Sistema per l'estrazione e purificazione di sostanze antiossidanti naturali nelle acque di vegetazione delle olive

The olive oil extraction industry is responsible for the production of high quantities of vegetation waters, represented by the constitutive water of the olive fruit and by the water used during the process. This by-product represent an environmental problem in the olive’s cultivation areas because of its high content of organic matter, with high value of BOD5 and COD. For that reason the disposal of the vegetation water is very difficult and needs a previous depollution. The organic matter of vegetation water mainly consists of polysaccharides, sugars, proteins, organic acids, oil and polyphenols. This last compounds are the principal responsible for the pollution problems, due to their antimicrobial activity, but, at the same time they are well known for their antioxidant properties. The most concentrate phenolic compounds in waters and also in virgin olive oils are secoiridoids like oleuropein, demethyloleuropein and ligstroside derivatives (the dialdehydic form of elenolic acid linked to 3,4-DHPEA, or p-HPEA (3,4-DHPEA-EDA or p-HPEA-EDA) and an isomer of the oleuropein aglycon (3,4-DHPEA-EA). The management of the olive oil vegetation water has been extensively investigated and several different valorisation methods have been proposed, such as the direct use as fertilizer or the transformation by physico-chemical or biological treatments. During the last years researchers focused their interest on the recovery of the phenolic fraction from this waste looking for its exploitation as a natural antioxidant source. At the present only few contributes have been aimed to the utilization for a large scale phenols recovery and further investigations are required for the evaluation of feasibility and costs of the proposed processes. The present PhD thesis reports a preliminary description of a new industrial scale process for the recovery of the phenolic fraction from olive oil vegetation water treated with enzymes, by direct membrane filtration (microfiltration/ultrafiltration with a cut-off of 250 KDa, ultrafiltration with a cut-off of 7 KDa/10 KDa and nanofiltration/reverse osmosis), partial purification by the use of a purification system based on SPE analysis and by a liquid-liquid extraction system (LLE) with contemporary reduction of the pollution related problems. The phenolic fractions of all the samples obtained were qualitatively and quantitatively by HPLC analysis. The work efficiency in terms of flows and in terms of phenolic recovery gave good results. The final phenolic recovery is about 60% respect the initial content in the vegetation waters. The final concentrate has shown a high content of phenols that allow to hypothesize a possible use as zootechnic nutritional supplements. The purification of the final concentrate have garanteed an high purity level of the phenolic extract especially in SPE analysis by the use of XAD-16 (73% of the total phenolic content of the concentrate). This purity level could permit a future food industry employment such as food additive, or, thanks to the strong antioxidant activity, it would be also use in pharmaceutical or cosmetic industry. The vegetation water depollutant activity has brought good results, as a matter of fact the final reverse osmosis permeate has a low pollutant rate in terms of COD and BOD5 values (2% of the initial vegetation water), that could determinate a recycling use in the virgin olive oil mechanical extraction system producing a water saving and reducing thus the oil industry disposal costs .

Novel asymmetric geopolymer membranes for oil/water emulsions separation

In this study, it was investigated the possibility of using a geopolymeric membrane as an alternative to the expensive ceramic ones. The goal was to synthesise a low-cost membrane made entirely of geopolymer that can perform equally to commercial membranes. This study initially investigated the feasibility of preparing a microporous support suitable for microfiltration through casting and pressing techniques. Subsequently, a selective geopolymeric layer was developed and deposited on the support, with the capability to operate within the microfiltration range and to effectively separate oil from oil-water emulsions. In order to evaluate the performance, the properties of the geopolymeric supports obtained through pressing were carefully evaluated during the experimentation phase investigating the effect of varying parameters such as sodium silicate content, water content, and applied pressure. The results obtained from these evaluations showed that it is possible to produce supports with excellent porosity and highly controlled narrow pore size distributions. The most promising geopolymeric pressed support was then used for the deposition of a selective layer on its surface. Following physical characterization, it was confirmed that the resulting geopolymer membrane was suitable for use in the microfiltration range. Subsequently, the membrane was tested for its ability to separate oil from water using various emulsions prepared with different surfactants at different concentrations and pH. The results revealed that the fluxes were highly dependent on the electrostatic interaction between the membrane and the emulsion, with best results being obtained with emulsions prepared using anionic surfactants. The rejection rate of the membrane was also found to be extremely high, with values over 95%, comparable to a commercial ceramic membrane. This suggests that geopolymer membranes are suitable alternatives to ceramic membranes, offering the added benefits of lower cost and reduced environmental impact during production.