A simple and reliable method for separation of mineral oil/polychlorobiphenyl mixtures

Abstract

Polychlorinated biphenyls (PCBs) were broadly applied worldwide as electrical insulators in transformers and power capacitors, due to their high dielectric constant and non-flammability. They were often added to mineral oils (MOs) and used as dielectric fluids, which are nowadays classified as hazardous waste. Indeed, the Stockholm Convention aims to eliminate the use of equipment with PCB content greater than 0.005 wt-% (=50 ppm) by 2025. Accurate identification and quantification of small traces of PCBs contained in MO thus represent a great analytical challenge. To achieve this goal, a simple, cost-effective and fast chromatographic process was developed to separate PCBs from MO, allowing to obtain reliable data to determine the concentration of PCBs, reduced to 2–3 ppm. Experimental and analytical methods, such as thin layer chromatography, column chromatography as well as gas chromatography coupled with mass spectroscopy, were applied to acquire a high level of qualitative and quantitative determination of PCBs in transformer MOs.

Exploring organo-bentonite adsorption properties for biphenyl removal from organic-aqueous media: kinetic study and industrial perspective

“…N the Avogadro number, V the volume of the mesh in Å 3 (cell parameters of bentonite clay are a=5.3 Å, b=9.05 Å, c=9.55 Å) and ρ the density of the clay in g/cm 3 which is equal to 2.44 g/cm 3 in the anhydrous state.…”

“…These xccompounds continue to be the subject of extensive research by various international entities, including state and municipal authorities [1] This scrutiny is driven by the well-documented toxic properties of PCBs, which present a direct threat to human health, whether through inhalation or indirectly via contamination of the food chain [2]. Despite the global ban on PCB production, large quantities of these Persistent Organic Pollutants (POPs) are still present in the environment [3]. It is important to note that PCBs are regarded as precursors for the formation of highly toxic substances, specifically polychlorinated dibenzofurans (PCDFs) and dibenzodioxins (PCDDs) [4,5].…”

“…However, their inventory shows that these molecules are still present due to intentional or unintentional releases in the environment [7,8]. The dechlorination of PCBs, whether anthropogenic or not, such as UV-Visible radiation, generates in most cases the biphenyl molecule, improperly called "PCB N°0" [9,10].…”

Petroleum sludge ash-derived MCM-41-silver nanocomposites for enhanced photocatalysis and antimicrobial effect in water treatment

“…One of the main sources of pollution is the production of petroleum sludge (PS) during the refining and wastewater treatment processes. 1,2 These sludges are classified as hazardous solid waste due to their complex composition and the presence of toxic substances, 3,4 notably heavy metals and polyaromatic hydrocarbons. 5,6 Various disposal methods are employed to manage petroleum sludge, among them, thermal treatment by incineration stands out as a popular choice due to its ability to recover energy and effectively treat the waste.…”