Recuperación de furfural de hidrolizados de agua subcrítica mediante un proceso de purificación por adsorción

Abstract

Corn is the second most abundant cereal crop in the world. It generates a large amount of agricultural residues (mainly stalks and leaves) which are commonly dumped in landfills, openly burned or used as fuelwood in boilers or ovens. This meant that, in 2010, 21 % of greenhouse gas emissions were due to the disposal of agricultural waste. In Spain, 819,553.8 tonnes of vegetal waste from agriculture, livestock, fisheries and forestry were produced in 2020. In addition, a total of 5.347 million tonnes of vegetal waste were produced in Castilla y León. The integration of agricultural waste as a raw material for other industrial processes is the essential basis of the circular economy concept to reach the zero waste target. In this sense, the use of corn waste as lignocellulosic biomass can be a cost-effective and sustainable alternative. Lignocellulosic biomass contains three main components based on their mass contributions: cellulose, hemicellulose and lignin. The high hemicellulose content shown in the chemical composition of corn agricultural waste from stalks and leaves (26-21 % hemicellulose) means that they can be considered as a renewable raw material with high potential for furfural production. Furfural is an aromatic aldehyde with a wide range of industrial applications due to its high solvent capacity, its efficacy as a fungicidal agent (even at low concentrations) and as a raw material in the production of succinic acid, furoic acid, piperidine and 2-methylfuran. Furfural is obtained on a large scale from a sulphuric acid hydrolysis process using as feedstock lignocellulosic biomass from sugar cane bagasse or corncob, followed by a purification process by distillation/rectification. The hemicellulose hydrolysis with subcritical water treatment and the adsorption as a purification step can be proposed as ecofriendly alternative technologies with potential to improve the furfural process performance. In this work, the recovery of furfural from subcritical water hydrolysates by an adsorption process was studied. The effect of the adsorbent type, temperature, desorption agent and the presence of impurities on the furfural adsorption has been examined. The most efficient adsorption agent for furfural recovery was the hydrophobic resin amberlite XAD-4, with a recovery factor close to 93 % when 16 % p/v of resin was used. The adsorption isotherms were determined at different working temperature and 25 ºC was selected. 2 % p/v of the XAD-4 resin and a desorption aqueous solution with 0,2 M of NaCl were required for recovery 78 % of the initial furfural of the subcritical water hydrolysate.