Universidade Federal do Ceará, Departamento de Engenharia Química, Campus do Pici, Bloco 709, 60440-900 Fortaleza, CE, Brazil.
Universidade Federal do Ceará, Departamento de Engenharia Química, Campus do Pici, Bloco 709, 60440-900 Fortaleza, CE, Brazil.
Ultrason Sonochem. 2021 Nov;79:105765. doi: 10.1016/j.ultsonch.2021.105765. Epub 2021 Sep 25.
Epoxy resins made from vegetable oils are an alternative to synthesize epoxy resins from renewable sources. Tung oil is rich in α -eleostearic fatty acid, which contains three double bonds producing epoxy resins with up to three epoxy groups per fatty acid. This work studied the production of tung oil epoxy resin using hydrogen peroxide as an oxidizing agent and acetic and formic acid as percarboxylic acid precursors, applying low frequency high power ultrasound. This study evaluated the effects of ultrasound power density, hydrogen peroxide concentration, acetic acid concentration, and formic acid concentration on the yield into epoxy resin, selectivity, and by-products formation. Application of ultrasound was carried out using a 19 kHz probe ultrasound (horn ultrasound) with a 1.3 cm diameter titanium probe, 500 W nominal power, 2940 W L maximum effective power density applied to the reaction mixture. Ultrasound technology yielded up to 85% of epoxy resin in 3 h of reaction. The use of formic acid resulted in a slightly lower oil conversion than acetic acid but with a much higher selectivity towards epoxidized tung oil. However, using acetic acid resulted in the production of high-value by-products, such as 2-heptenal and 2,4-nonadienal. The ultrasound-assisted epoxidation showed to be particularly efficient when applied to oils containing conjugated double-bonds.
由植物油制成的环氧树脂是合成可再生来源环氧树脂的替代品。桐油富含α-桐酸，其中含有三个双键，可产生每个脂肪酸含有三个环氧基团的环氧树脂。本工作研究了用过氧化氢作为氧化剂，用乙酸和甲酸作为过氧羧酸前体，应用低频高功率超声制备桐油环氧树脂。本研究评估了超声功率密度、过氧化氢浓度、乙酸浓度和甲酸浓度对环氧转化率、选择性和副产物形成的影响。超声应用采用直径为 1.3cm 的钛探头、标称功率为 500W 的 19kHz 探头超声（号角超声），在反应混合物上施加 2940W/L 的最大有效功率密度。超声技术在 3 小时的反应中可得到高达 85%的环氧树脂。甲酸的使用导致油转化率略低于乙酸，但对氧化桐油的选择性要高得多。然而，使用乙酸会产生高价值的副产物，如 2-庚醛和 2,4-壬二烯醛。超声辅助氧化在应用于含有共轭双键的油时表现出特别高的效率。
