**3.3.2 Results and discussion**

422 Biodiesel – Feedstocks and Processing Technologies

The experimental study was done with rapeseed oil of Romanian origin or soya oil and by using the lipase from the yeast *Candida rugosa* DSM 70761 obtained in aerobic bio processing, isolated from the cultivation medium and immobilized by adsorption on Merck

The transesterification was done in two variants: (a) in anhydrous medium without organic

The experimental working procedure was: the transesterification reaction was performed in Erlenmayer flasks of 100 mL, containing the tested vegetable oil in a concentration to determine a final triglycerides content of 0.08 mol / L and methanol (this last reagent in molar ratios between 3:1 and 8:1 with the triglycerides substrate). The immobilized enzyme was added in a chosen concentration after a period of 30 minutes at 370C. The reaction was done with continuous mixing of 250 rpm. Each 4 hours' sample from the liquid was analysed by thin layer chromatography and gas chromatography to determine the reaction

a. Thin layer chromatography was done by using the Silicagel G on Al support as stationary phase and the migration solvent was a mixture of petroleum ether: ethylic ether: acetic acid = 80:30:1; the spots were put into evidence in a iodine vapour

b. The fatty acids content in methylic esters was analysed by gas chromatography (GC) using a capillary column with a stationary phase composed from 5% phenyl – 95%

The apparatus was a gas chromatograph 6890N – AGILENT with FID detector and

Reagents: N-hexane; the methylic esters of several fatty acids mostly presented in the


The evaluation is done by the determination of the content in palmitic, oleic, arachidonic

a. Batch enzymatic transesterification with methanol and without organic solvent, characterised by : vegetable oil concentration of 0.09 M; methanol concentration of 0.54 M (ratio of 8:1 methanol: triglycerides substrate); biocatalyst concentration of 5000 UEA / 100 mL reaction medium; reaction temperature of 370C; mixing of 250 rpm;

**3.3 Lipase transesterification 3.3.1 Materials and methods** 

advancement.

atmosphere.

Working conditions:

methylpolysilane.

Celite support (lipase activity of 4701 UEA / g support).

autosampler 7683B; column HP 5, L=30m; φ=0.32mm.

240°C, during 5min.; heating rate of 5°/min.


Three experimental models were studied:

reaction total duration of 24 hr.

and erucic acids. The external standard method is applied.

vegetable oils (rapeseed oil or soya oil).



solvents adding; (b) in hexane (Biosolve).

The most important transesterification results are presented in the Figure 8.

Fig. 8. The vegetable oils transesterification yield for the 3 experimental models: a1-batch model without solvent, with soya oil; a2-batch model without solvent, with rapeseed oil; b-semibatch model without solvent, with soya oil; c1-batch model in hexane with soya oil; c2-batch model in hexane with rapeseed oil

The transesterification was realised with the following biotransformation yields: 56-67 % for the experimental variant a, 69% for the variant b, and 56-63% for the variant c; these results can be improved by adequate optimization procedures to be applied for each technological phase, comprising enzyme obtaining in aerobic bioprocess, lipase immobilization and transesterification performing.
