Vol.:(0123456789) 1 3 Waste Biomass Valor DOI 10.1007/s12649-017-9989-7 ORIGINAL PAPER Efect of Steam Explosion Pretreatment Catalysed by Organic Acid and Alkali on Chemical and Structural Properties and Enzymatic Hydrolysis of Sugarcane Bagasse Thiago Alves Lopes Silva 1  · Hernán Dário Zamora Zamora 1  · Leandro Henrique Ribeiro Varão 1  · Natália Soares Prado 1  · Milla Alves Baf 2  · Daniel Pasquini 1   Received: 5 February 2017 / Accepted: 12 June 2017 © Springer Science+Business Media B.V. 2017 Keywords Steam explosion · Lignocellulosic biomass · Enzymatic hydrolysis · Total reducing sugars Introduction At present, the global energy matrix uses on average 80% of non-renewable fossil fuels to support the growing demand for energy required by various sectors of the economy [1]. However, the exhaustion and lack of uniformity in the dis- tribution of reserves, fuctuations in prices and the various environmental impacts caused by fossil fuel burning, such as the release of greenhouse gases and global warming [2], have boosted the search for renewable energy sources. The most commonly produced renewable source fuel is frst-generation ethanol, which is commonly obtained from corn, wheat, sugar beet and sugar cane [3]. In this context, Brazil occupies a prominent place, along with the United States, in ethanol production; however, the Brazilian model uses the fermentation of carbohydrates present in sugarcane juice (sucrose), while the North American model uses the enzymatic activity on corn starch [4]. Another source of renewable raw material for ethanol production by the second generation route is lignocellulosic residues, which represent 50% of the available biomass in the world [5]. Several studies have demonstrated the use of lignocellulosic materials in the production of second gen- eration ethanol, such as corn straw [6], sugarcane straw [7], sugarcane bagasse (SCB) [8–10], rice straw [11, 12] and wheat straw [13], among others. In the Brazilian scenario, SCB is a highlight. It is the residue obtained after the crushing of sugarcane carried out to obtain the juice used in sugar and ethanol production. In Brazil, the high production of sugar and alcohol has gener- ated large amounts of bagasse [14]. According to Clauser Abstract This study researched the steam explosion efect catalysed by citric acid and sodium hydroxide on the chemical and structural properties of sugarcane bagasse and on the enzymatic hydrolysis process. Chemical and structural characterisation of raw and pretreated biomass was performed by reference methodologies for lignocel- lulosic materials, FTIR, XRD, TGA and SEM. Enzymatic hydrolysis was performed with a fnal volume of 20 mL consisting 3% sugarcane bagasse (dry weight), sodium cit- rate bufer 50 mM (pH = 5.0) and 1 g enzyme/100 g cel- lulose of Cellic ® Cetec 3 enzyme complex. The total reduc- ing sugars were determined by a 3,5-dinitrosalicilic acid method. In explosion pretreatment catalysed by citric acid, a biomass was obtained with a lesser amount of hemicel- luloses (16.16%), a higher initial degradation tempera- ture and formation of cracks in fbre cell wall. Pretreated bagasse by NaOH steam explosion showed complete destructuring of fbre, lignin removal of 65% and hemicel- lulosic fraction preservation. Sugarcane bagasse obtained after NaOH steam explosion showed the highest produc- tion of reducing sugars (9.07 g L −1 ), which can be attrib- uted to greater exposure of carbohydrate fraction promoted by lignin removal, since these parameters showed a strong negative correlation (r = −0.99, p < 0.05). * Daniel Pasquini daniel.pasquini@ufu.br 1 Chemistry Institute, Federal University of Uberlândia, Av. João Naves de Ávila, 2121, Santa Mônica, Polymer Recycling Laboratory, Bloco 3O, Uberlândia, MG CEP 38400-902, Brazil 2 Agricultural Sciences Institute, Federal University of Uberlândia, Av. Amazonas, s/n, Umuarama, Environmental Microbiology Laboratory, Bloco 2E, Uberlândia, MG CEP 38405-320, Brazil