User:Xin Zhu/Methyl Ester Sulphonate

Methyl Ester Sulphonate (MES) is an anionic surfactant derived from renewable natural resources – palm oil, through esterification and sulphonation. MES offers environmental friendly alternative to the widely used petrochemical based surfactant such as Linear Alkyl Benzene Sulphonate (LAS).



Application
MES is usually used as an ingredient of laundry detergent due to its physicochemical properties and excellent washing performances. MES in granules form can be directly post-added to form a powder detergent without spray drying. This technology is an advantage as it allows detergent manufacturers to use low-cost equipment without the energy and environmental penalties of spray drying.

One of the challenges for MES application is the formulation constraints when using MES in liquid detergent as MES is easily hydrolyzed in concentrated aqueous solution and at high pH values of the detergent manufacturing process. The precipitation of MES in liquid detergent formulation at low temperature is also an obstacle for the formulators.

Detergency
The detergency properties of MES were evaluated and it showed good detergency performance under various washing conditions. This is related to its high adsorption and dispersing capabilities for particles and oily soil, as well as its good solubilization ability.

However, the detergency of MES is influenced by its carbon chainlength. Among the various carbon numbers, the best detergency was obtained with C16, followed by C18 and the third one is C14. A study by Lion Corporation on the C1618 MES showed a superior performance compared to LAS or AS under low temperature wash conditions and at water hardness of levels of 100ppm.

Water Hardness Tolerance
MES is also well known for its high tolerance against calcium ion. The sensitivity of MES to water hardness is small relative to that of LAS.

Environmental Features of MES
From the viewpoint of environmental acceptability, MES has an advantage of high biodegradability. It was found that the biodegradation of MES starts quickly then proceeds rapidly to ultimate degradation at sewage treatment plants and in natural river water. A study made by the Malaysian Palm Oil Board (MPOB) showed that MES has the potential to biodegrade faster than LAS.

Being plant-based, MES is also carbon neutral as the carbon dioxide released during the biodegradation process is naturally recycled back by plants. Therefore, detergents containing MES emit lower quantity of carbon dioxide in their entire life cycle than conventional detergents.

In addition, smaller amounts of surfactant are required to obtain satisfactory detergency thanks to its excellent washing performance. This contributes to the reduction of organic load in wastes discharged to the natural environment.

Production Process
MES has a lot of advantages as a surfactant but manufacturing good quality MES on a commercial basis is quite difficult. This is the reason for its slow growth. MES has been manufactured by Stepan Company, Sun Products (formerly Huish Detergents) in USA and by Lion Corporation in Japan.

Sun Products uses Chemithon technology where the continuous process starts from sulphonation of methyl ester by sulfur trioxide (SO3). The methyl ester sulphonic acid (MESA) formed is then bleached and neutralized to produce MES. Unlike Chemithon process, Lion has developed a unique technology to make free flowing MES granules based on its 20 years of experience in MES application in its branded products in Japan.

MES in free flowing granules form facilitates its post addition into powder detergents. This will provide the detergent formulators with the flexibility of optimizing their formulations based on market dynamics.