Silicate Removal in Aluminum Hydroxide Co-Precipitation Process
The removal mechanisms of silicate using an aluminum hydroxide co-precipitation process was investigated and compared with an adsorption process, in order to establish an effective and validated method for silicate removal from wastewater. Adsorption isotherms, XRD and FT-IR analyses showed that si...
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doaj-9e23bfbf804b483cb7567e61846ba7f22020-11-24T23:55:23ZengMDPI AGMaterials1996-19442014-02-01721084109610.3390/ma7021084ma7021084Silicate Removal in Aluminum Hydroxide Co-Precipitation ProcessChiharu Tokoro0Shinya Suzuki1Daisuke Haraguchi2Sayaka Izawa3Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, JapanGraduate School of Creative Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, JapanGraduate School of Creative Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, JapanGraduate School of Creative Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, JapanThe removal mechanisms of silicate using an aluminum hydroxide co-precipitation process was investigated and compared with an adsorption process, in order to establish an effective and validated method for silicate removal from wastewater. Adsorption isotherms, XRD and FT-IR analyses showed that silicate uptake occurred by adsorption to boehmite for initial Si/Al molar ratios smaller than two, but by precipitation of poorly crystalline kaolinite for the ratios larger than two, in both co-precipitation and adsorption processes. Silicate was removed by two steps: (i) an initial rapid uptake in a few seconds; and (ii) a slow uptake over several hours in both processes. The uptake rate in the first step was higher in the co-precipitation process than in adsorption process, presumably due to increased silicate adsorption to boehmite and rapid precipitation of kaolinite. These results suggest that silicate removal using aluminum salts could be effectively achieved if the pH adjustment and aluminum concentration are strictly controlled.http://www.mdpi.com/1996-1944/7/2/1084co-precipitationadsorptionaluminum hydroxideboehmitekaolinitesorption density |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Chiharu Tokoro Shinya Suzuki Daisuke Haraguchi Sayaka Izawa |
spellingShingle |
Chiharu Tokoro Shinya Suzuki Daisuke Haraguchi Sayaka Izawa Silicate Removal in Aluminum Hydroxide Co-Precipitation Process Materials co-precipitation adsorption aluminum hydroxide boehmite kaolinite sorption density |
author_facet |
Chiharu Tokoro Shinya Suzuki Daisuke Haraguchi Sayaka Izawa |
author_sort |
Chiharu Tokoro |
title |
Silicate Removal in Aluminum Hydroxide Co-Precipitation Process |
title_short |
Silicate Removal in Aluminum Hydroxide Co-Precipitation Process |
title_full |
Silicate Removal in Aluminum Hydroxide Co-Precipitation Process |
title_fullStr |
Silicate Removal in Aluminum Hydroxide Co-Precipitation Process |
title_full_unstemmed |
Silicate Removal in Aluminum Hydroxide Co-Precipitation Process |
title_sort |
silicate removal in aluminum hydroxide co-precipitation process |
publisher |
MDPI AG |
series |
Materials |
issn |
1996-1944 |
publishDate |
2014-02-01 |
description |
The removal mechanisms of silicate using an aluminum hydroxide co-precipitation process was investigated and compared with an adsorption process, in order to establish an effective and validated method for silicate removal from wastewater. Adsorption isotherms, XRD and FT-IR analyses showed that silicate uptake occurred by adsorption to boehmite for initial Si/Al molar ratios smaller than two, but by precipitation of poorly crystalline kaolinite for the ratios larger than two, in both co-precipitation and adsorption processes. Silicate was removed by two steps: (i) an initial rapid uptake in a few seconds; and (ii) a slow uptake over several hours in both processes. The uptake rate in the first step was higher in the co-precipitation process than in adsorption process, presumably due to increased silicate adsorption to boehmite and rapid precipitation of kaolinite. These results suggest that silicate removal using aluminum salts could be effectively achieved if the pH adjustment and aluminum concentration are strictly controlled. |
topic |
co-precipitation adsorption aluminum hydroxide boehmite kaolinite sorption density |
url |
http://www.mdpi.com/1996-1944/7/2/1084 |
work_keys_str_mv |
AT chiharutokoro silicateremovalinaluminumhydroxidecoprecipitationprocess AT shinyasuzuki silicateremovalinaluminumhydroxidecoprecipitationprocess AT daisukeharaguchi silicateremovalinaluminumhydroxidecoprecipitationprocess AT sayakaizawa silicateremovalinaluminumhydroxidecoprecipitationprocess |
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1725462784146145280 |