Coal combustion product in the form of fly ash has been sieved and successfully utilised as a main substrate and a carrier of silicon and aluminium in a set of hydrothermal syntheses of zeolites. The final product was abundant in zeolite X phase (Faujasite framework). Raw fly ash as well as its derivatives, after being sieved (fractions: ≤ 63, 63–125, 125–180 and ≥ 180 µm), and the obtained zeolite materials were subjected to mineralogical characterisation using powder X-ray diffraction, energy-dispersive X-ray fluorescence, laser diffraction-based particle size analysis and scanning electron microscopy. The influence of fraction separation on the zeolitization process under hydrothermal synthesis was investigated. Analyses performed on the derived zeolite X samples revealed a meaningful impact of the given fly ash fraction on synthesis efficiency, chemistry, quality as well as physicochemical properties, while favouring a given morphological form of zeolite crystals. The obtained zeolites possess great potential for use in many areas of industry and environmental protection or engineering.
Due to the restriction such as the Minamata Convention as well as the IED of the European Commission, mercury removal from flue gases of coal-fired power plants (CPP) is an increasingly important environmental issue. This makes this topic very crucial for both the energy industry and scientists. This paper shows how mercury arises from natural resources, i.e., coals, through their combustion processes in CPP and considers the issue of mercury content in flue gases and solid-state coal combustion by-products. The main part of this paper presents a review of the solid sorbents available for elemental mercury control and removal processes, tested on a laboratory scale. The described solutions have a potential for wider usage in exhaust gas treatment processes in the energy production sector. These solutions represent the latest developments in the field of elemental mercury removal from gases. The authors present an overview of the wide range of solid sorbents and their modifications intended to increase affinity for Hg0. Among the presented sorbents are the well-known activated carbon solutions but also novel modifications to these and other innovative sorbent proposals based on, e.g., zeolites, biochars, other carbon-based materials, metal-organic frameworks. The paper presents a wide range of characteristics of the described sorbents, as well as the conditions for the Hg0 removal experiments summarizing the compendium of novel solid sorbent solutions dedicated to the removal of elemental mercury from gases.
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