Preparation of Manganese-Iron Oxide Coated Rice Husk Ash Silica Xerogel for Removal of Heavy Metals in Wastewater
This research was to prepare low cost adsorbents that had significant potential for modification and enhancement of heavy metals adsorption capabilities. Silica from extraction of rice husk ash and coated with manganese and iron oxides was prepared. The adsorption capabilities of various ratios of coating Fe and Mn (Fe100, Fe80, Fe60, Fe40, Fe20 and Mn100) were investigated in Pb, Cd, Ni and Zn solutions by batch experiments. The results showed that in each heavy metal solution (40 mg/L), Fe20 and Mn100 coated silica showed the same high adsorption capability around 3.8-4.0 mg/g. The adsorption mechanism of both Pb and Cd on Mn100 coated silica was agreed with Langmuir and Freundlich. In addition, application of Mn100 coated silica for heavy metals treatment in 500 mL of the synthetic wastewater was conducted on jar test apparatus. The maximum removal efficiencies obtained were 99.87% Pb, 95.40% Cd, 95.90% Ni and 95.02% Zn at pH 7, agitation at 50 rpm/min for 15 min and 1 g of adsorbent. Therefore, this chemically modified silica had a high potential for removals of Pb, Cd, Ni and Zn in wastewater.
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