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Soil fulfils vital functions for life on Earth and so, just like water and air, its protection from all sources of contamination is a major concern. However, the extensive use of petroleum derived products, either as energy sources or as commodities, leads to important environmental liabilities. Ex situ soil washing is a technology to concentrate contaminants, allowing soil cleaning and the reuse of extracted petroleum derived products. This work focuses on the optimization of ex situ soil washing process using surfactants, introducing an evaluation of the washing solution recycling and its after use safe disposal, promoting the reduction of raw materials, energy and water resources costs. Two surfactants, sodium dodecyl sulphate (SDS) and polyoxyethylene sorbitan monooleate (Tween 80), were tested in the decontamination of an artificially contaminated soil with engine lubricant oil waste. The optimization of the washing conditions, such as stirring speed, liquid–solid ratio, number of washing stages, and surfactant concentration, was carried out using a design of experiments (DOE) software, so that the maximum extraction efficiency of total petroleum hydrocarbons (TPHs) was achieved. A TPH removal efficiency of (80.7 ± 3.2)% was obtained with Tween 80 after 5 h of washing and (90.7 ± 2.8)% with SDS after 2 h at 200 rpm on an orbital shaker with a liquid to solid ratio (L/S) of 15. The potential for reuse of the washing solutions was evaluated. Finally, the discharge of the washing solution was considered using activated carbon to remove the surfactants and ensure its safe disposal. [ABSTRACT FROM AUTHOR]

Polyolefins comprise some of the most abundant plastics, but their recycling faces several difficulties. This work focuses on the recycling of high-density polyethylene (HDPE) through the dissolution–precipitation method. Although few works have been published on this topic, this is an extremely promising plastic recycling strategy. However, for this kind of process to become a viable alternative, the replacement of conventional solvents by green solvents and the minimization of energy usage need to be implemented. In this work, several natural terpenes were screened based on COSMO-SAC predictions for HDPE solubility, and three were tested: limonene, α-pinene, and p-cymene. These solvents showed a good capability of dissolving HDPE, confirming the computational predictions. The dissolution and precipitation conditions were optimized based on the results for limonene, with the optimal values being 3 wt% initial concentration of the polymer in the solvent, a dissolution period of 10 min at a temperature of 110 °C, and an antisolvent/solvent ratio of 2/1. Comparing both HDPE and solvent recoveries for the three selected solvents, the best results were obtained for α-pinene as the solvent and ethanol as the antisolvent. The recovered HDPE samples were analyzed by TGA, FTIR, and DSC, showing little modification between the recycled and pristine materials. Scaling up of the process and solvent reuse were also investigated. Through process simulation, it was concluded that solvent recovery and reuse is a crucial step for economic viability. HDPE dissolution–precipitation with α-pinene was found to be a sustainable process from preliminary sustainability analysis, and the separation of HDPE and PET (polyethylene terephthalate) was successfully carried out. [ABSTRACT FROM AUTHOR]

Aqueous biphasic systems (ABS) extraction is a simple, selective, efficient and easy to scale-up technology that, over the years, has attracted a considerable attention from the researcher community as an alternative methodology in downstream processing of a wide variety of biomolecules. This review summarizes and discusses the fundamental features of ABS, as well as its advantages and disadvantages, as a separation and purification technology of biomolecules. Nevertheless, the focus of this review are quaternary ABS formed by the addition of neutral salts and ionic liquids to conventional ABS or those ABS composed by deep eutectic solvents and another phase forming compound. The advantages brought by quaternary ABS in terms of separation and purification of biomolecules, as well as the main issues governing the phase behavior of these systems, are discussed. With examples of application of quaternary ABS as an alternative extraction and purification methodology, it is shown that such ABS are a promising method to improve the effectiveness of biomolecules downstream processing, potentially providing a response to the increasing demand for high purity bioproduct. Furthermore, some of the discussed quaternary ABS have a great potential as a novel, sustainable and cost-effective purification platform for biomolecules downstream processing that can potentially simplify the whole ABS-based purification process due to no need for target bioproduct recovery or phase formers removal. Finally, perspectives of such quaternary ABS are made, and some future challenges pointed out. [ABSTRACT FROM AUTHOR]