Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: wolfekeeper on 29/03/2021 23:46:14

Title: All-in-one Dishwasher detergents and water softeners
Post by: wolfekeeper on 29/03/2021 23:46:14

I'm not sure I get this. Originally there were phosphates in dishwasher detergents and apparently cleaning was AMAZING. And then they took them out, and people were UPSET.

What did the phosphates do (apart from harm the environment)? All I can find suggests that the phosphates soften the water, and the lack of phosphates is a problem in hard water areas. Like... most of Britain?

And now they've come up with 'all-in-one' tablets, which just seem to contain water softeners and rinse agents.

I'm confused, don't dishwashers basically always have water softeners anyway? Don't they work? Did phosphates do anything other than soften water, or do the water softeners not soften well enough?

What's going on? What's the science?

Title: Re: All-in-one Dishwasher detergents and water softeners
Post by: Bored chemist on 30/03/2021 18:46:59

The old formulation of dishwasher detergent contained trisodium phosphate, not because it softened the water (which isn't an issue since they used soapless detergents anyway), but because the stuff is very strongly alkaline and destroyed fats etc .

Title: Re: All-in-one Dishwasher detergents and water softeners
Post by: wolfekeeper on 31/03/2021 01:36:45

Right. That makes more sense. So it saponifies the fats which then dissolve in the (softened) water. So it does two different things. Thanks!