Category Archives: Biomass Conversion

Two-Stage Systems

Complete degradation of 1 mol of glucose can yield a 12 mol of hydrogen by combining fermentation and photofermentation in a two stage system. According to the Gibbs free energy of this reaction, complete oxidation of glucose into hydrogen and carbon dioxide is not feasible thermodynamically (Eq. 10.15).

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Evolution of Products and Temperature During Lignin Oxidation

The typical profiles of phenolic products and temperature as function of time is shown in Fig. 12.8 for the oxidation of a softwood kraft lignin (a) and hardwood organosolv lignin (b) [20]. The yields of vanillin and syringaldehyde clearly predominate over the vanillic acid and syringic acid. The concentration of the phenolic aldehydes and their respective acids increases continuously until […]

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Dilute-Acid Hydrolysis

Pretreatment by using dilute-acid processes for the hydrolysis of hemicellulose renders the cellulose fraction more amenable for a further enzymatic treatment, but in this case a two-step-hydrolysis is required. The dilute acid process is conducted under high temperature and pressure, and has a reaction time in the range of seconds or minutes, which facilitates continuous processing. The difference between these […]

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Ion Exchange Processes

Another direct method to recover vanillin from the oxidized liquor is based on adsorption and ion exchange principles. Using a strong sulfonic acid resin in its Na+ form, sodium vanillate can be separated from lignosulfonates, sodium hydroxide and sodium carbonate, which are eluted first [166, 167]. This treatment should be performed between oxidation and extraction steps in vanillin production showing […]

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Substrates for Dark Fermentation

A wide range of different organic substrates can be used for biohydrogen pro­duction by dark fermentation. As noted above, carbohydrates are the most suitable, and thus the most studied carbon sources, since they have a hydrogen production potential 20 times higher than with fat and proteins [62]. Biodegradability, availability, cost and carbohydrate content are the most important factors for selection […]

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Producers and End Users

Kraft lignin is presently available from MeadWestvaco Corp. (USA) and Borreg — aard Lignotech (about 10 thousand t/year at Backhammar plant), accounting for a total annual production around 1 million t [5]. This is a rather low production value considering that a mill with capacity for 500 thousand t of kraft pulp can produce about 200 thousand t of lignin […]

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Brief Description of Bioextraction Process

Bioextraction incorporates a range of technologies that not only use plants to remove, reduce, degrade, or immobilize environmental pollutants from soil and water, for restoration of contaminated sites to a relatively clean, non-toxic envi­ronment but also use microbes to extract metals from the low grade ores. This relatively new and growing technology uses natural processes to break down, stabilize, or […]

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Organosolv Fractionation of Lignocelluloses for Fuels, Chemicals and Materials: A Biorefinery Processing Perspective

Ming-Fei Li, Shao-Ni Sun, Feng Xu and Run-Cang Sun 11.1 Introduction Fractionation of lignocellulosic materials into their major macromolecular fractions—cellulose, hemicelluloses and lignin, is a challenging work that attracted increased attention in recent years. As a matter of fact, in addition to chemical pulping, an existing fractionation process used worldwide, numerous approaches for the separation of lignocelluloses have been studied […]

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