Mechanism of selective hydrolysis of alginates under hydrothermal conditions

IF 20.2 Q1 MATERIALS SCIENCE, PAPER & WOOD
Taku Michael Aida , Yasuaki Kumagai , Richard Lee Smith Jr
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引用次数: 0

Abstract

Mechanisms of selective hydrolysis of alginates under hydrothermal conditions were investigated by comparing reactivities of sodium alginate (Na-ALG, 960 ku) solutions and calcium alginate (Ca-ALG) gels as substrates. Under hydrothermal conditions (150 °C), hydrolysis of Na-ALG gave product molecular weights of 223, 66, 26 and 17 ku while those of Ca-ALG gave product molecular weights of 340, 102, 45 and 31 ku for reaction times of 10, 20, 30 and 60 min, respectively. The ratios of mannuronic acid (M) to guluronic acid (G) varied only slightly (from 1.3 to 1.2) for Na-ALG over the range of reaction times at 150 °C, while ratios (M/G) for Ca-ALG exhibited a remarkable decrease (from 1.1 to 0.8). Diad sequence of alginate products obtained for Na-ALG were 17%, 23%, 27% and 31% (GG); 30%, 32%, 36% and 38% (MM); and 53%, 46%, 37% and 32% (GM+MG); while for Ca-ALG they were 18%, 22%, 24% and 33% (GG); 26%, 23%, 26% and 18% (MM); and 56%, 54%, 50% and 48% (GM+MG). Reaction mechanisms are proposed for hydrolysis of alginate solutions and alginate gels under hydrothermal conditions; de-polymerization of alginates into monomers and monomeric sequences can be controlled not only by hydrothermal conditions, but also by varying the physical state (solution, gel) of the starting materials.

水热条件下海藻酸盐选择性水解机理研究
通过比较海藻酸钠(Na-ALG, 960 ku)溶液和海藻酸钙(Ca-ALG)凝胶作为底物的反应活性,研究了水热条件下海藻酸盐选择性水解的机理。在水热条件下(150℃),反应时间分别为10、20、30和60 min, Na-ALG水解产物分子量分别为223、66、26和17 ku, Ca-ALG水解产物分子量分别为340、102、45和31 ku。在150°C的反应时间范围内,Na-ALG的甘露醛酸(M)与古鲁醛酸(G)的比值变化不大(从1.3到1.2),而Ca-ALG的比值(M/G)则显著下降(从1.1到0.8)。Na-ALG获得的海藻酸盐产物双序列分别为17%、23%、27%和31% (GG);30%、32%、36%、38% (MM);53%、46%、37%和32% (GM+MG);Ca-ALG分别为18%、22%、24%和33% (GG);26%、23%、26%、18% (MM);56%、54%、50%和48% (GM+MG)。提出了水热条件下海藻酸盐溶液和海藻酸盐凝胶水解的反应机理;海藻酸盐解聚成单体和单体序列不仅可以通过水热条件控制,还可以通过改变起始材料的物理状态(溶液、凝胶)来控制。
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来源期刊
Journal of Bioresources and Bioproducts
Journal of Bioresources and Bioproducts Agricultural and Biological Sciences-Forestry
CiteScore
39.30
自引率
0.00%
发文量
38
审稿时长
12 weeks
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