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Synthesis of Zeolites Na-P1 from South African Coal Fly Ash: Effect of Impeller Design and Agitation
Department of Chemical Engineering, Cape Peninsula University of Technology, P.O Box 652, Cape Town 8000, South Africa
Environmental and Nano Sciences Research Group, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa
* Author to whom correspondence should be addressed.
Received: 16 March 2013; in revised form: 15 April 2013 / Accepted: 26 April 2013 / Published: 16 May 2013
Abstract: South African fly ash has been shown to be a useful feedstock for the synthesis of some zeolites. The present study focuses on the effect of impeller design and agitation rates on the synthesis of zeolite Na-P1 which are critical to the commercialization of this product. The effects of three impeller designs (4-flat blade, Anchor and Archimedes screw impellers) and three agitation speeds (150, 200 and 300 rpm) were investigated using a modified previously reported synthesis conditions; 48 hours of ageing at 47 °C and static hydrothermal treatment at 140 °C for 48 hours. The experimental results demonstrated that the phase purity of zeolite Na-P1 was strongly affected by the agitation rate and the type of impeller used during the ageing step of the synthesis process. Although zeolite Na-P1 was synthesized with a space time yield (STY) of 15 ± 0.4 kg d−1m−3and a product yield of 0.98±0.05 g zeolites/g fly ash for each impeller at different agitation speeds, zeolite formation was assessed to be fairly unsuccessful in some cases due the occurrence of undissolved mullite and/or the formation of impurities such as hydroxysodalite with the zeolitic product. This study also showed that a high crystalline zeolite Na-P1 can be synthesized from South African coal fly ash using a 4-flat blade impeller at an agitation rate of 200 rpm during the ageing step at 47 °C for 48 hours followed by static hydrothermal treatment at 140 °C for 48 hours.
Keywords: fly ash; zeolites; impeller design; agitation; zeolites Na-P1
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MDPI and ACS Style
Mainganye, D.; Ojumu, T.V.; Petrik, L. Synthesis of Zeolites Na-P1 from South African Coal Fly Ash: Effect of Impeller Design and Agitation. Materials 2013, 6, 2074-2089.
Mainganye D, Ojumu TV, Petrik L. Synthesis of Zeolites Na-P1 from South African Coal Fly Ash: Effect of Impeller Design and Agitation. Materials. 2013; 6(5):2074-2089.
Mainganye, Dakalo; Ojumu, Tunde V.; Petrik, Leslie. 2013. "Synthesis of Zeolites Na-P1 from South African Coal Fly Ash: Effect of Impeller Design and Agitation." Materials 6, no. 5: 2074-2089.