An Overview Of Sodium Carboxymethyl Cellulose （CMC）

Agricultural wastes or by-products from agricultural activities are blamed for causing massive litter to landfill and leading to pollution. The increasing environmental concerns have forced researchers to utilize material from agricultural waste to obtain useful industrial materials. Agriculture waste consists of carbohydrate polymers (polysaccharides), which contains various fine chemicals through chemical and biochemical modifications. The conversion of agricultural waste into fine chemicals would lighten a variety of socio-economic problems.

The main component of these agricultural wastes is cellulose from plant cell walls. Cellulose can be chemically altered to be converted to useful chemical feedstock . As cellulose is a renewable natural resource, it has economic gains over other synthetic polymers and can be utilized in various industries such as paper and packaging materials. However, due to inter- and intra- molecular hydrogen bonds in its structure, cellulose does not melt nor dissolve in most common solvents. To utilize cellulose in the food industry as a thickening, gelling, or stabilizing agent, cellulose must be converted to its derivatives. Food additive Sodium Carboxymethyl Cellulose （CMC）is essential to food processing.

Among all these modified cellulosic products, CMC has been produced largely due to its wide commercial applications. Sodium carboxymethylcellulose [sodium O-(carboxymethyl)cellulose] is a water-soluble cellulose ether produced by reacting alkali cellulose with sodium monochloroacetate. Carboxymethylation of cellulose is a versatile modification since it provides access to water-soluble materials. It can also be intermediate with various valuable features . CMC has been accepted in a broad circle of applications within different industries, including food ingredients, pharmaceuticals, cosmetics, paper products, ceramics, detergents, adhesives, lithography, and materials. Large quantities of industrial CMC are produced in crude commercial grades, without any further refining, used as a component in detergents, cloth, pesticide, adhesives, ceramics, lubricants, oil drilling mud, cement, and in the paper and coating industry. Only high-purity grades CMC will be used in the food and pharmaceutical industries. Sodium carboxymethyl cellulose is man modified water-soluble cellulose derivatives produced by converting alkali cellulose swollen in a certain concentration of sodium hydroxide (NaOH) and organic solvent with monochloracetic acid or its sodium salt under heterogeneous reaction conditions. There are 3 hydroxyl groups (-OH) in cellulose structure and usually can be replaced by carboxymethyl groups in the order of C2>C6>C3.

Most of the cellulose sources used to produced CMC commercially are cotton and wood, but many other resources could also be used. Some papers have reported the synthesis of CMC, from different agro-cellulosic sources, such as paddy straw , kenaf , sugar cane bagasse, pulp beet , cavendish banana pseudostem, bagasse of sago, pod husk cacao, asparagus stalk , tea stalk etc.