Sustainable Exploitation of Residual Cynara cardunculus L. to Levulinic Acid and n-Butyl Levulinate

Abstract

Hydrolysis and butanolysis of lignocellulosic biomass are efficient routes to produce two valuable bio-based platform chemicals, levulinic acid and n-butyl levulinate, which find increasing applications in the field of biofuels and for the synthesis of intermediates for chemical and pharmaceutical industries, food additives, surfactants, solvents and polymers. In this research, the acid-catalyzed hydrolysis of the waste residue of Cynara cardunculus L. (cardoon), remaining after seed removal for oil exploitation, was investigated. The cardoon residue was employed as-received and after a steam-explosion treatment which causes an enrichment in cellulose. The effects of the main reaction parameters, such as catalyst type and loading, reaction time, temperature and heating methodology, on the hydrolysis process were assessed. Levulinic acid molar yields up to about 50 mol % with levulinic acid concentrations of 62.1 g/L were reached. Moreover, the one-pot butanolysis of the steam-exploded cardoon with the bio-alcohol n-butanol was investigated, demonstrating the direct production of n-butyl levulinate with good yield, up to 42.5 mol %. These results demonstrate that such residual biomass represent a promising feedstock for the sustainable production of levulinic acid and n-butyl levulinate, opening the way to the complete exploitation of this crop.

Isolation of Pure Lignin and Highly Digestible Cellulose from Defatted and Steam-Exploded Cynara cardunculus

“…The composition of defatted and steam-exploded cardoon ( EC ), measured by the Klason method, − is presented in Table . The analyses are in agreement with that previously reported . After the steam explosion treatment, the biomass displays a minor content of hemicellulose fraction (only 4.7 wt %) and ash (only 0.5 wt %), while cellulose (60.1 wt %) and the acid insoluble fraction (34.7 wt %), usually identified with lignin, represent its major components.…”

“…Defatted cardoon pretreated by steam explosion ( EC ) was provided by University of Perugia. It was collected from the same batch of EC used in previous work . The particle size of the EC fibers was in the range of 2.0–6.0 mm.…”

“…It represents a strategic and promising feedstock for biorefinery processes since it grows on marginal or underutilized lands and in regions with dry climates requiring low levels of fertilization and irrigation. , Due to these properties, many cultivars of cardoon are exploited to produce lignocellulosic biomass and oil seeds as potential building blocks for the manufacture of bioplastic and biofuels. Since cardoon shows interesting dry yield in terms of both lignocellulose biomass (15 tons/hectare/year) and seeds (2 tons/hectare/year), it represents one of the key bioenergy crops in the Mediterranean environment . The agroindustrial waste used in this work consisted of the lignocellulosic fraction without seeds, derived from cardoon oil production.…”

Physicochemical Characterization of Cardoon “Cynara cardunculus” Wastes (Leaves and Stems): A Comparative Study

“…The crystallinity index (CI) was calculated according to the method of Segal, ref. [18] using Equation ( 5): CI% = 100 * I 002 − I am I 002 (5) where:…”

“…The high abundance of this plant in most regions of the country, as well as its nutritional value make their wastes an important resource that needs to be better studied and economically exploited, given that the research on this topic is scant. The improper management of the organic remains of Cardoon led scientists towards finding adequate solutions for reducing their accumulation in the environment and for better capitalisation pathways, such as their use as adsorbents of organic dyes and heavy metals [3,4], feedstock for the sustainable production of levulinic acid and n-butyl levulinate [5], for energy production (e.g., solid biofuel, biodiesel, biomethane and ethanol), for cellulose, pulp and paper production, and for phytochemical and pharmacological purposes [6].…”