逆浸透法によるアクリル酸と酢酸の濃度に関する研究

Study on The Concentration of Acrylic Acid and Acetic Acid by Reverse Osmosis.

• Qian Liu
• Lixin Xie
• Hanxiao Du
• Shichang Xu
• Yawei Du

抄録

アクリル酸の製造では、吸着塔からのアクリル酸水溶液の濃度が低いため、アクリル酸を精製するための蒸留工程でのエネルギー消費が大きく、大量の廃液が発生するという問題があった。そこで、吸着塔内の特定のトレイから取り出したアクリル酸水溶液を濃縮する逆浸透法（RO法）が提案された。市販の2つのRO膜(SWC5とSWC6)を用いて、浸透流束と酸保持量に及ぼす運転条件の影響を調べた。運転圧力を4MPa、温度を25℃とした場合、2つの膜の透過液フラックスは約20L・m・hであった。アクリル酸保持率は約８０％、酢酸保持率は約７８％であった。酸溶液に数ヶ月間浸漬した後、２つの膜の特性を試験して耐酸性を評価した。アクリル酸2.5%と酢酸2.5%を含む酸溶液に6ヶ月間浸漬したところ、アクリル酸の保持率はSWC5で5.7%と4.1%、酢酸の保持率はSWC6で4.9%と2.2%減少した。膜表面の形態や化学組成の変化から、一部のアミド結合の加水分解が見られた。

In the production of acrylic acid, the concentration of acrylic acid solution from the adsorption tower was low, which would lead to significant energy consumption in the distillation process to purify acrylic acid, along with the production of a large amount of wastewater. Reverse osmosis (RO) was proposed to concentrate the acrylic acid aqueous solution taken from a specific tray in the absorption tower. The effects of operating conditions on the permeate flux and acid retention were studied with two commercial RO membranes (SWC5 and SWC6). When the operating pressure was 4 MPa and the temperature was 25 °C, the permeate fluxes of two membranes were about 20 L·m·h. The acrylic acid and acetic acid retentions were about 80% and 78%, respectively. After being immersed in the acid solutions for several months, the characteristics of the two membranes were tested to evaluate their acid resistance. After six months of exposure to the acid solution containing 2.5% acrylic acid and 2.5% acetic acid, the retentions of acrylic acid and acetic acid were decreased by 5.7% and 4.1% for SWC5 and 4.9% and 2.2% for SWC6, respectively. The changes of membrane surface morphology and chemical composition showed the hydrolysis of some amide bonds.