Compositional analysis of the sterol fraction of olive oil can be used to assess the degree of purity of the oil and the absence of admixture with other plant oils. This determination also permits characterization of the type of olive oil in question: virgin, refined, or solvent‐extracted. In the present work, 130 samples of olive oil were analyzed, the sterol fractions were separated from the unsaponifiable fraction by silica gel plate chromatography, and later they were analyzed as the trimethylsilyl ether derivatives by capillary column gas chromatography. From the results obtained, it was concluded that this methodology is able to differentiate among virgin, refined, and solvent‐extracted olive oils. Stigmasterol, clerosterol, Δ5‐avenasterol, Δ7‐stigmasterol, and Δ7‐avenasterol permit the differentiation of the three types of oil from one another. Campesterol, Δ5, 23‐stigmastadienol, β‐sitosterol, and Δ5,24‐stigmastadienol permit the differentiation of only two oils from each other but confirm the conclusions obtained for other sterols. Correlations between the different sterols of virgin, refined, and solven‐extracted olive oil also have been obtained.
The adsorption by different silicate minerals of some heavy metals, present in industrial waste water, has been studied. These adsorbents (mainly clay minerals) are readily available, inexpensive materials and offer a cost-effective alternative to conventional treatment of wastes from the metal finishing industry. The results show that some mineral species are suitable for the purification of such residual waters down to the limits prescribed by current legislation concerning industrial wastes. The Langmuir model was found to describe such adsorption processes best. Sepiolite (Orera, Spain) has an adsorption capacity of 8.26 mg g-1 for Cd2+, the capacities depending on the metal adsorbed in the order: Cd2+ > Cu2+ > Zn2+ > Ni2+. This mineral shows the highest sorption capacity relative to the other minerals studied. Factors in the reaction medium such as pH and ionic strength influenced the adsorption process.
The adsorption by different silicate minerals of some heavy metals, present in industrial waste water, has been studied. These adsorbents (mainly clay minerals) are readily available, inexpensive materials and offer a cost-effective alternative to conventional treatment of wastes from the metal finishing industry. The results show that some mineral species are suitable for the purification of such residual waters down to the limits prescribed by current legislation concerning industrial wastes. The Langmuir model was found to describe such adsorption processes best. Sepiolite (Orera, Spain) has an adsorption capacity of 8.26 mg g 1 for Cd 2+, the capacities depending on the metal adsorbed in the order: Cd 2 § > Cu 2 § > Zn 2 § > Ni 2+. This mineral shows the highest sorption capacity relative to the other minerals studied. Factors in the reaction medium such as pH and ionic strength influenced the adsorption process.
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