The separation of used engine oil (UEO) with an ultrafiltration (UF) membrane made of commercial copolymer of poly(acrylonitrile-co-methyl acrylate) (P(AN-co-MA)) has been investigated. The P(AN-co-MA) sample was characterized by using FTIR spectroscopy, ¹³C NMR spectroscopy, and XRD. The UF membrane with a mean pore size of 23 nm was fabricated by using of non-solvent-induced phase separation method—the casting solution of 13 wt.% P(AN-co-MA) in dimethylsulfoxide (DMSO) was precipitated in the water bath. Before the experiment, the used engine oil was diluted with toluene, and the resulting UEO solution in toluene (100 g/L) was filtered through the UF membrane in the dead-end filtration mode. Special attention was given to the evaluation of membrane fouling; for instance, the permeability of UEO solution was dropped from its initial value of 2.90 L/(m²·h·bar) and then leveled off at 0.75 L/(m²·h·bar). However, the membrane cleaning (washing with toluene) allowed a recovery of 79% of the initial pure toluene flux (flux recovery ratio), indicating quite attractive membrane resistance toward irreversible fouling with engine oil components. The analysis of the feed, retentate, and permeate by various analytical methods showed that the filtration through the UF membrane made of P(AN-co-MA) provided the removal of major contaminants of used engine oil including polymerization products and metals (rejection—96.3%).

In this study, ultrafiltration membranes were developed via a nonsolvent-induced phase separation method for the removal of asphaltenes from crude oil. Polyacrylonitrile (PAN) and acrylonitrile copolymers with acrylic acid were used as membrane materials. Copolymerizing acrylonitrile with acrylic acid resulted in an improvement in the fouling resistance of the membranes. The addition of 10% of acrylic acid to the polymer chain decreases the water contact angle from 71° to 43°, reducing both the total fouling and irreversible fouling compared to membranes made from a PAN homopolymer. The obtained membranes with a pore size of 32–55 nm demonstrated a pure toluene permeance of 84.8–130.4 L/(m²·h·bar) and asphaltene rejection from oil/toluene solutions (100 g/L) of 33–95%. An analysis of the asphaltene rejection values revealed that the addition of acrylic acid increases the rejection values in comparison to PAN membranes with the same pore size. Our results suggest that the acrylonitrile–acrylic acid copolymer ultrafiltration membranes have promising potential for the efficient removal of asphaltenes from crude oil.

The regeneration (purification) of waste oils for their subsequent reuse or for preparation of other kinds of lubricants (e.g., greases) is an essential step in the closed loop of petroleum products. Numerous approaches to waste oil valorization are known today. The use of membranes for waste oil treatment has a number of advantages and is an actively developing field of science and engineering. This review discusses the latest achievements in the use of membranes for reprocessing waste motor oils, taking into account their chemical composition and physicochemical characteristics influencing the membrane performance.

Approximately 90 million barrels of crude oil are processed daily worldwide, with separation processes such as distillation accounting for 10–15% of global energy consumption. In this regard, the scientific community is faced with the ambitious task of finding alternative fractionation technologies that are not based on the volatility of individual components of complex liquid mixtures. The driving force of ultrafiltration is the pressure difference across the membrane. Therefore, separation occurs without phase transitions and with significantly lower energy consumption compared to distillation. In recent years, there has been a growing interest in the development of membrane technologies for the purification and reuse of used lubricating oil. One of the key challenges in membrane filtration of oil and lubricants is their high viscosity. This review examines two approaches to reducing the viscosity of such systems: filtration at elevated temperatures and pre-dilution of the feedstock followed by filtration. A literature analysis revealed that in most cases, ultrafiltration with ceramic membranes is employed in the former approach, while the latter uses more cost-effective polymer membranes. Special attention in the review is given to the issues of membrane fouling and regeneration.

Depending on the method of cellulose production, the proportion of alpha fraction in it can vary significantly. Paper pulp, unlike dissolving cellulose, has an alpha proportion of less than 90%. The presence of cellulose satellites in the system does not impede the formation of concentrated solutions of N-methylmorpholine-N-oxide (NMMO). In the current study, spinning solutions based on cellulose with a low alpha fraction (up to 90%) (pulp cellulose) are investigated. The morphological features and rheological behavior of such solutions are examined. It is suggested to roll the obtained solutions in order to obtain cellulose membranes. X-ray diffraction, IR spectroscopy, AFM and SEM were used to investigate the resulting structure and morphology of the obtained membranes. It is shown that the degree of crystallinity for the membranes varies based on the impurity content in the sample. The morphology of the films is characterized by a dense texture and the absence of vacuoles. The highest strength and elastic modulus were found for membranes made of bleached hardwood sulfate cellulose, 5.7 MPa and 6.4 GPa, respectively. The maximum values of the contact angle (48°) were found for films with a higher proportion of lignin. The presence of lignin in the membranes leads to an increase in rejection for the anionic dyes Orange II and Remazol Brilliant Blue R.