Starch modification

The physical and chemical properties of starch restrict its use. One of the most effective ways to modify starch is by hypochlorite oxidation, which adds a larger number of carbonyl and carboxyl groups to the starch molecules.

In turn, this changes the chemical and physical properties of the starch dramatically, creating a wide range of new products in both food and non-food applications. Oxidation of starch has a long history, beginning with Liebig who used chlorine to oxidize starch in 1829.

Examples are oxidation of aldehydes to carboxyl groups, C-6 methylol groups to carboxyl groups, 2,3-glycol units to dialdehyde and dicarboxylic acid units. During the modification step the pH determines the selectivity according to aldehyde groups and carboxyl groups.

Like regular starch, common sodium hypochlorite oxidized starch is granular in form but with few surface changes. Oxidized starch is whiter because of the bleaching action of sodium hypochlorite.

A high percentage of oxidized starch is used in the paper industry to bind high-solid pigment coating colors. Oxidized starch is also used in textile manufacturing, laundry finishing, construction materials and hardening agents.

 

Rubber processing Chemicals

As the quality of untreated rubber deteriorates withindays, it is of limited use.

To resolve this, various rubber processing chemicals are added in a process known as ‘compounding’. Rubber processing chemicals, which can be divided into anti-degraders (stabilizers, anti-oxidants and anti-ozonants), accelerators (accelerators, activators or vulcanizers) and other rubber processing chemicals (anti-sear agents, blowing agents, polymerization regulators and shortstops), are predominantly used in the production of tires.

As an oxidizing agent, sodium hypochlorite is used in the production of (a group of) accelerators that speed up the vulcanization process.

 

Cyanide destruction

Cyanide (CN) is a common waste product in the steel, metal-finishing, electroplating, and, to some extent, chemical manufacturing industries (e.g. certain plastics and synthetic fibers).

Cyanides are toxic to aquatic life, interfere with normal biological self-purification processes in streams, and have a detrimental impact on water sources (agricultural and household use). Apart from cyanides, the waste products created by the above industries may contain copper and zinc ions, which are toxic to fish and other aquatic life.

Alkaline chlorination is arguably the most widely used means of destroying cyanide through oxidation. However, where large volumes of cyanide need to be destroyed, the use of sodium hypochlorite is preferable.