Nanometric particles of high economic value in coal fire region: Opportunities for social improvement

Abstract

Spontaneous coal combustion in the La Guajira coals was studied for the presence of carbon nanophases (e.g., carbon nanotubes), occurrence of rare earth elements (REEs) in them, and the probable mechanisms for concentration of these rare compounds. For this purpose, various techniques such as scanning electron microscopy (SEM), Field-emission SEM, transmission electron microscopy (TEM), high-resolution TEM, and focused ion beam (FIB) were used. The development and alteration of the nanoparticles by geo-processes during the early modification periods of coal combustion were explored. Certain types of carbon nanophases and REE compounds may constitute nanominerals and ultra-fine particles accumulated in the coal peat. Assemblages of these nanophases (crystalline and amorphous compounds), predominantly the clay-monazite relationship and its connection to tonsteins in the coal combustion zones in the east region of the coal mines studied in this work, indicate that the coal area was subjected to REE concentration. The carbon nanophases contained several potential hazardous elements (PHEs), including, arsenic, bromine, cadmium, chlorine, fluorine, mercury, and other PHEs. While carbon nanotubes have been known to be produced from spontaneous combustion of coal of varying ranks, the present work is the first report on the naturally occurring REEs and carbon nanophases in the Colombian coal mining area.

The role of airborne particles and environmental considerations in the transmission of SARS-CoV-2

“…Virus-containing aerosol is most likely to penetrate deep into the distal respiratory airways of the lung. From there, they can penetrate the alveolar membrane, enter the bloodstream directly and translocate to vital organs ( Drossinos and Stilianakis, 2020 , Silva et al, 2020 , Silva et al, 2021 ). Substances attached to smaller particles may have more harmful health effects than those attached to larger particles ( Leung et al, 2018 ).…”

A review of the mineralogical and chemical composition of nanoparticles associated with coal fires

“…Since the industrial revolution, people have been attracted by the low cost and convenience of coal, which has had a large impact on the environment and human health (Finkelman et al., 2021; León‐Mejía et al., 2018; Munawer, 2018). The environmental impact of coal mining can be studied on various scales, ranging from the global scale of climate change to the thousands‐of‐meter scale of coal mining (10 5 m), to the nanometer scale (10 −9 m) of emitted pollutants (Silva, Crissien, Schneider, et al., 2020).…”

“…Coal fires occur in many regions, such as Australia, Brazil, China, Colombia, India, Indonesia, United States, South Africa, Venezuela, and Europe (Figure 1) (Civeira et al., 2016; Hower et al., 2013; Liang et al., 2014; Pone et al., 2007; Quintero et al., 2009; Ribeiro et al., 2010; Silva, Crissien, Schneider, et al., 2020; Stracher & Taylor, 2004; Syed et al., 2018). Following the industrial revolution, coal fires dramatically increased in number (Kuenzer et al., 2012) and occurred in all countries that had coal mining or exposed coal deposits (Figure 1) (Silva et al., 2021).…”

“…Hence, the impact of PM emitted from coal fires on climate change depends strongly on its type and quantity as well as on its size because NPs have commonly longer residence times in the atmosphere than their micrometer‐sized counterparts. Due to their larger surface‐to‐mass ratio, NPs also have greater solubility (Oliveira et al., 2012, 2019; Silva, Wollenschlager, et al., 2011; Silva, Crissien, Schneider, et al., 2020; Silva, Crissien, Tutikian, et al., 2020) and thus alter faster in chemical composition, physical properties, size, and shape due to particle–gas interaction (Duarte et al., 2019; Gredilla et al., 2019).…”

“…Recent advances in analytical techniques, such as new generations of transmission electron microscopes, have allowed the mineralogical and chemical characterization of NPs emitted by coal fires (Sehn et al., 2016; Silva et al., 2012; Silva, Crissien, Schneider, et al., 2020; Silva, Crissien, Tutikian, et al., 2020) and have provided a better understanding of their potential impacts on coal miners and the surrounding environment. However, there are in our opinion two major challenges with respect to the sampling and characterization of NPs emitted by coal fires.…”