One-Pot Reduction of Metal Oxides/Salts with Carbohydrate Biomass Under Mild Hydrothermal Conditions

<p></p><p>Development of novel strategies to make full use of highly functionalized biomass molecules to expand its application fields is crucial to biomass utilization. Due to possessing diverse reducing functional groups such as hydroxyl and aldehyde, carbohydrate biomass can be employed as reductant for metallic material preparation. Particularly, the reducing ability of carbohydrate biomass is enhanced under hydrothermal conditions. The reported studies focused on reduction of metal ions in acidic solution with the aid of biomass. However, we found alkali hydrothermal conditions are favorable to metal compounds reduction, even direct conversion metal oxides to metals. Meanwhile, low molecular weight organic acids were obtained from biomass oxidation. <a>Based on our previous research on direct reduction of CuO and NiO into the corresponding metals, herein, we investigated metal salts reduction with carbohydrates and compared the reduction performance on glucose and cellulose which are the two most abundant carbohydrates with and without alkali addition. Moreover, conversion of other metal oxides (</a>Fe₂O₃, MnO₂, Co₃O₄, PbO₂) with glucose were studied to illustrate the feasibility to direct reduction of metal oxides with carbohydrates under alkali hydrothermal conditions. The reduction pathway study showed not only carbohydrates but also decomposed intermediates can reduce metal oxides. This study may provide an alternative approach to metal preparation in hydrometallurgy.</p><br><p></p>

One-Pot Reduction of Metal Oxides/Salts with Carbohydrate Biomass Under Mild Hydrothermal Conditions

<p></p><p>Development of novel strategies to make full use of highly functionalized biomass molecules to expand its application fields is crucial to biomass utilization. Due to possessing diverse reducing functional groups such as hydroxyl and aldehyde, carbohydrate biomass can be employed as reductant for metallic material preparation. Particularly, the reducing ability of carbohydrate biomass is enhanced under hydrothermal conditions. The reported studies focused on reduction of metal ions in acidic solution with the aid of biomass. However, we found alkali hydrothermal conditions are favorable to metal compounds reduction, even direct conversion metal oxides to metals. Meanwhile, low molecular weight organic acids were obtained from biomass oxidation. <a>Based on our previous research on direct reduction of CuO and NiO into the corresponding metals, herein, we investigated metal salts reduction with carbohydrates and compared the reduction performance on glucose and cellulose which are the two most abundant carbohydrates with and without alkali addition. Moreover, conversion of other metal oxides (</a>Fe₂O₃, MnO₂, Co₃O₄, PbO₂) with glucose were studied to illustrate the feasibility to direct reduction of metal oxides with carbohydrates under alkali hydrothermal conditions. The reduction pathway study showed not only carbohydrates but also decomposed intermediates can reduce metal oxides. This study may provide an alternative approach to metal preparation in hydrometallurgy.</p><br><p></p>

Quality Enhancement Mechanism of Alkali-Free Chinese Northern Steamed Bread by Sourdough Acidification

Alkali was used to adjust the pH and neutralize the excess acids of dough in the processing of Chinese northern steamed bread (CNSB). However, extra alkali addition generally resulted in alkalic flavor and poor appearance. The aim of this work was to investigate the role of proofed dough pH on the texture of CNSB. Correlation analysis demonstrated that the pH value of proofed dough has a significant effect on the textural properties of CNSB. The mechanism studies found that gradual acidification of dough by lactic acid bacteria is a critical factor affecting the process. Conversely, chemical acidification weakened the texture property of products and reduced the dough rheology. Scanning electron microscope (SEM) analysis showed that fermentation with starter for 12 h produced a continuous and extensional protein network in the proofed dough. Furthermore, the decreasing pH of proofed dough increased the extractability of protein in a sodium dodecyl sulfate (SDS)-containing medium and the content of free sulfhydryl (SH). The structure and content of gluten, especially influenced by gradual acidification level, change the quality of the final product. It is a novel approach to obtain an alkali-free CNSB with excellent quality by moderate gluten adjustment.

Alkali addition and roughage inclusion effect on performance and carcass characteristics of feedlot steers fed diets containing 60% dried distillers grains with solubles

Three experiments were conducted to determine the effectiveness of calcium hydroxide (Ca(OH)2) addition and roughage inclusion on digestibility, performance, and carcass characteristics of steers fed 60% dried distillers grains with solubles (DGS). Statistical analyses for studies were conducted using the MIXED procedures of SAS. In experiment 1, 48 steers (353.5 ± 7.55 kg) were allotted to individual pens and fed 1 of 3 diets (dry matter [DM] basis) containing 60% dried DGS, 20% corn silage, and 4% supplement with: 1) 14.5% corn and no Ca(OH)2; 2) 14% corn and 2% Ca(OH)2; and 3) 14.5% additional corn silage and no Ca(OH)2. Steers fed Ca(OH)2 consumed the least (P = 0.03) and steers fed added corn silage consumed the most and had the least gain:feed (P = 0.02). Gain and carcass quality were not affected by treatment (P ≥ 0.48). In experiment 2, 112 steers (375.3 ± 19.25 kg) were allotted to pens (four pens per treatment; seven steers per pen) arranged as a 2 × 2 factorial (roughage × Ca(OH)2) and fed one of four diets (DM basis) containing 60% dried DGS, 17% corn silage, and 4% supplement with: 1) 17.5% corn silage and no Ca(OH)2; 2) 17% corn silage and 2% Ca(OH)2; 3) 17.25% corn stover and no Ca(OH)2; and 4) 17% corn stover and 2% Ca(OH)2. Added stover decreased average daily gain (ADG) compared to added corn silage (P = 0.04). Ca(OH)2 increased ADG when steers were fed stover, but not when steers were fed only corn silage (P = 0.05; interaction). In experiment 3, six ruminally cannulated steers (initial body weight = 352 ± 14.8 kg) were randomly allotted to a 6 × 6 Latin square design to determine the effects of roughage inclusion (corn, corn silage, stover) and Ca(OH)2 addition (0% or 2%) on ruminal characteristics. Feeding stover decreased total volatile fatty acid(s) (VFA) concentration and DM digestibility compared to corn silage or corn (P &lt; 0.01), whereas Ca(OH)2 resulted in greater total VFA concentrations and DM digestibility (P ≤ 0.02). Stover increased rate of DM degradation (Kd) and rate of particle outflow from the rumen (P ≤ 0.04) but decreased extent of DM digestion and mean retention time (P ≤ 0.02) compared to corn or silage. Ca(OH)2 increased Kd (P &lt; 0.01) and tended to increase (P = 0.06) liquid passage rate. In conclusion, added roughage did not improve performance of cattle fed 60% dried DGS. Ca(OH)2 may decrease intake and maintain performance of cattle fed 60% dried DGS with corn silage as the roughage source and increases ADG when corn stover replaces a portion of the corn silage.

Effect of photocatalytic pretreatment of potato starch for bioethanol production using Saccharomyces cerevisiae during simultaneous saccharification-fermentation (SSF)

In this study, the effect of the photocatalytic (PC) pre-treatment with TiO2 during gelatinization (GE) stage in a simultaneous saccharification-fermentation process (SSF) of potato starch for bioethanol production was evaluated. Maximum amount of reducing sugars was 119.3, 114.6 and 104.8 g l-1 for PC→GE, GE→PC and reference (without PC), respectively while bioethanol concentration it increased gradually up to a maximum amount of 128.21, 106.74 and 85.91 g l-1 after 30 h, for PC→GE, GE→PC and reference (without PC), respectively. These results were consistent with the reducing sugars concentration, because bioethanol concentration increased slightly during 18–30 h of fermentation. Although enzymatic activity (ʋmax) for reactions was similar, in reference (without PC pre-treatment) it not promoted quick substrate conversion into ethanol, despite showing the higher affinity enzyme-substrate (Km). Considering traditional potato starch hydrolysis, PC pre-treatment shortened the reaction time of the biological reactions. Thus, the PC pre-treatment of potato starch for bioethanol production could be an environmentally feasible process without acid and alkali addition.