1,720,981 research outputs found
Fermentable Sugar Production from a Coffee Processing By-product after Deep Eutectic Solvent Pretreatment
No full textKinetic Characterization of Enzymatic Hydrolysis of Apple Pomace as Feedstock for a Sugar-based Biorefinery
No full textThe enzymatic hydrolysis of cellulose from biomass feedstock in the sugar-based biorefinery chain is penalized by enzyme cost and difficulty to approach the theoretical maximum cellulose conversion degree. As a consequence, the process is currently investigated to identify the best operating conditions with reference to each biomass feedstock. The present work reports an investigation regarding the enzymatic hydrolysis of apple pomace (AP). AP is an agro-food waste largely available in Europe that might be exploited as a sugar source for biorefinery purposes. A biomass pre-treatment step was required before the enzymatic hydrolysis to make available polysaccharides chains to the biocatalyst. The AP samples were pre-treated through alkaline (NaOH), acid (HCl), and enzymatic (laccase) delignification processes to investigate the effect of lignin content and polysaccharides composition on enzymatic hydrolysis. Enzymatic hydrolysis tests were carried out using a commercial cocktail (Cellic®CTec2) of cellulolytic enzymes. The effect of mixing speed and biomass concentration on the experimental overall glucose production rate was assessed. The characterization of the glucose production rate by the assessment of pseudo-homogeneous kinetic models was proposed. Data were analysed to assess kinetic parameters of pseudo-mechanistic models able to describe the glucose production rate during AP enzymatic hydrolysis. In particular, pseudo-homogeneous Michaelis and Menten, as well as Chrastil’s models were used. The effect of lignin content on the enzymatic hydrolysis rate was evaluated. Chrastil’s model provided the best description of the glucose production rate
Integrated enzymatic pretreatment and hydrolysis of apple pomace in a bubble column bioreactor
No full textWaste biomass from agro-food industry can be exploited to produce several products according to the sugar-based biorefinery concept. The success of the biomass exploitation stems from the equilibrium among severalissues regarding the process costs, the environmental impact, and the energy efficiency. The present work isfocused on the use of apple pomace as possible renewable feedstock for the production of biofuels and of bio-commodities. The aim of the present work was the optimization of the enzymatic pretreatment and hydrolysis ofapple pomace in a bubble column bioreactor by using a recombinant laccase as biocatalyst for the delignificationstep and commercial cellulases for the hydrolysis step. Both the enzymatic processes were investigated to selectthe optimal operating conditions for the maximization of sugar yields. Optimal conditions for the sequentialenzymatic delignification and hydrolysis process in the bubble column were: 15%w/v biomass concentration;60 nL/h airflow rate, 30 U/gbiomasslaccase activity; 20 FPU/gcellulosecellulase activity. Moreover, the selectedoperating conditions were applied to a long term test of the sequential pretreatment/hydrolysis in the bubblecolumn that resulted in a maximum sugar yield of 0.34 gsugars/graw biomassand 0.61 gsugars/gsugars in the pretreatedbiomassfrom the raw apple pomace. Result discussion highlighted advantages and drawback of pneumatic mixingand sequential pretreatment/hydrolysis strategy applied to enzymatic delignification and cellulose hydrolysis
Bio-butanol recovery by adsorption/desorption processes
No full texthe Acetone-Butanol-Ethanol (ABE) fermentation route to produce chemicals and fuels from renewable resources still suffers from several issues that severely limit the industrial development. In particular, the low butanol concentration in the fermentation broth - due to butanol toxicity to microorganisms – affects the energy sustainability of technologies for butanol recovering. Novel techniques have been investigated in the last years. Among these, adsorption-based technique has been proposed as the most promising one. Present study reports on the assessment of the efficiency of butanol recovery according to adsorption and desorption processes. Tests were carried out using Amberlite XAD-7 as adsorbent material with respect to butanol, ethanol, acetone, and acetic/butyric acids in aqueous solutions. Amberlite XAD-7 was successfully used in fixed-bed column lab apparatus. Two desorption techniques were investigated – thermal drying/desorption and displacement desorption by methanol – to select the best candidate in terms of mass and energy efficiency. This study proved that Amberlite XAD-7 is a potential good adsorbent material to be successfully used in the process of butanol recovery. Amberlite XAD-7 was characterized by high adsorption capacity and selectivity towards butanol. Indeed, the adsorption capacity for acetone, butanol, ethanol, acetic and butyric acid was 17.1, 102.1, 4.2, 14.1 and 21.3 mg/g, respectively when using a solution of 13 g/L of butanol, 5.8 g/L of acetone, 1.6 g/L of ethanol, 6 g/L of acetic acid and 9 g/L of butyric acid. Moreover, adsorbed butanol was recovered as a high butanol concentration solution according to thermal (butanol concentration higher than 800 g/L) and chemical desorption processes (butanol concentration in methanol solution higher than 20 g/L, that is about 1.7 times the concentration in the stream used to saturate the resin). The stability of the performance of Amberlite XAD-7 bed with respect to butanol capture and concentration was provided by carrying out the adsorption–desorption cycle ten times. Butanol recovery was always higher than 97% for both the recovery techniques investigated. The overview of the energy demand for the proposed adsorption/thermal drying/desorption process was reported. The energy demand to concentrate butanol from diluted aqueous mixtures (about 13 g/L) is about 13 MJ/kgB, which is a fraction of the energy content of butanol (36 MJ/kgB)
Effect of enzymes adsorption on enzymatic hydrolysis of coffee silverskin: Kinetic characterization and validation
No full textThe use of waste lignocellulose feedstock for sugar-based biorefineries is attracting the interest of the scientific and industrial communities. The aim is to develop efficient sustainable processes to produce fuels and chemicals via the biotechnological route. However, the rational design of processes aimed at fermentable sugar recovery from lignocellulosic wastes asks for reliable quantitative data of a wide spectrum of biomass. Waste biomasses from food industries are among the most studied potential carbon sources. In the present study, the kinetics of enzymatic hydrolysis of coffee silverskin has been characterized. Coffee silverskin is one of the most abundant fractions of the coffee industry waste and it has been already used for saccharification purposes. The experimental investigation provided kinetic parameters of a semi-mechanistic model of glucose production rate from coffee silverskin catalyzed by a commercial cellulase cocktail. In addition, the adsorption of the enzymes on the solid biomass substrate has been characterized according to a Langmuir type model. The effect of enzymes adsorption on cellulose conversion and the process dynamics have been highlighted by validation tests. The optimization of biocatalyst use has been provided via a two-step hydrolysis procedure. The developed procedure can be successfully applied in the future to several biomasses to describe a wide range of possible substrates
Cell Factories for Industrial Production Processes: Current Issues and Emerging Solutions
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Agro Food Wastes and Innovative Pretreatments to Meet Biofuel Demand in Europe
No full textThe use of agricultural residues (AR) and agro-food waste (AFW) as potential feedstocks for the production of second-generation ethanol and butanol is reviewed. The maximum biofuel production rate from AR and AFW was estimated on the basis of the feedstock availability rate, the average composition, and the biofuel yields reported in the literature. According to the estimations, the contribution of ethanol and butanol to current European biofuel accounts could be 32 and 23 % if traditional pretreatments are applied, and 40 and 19 % if they are produced by innovative pretreatments, respectively. Finally, the analysis was applied to a local scenario (Campania, Italy), with a view to potential decentralized exploitation of AR and AFW.</p
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