RESUMEN
Microplastics are a pollutant of growing concern. Several studies have found microplastics in table salt worldwide in the last decade, although most have focused on already prepackaged salt. To the best of our knowledge, there is no previous research analysing the entire salt production process. In this study focused on solar evaporation salinas, brine and salt samples were obtained from each stage of production, starting with the entrance of seawater/brine until the final stage of ready-to-sell salt, in six sites in Spain. We extracted microplastics from each sample after 30 % H2O2 digestion and filtration through cellulose nitrate 5 µm pore filters. Microplastic fibres were optically analysed with an Olympus DSX1000. Results indicate that microplastics are present both in seawater and air, with atmospheric fallout identified as the primary source. Microplastic concentrations from the entrance to the salina till the inlet to the crystallizers ranges from 256 to 1500 items per liter and from 79 to 193 microplastics per kg for packaged salt were estimated. Artisanal salina F shows the highest content in microplastics. This study hopes to give insight into the origin and causes of microplastic pollution in solar evaporation salinas and contribute to preventing this form of pollution in food-grade salt.
RESUMEN
Objetivo: Estudiar el efecto de la adición de diferentes nanocargas en la resistencia mecánica y en el proceso de curado de un cemento óseo. Material y método: Se preparó un cemento óseo de formulación similar a los cementos comerciales, al que se añadieron nanotubos de carbono (MWCNT), un modificador de la tenacidad basado en copolímeros en bloque (Nanostrength®). Para evaluar el efecto sobre el cemento base, se utilizaron diferentes cantidades de carga, en un rango de entre 0,1 y 1% p/p (MWCNT) y entre 1 y 10% p/p (Nanostrength®). Se efectuaron ensayos de flexión, compresión y fractura para determinar las propiedades mecánicas y las propiedades térmicas. Resultados: Encontramos una disminución en la temperatura máxima alcanzada durante el curado del cemento con la adición de los MWCNT, sin verse afectadas sus propiedades mecánicas. En el caso del Nanostrength®, los resultados obtenidos no presentaron mejoras significativas en sus propiedades mecánicas, fundamentalmente la tenacidad, pero si un ligero aumento en su temperatura de curado y una disminución en el tiempo de fijación. Conclusión: La adición de diferentes porcentajes de nanotubos de carbono a la formulación base de un cemento óseo mejora sus propiedades térmicas sin reducir las propiedades mecánicas. El Nanostrength®, por el contrario, no mejoró el comportamiento térmico ni mecánico del cemento óseo (AU)
Objective: To study the effect of the addition of different nanofillers on the mechanical properties and in the curing process of the bone cement. Methods: A bone cement of similar formulation to commercial cements was prepared in the laboratory. Two nanofillers were used: carbon nanotubes (MWCNT) and a toughness modifier based on block copolymers (Nanostrength®). To evaluate the effect on the cement, weigth loadings ranging from 0,1 to 1 wt% (MWCNT) from 1 to 10 wt% (Nanostrength®) were used. Bending, compressive and fracture test were achieved to determine their mechanical properties. In addition, thermal properties were studied. Results: The results show a significant decrease in the maximum curing temperature of the cement with the addition of MWCNT, without being affected its mechanical properties. In the case of Nanostrength®, significant improvements were not found in their mechanical properties, mainly tenacity, but a slight increase in temperature and a decrease of curing time of fixation were observed. Conclusions: The addition of carbon nanotubes to the basic formulation of a bone cement enhances the thermal properties without a reduction of the mechanical properties. Nanostrength® does not seem to improve the thermal and mechanical behavior of the bone cement (AU)