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

Abstract

Crude glycerol, a by-product of the biodiesel production process, contains a high amount of fatty acids that cannot be used directly without removing the strong dark color. This study aims to remove the color impurities in crude fatty acids, prepared by acid-precipitation and hexane extraction, using acid-activated clay as an adsorbent. The effects of bleaching temperature, contact time, the amount of acid-activated clay, and concentration of color impurities were investigated. No significant effects of bleaching temperature or contact time were observed. In an optimization study using the central composite design, complete decolorization was achieved at an optimized condition, in which 3.5 g of clay was added to 10 mL of crude fatty acid solution with an optical density at 373 nm of 20. Notably, more than 80% of the peroxides was concurrently removed. However, a 37% loss in fatty acids was observed during decolorization. The clay was repeatedly used without loss of adsorption capability if it was calcined at 600 o C after use.

Microalgal polyunsaturated fatty acids: Hotspots and production techniques

“…Activated clay is preferred over other decolorization materials, such as activated carbon, activated fuller's earth and attapulgite clay, making it a more suitable choice (Liu and Chen, 2012). Not only can activated clay effectively decolorize crudely extracted biodiesel, but it can also remove most peroxides (Su et al, 2014). For example, commercial montmorillonite clay from Leping, Jiangxi, China (Yang M et al, 2019), and upper Eocene sedimentary clay from Kairouan, Tunisia (Eloussaief et al, 2020) can be modified through proper treatment, greatly improving the adsorption capacity of pigment molecules in oil.…”

Decolorization of Biofuels and Biofuel Blends for Biogenic Carbon Quantification with Liquid Scintillation Radiocarbon Direct Measurement

“…The second wavelength at 400 nm is the peak emission of bis-MSB and peak sensitivity of the liquid scintillation counter. Previously, it has been suggested to quantify decolorization at 375 nm 41 or at 410 nm. 18 The shorter wavelength, 375 nm, is important for energy transfer between the primary and secondary fluors but is near the edge of detection for the spectrophotometer.…”