Adsorption of glycerol, monoglycerides and diglycerides present in biodiesel produced from soybean oil

Abstract

The most common methods currently used for the removal of waste glycerol, monoglycerides and diglycerides remaining after phase separation during biodiesel production involve wet processes. These procedures are not environmentally viable because they require large volumes of water and thus generate significant quantities of effluent. In this study, adsorption was employed to replace this purification step. Some commercial activated carbons were tested along with adsorbents chemically modified with HNO3. A kinetics study was conducted at 30 degrees C and adsorption isotherms were obtained at 20 degrees C, 30 degrees C and 40 degrees C. The results indicated that the adsorption of glycerol increased with the use of chemically-modified activated carbon, showing that pH has a strong influence on glycerol adsorption. The pseudo-first-order kinetic model provided the best fit with the experimental data for the monoglycerides while the pseudo-second-order model showed a better fit for the glycerol and diglycerides. The Freundlich model had the best fit with experimental data on the adsorption equilibrium for all temperatures. The thermodynamic study indicated that the adsorption process is endothermic and thus adsorption is favoured by increasing the temperature. The adsorption process using chemically-modified activated carbon was therefore very effective for the removal of waste glycerol resulting from biodiesel production, which is of considerable significance given the legal limits imposed.

Epoxy resin blends and composites from waste vegetable oil

“…As there is no literature supporting the purification of WVO specifically for the production of epoxy resins, different purification procedures were tested based on existing methodologies reported for the biodiesel area. [26,27] These procedures target the removal of highly oxidized compounds formed by the frying process (e.g. aldehydes) and hydrolysis products such as mono-and diglycerides.…”

“…aldehydes) and hydrolysis products such as mono-and diglycerides. Samples were purified by extraction of polar products with water at 60 C (single and multiple extraction) and adsorption with activated carbon and chemically modified activated carbon with nitric ions as described by Vásques et al [27] This permitted the classification of the oil samples in three different categories: ppm are specifically associated with n-alkanals, (E)-2-alkenals and (E,E)-2,4-alkadienals. [31,32] Investigation of spectra of samples after performing the purification methods demonstrated that all methods were efficient to remove highly oxidized compounds as signals at the 9 -10 ppm region were eliminated.…”

Recent advances in synthesis of polymers based on palm oil and its fatty acids

“…WVO was purified by single 117 and multiple extractions and subsequently purified with activated carbon. 118 Moreover, Issam et al reported on the study of properties of blending various ratios of palm oil-based alkyd to epoxy resins. 113 In general, alkyd resin and epoxy resin showed good compatibility.…”