**4. Conclusion**

The use of the oilseed deriving from alternative crops or waste oils as a feedstock for biodiesel production represents a very convenient way in order to lower the production costs of this biofuel.

From the agronomic point of view the authors verified that the green manure of *B.juncea* resulted in nematode infestation drastically decreased and improved soil quality, reflected in higher yield of crops in agronomic succession. In the first year of experimentation *B. juncea* was preferred to *B.carinata* because of its suitability to spring planting (starting period

Non Edible Oils: Raw Materials for Sustainable Biodiesel 19

A process simulation of the FFA esterification, able to predict the reaction progress through a thermodynamic and kinetic analysis was successfully performed using the software PRO II (SimSci). A pseudohomogeneous model was used for describing the kinetic behaviour of the reaction, using a modified UNIFAC model for the calculation of the activity coefficients (used not only for the phase and chemical equilibria calculations, but also for the kinetic expressions). The data obtained from the use of this model showed to be in a very good

The authors gratefully acknowledge the financial support by Italian Ministero delle Politiche

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**5. Acknowledgment** 

**6. References** 

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of the project SUSBIOFUEL). Further work will be necessary to improve the setting up of the agronomic proposal. Winter sowing of *B.carinata* will be done in the next years and alternative promising patented variety of tobacco (selected for seed production)5 are currently under test. The authors are also evaluating the proposed rotation in comparison with commercial pellets6 of defatted Brassicaceae meal. In addition, more outcomes are attended: yield grains7, evaluation of the weed control potential of *B. juncea* and survival rate of transplanted *N.tabacum* plantlets following the green manuring or not.

The flexibility of Brassicaceae (efficient green manure and/or oil crop) allows using these species with a dual aim according to the situation, thus increasing the sustainability of the system. On the other hand new tobacco varieties promise yields above the best rape harvests around Europe. Under this light tobacco is a really interesting alternative oil crop especially in countries like Italy where it has been cultivated since a long time and Good Agricultural Practices (GAP) for this crop have long been known: all points in favour to the conversion of tobacco cultivation toward oil seeds production. To give a more comprehensive evaluation of innovations introduced in the whole biodiesel production chain, the authors aim to develop a method able to assess biodiesel sustainability.

The authors are aware that their proposal alone does not solve the overall sustainability problem of biodiesel production, but it contributes significantly to a wider portfolio of landuse strategy, stimulating the call for innovations both in technology and emissions reduction measures. Food production from marginal soils would worsen soil depletion and nematodes infestation. The restoring of soil fertility avoiding the chemicals usage, and in the mean time the generation of income from vegetable oils, assure the ethical, economical and environmental sustainability of the solution. Policy strategies will be needed to increasingly shift abandoned or low biodiversity value marginal lands to this kind of ecologically-friendly practices.

From the chemical point of view, the high concentration of FFA contained in these raw materials (waste or alternative crops) leading to the formation of soaps during the final transesterification step can be easily overcome by performing a pre-esterification reaction. This treatment allows lowering the acid content of the raw material below the limit required by the biodiesel standard, so avoiding also the formation of soaps during the transesterification stage. The FFA esterification is also helpful in increasing the final yield in biodiesel as it produces methyl esters.

Oilseeds of Brassica juncea, Nicotiana tabacum, rapeseed, palm, soybean and sunflower have been successfully deacidified with esterification reaction. Waste cooking oil (WCO) itself does not represent a good potential raw material for biodiesel production due to its properties which hardly match the required standards. Nevertheless it is possible to exploit this kind of feedstock by its use in blends with other oils characterized by a lower viscosity. The authors have successfully deacidified blend of WCO and rapessed oil, also obtaining an increase of the reaction rate.

Two acid ion exchange resins have been selected as catalysts: Amberlyst®46 (Dow Advanced Materials) and Purolite® D5081 (Purolite). Both these resins gave satisfactory results in the studied reaction. D5081 resulted to me more active than A46, being able to give the maximum of conversion in shorter times than A46, other conditions being equal.

<sup>5</sup> Kindly supplied by Sunchem Holding S.r.l.

<sup>6</sup> Biofence by Triumph Italia S.p.a.

<sup>7</sup> This kind of data is necessary to express results in terms of functional unit as required by a life cycle thinking approach.

A process simulation of the FFA esterification, able to predict the reaction progress through a thermodynamic and kinetic analysis was successfully performed using the software PRO II (SimSci). A pseudohomogeneous model was used for describing the kinetic behaviour of the reaction, using a modified UNIFAC model for the calculation of the activity coefficients (used not only for the phase and chemical equilibria calculations, but also for the kinetic expressions). The data obtained from the use of this model showed to be in a very good correlation with the experimental results
