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Heavy metal adsorption on iron oxide and iron oxide-coated silica ...

Heavy metal adsorption on iron oxide and iron oxide-coated silica ...

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615.3 SummaryFrom the results of XRD analysis, Alfa Aesar <strong>and</strong> US <strong>silica</strong> have XRD patterns that aresimilar with the st<strong>and</strong>ard PDF of a-quartz. Based <strong>on</strong> XRF the purity was 100% for AlfaAesar <strong>silica</strong> <strong>and</strong> 98.759% for US <strong>silica</strong>. The modes of the size distributi<strong>on</strong>s revealed 220μm for Alfa Aesar <strong>silica</strong> <strong>and</strong> 900 μm for US <strong>silica</strong>. From ESEM micrographs, AlfaAesar <strong>and</strong> US <strong>silica</strong> show comparable surface roughness, both are potentially suitable forgoethite coating with respect to column works. Because a pH greater than 9 may changethe <strong>silica</strong> surface permanently <strong>and</strong> influence the surface charge determinati<strong>on</strong> further,titrati<strong>on</strong>s of <strong>silica</strong> were c<strong>on</strong>ducted with base in which the initial pH is low. The PZC ofUS <strong>silica</strong> is about 2.85 <strong>and</strong> is c<strong>on</strong>sistent with other studies.In the next chapter, characterizati<strong>on</strong> results <strong>on</strong> ir<strong>on</strong> <strong>oxide</strong>-<strong>coated</strong> <strong>silica</strong> arediscussed, where US <strong>silica</strong> is applied.

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