Materials 2013, 6(5), 2074-2089; doi:10.3390/ma6052074
Article

Synthesis of Zeolites Na-P1 from South African Coal Fly Ash: Effect of Impeller Design and Agitation

1 Department of Chemical Engineering, Cape Peninsula University of Technology, P.O Box 652, Cape Town 8000, South Africa 2 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
(This article belongs to the Section Porous Materials)
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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.

AMA Style

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.

Chicago/Turabian Style

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.

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