Cereal bran biorefinery to obtain high value-added products. Fractionation and catalytic dehydration.

LUCAS RETAMAR; FEDERICO PIOVANO; ALICIA BOIX; SOLEDAD ASPROMONTE

Buenos Aires

Congreso; WCCE11-11th World Congress of Chemical Engineering; 2023

Currently, the production systems implemented are based on fossil fuel refineries, which take the exploitation of scarce resources and a considerable environmental impact, contributing to the carbon footprint, acid rain and global warming, as a consequence of the emission of greenhouse gases (GHG) and a high generation of waste. In this sense, biorefineries based on a circular economy arise as a strong alternative to solve this problem, producing CO2 neutral emissions and allowing the revaluation of waste.In this work, the revaluation of a by-product of agricultural production such as wheat bran (WB) was proposed in order to obtain compounds of commercial interest, such as furans (HMF and furfural) and lactic acid (LA).In the first instance, the bran grain was fractionated obtaining an extract (Extracted WB) rich in C6 sugars and a residual solid (Destarched WB) rich in sugars of C5 group. Fractionation process consisted of a hydrothermal extraction at 90 °C with continuous stirring and microwave-assisted heating. Procedure was carried out with suspensions at a concentration of 0.033 g/ml (g WB/ml H2O) and after the extraction was finished (15 min) the aqueous phase was separated by centrifugation (4000 rpm) from the remaining solid (Destarched WB). From the aqueous phase the corresponding extract (Extracted WB) was obtained by ethanol precipitation (95 % v/v). Such procedure is relate to others already reported in literature (1, 2). Both the original raw material (WB) and the different fractions obtained were exhaustively characterized, determining the contents of sugars, starch, protein, cellulose, hemicellulose, lignin, ash and moisture, by means of techniques such as High Performance Liquid Chromatography (HPLC), Fourier-transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), UV-Vis spectroscopy (UV-Vis), Elemental Analysis (CHONS), X-Ray Fluorescence (FRX) along with other analytical procedures. In addition, several images were obtained by Optical Microscopy (OM) and Scanning Electron Microscopy (SEM).In turn, both fractions obtained (WB Extract and Destarched WB) were catalytically evaluated in a dehydration reaction using a stirred batch reactor at 180 °C, 30 atm of N2 and during 120 min. A mesopourous hydrous zirconia (ZrO2) catalyst with a pore diameter of 2.3 nm, a specific surface area of 295 m2/g and a pore volume of 0.21 cm3/g was used in the catalytic process. The catalyst was synthesized by the Sol-Gel method assisted by a non-ionic surfactant, using zirconium n-propoxide as zirconia precursor, Pluronic P123 as surfactant and isopropanol as synthesis medium.The reaction products and by-products derived from the above mentioned tests were identified and quantified by HPLC using UV-Vis and Refraction Index (RI) detectors. Mass yields of 13.0 % for LA and 12.4 % for total furans were obtained for the WB Extract fraction, while mass yields of 11.6 % and 9.1 % for LA and total furans, respectively, were obtained for the Destarched WB fraction. The results achieved are promising and motivate to continue with the optimization of the fractionation processes to improve the mass yields obtained.