materials biodegradable nature. The various ways of removal are precipitation, ion exchange, solvent extraction andadsorption Exploring ways of developing lowcost materials for use in remediation were confirmed as zeolitic materials by phase matches of their X-ray diffraction scattering patterns. Sorption studies on the materials were done using batch experiments where the effects of contact, time, initial concentration, dosage, temperature, pH, and turbidity of lead and cadmium ions were investigated. The data obtained from the sorption studies for all the three adsorbent materials were found to fit into Freundlich isotherm model based on their R2 values of greater than 0.98. For removal of lead ions from 100 mgIL solutions, the optimum conditions were found to be 0.2 g of ZSA, contact time of 120 minutes, temperature of 318 K and a pH 5; 0.2 g of ZSB, contact time of 60 minutes, 298 K, and pH 5 and 0.3 g of ZSC, contact time of 120 minutes, 328 K and a pH 7. For removal of cadmium ions from 100 mg/L solutions, the optimum conditions were found to be O.4g of ZSA, contact time of 60 minutes, temperature of 318 K and a pH 7, 0.3 g of ZSB, contact time of 120 minutes, temperature of 318 K, and a pH 9 and 0.2 g of ZSC contact time of 60 minutes, temperature of 318 K, and a pH 2. The adsorption capacity, (Kj) of the adsorbents for cadmium ions were 1.54, 17.78 and 8.85mglg for ZSA, ZSB and ZSC respectively and 3.99, 1.73 and 3.30mgl forlead ions. The results indicated that zeolitic material materials synthesized from agricultural waste are effective in adsorption of cadmium (II) and lead (II) ions from contaminated water. This shows that rice husk and bagasse waste can find use in production of adsorbents for use in water treatment.