Cottonseed oil bleaching by acid-activated montmorillonite

Abstract

A progressive decrease in cation exchange capcity (CEC) values was observed by treating Ca-montmorillonite with sulphuric acid solutions and this can be understood in terms of the layered structure of the clay. Elemental analysis showed that moderate activation occurred and only 25–30% of the octahedral cations were removed. At the same time the total surface area and the clay acidity increase. X-ray and FTIR data confirmed that acid activation affects both the octahedral and the tetrahedral sheets. The efficiency of acid-activated montmorillonite for the bleaching of cottonseed oil was investigated. The differences in bleaching efficiency appeared to be due to differences in the physical and chemical properties of the bleaching media. The oil acid value was not affected by the bleaching procedure but a slight shift in the absorption maximum of the bleached cottonseed oil was observed. Medium activation of the clay (treatment of Ca-montmorillonite with 4 N H2SO4) was the most effective in bleaching the cottonseed oil, resulting in the best colour index and the lowest peroxide value. A linear dependence of the bleaching efficiency on the clay surface area and acidity was observed. The role of the increased Bronsted acidity is also discussed.

Combination of Raman, Infrared, and X-Ray Energy-Dispersion Spectroscopies and X-Ray Diffraction to Study a Fossilization Process

“…The occurrence of silicates and aluminosilicates in both samples is confirmed by other peaks in the FTIR spectra, such as the one at 692 cm −1 , which we associate with Si-O bending, and the peaks at 878 and 911 cm −1 in the fossil spectrum, which we associate with Al-OH stretching [16]. Stretching vibrations of Si-O-Si [15][16][17] were observed at 1,024 and 1,032 cm −1 in the IR spectra of the fossil and matrix, respectively, while a band at 1,120 cm 1 is associated to a bending of the Si-O unit [15]. Finally, the IR spectra of both the fossil and the matrix show vibrations between 3,600 and 3,735 cm −1 , which we associate with Si-OH stretching.…”

“…This indicates that the fossil and matrix contain other minerals. The peak at 526 cm −1 is assigned to Al-Si-O bending [15][16][17], possibly due to aluminosilicate crystalline structures. The occurrence of silicates and aluminosilicates in both samples is confirmed by other peaks in the FTIR spectra, such as the one at 692 cm −1 , which we associate with Si-O bending, and the peaks at 878 and 911 cm −1 in the fossil spectrum, which we associate with Al-OH stretching [16].…”

Adsorption of Gossypol from Cottonseed Oil on Oxides

“…There are discrepancies about the respective influence of the SiO 2 and Al 2 O 3 contents of adsorbents and their efficiency (14,15,18,19). Acid activation of clay generally leads to an improvement of bleaching capacity (17,18,21). However, few authors (17)(18)(19)(20) characterized the texture of the adsorbents; Zaki et al (18) found that the bleaching capacity of activated natural clays varied with pore size and an optimum was observed at a pore diameter of 10 to 12 nm.…”

“…A number of studies have been carried out on the removal of pigments from cottonseed oil by adsorption (12)(13)(14)(15)(16)(17)(18)(19)(20)(21). The results obtained are hardly comparable since the experimental conditions are different from each other and the examined systems are often complex.…”

Optimization of decoloring conditions of crude fatty acids recovered from crude glycerol by acid-activated clay using response surface method

“…This result clearly indicates that clay can remove peroxides concomitantly as well as color impurities from a crude fatty acid solution. The destruction of peroxides in oils by acid-activated clays has been demonstrated in previous reports [17,18,26,27].…”