En este trabajo se ha estudiado la viabilidad de la adsorción con la resina polimérica amberlite XAD-4 como proceso de purificación para la recuperación de furfural de hidrolizados en agua subcrítica obtenidos a partir de rastrojo de maíz. Se analizó el equilibrio de adsorción, obteniéndose una isoterma de adsorción física monocapa favorable para concentraciones de resina superiores al 2 % (p/v). También se examinó el equilibrio de desorción para seleccionar un agente de desorción adecuado, optándose finalmente por el agua.
Después de realizar diversos estudios cinéticos con soluciones acuosas sintéticas de furfural, se determinaron las condiciones óptimas para los procesos de adsorción/desorción en un sistema de lecho fijo y se aplicaron al hidrolizado de agua subcrítica. Se alcanzó un rendimiento del 74,03% en la etapa de adsorción y del 91% en la de desorción. Se obtuvo un rendimiento global de extracción de furfural cercano al 60% con una pureza del 99%.
Corn is the second most abundant cereal crop in the world, growing more than 1100 million
tonnes in 2022 and 3,6 million tonnes in Spain. Its stem and leaves have a rich composition in
hemicellulose, cellulose and lignin, making the use of corn waste a more sustainable
alternative as lignocellulosic biomass for furfural production. Furfural is an aromatic aldehyde
with several applications such as being a great fungicidal agent, removing aromatic
compounds from diesel or its use as raw material in the production of succinic acid,
tetrahydrofuran or furoic acids. Furfural is industrially produced through an acid-base
homogeneous catalysis. First, a sulphuric acid hydrolysis of lignocellulosic biomass followed
by purification process. In this work, the feasibility of adsorption as a downstream purification
process for the recovery of furfural from subcritical water hydrolysates from corn solid waste
was studied. The adsorption equilibrium was studied, obtaining a favorable single-layer
physical adsorption isotherm for resin concentrations above 2 % (w/v) and determining the
negative influence of temperature on the process. Desorption equilibrium was studied to
choose the appropriate desorption agent, ultimately going for water. After various kinetic
studies with aqueous solutions of furfural, optimal conditions for adsorption/desorption
processes in fixed-bed were determined, which were applied to the subcritical water
hydrolysate. A yield of 74,03 % was obtained for the adsorption stage and 91, % for desorption,
althougt the latter was the limiting stage of the process. A total yield of furfural extraction of
nearly 60 % and a purity of 99 % were obtained.
