Enzymatic demulsification of long-chain alkanoylcholine-based oil-in-water emulsions and microemulsions

Long-chain alkanoylcholines (LCAC) are potential candidates to limit viruses’ transmission and suitable substrates of butyrylcholinesterase (BChE) to be hydrolyzed. Thus, BChE-catalyzed LCAC hydrolysis is expected to be a safer and greener demulsification strategy in demulsifying LCAC-based emulsions and/or microemulsions . Myristoylcholine bromide (MCB)-based oil-in-water (O/W) emulsions with different oils, from hydrocarbon nonpolar oil (octane and D80) to ester-containing polar oil (jojoba oil and edible oil) as well as the complex oily mixture (crude oil), were constructed. MCB-based microemulsions were constructed by pseudo-ternary phase diagram method. The BChE-catalyzed hydrolysis of MCB was monitored by using of two-phase titration. MCB-based O/W type emulsions and microemulsion can be actively demulsified by using of BChE under mild conditions of pH = 7.4 and 37 °C. No lethal adverse effect of the oil type on the BChE-catalyzed hydrolysis of MCB was observed in demulsifying emulsions. BChE can be reused and presented an excellent reusability over five times of recycling, clarifying a promising prospect of this enzymatic demulsification strategy in the treatment of LCAC-emulsified wastewater.