Adsorção de azul de metileno por zeólita sintetizada a partir das cinzas leves da gaseificação do carvão mineral de Candiota/RS

Abstract

The textile industry is considered the most polluting among all industrial sectors and the effluent generated has visible coloration as one of the characteristics that make up its pollution load. Many methods are used to remove dyes from these effluents, with adsorption offering the best prospects for removal. The adsorbents used are porous solid particles with interconnected pore networks that provide a large specific area and allow adsorption in a short period of time. Industrial and agricultural waste has been used as alternative adsorbents, such as coal ash, clays, rice husk, fly ash zeolites, among other materials. Coal ash has a high potential for use as a raw material for the synthesis of zeolites, as they are mainly made of Si and Al. Zeolites are one of the most widely used materials as adsorbents in adsorption processes. Zeolites are minerals that have a structure consisting of channels and uniform cavities, which provides selective mass transfer for the size and shape of the adsorbate. That way, three articles were written. The purpose of the first article was to synthesize a zeolite using coal ashes and an aluminum source as raw materials. The second article was intended to study the adsorption of methylene blue by the synthesized zeolitic material using only the ash as raw material. Finally, the purpose of the third article was study the synthesis of zeolites without the addition of aluminum source by varying factors of the alkaline melting stage of the synthesis, as well as to study the adsorption of methylene blue by the zeolitic materials formed. In the first article, the synthesized zeolite was of sodalite type, with synthesis mass yield of 44.6% and physical characteristics within the literature range. In the second article the mass yield of the synthesis process was 29.1% and the experimental adsorption capacity of methylene blue by the synthesized material was 36.03 mg g-1 . The third article revealed that the NaOH/ash ratio is the alkaline melting factor that have the most influence synthesis. The structure formed was the zeolite Na-X. Adsorption studies have revealed that convection is the mechanism that governs the process overall mass transfer. In addition, the experimental adsorption capacity of methylene blue ranged from 41.24 to 86.93 mg g-1.