Sorption behavior of real microplastics (MPs): Insights for organic micropollutants adsorption on a large set of well-characterized MPs.

Microplastics (MPs) have been recognized as transport vectors for micropollutants in the natural water environment and the food web; therefore, the sorption behavior of contaminant on MPs has recently gained an increased attention. However, a consensus has not yet been reached and information about the adsorption of water contaminants on real MPs remains elusive. Herein, we raise the question of "Should we continue using pure polymers as surrogates for real MPs?" This first systematic study compared the adsorption of multiple micropollutants (i.e. a pesticide, a pharmaceutical, and perfluoroalkyl substances (PFAS)) on a large set of MPs (i.e. 20 well-characterized MPs) and kaolin. Material characterizations results showed various physicochemical and compositional differences between real and pure MPs. Pure polymers had lower normalized uptake values than real MPs in most cases. This was attributed to the surface roughness and/or the presence of fillers (e.g. talc and glass fiber) in real samples. Further, preloaded MPs with natural organic matter (NOM) showed an increased uptake of micropollutants due to forming a complex with NOM and/or co-sorption. These findings indicate that employing real MPs in research studies is critical for obtaining environmentally meaningful results, and the evaluation of MPs sorption behavior without NOM preloading can result in a significant underestimation for their actual values. We also provided an outlook the key areas for further investigations.

Removal of Hydrocarbons from Contaminated Soils by Using a Thermally Expanded Graphite Sorbent.

Lab-scale experiments on three soil matrices featured by increasing granulometry (sea sand, silica sand and gravel) were carried out in order to evaluate the adsorption capability and the removal efficiency of a new graphene-based material. Soil samples, firstly contaminated with different quantities of used lubricant oil up to final concentrations of 12.5, 25.0, 50.0 g kg-1, were treated with an opportune amount of thermally expanded graphite (TEG) (i.e. 1/10, 1/20, 1/40 as TEG/pollutant ratio). Results show that the removal efficiency of TEG is directly correlated to the contamination level of the soil. The best removal efficiency (87.04%) was obtained during the treatment of gravel samples at the maximum contamination level by using the highest dosage of TEG. A good removal efficiency (80.83%) was also achieved using lower TEG/pollutant ratio. Moreover, TEG at ratio 1/10 showed worse removal efficiencies in treating sea (81.17%) and silica sand (63.52%) than gravel. In this study, also the thermal regeneration was investigated in order to evaluate a possible reuse of TEG with subsequent technical and economic advantages. TEG-technique proves to be technologically and economically competitive with other currently used technologies, revealing the best choice for the remediation of hydrocarbon-contaminated soils.

Method development and optimization for the determination of benzene, toluene, ethylbenzene and xylenes in water at trace levels by static headspace extraction coupled to gas chromatography-barrier ionization discharge detection.

Benzene, toluene, ethylbenzene, and xylenes, more commonly named BTEX, represent one of the most ubiquitous and hazardous groups of atmospheric pollutants. The goal of our research was the trace quantification of BTEX in water by using a new simple, low-cost, and accurate method, based on headspace (HS) extraction and gas chromatography (GC) coupled to barrier ionization discharge detector (BID). This water application dealt with simple matrices without protein, fat, or humic material that adsorb target analytes, thus the external standard calibration was suitable to quantify each compound. The validation steps included the study of linearity, detection and quantification limits, and accuracy. LODs and LOQs varied from 0.159 to 1.845 µg/L and from 0.202 to 2.452 µg/L, respectively. The recovery was between 0.74 ±â€¯0.13 and 1.15 ±â€¯0.09; relative standard deviations (% RDSs) were less than 12.81% (n = 5) and 14.84% (n = 10). Also, GC performance was evaluated in term of efficiency, peak tailing and resolution. Preliminary results from practical applications to analyses of real samples are presented. The results indicate that static HS coupled to GC-BID is a successful method for BTEX analysis in water samples at the µg/L levels, provided that hydrocarbons interference occur at similar concentration levels. GC-BID may become a routine reference method alongside the official analytical techniques for quality control purposes of contaminated waters. Moreover, the new method is amenable to automation by using commercial HS units.