This review paper collects the recent updates regarding the use of nanomaterials in cosmetics. Special focus is given to the applications of nanomaterials in the cosmetic industry, their unique features, as well as the advantages of nanoscale ingredients compared to non-nanoscale products. The state-of-the-art practices for physicochemical and toxicological characterization of nanomaterials are also reviewed. Moreover, special focus is given to the current regulations and safety assessments that are currently in place regarding the use of nanomaterials in cosmetics—the new 2019 European guidance for the safety assessment of nanomaterials in cosmetics, together with the new proposed methodologies for the toxicity evaluation of nanomaterials. Concerns over health risks have limited the further incorporation of nanomaterials in cosmetics, and since new nanomaterials may be used in the future by the cosmetic industry, a detailed characterization and risk assessment are needed to fulfill the standard safety requirements.

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Two of the main challenges in post-combustion CO2 capture with ethanolamine are solvent degradation and material corrosion. It has been shown that there is a correlation between degradation and corrosion. The present paper examines this correlation by studying the effect of 10 MEA degradation products on corrosion. Thermal degradation experiments were conducted under stripper conditions for 5 weeks. 30wt% MEA solution with 1wt% of the various degradation products were placed in 316 SS cylinders and stored in a thermostat chamber at 135 °C. ICP-MS was used for the metal concentration analyses for all the solutions, while ion chromatography was used for the quantitative determination of heat stable salts anions and MEA concentrations. The solutions were also analyzed for degradation products in order to study the formation and thermal stability of these compounds. For corrosion monitoring, in addition to ICP-MS analyses, SEM-EDS was used for examining the cylinders surface morphology and elemental composition while XRD was used for corrosion product identification. In the present paper, the influence of the secondary degradation products on corrosion is studied. Results show that some specific degradation products, like bicine, HeGly and HEEDA enhance corrosion while others don't seem to have a significant effect on corrosion of stainless steel.

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In amine based post-combustion CO2 capture and storage, solvent degradation and corrosion of steel materials are the main operational challenges. In this paper the focus was on minimizing degradation and corrosion by addition of inhibitors. The tested amine solution was 30wt% of the benchmark solvent ethanolamine (MEA). The tested inhibitors were pyrogallol, alpha,alpha'-(1-Methylethylenediimino)di-ortho-cresol, carbohydrazide, 2butanone oxime (MEKO), tricine and 1,3-Diaminopropane-N,N,N′,N′-tetraacetic acid (PDTA). The tests were performed under oxidative degradation conditions. After two weeks, PDTA showed the best inhibition performance. In addition to the oxidative degradation experiments, the thermal stability of carbohydrazide and PDTA were tested at 120 °C. After 2 weeks at stripper conditions, the PDTA loss was less than 50%. However, PDTA showed high metal concentration, indicating possible corrosion problems on the steel surface.Carbohydrazide, on the other hand, showed excellent corrosion protection properties, but it is not stable at 120 °C.

The biological activity occurring in urban sewerage systems usually leads to the (biogenic) corrosion of pipe infrastructure. Anti-corrosion coating technology was developed in an effort to protect sewer pipes from degradation. This study evaluates a new class of relatively low-cost magnesium hydroxide-based coatings, regarding their ability to adhere efficiently onto the concrete surface, and offer efficient corrosion protection. Six magnesium hydroxide-based coatings were prepared with the addition of two different types of cellulose, used as adhesion additives, and these were applied on concrete specimens. Pull-off measurements showed that the addition of higher amounts of cellulose could improve the coating adhesion onto the concrete surface. An accelerated sulfuric acid spraying test was used to evaluate the consumption time of the applied coatings and their efficiency in maintaining over time slightly alkaline pH values (above 8) on the coated/protected surfaces. At the end of spraying test, a mineralogical analysis of surface samples was performed, indicating that the formation of corrosion by-products (mainly gypsum) was increased when the added amount of cellulose was lower. Hardness and roughness measurements were also conducted on the concrete surfaces, revealing that the coatings helped the concrete surface to preserve its initial surface properties, in comparison to the uncoated specimens. A SEM/microstructure analysis showed that aggregates were formed (possibly consisting of Mg(OH)2), affecting the reactivity of the protected surface against sulfuric acid attack.

Membrane fouling investigations in membrane bioreactors (MBRs) are a top research issue. The aim of this work is to study the combined effect of colloids and soluble microbial products (SMPs) on membrane fouling. Two lab-pilot MBRs were investigated for treating two types of wastewater (wwt), synthetic and domestic. Transmembrane pressure (TMP), SMP, particle size distribution and treatment efficiency were evaluated. Chemical Oxygen Demand (COD) removal and nitrification were successful for both kinds of sewage reaching up to 95–97% and 100%, respectively. Domestic wwt presented 5.5 times more SMP proteins and 11 times more SMP carbohydrates compared to the synthetic one. In contrast, synthetic wwt had around 20% more colloids in the mixed liquor with a size lower than membrane pore size (<400 nm) than domestic. Finally, the TMP at 36 days reached 16 kPa for synthetic wwt and 11 kPa for domestic. Therefore, synthetic wwt, despite its low concentration of SMPs, caused severe membrane fouling compared to domestic, a result that is attributed to the increased concentration of colloids. Consequently, the quantity of colloids and possibly their special characteristics play decisive and more important roles in membrane fouling compared to the SMP—a novel conclusion that can be used to mitigate membranes fouling.