Alkaline pretreatment and enzymatic hydrolysis of corn stover for bioethanol production

The demand for ethanol in Brazil is growing. However, although the country is one of the largest producers of this fuel, it is still necessary to diversify the production matrix. In that regard, studies with different raw materials are needed, mainly the use of low cost and high available wastes such as lignocellulosic residues from agriculture. Therefore, this study aimed to analyze the bioethanol production from corn stover. An alkaline pretreatment (CaO) was carried out, followed by enzymatic hydrolysis (Cellic Ctec2 and Cellic Htec2) to obtain fermentable sugars. The best experimental condition for the pretreatment and hydrolysis steps resulted in a solution with 0.31 gsugar∙gbiomass-1. Then, the fermentation was performed by the industrial strain of Saccharomyces cerevisiae (PE-2) and by the wild yeast strain Wickerhamomyces sp. (UFFS-CE-3.1.2). The yield obtained was 0.38 gethanol∙gdry biomass-1 was, demonstrating the potential of this process for bioethanol production.

Estimativa da produção de etanol a partir de biomassas lignocelulósicas pré-tratadas com peróxido de hidrogênio

The objective of this work was to compare pre-treatments with hydrogen peroxide at 1 and 2% (v/v) and pH at 11.5 used in elephant-grass (EC), mulatto-grass (HD364) lignocellulosic biomass, bark of rice (CA) and leaves of the pineapple (AB) plant to estimate the production of second-generation ethanol (2G). The experimental design was completely randomized in a 4x2 factorial scheme with four replicates per treatment. Enzymatic hydrolysis was performed with the pretreated biomasses using Cellic/CTec2 enzyme. 7 ml of the hydrolyzed material and 0.14 g of non-isolated Saccharomyces cerevisiae yeast were used. After this dilution the material was taken to a styrofoam oven and measured at the temperature and volume of the gas produced at the time of 0,04; 0,08; 0,2; 0,63; 0,92; 1,19; 1,93; 2,19; 2,82; 3,15; 3,94 hours post-incubation. The results showed that the observed differences between the pretreatments influenced the yield in 2G ethanol differently between the biomasses, being the CE that presented the best yield, however, when evaluating the yield by the peroxide content within each biomass, both AB and EC showed no differences between pre-treatments. HD364 had better yield with 1% peroxide and CA with 2% peroxide.

An Integrated Enzymatic Approach to Produce Pentyl Xylosides and Glucose/Xylose Laurate Esters From Wheat Bran

Alkyl glycosides and sugars esters are non-ionic surfactants of interest for various applications (cosmetics, food, detergency,…). In the present study, xylans and cellulose from wheat bran were enzymatically converted into pentyl xylosides and glucose and xylose laurate monoesters. Transglycosylation reaction catalyzed by the commercial enzymatic cocktail Cellic Ctec2 in the presence of pentanol led to the synthesis of pentyl β-D-xylosides from DP1 to 3 with an overall yield of 520 mg/g of xylans present in wheat bran. Enzymatic hydrolysis of wheat bran with Cellic Ctec2 and subsequent acylation of the recovered D-glucose and D-xylose catalyzed by the commercial lipase N435 in the presence of lauric acid or methyl laurate produced one D-glucose laurate monoester and one D-xylose laurate monoester. An integrated approach combining transglycosylation and (trans)esterification reactions was successfully developed to produce both pentyl xylosides and D-glucose and D-xylose laurate esters from the same batch of wheat bran.

Effect of Microwave Pretreatment on Production of Reducing Sugar from Oil Palm Empty Fruit Bunches

Perlakuan pendahulan biomassa merupakan tahapan terpenting dalam memproduksi produk-produk berbasis bio (bio-based products) secara biologis. Pada penelitian ini, energi gelombang mikro (microwave) digunakan selama perlakuan pendahuluan untuk meningkatkan kinerja proses sakarifikasi tandan kosong kelapa sawit (TKKS) menjadi gula-gula pereduksi. Faktor-faktor yang mempengaruhi perlakuan pendahuluan seperti daya (180-360 watt), waktu iradiasi (5-30 menit), dan solid loading (2,5%-7,5%) dievaluasi. Kinerja hidrolisis TKKS yang telah diberi perlakuan pendahuluan selanjutnya dianalisis dengan Cellic CTec2. Hasil penelitian menunjukkan bahwa cairan residu yang diperoleh setelah perlakuan pendahuluan menghasilkan gula pereduksi dalam jumlah yang rendah, yaitu antara 1,39 dan 3,92 mg/g-TKKS. Akan tetapi, setelah padatan residu dihidrolisis secara enzimatis, rendemen gula pereduksi meningkat secara signifikan. Menariknya, hanya pada level daya terendah (180 watt), gula pereduksi meningkat seiring dengan perpanjangan waktu iradiasi untuk semua solid loading. Sebaliknya, pada 360 watt, semakin lama waktu iradiasi diterapkan, semakin rendah gula pereduksi yang diperoleh untuk semua solid loading. Gula pereduksi tertinggi dihasilkan hingga 151 mg/g-TKKS, yaitu menggunakan 5% padatan pada 180 watt selama 25 menit. Berdasarkan hasil-hasil ini, perlakuan pendahuluan menggunakan gelombang mikro yang diikuti dengan hidrolisis enzimatis merupakan salah satu metode yang potensial untuk memproduksi gula dari TKKS.Pretreatment of biomass is the most crucial step in the biological production of bio-based products. In this study, microwave energy was used during the pretreatment process to enhance the saccharification performance of oil palm empty fruit bunches (OPEFB) into reducing sugar. The influential factors of pretreatment such as power level (180-360 watt), irradiation time (5-30 min), and solid loading (2.5%-7.5%) were evaluated. The performance of pretreated OPEFB hydrolysis was subsequently assessed by Cellic CTec2. The result showed that spent liquor produced after pretreatment only released a low amount of reducing sugar in the range between 1.39 and 3.92 mg/g-OPEFB. After residual solid was enzymatically hydrolyzed, a significant increase in the reducing sugar yield occurred. Interestingly, only at the lowest power level (180 watts), the reducing sugar rose along with the extension of irradiation time for all solid loadings. On the contrary, the longer irradiation time was applied, the lower reducing sugar was acquired at 360 watts for all solid loadings. The highest reducing sugar was produced up to 151 mg/g-OPEFB using 5% solid at 180 watts for 25 min. This indicated that microwave pretreatment followed by enzymatic hydrolysis was one of the potential methods to recover sugars in OPEFB.

Produção de suspensões nanofibrilares de celulose vegetal por meio de processo combinado – Avaliação do gasto energético

RESUMO O presente estudo tem por objetivo produzir nanofibrilas de celulose vegetal com polpa Kraft marrom e branqueada por meio de um pré-tratamento enzimático e posteriormente um mecânico, denominado assim como processo combinado, com o intuito de diminuição de gasto energético. Para isso, as amostras de polpas de celulose foram previamente desestruturadas e encharcadas em água destilada com concentração de 3% de sólidos, afim de homogeneizá-las. Na hidrólise enzimática utilizou-se a enzima comercial Cellic CTec2, em porcentagens que variaram de 0,01 a 0,1% por diferentes períodos (1 e 2 horas). Após o tempo de hidrólise, a polpa foi passada em um moinho de discos, onde nesse processo ocorreu a medida do consumo do gasto energético com auxílio de um medidor de energia. Para a produção do gel, as polpas foram processadas pelo moinho de disco em ciclos de passagens. Para a inibição enzimática o conteúdo foi aquecido à 85°C. Os géis foram armazenados em resfriamento de 5°C. O processo foi caracterizado pelo gasto energético medido a cada amostra, além de ser medido o rendimento de cada gel produzido. De acordo com os resultados o processo combinado, apresentou-se viável para a produção de nanofibrilas de celulose vegetal, pois este diminui o gasto energético comparado com o processo mecânico e com a menor carga enzimática (0,01%). A polpa marrom mesmo sem ter passado por processos de deslignificação mostrou-se promissora na produção das nanofibrilas de celulose vegetal.