Alfano Sara, Lorini Laura, Majone Mauro, Sciubba Fabio, Valentino Francesco, Martinelli Andrea
Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy.
NMR-Based Metabolomics Laboratory (NMLab), Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy.
Polymers (Basel). 2021 Aug 19;13(16):2789. doi: 10.3390/polym13162789.
Volatile fatty acids obtained from the fermentation of the organic fraction of municipal solid waste can be used as raw materials for non-toxic ethyl ester (EE) synthesis as well as feedstock for the production of polyhydroxyalkanoates (PHAs). Taking advantage of the concept of an integrated process of a bio-refinery, in the present paper, a systematic investigation on the extraction of intracellular poly(3-hydroxybutyrate--3-hydroxyvalerate), produced by mixed microbial culture by using EEs was reported. Among the tested EEs, ethyl acetate (EA) was the best solvent, dissolving the copolymer at the lowest temperature. Then, extraction experiments were carried out by EA at different temperatures on two biomass samples containing PHAs with different average molecular weights. The parallel characterization of the extracted and non-extracted PHAs evidenced that at the lower temperature (100 °C) EA solubilizes preferentially the polymer fractions richer in 3HV comonomers and with the lower molecular weight. By increasing the extraction temperature from 100 °C to 125 °C, an increase of recovery from about 50 to 80 wt% and a molecular weight reduction from 48% to 65% was observed. The results highlighted that the extracted polymer purity is always above 90 wt% and that it is possible to choose the proper extraction condition to maximize the recovery yield at the expense of polymer fractionation and degradation at high temperatures or use milder conditions to maintain the original properties of a polymer.
从城市固体废物有机部分发酵获得的挥发性脂肪酸可作为合成无毒乙酯（EE）的原料以及生产聚羟基脂肪酸酯（PHA）的原料。利用生物炼制综合工艺的概念，本文报道了关于使用乙酯提取混合微生物培养产生的细胞内聚（3-羟基丁酸酯-3-羟基戊酸酯）的系统研究。在所测试的乙酯中，乙酸乙酯（EA）是最佳溶剂，能在最低温度下溶解共聚物。然后，用EA在不同温度下对两个含有不同平均分子量PHA的生物质样品进行了提取实验。对提取的和未提取的PHA进行的平行表征表明，在较低温度（100℃）下，EA优先溶解富含3HV共聚单体且分子量较低的聚合物级分。将提取温度从100℃提高到125℃时，回收率从约50 wt%提高到80 wt%，分子量降低48%至65%。结果表明，提取的聚合物纯度始终高于90 wt%，并且可以选择合适的提取条件，以牺牲聚合物在高温下的分级和降解为代价来最大化回收率，或者使用较温和的条件来保持聚合物的原始性能。
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