Ionic liquids (ILs) are new solvents widely used in many technologies due to their unique and advantageous physicochemical properties. In biotechnological applications, ILs can be used along with microorganisms such as Saccharomyces cerevisiae. Due to the enormous number of ILs that can be synthesized through the combination of different anions and cations, it is necessary to have an easy and quick tool for the preliminary screening of their biocompatibility for being used in biotechnological applications. In this work, the agar well diffusion test was successfully applied as a rapid method to identify toxic/nontoxic ILs toward S. cerevisiae. Sixty-three ILs containing a diverse set of cations and anions were used. Through this methodology, nine fully biocompatible ILs toward S. cerevisiae were identified, including: [Bmim⁺] [NO₃⁻], [HOPmim⁺] [NO₃⁻], [Bmim⁺] [NTf2⁻], [N_8,8,8,1⁺] [NTf2⁻], [S_2,2,2⁺] [NTf2⁻], [EMPyr⁺] [NTf2⁻], [BMPi⁺] [NTf2⁻], [Moxa⁺] [MeSO₄⁻] and [Chol⁺] [H₂PO₄⁻]. The analysis of the results also provides preliminary rules to enable the design of biocompatible ILs with S. cerevisiae. In this context, the toxicity was mainly determined by the cation nature although some anions can also display a strong influence on the IL biocompatibility as the bistriflimide anion. Besides, it was observed that an increase in the alkyl chain length of cations, such as imidazolium or pyridinium, involves an increase in the IL toxicity.

Olive leaf and olive mill wastewater are wastes which are produced in olive industry and can be used to obtain value-added products such as polyphenols. In this work, extracts of polyphenols from olive mill wastewater and olive leaf in an aqueous medium are obtained and their composition in polyphenols were determined and compared with those obtained using the conventional extract agent (methanol–water). The antioxidant capacity of the aqueous extracts of olive mill wastewater and olive leaf were also analysed. It was observed that the olive mill wastewater extracted in water provides a similar content of phenolic compounds in the final extract compared to extraction with methanol–water, with the main polyphenols being hydrotyrosol and tyrosol (20.1 and 6.61 mg gdw⁻¹). In the case of leaf extraction, the methanol-free extract (recovery in water after extraction with methanol–water) had a lower total phenol content compared to the methanolic extract, with the main polyphenol being oleuropein (22.73 and 9.05 mg gdw⁻¹, for the methanol and methanol-free extract, respectively). However, both extracts obtained in aqueous solution present a similar antioxidant capacity at very diluted concentrations of the original extract, with IC50 values (half-maximal antioxidant concentration) of about 20 mg TS L⁻¹. The antioxidant capacity of the extract in aqueous solution facilitates its application as an antioxidant in biological systems, like animal food, where the use of extracts based on organic solvents, like methanol, are not suitable.

Ionic liquids (ILs) are widely used as reaction and separation media in many technologies due to their unique and advantageous physicochemical properties. Thus, further studies approaching the study of the toxicity of these materials are required. Moreover, they are utilized in devices in which microorganisms such as Shewanella sp. act as biocatalysts. Thus, in this work, the toxicity of 69 ILs on the marine bacterium Shewanella sp. was tested. Specifically, the ILs analyzed were based on the cations imidazolium, pyridinium, pyrrolidinium, piperidinium, morpholinium, oxazolinium, phosphonium, ammonium, and sulfonium, in combination with different anions. The toxicities of this wide group of ILs on Shewanella sp. were determined using two methods: 1) the agar disk-diffusion test and 2) the growth inhibition test in liquid media. The relationship between toxicity and IL chemical structure was elucidated. A decrease in the hydrophobicity of the alkyl chain length was found to be a key factor to reduce IL toxicity. On the other hand, phosphonium-based ILs containing long alkyl chains were shown to be largely incompatible with Shewanella sp.

In this work, poly(vinyl chloride)-based polymeric ionic liquid inclusion membranes were used in the selective separation of Fe(III), Zn(II), Cd(II), and Cu(II) from hydrochloride aqueous solutions. The ionic liquids under study were 1-octyl-3-methylimidazolium hexafluorophosphate, [omim⁺][PF₆⁻] and methyl trioctyl ammonium chloride, [MTOA⁺][Cl⁻]. For this purpose, stability studies of different IL/base polymer compositions against aqueous phases were carried out. Among all polymer inclusion membranes studied, [omim⁺][PF₆⁻]/PVC membranes at a ratio of 30/70 and [MTOA⁺][Cl⁻]/PVC membranes at a ratio of 70/30 were able to retain up to 82% and 48% of the weight of the initial ionic liquid, respectively, after being exposed to a solution of metal ions in 1 M HCl for 2048 h (85 days). It was found that polymer inclusion membranes based on the ionic liquid methyl trioctyl ammonium chloride allowed the selective separation of Zn(II)/Cu(II) and Zn(II)/Fe(III) mixtures with separation factors of 1996, 606 and, to a lesser extent but also satisfactorily, Cd(II)/Cu(II) mixtures, with a separation factor of 112. Therefore, selecting the appropriate ionic liquid/base polymer mixture makes it possible to create polymeric inclusion membranes capable of selectively separating target metal ions.

Response surface methodology (RSM) and Box–Behnken design (BBD) were investigated to optimize the coagulation–flocculation process (CF) of cardboard industry effluent using polyaluminum chloride (PAC) and cationic polyacrylamides (c-PAM). The aim is to identify the optimum combination of coagulant dose, pH, and flocculant dosage for the highest removal efficacy of chemical oxygen demand (COD) and anionic surfactant removal. According to the results, COD reduction was principally controlled by PAC and c-PAM, while anionic surfactant was affected by pH and PAC. In addition, COD and anionic surfactant removal models fitted well with the experimental results (R² > 0.85). Coagulation/flocculation using optimum conditions of pH, PAC, and c-PAM led to the total removal of anionic surfactant and the reduction of more than 95% of COD.