The focus of this study is the assessment of total suspended particles (TSP) and particulate matter (PM) with various aerodynamic diameters in ambient air in Guayaquil, a city in Ecuador that features a tropical climate. The urban annual mean concentrations of TSP (Total Suspended Particles), and particle matter (PM) with various aerodynamic diameters such as: PM10, PM2.5 and PM1 are 31 ± 14 µg m−3, 21 ± 9 µg m−3, 7 ± 2 µg m−3 and 1 ± 1 µg m−3, respectively. Air mass studies reveal that the city receives a clean Southern Ocean breeze. Backward trajectory analysis show differences between wet and dry seasons. During the dry season, most winds come from the south and southwest, while air masses from the peri urban may contribute as pollutant sources during the wet season. Although mean values of PM10 and PM2.5 were below dangerous levels, our year-round continuous monitoring study reveals that maximum values often surpassed those permissible limits allowed by the Ecuadorian norms. A cluster analysis shows four main paths in which west and southwest clusters account for more than 93% of the pollution. Total vertical column of NO2 shows the pollution footprint is strongest during the dry season, as opposed to the wet season. A microscopic morphological characterization of ambient particles within the city during the wet and the dry season reveals coarse mode particles with irregular and rounded shapes. Particle analysis reveals that samples are composed of urban dust, anthropogenic and organic debris during the dry season while mainly urban dust during the wet season.

Exploiting the kinetic domain provided by hydrothermal conditions, it was possible to isolate three transient metastable crystal structures, each bearing concomitant pairs of octamolybdate isomers, namely, α–β, γ–β or βcs–βgp stabilized by distinctive homoleptic [Co(bpy)3] n+ (bpy = 2,2′-bipyridine; n = 2 or 3) cations generated in situ: [Co(bpy)3]4[(α-Mo8O26)(β-Mo8O26)]·5H2O (1), [NH4][Co(bpy)3][(γ-Mo8O26)0.5(β-Mo8O26)0.5]·4H2O (2) and [Co(bpy)3]2[(βcs-Mo8O26)0.5(βgp-Mo8O26)]·12H2O (3). Solid 1 with the space group P21/n and unit-cell parameters a = 22.160 (6), b = 14.209 (3), c = 24.641 (4) Å, β = 99.10 (2)° and V = 7661 (3) Å3 resulted in the same crystal structure as that synthesized previously under different conditions by Sun et al. [J. Mol. Struct. (2005), 741, 149–153]. Factors directing the reaction, such as product composition and phase stability, were monitored by analysis of the PXRD patterns of the bulk solids obtained under different experimental conditions. The relative proportions of the mixed phases 1–3 or their stabilization are highly dependent on the initial Co:Mo molar ratio and the reaction temperature. In particular, an increase in temperature induces the transformation of 1–3 into more thermodynamically stable phases formed by one-dimensional coordination polymers [Co(bpy)2(β-Mo8O26)0.5] n (4) and [(MoO3)(bpy)] n (5). The crystal structures of 1–3 correspond to molecular salts self-assembled by C—H...O—Mo, C...H and H...H intermolecular contacts. A Hirshfeld surface analysis for 1 showed that the C...H and H...H interactions represent an average of 51.8% of the total cation–cation intermolecular contacts. In contrast, these interactions are vastly reduced in 2 (23.0%) and 3 (average 28.5% for both isomers). EPR experiments indicated that the crystal structures of 1 and 3 are paramagnetic, and that for 2 is diamagnetic. The paramagnetism of 3 stems from the in situ formation of [Co(bpy)3]3+ in a high-spin configuration. The structure-directing properties of the [Co(bpy)3] n+ cations in the isolation and self-assembly of concomitant octamolybdate isomers are also described from the viewpoint of crystal engineering.

The research of organoclays has been occurring for many years to develop and add value to these inorganic materials for several industrial applications, such as pollutant absorbers or impermeable plastics. The organoclay applications are intrinsically related to organo-modification and the structure of clays. This study shows the preparation and characterization of organoclays produced by a nontronite type clay (calcic bentonite) from the Tosagua Formation in the peninsula of Santa Elena in Ecuador. These clays were purified and centrifuged before organo-treatment. The purification and separation processes were used to remove organic matter and carbonates, and a cationic interchange from calcic to sodic (Ca2+ to Na+) was carried out. Organo-modification was performed using two types of cationic compounds, i.e., Oleylmethylbis (2-hydroxyethyl) ammonium chloride and Di (hydrogenated tallow alkyl) quaternary amine to organoclay with different surface hydrophobicity. The samples were characterized by X-ray diffractometry (XRD), infrared spectrometry (FT-IR), thermo-gravimetry (TGA), and scanning electron microscopy (SEM) to analyze the effect after the mentioned treatment and the resulting organoclays by the addition of these surfactants. The results confirm the significant intercalation of the organic treatment suitable for environmental remediation, compatibilizing recycled plastics, or improving performance in different hydrophobicity systems for industrial applications.