The high Si and Al contents in the amorphous phase of coal fly ash have been used for its conversion into zeolites. This process converts a toxic low-value by-product into a product used in a number of environmental applications, but has the disadvantage of introducing contaminants. Despite the large number of studies on the conversion of fly ash into zeolites, few report this drawback or discuss the efficiency of the proposed processes from a technical or ecological perspective. In this respect, the present study conducts a detailed assessment of two routes for integrated hydrothermal synthesis of zeolites 4A and Na-P1 obtained from coal fly ash. The processes are evaluated and compared in relation to the presence of undesirable metals and elements in the different steps of synthesis, as well as the feedstock and final product. Different performance parameters are presented and applied in the assessment of both processes and the most sustainable is recommended.

Coal fly ash has been proposed as an alternative raw material for zeolite synthesis, however, the mobilization of toxic elements of this material into zeolite products, washing water and effluent is rarely addressed. In this study, Brazilian coal fly ash was used in the integrated synthesis (two steps) of zeolites Na-P1 and 4A and the distribution of approximately 40 major, minor and trace elements was investigated in all the input and output flows involved in the process. The mobilization of several elements was observed in the zeolite products, a number of which are highly toxic, such as As, Cd, Cr, Ni and Pb. With regard to the amount present in the ash, both zeolites were enriched in several elements, such as Ni in zeolite Na-P1 and As in zeolite 4A. The latter exhibited high purity, with most of the elements investigated having concentrations close to those measured in commercial zeolite 4A. Important information was gathered regarding zeolite synthesis using fly ash, which will ensure safer application of these materials and, if necessary, propose a contaminant-free synthesis route.

The species and density of Eucalyptus wood poles installed in the electrical network are useful parameters which must be considered when it is necessary to establish the service life of these structures. In this work, eucalyptus poles samples were collected and analyzed by scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS). SEM image analysis showed that the lumen diameter average of fiber substantially is variable between the three species studied, in line with the wood density obtained in laboratory, for poles with several years in service in the electricity network, as well as for not used poles. In addition, EDS microanalysis was utilized for identify the presence of chemical preservatives employed in the conservation these poles. The analysis method proposed proved effective for characterization for this timber.