Continuous Flow Synthesis of Zeolite-A from Coal Fly Ash Utilizing Microwave Irradiation with Recycled Liquid Stream

Salman Bukhari,Sohrab Rohani

doi:10.3844/ajessp.2017.233.244

Salman Bukhari, Sohrab Rohani

Open Access

https://doi.org/10.3844/ajessp.2017.233.244

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Abstract

Coal Fly Ash (CFA) was converted to zeolite using continuous microwave reactors while minimizing the wastewater produced during the zeolitization process. At bench scale, a continuous flow tubular microwave reactor was used to explore the effect of microwave irradiation on the crystallinity of the product. The waste water was reused in consecutive runs and Inductively Coupled Plasma (ICP) analysis was conducted during and after each run to observe the concentration of the cations. An increase in the production of hydroxysodalite compared to zeolite-A was noted at higher levels of microwave energy. The XRD and SEM analyses were also conducted to corroborate the results. The Cation Exchange Capacity (CEC) measurement showed the highest value of 0.405 meq/g when Deionized (DI) water was used, the CEC dropped to 0.177 meq/g for thrice recycled waste stream. It was also found that higher microwave irradiation resulted in faster crystal growth and the product crystallinity reached its maximum at 810 W of microwave irradiation in 60 min while 335 W of microwave irradiation resulted in the same crystallinity after 120 min of reaction.

Highlights

Despite public and private investments and advances in renewable energies, coal remains the leading source of electricity generation in the world
It was found that higher microwave irradiation resulted in faster crystal growth and the product crystallinity reached its maximum at 810 W of microwave irradiation in 60 min while 335 W of microwave irradiation resulted in the same crystallinity after 120 min of reaction
About 40% of the global electricity is produced by coal and it is predicted to account for 33% by 2035 according to International Energy Agency (IEA, 2013) Even with this reduced share, coal will stay a major source of electricity production around the world

Summary

Introduction

Despite public and private investments and advances in renewable energies, coal remains the leading source of electricity generation in the world. About 40% of the global electricity is produced by coal and it is predicted to account for 33% by 2035 according to International Energy Agency (IEA, 2013) Even with this reduced share, coal will stay a major source of electricity production around the world. There has been much research conducted on producing value added products such as zeolites (Bukhari et al, 2015a) from the accumulated CFA. Pioneering studies in zeolitization of CFA was reported using conventional heating (Holler and Wirsching, 1985; Shigemoto et al, 1993; Hollman et al, 1999), recently many researchers have focused their efforts on utilizing novel energy sources such as Microwave (MW) (Behin et al, 2014; Bukhari et al, 2014; Querol et al, 1997) and ultrasound (Bukhari et al, 2016; Belviso et al, 2011; Wang and Zhu, 2005; Musyoka et al, 2011a)

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