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China Surfactant Detergent & Cosmetics ›› 2025, Vol. 55 ›› Issue (10): 1245-1251.doi: 10.3969/j.issn.2097-2806.2025.10.003

• Basic research • Previous Articles     Next Articles

Reversible pH response of disodium monotetradecyl phosphate and how to recover it from solutions or emulsions

Yu Yao1,Huanjin Zou2,Xuefeng Liu1,*()   

  1. 1. Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi, Jiangsu 214122, China
    2. Zanyu Technology Group Co., Ltd., Hangzhou, Zhejiang 310030, China
  • Received:2024-11-25 Revised:2025-10-28 Online:2025-10-22 Published:2025-12-03
  • Contact: Xuefeng Liu E-mail:xfliu@jiangnan.edu.cn

Abstract:

The aim of this study was to verify whether disodium monoalkyl phosphate was reversibly pH-responsive. In this work, monotetradecyl phosphate (MC14P) was synthesized by pyrophosphoric acid method, and then the disodium salt (MC14P-2Na) and monosodium salt (MC14P-Na) thereof were obtained by neutralizing MC14P with NaOH. The results showed that MC14P-2Na was a precipitation-dissolution switchable surfactant with good reversible pH response. At pH of 11.5, the Krafft temperature (KT) of MC14P-2Na was approximately 0.4 ℃, and the critical micelle concentration (cmc) was approximately 1.9×10-2 mol/L (at 25 ℃); at pH of 6.3, MC14P-2Na was changed into the poorly water-soluble MC14P-Na with a KT of approximately 47.9 ℃ and thus poor surface activity and interfacial activity; when pH was cycled between 11.5 and 6.3, corresponding cycles between MC14P-2Na and MC14P-Na were found, without abnormalities for at least 10 cycles. Based on the pH-dependent reversible change between MC14P-2Na and MC14P-Na, MC14P-2Na could be recovered from micellar solutions and emulsions by converting MC14P-2Na to MC14P-Na with average recovery rate of approximately 96.9% and 95.1%, respectively, and the MC14P-Na thus gathered could be converted back to MC14P-2Na by neutralizing with NaOH.

Key words: monotetradecyl phosphate, reversible control via pH, surfactant recovery

CLC Number: 

  • TQ423