In the last post, the use of phosphates in detergents was introduced. They were added into the detergent manufacturing process originally as they help to improve the cleaning property of the tremendously by providing other properties apart from being a builder. Phosphates in detergent help to maintain the pH optimal to ensure removal of bacteria. It also confers cleaning properties such as dirt-suspension to prevent redeposition and prevents scaling or deposits leftover.
Furthermore, being extremely soluble in water, the end product is usually a smooth powder (does not clump during wash) or stable but highly soluble tablets. Phosphates were so greatly used in detergents that some formulation could consist 50% of phosphates by weight.
However, with the intense use of phosphates in detergents, a problem soon arose. From 1940 to 1970s, phosphates additives in city wastewater increased from 20 000 to 15 000 tons per year. Along with the excess phosphates in wastewater (that often finds its way to stagnant waterbody), the issue of eutrophication surfaces. These addition phosphates act as nutrients for the aquatic plants in the water, especially the algae found in water. This leads to an algae bloom. The sudden increase of aquatic plants depletes the oxygen in the water, which may cause the death of other aquatic animals living together.
Water stream filled with algae bloom
In lieu of this major problem, the phosphates in detergents were reduced and replaced with zeolites. Today, phosphates have phased out and slowly no longer being used in detergent manufacturing process. Currently, 16 states in USA have banned the use of phosphates in detergents. The detergent giant, Procter & Gamble, has also announced plans to remove the use of phosphates in all their detergent products worldwide by this year.
History of ingredients used in detergent
Zeolites, crystalline aluminium silicates, were designed to substitute phosphates. Zeolites in detergents have a high aluminium content, in order to allow maximum Na+ ions. As the sodium ions are able to move in the zeolite pores, they are then able to exchange with calcium ions, thereby preventing the formation of scum and act as a builder.
Zeolites occur naturally, with about 45 variations in them. However, they only offer a limited range of atomic structures and properties, whereas synthetic zeolites are able to provide the specific property required in the industry.
As zeolites in detergents are a general group of chemicals with aluminium, sodium, silica dioxide and water, scientists have been able to come up with different crystalline structures that improve its cleaning function.
To find out more about detergent raw chemicals, visit our detergent website.