The Sirius Effect: 

This article will explain chelates and the road to more environmentally friendly versions. As chelates are pretty active, if not aggressive, materials, engineering a green chelate without giving in on their characteristics poses a challenge. At the moment Sirius is working with a manufacturer to bring an effective, biodegradable chelate manufactured without using toxic cyanides or nitriles, to the market, in powdered and granulated form. Ideally it should reach the market in the next few months. Just like good chelates, Sirius and its partners do not sit still.

Chelating agents are a critical addition in many applications where salts need to be carried into or out of a system. In agriculture, for example, trace elements are administered to plants in tiny ppm levels. In cleaning and water treatment, salts are removed before even the lowest concentrations can initiate lime scale and other deposits. Chelates are your persistent transport molecules for capturing the ions that form such trace elements and salts. Chelates build extremely powerful complexes with ions; they are able to tear ions out of crystal forms. Thus, unwanted deposits are dismantled or at least stopped from further growth.

The word ‘chelate’ dates back to the Greek word for crab scissors; ‘chele’.

A conventional effective chelate is EDTA with its molecular structure.

The two nitrogen atoms direct the negative charges in this molecule such, that the four outward carboxyl-groups exercise an irresistible attractive force towards positively charged ions. As the C-N bonds all rotate freely in space, the ‘arms’ of the crab are able to embrace positively charged ions. Hence the analogy between a crab-silhouette and EDTA-structure. This mechanism is exemplary for all chelates discussed in this blog. Unfortunately, strong chelates like NTA and EDTA have been subject to debate due to health hazards.

Phosphates, another group of chelates, have been banned from consumer detergents, because in the 60s and 70s it turned out that, after a job well done, phosphates provided such good feeding grounds for algae, that surface waters turned greener while consumers got cleaner.

Ion combatting soldiers which are still broadly deployed are the phosphonic acids and phosphonates Britequest. Each Britequest type has its own preference for specific ions. Britequest ATMP is the most generalistic phosphonic acid, building complexes with most ions. But if you wish to carry or remove salts such as BaSO4, Fe,Cu,Zn-salts or silicates, Britequest DTPMP, Britequest HEDP respectively Britequest PAPEMP are suited.

Most conventional strong chelates degrade slowly in the environment. Moreover, they are manufactured from petrochemical sources and contain phosphorus and nitrogen, two elements which are under political debate. So there is room for improvement to free chelates from their disadvantages without letting the ions escape.

Relatively recently, two chelating agents have been developed that are more eco-friendly than most. These chelates are readily biodegradable and still function over a broad pH-range and catch a wide range of ions. Briteframe MGDA is derived from 100% non-sustainable raw materials, but it can be supplied as a powder. Briteframe GLDA is a partly sugar-based chelate, so more sustainable, but it can only be used when it is a liquid form.

The quest for 100%bio, readily degradable, effective chelates is on-going. Readily degradable supporting molecules were developed, such as Briteframe PASP and Briteframe PESA; polymers which disperse ions and thus facilitate chelation. In our own studies, Sirius found synergies between Citribrite CAA, Citribrite CAM and chelates.

So it seems there is always a give-and-take when it comes to chelating agents. However, this does not have to be the case. Stay tuned so you do not miss out when Sirius delivers its next generation chelating agents soon; still greener. With pinpoint accuracy, as is customary with chelates.

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