Research Progress in Liquid-liquid Extraction Technology for In Situ Extraction of Medium Chain Carboxylic Acids

doi:10.13560/j.cnki.biotech.bull.1985.2025-1171

Abstract

Abstract:

Medium chain carboxylic acids (MCCAs), as high-value platform chemicals, show extensive applications in food, chemical, pharmaceutical, and biomaterial industries due to their unique physicochemical properties. There are numerous technical bottlenecks, including high dependence on petrochemical resources, low product yield and purity, high energy consumption, and poor stability of the vegetable oil raw material supply chain in traditional chemical synthesis methods for producing MCCAs. Existing production capacity can no longer meet the rapidly growing market demand. Therefore, the application of microbial carbon chain elongation technology to convert waste biomass into high-value MCCAs not only facilitates the recycling of organic carbon sources, but also mitigates reliance on fossil resources. This synergistically integrates environmental sustainability, economic viability, and industrial scalability, positioning it as a highly promising strategy in green biomanufacturing. However, the efficient separation technology for microbial carbon chain elongation-derived MCCAs is still a critical bottleneck. Among various separation technologies, liquid-liquid extraction stands out with its significant advantages, demonstrating considerable potential for in situ extraction and purification of MCCAs. This review begins with the metabolic pathway of microbial carbon chain elongation for MCCAs synthesis. Through a comparative analysis of several in-situ separation technologies for MCCAs, it systematically reviews the technical principles, process parameters, key influencing factors, and bottlenecks in scale-up application of liquid-liquid in-situ extraction of MCCAs. In the future, the large-scale application of MCCAs production technology can be facilitated through innovations in extractant formulations and digital upgrades to online extraction processes, thereby contributing to the achievement of the “dual carbon” goal.

Key words: medium chain carboxylic acids, microbial carbon chain elongation, waste biomass, liquid-liquid extraction, in situ extraction

WANG Ting, XU Shao-qin, MING Ting-hong, XU Jia-jie. Research Progress in Liquid-liquid Extraction Technology for In Situ Extraction of Medium Chain Carboxylic Acids[J]. Biotechnology Bulletin, 2026, 42(7): 81-96.

Figures/Tables 8

References 82

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类别 Category	化合物 Compound	碳原子数 Number of carbon atoms	溶解度 Solubility （mg/L） ^a	电子密度 Electron density （g COD/g） ^b	酸度系数 Acidity coefficient （pKa）
短链羧酸	乙酸	2	互溶	1.07	4.76
	丙酸	3	互溶	1.51	4.88
	丁酸	4	60 000	1.82	4.82
	戊酸	5	24 000	2.04	4.84
中链羧酸	己酸	6	10 300	2.20	4.80
	庚酸	7	2 820	2.34	4.80
	辛酸	8	735 ^c	2.44	4.89
	壬酸	9	284 ^d	2.53	4.95
	癸酸	10	62	2.60	4.90
	十一烷酸	11	52	2.66	4.95
	月桂酸	12	4.8	2.72	5.30

类别 Category	化合物 Compound	碳原子数 Number of carbon atoms	溶解度 Solubility （mg/L） ^a	电子密度 Electron density （g COD/g） ^b	酸度系数 Acidity coefficient （pKa）
短链羧酸	乙酸	2	互溶	1.07	4.76
	丙酸	3	互溶	1.51	4.88
	丁酸	4	60 000	1.82	4.82
	戊酸	5	24 000	2.04	4.84
中链羧酸	己酸	6	10 300	2.20	4.80
	庚酸	7	2 820	2.34	4.80
	辛酸	8	735 ^c	2.44	4.89
	壬酸	9	284 ^d	2.53	4.95
	癸酸	10	62	2.60	4.90
	十一烷酸	11	52	2.66	4.95
	月桂酸	12	4.8	2.72	5.30

类别 Category	萃取机理 Extraction mechanism	代表性萃取剂 Representative extractant	萃取的羧酸 Extracted carboxylic acids	参考文献 Reference
非极性萃取剂	主要通过范德华力与MCCAs分子发生疏水性缔合	正己烷	己酸	［45］
磷基萃取剂	通过磷氧基（P=O）上的孤对电子与MCCAs的羧基形成配位键或氢键	磷酸三丁酯（TBP）	己酸	［46］
		三辛基氧膦（TOPO）	乙酸、丁酸、丙酸、己酸、辛酸	［47-49］
		Cyanex 923	己酸、辛酸	［47， 49］
胺基萃取剂	与MCCAs形成氢键或离子对（酸碱反应）	三辛胺（TOA）	己酸、辛酸	［47］
		Aliquat 336	己酸	［50］
		三月桂胺（TDA）、三己胺（THA）、三丙胺（TPA）、三辛胺（TOA）	己酸	［51］

类别 Category	萃取机理 Extraction mechanism	代表性萃取剂 Representative extractant	萃取的羧酸 Extracted carboxylic acids	参考文献 Reference
非极性萃取剂	主要通过范德华力与MCCAs分子发生疏水性缔合	正己烷	己酸	［45］
磷基萃取剂	通过磷氧基（P=O）上的孤对电子与MCCAs的羧基形成配位键或氢键	磷酸三丁酯（TBP）	己酸	［46］
		三辛基氧膦（TOPO）	乙酸、丁酸、丙酸、己酸、辛酸	［47-49］
		Cyanex 923	己酸、辛酸	［47， 49］
胺基萃取剂	与MCCAs形成氢键或离子对（酸碱反应）	三辛胺（TOA）	己酸、辛酸	［47］
		Aliquat 336	己酸	［50］
		三月桂胺（TDA）、三己胺（THA）、三丙胺（TPA）、三辛胺（TOA）	己酸	［51］