Detergents shift to greener builders

The sodium tripolyphosphates are being replaced by greener alternative builders such as citric acid

FORTY YEARS after phosphates were fingered for their links to water pollution, sodium tripolyphosphates (STPPs) may finally relinquish their prominence among the builders used in the consumer detergents of North America and Europe. Phosphates have also been losing favor in emerging markets, particularly China, where they have dominated household detergents. Alternatives such as zeolites, sodium carbonate and citric acid have gained.

STPPs have long played an essential role in detergents, binding hard-water ions such as magnesium and calcium that would otherwise diminish the effectiveness of the surfactants by forming poorly soluble complexes. Despite their high level of performance, however, phosphates in general have come under increasing pressure from environmentalists and politicians because of their contribution to the eutrophication of water, which promotes excessive plant growth and decay, severely reducing water quality.

After a recent study in the US, the National Oceanic and Atmospheric Administration (NOAA) warned that “the potential for serious degradation in most of our estuaries necessitates that we invigorate efforts to address nutrient pollution.”

STPPs have already been virtually sidelined in the laundry detergent markets in both North America and Europe, although for different reasons. In the US the predominance of liquid detergents and the minimal hardness of water supplies have decreased the need for STPPs.

Despite significant water hardness, individual European countries have also been restricting or banning phosphates in detergents to prevent eutrophication. The UK, Spain and some Eastern European countries are now the only parts of the European Union not taking strong action against STPPs.

Their retreat from consumer detergents should provide the greatest windfall to well-established alternatives such as zeolites, sodium carbonate and citric acid, as well as cobuilders such as polycarboxylates and polyphosphonates.

At the same time, doubts about the ecological advantages of combinations of these builders are creating opportunities for innovative, greener alternatives such as the new aminocarboxylates methylglycinediacetic acid (MGDA) and glutaminic acid diacetic acid. MGDA, because of its broad range of properties, can be “used to completely replace phosphate” in dishwashing detergents, says German producer BASF.

The versatility of STPP remains unmatched, however, and in the institutional and industrial (I&I) sectors of North America and Europe, STPP seems likely to remain exempt from regulations restricting phosphates.

“The technical requirements of the I&I market are so high in terms of lengths of the washing cycles and levels of cleanliness, particularly in the food sector, that’s it’s not possible to replace phosphates and reach the same standards,” says Sylvie Lemoine, technical and regulatory affairs director at the International Association of Soaps, Detergents and Maintenance Products (AISE), Europe’s trade association for detergent producers.

In both North America and Europe, zeolites, sometimes in combination with polycarboxylates or polyphosphonates, have established themselves as the leading alternatives in the laundry segment.

STPP STOPS SPOTS

STPPs have had more staying power in the automatic dishwashing (ADW) segment, lower consumption and the lack of adequate alternatives have persuaded regulators to accept their continued dominance, but attitudes are changing.

“Phosphates have a very big presence in automatic dishwashing because of their strong performance,” explains Joel Houston, president of Colin Houston & Associates, New York. “There was an attempt to switch from phosphates to zeolites in the early 1990s in automatic dishwashing, but the tendency of zeolites to cause spotting of glassware became too much of an issue.”

Substitutes, such as citric acid combined with cobuilders, have improved since then.

“Now, dishwashing detergent producers in the US are trying to cut out phosphates,” says Houston. “Citric acid is one alternative which would be widely accepted environmentally. Producers can rest assured that they will not run into another environmental issue down the road with it.”

When several US states considered joining the state of Washington in banning phosphates in household automatic dishwashing detergents, the US Soap and Detergent Association (SDA) negotiated a deal under which the states would phase out phosphates by July 2010, with the exception of I&I cleaners. The states decided they would not take the political risk of compromising the performance of I&I detergents.

“The whole of the US will now virtually go over to phosphate-free detergents,” projects one European-based consultant. “It needs only a minority of states to introduce bans on phosphates and the whole of the country will move over to phosphate-free detergents because producers want to make detergents in only in a few plants. The next step will be for the whole of Europe to go the same way.”

The European Commission, the EU executive, is currently considering the possibility of introducing an EU-wide ban on phosphates in all consumer detergents, which would effectively bring the region in line with the US early in the next decade.

ALL IN FAVOR OF HARMONY?

The European detergents industry, unhappy with the current patchwork of rules among the 27 EU states, would probably support the initiative.

“We’re in favor of harmonization on phosphate regulations in EU member states for the sake of preserving a single market in detergents,” says Lemoine. “We should first focus on harmonization in the laundry detergents sector because the alternative zeolite technology is widely available there, is cost effective and is accepted by consumers.

“The Commission wants to make sure that the replacements to phosphates don’t themselves pose problems to health and the environment,” she adds. “It has still not reached any final conclusions. But generally speaking it is unlikely that the alternatives will be seen to be creating new environmental problems. But the magnitude of the environmental benefits to be gained by replacing phosphates is still questionable.”

At the moment, citric acid is emerging as one of the most attractive alternatives in both the laundry and ADW markets of Europe. Chinese producers are major suppliers to the region, and their position continues to strengthen despite the unfavorable outcome of an antidumping investigation last year by the European Commission, which set a minimum price on Chinese citric acid imports of around €900 ($1,257)/tonne – about 10% higher than the world market price in December.

“The citric acid price in Europe is lower than it was in mid-2008, but the production and transportation costs of Chinese exporters have come right down,” says Reza Selazade, trading manager at Kasel Chemicals, a Vienna-based citric acid trader. “They’ve still got good selling prices and good margins.”

Selazade estimates that demand for citric acid in Europe is growing at 5-7%. “In Eastern Europe, there’s a lot of switching from phosphates to citric acids in detergents,” he explains. “The Chinese producers have shown they can deal with extra demand in the high season for citric in beverages, which is its main market in Europe. There’ll be no problems at the moment for the Chinese in meeting a big increase of demand because of what’s happening in detergents.”

However, in the longer term, with STPPs losing support in China with their share of the detergents market plummeting from around 80% to 50%, domestic needs citric acid builders could be considerably strengthened. Chinese producers would then be in the happy position of serving strong demand in both their home and export markets.

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