Anyone know how to remove brown/rust-color stains from pavements? What chemical I should buy?

Some of my citrus containers sit on concrete pavement. Over time, the water leaches out of the bottom holes and stains the pavement. I believe the stains came from the iron sulfate in the soil/fertilizer. Also, sometime I would add iron sulfate to my lawn and accidentally spill some on the sidewalk (those white granules I don't see).

I would greatly appreciate it if you can tell me how to remove this iron staining. What are some of your tricks?

Thanks.

Mix 1 ounce of tri-sodium phosphate (TSP) in a gallon of HOT water. This chemical can be found at hardware and paint stores. Wet the concrete and use a scrub brush to apply the solution. Scrub vigorously and let the solution soak into the concrete for 10 to 15 minutes. Rinse well.

Try a product called Iron Out, which is sold in plumbing supply stores.

Millet

Thanks Millet for the quick reply.

Looks like I'll be busy with the driveway/walkway this weekend

You can also try Jomax & bleach, works on almost everything.

Just use oxalic acid. It will chelate the iron and it will be washable.

Sylvain Oxalic acid can be very harmful.

Quote:

SAF-T-DATA(tm) Ratings (Provided here for your convenience) ----------------------------------------------------------------------------------------------------------- Health Rating: 4 - Extreme (Poison) Flammability Rating: 1 - Slight Reactivity Rating: 1 - Slight Contact Rating: 3 - Severe (Corrosive) Lab Protective Equip: GOGGLES & SHIELD; LAB COAT & APRON; VENT HOOD; PROPER GLOVES Storage Color Code: White (Corrosive) ----------------------------------------------------------------------------------------------------------- Potential Health Effects ---------------------------------- Oxalic acid is corrosive to tissue. When ingested, oxalic acid removes calcium from the blood. Kidney damage can be expected as the calcium is removed from the blood in the form of calcium oxalate. The calcium oxalate then obstructs the kidney tubules. Inhalation: Harmful if inhaled. Can cause severe irritation and burns of nose, throat, and respiratory tract. Ingestion: Toxic! May cause burns, nausea, severe gastroenteritis and vomiting, shock and convulsions. May cause renal damage, as evidenced by bloody urine. Estimate fatal dose is 5 to 15 grams. Skin Contact: Can cause severe irritation, possible skin burns. May be absorbed through the skin. Eye Contact: Oxalic acid is an eye irritant. It may produce corrosive effects. Chronic Exposure: May cause inflammation of the upper respiratory tract. Prolonged skin contact can cause dermatitis, cyanosis of the fingers and possible ulceration. May affect kidneys. Aggravation of Pre-existing Conditions: Persons with pre-existing skin disorders or eye problems, or impaired kidney or respiratory function may be more susceptible to the effects of the substance.

Oxalic acid is a very common chemical in laboratories.
It is a weak acid and it is a solid. I mean, very hard to breath ...
If you read the security datas of any common product you will find this type of things.
Indeed, it is a chelate and therefore can be a poison because it can "enclose" bi and trivalent ions as iron, calcium, magnesium etc.
But you can die if you eat 1 kg of sugar or drink 1 l of whiskey.
And sugar is still free for sale.
Oxalic acid is very common in your food and can be found in high dose in Spinach (Spinacia oleracea), Common sorrel (Rumex acetosa) and all the Oxalis. Till now, nobody as died of eating spinach or sorrel!
To remove your stains, try sorrel juice...
5 mn later: writing this last joke (I love to joke and I am often the only one to laugh) I thought that I have plenty of sorrel and oxalis in my garden and plenty of iron stains in my house, so I tryied:
sorrel doesn't work but oxalis does! (a little).

I've used oxalic acid for 20 years or so and am still here to write about it. I have a long history with oxalic history and, as they say, you learn most from your mistakes. As a young teenager I once chased a rooster and stepped on a board with a nail sticking up about 2 inches. Ouch. My parents weren't home so I decided I should soak my foot in something that mom would prepare for us. I don't know what that might have been but I do now that I grabbed the wrong container and used some oxalic acid in the bucket of water. It burned quite a bit and burned a lot more. The next day the doctor asked me what on earth I thought I was doing! Mom had used the oxalic acid to remove rust stains from the dishwasher. That was about 35 years ago and I improved my practices after that. Somebody at one point told me that I could request some oxalic acid from my pharmacy. I did that a couple of times and had to wait a week or so for it to arrive. Then, about 20 years ago an old hardware store was closing up and they had a big sale on everything. I saw that they had about 20 pounds of oxalic acid in a bag stored in a metal trash can, the same as they had some other items. I bought a couple of pounds and they salesman suggested that I buy it all because he did not want to handle it. It was a bit nasty to breath, but not that bad. I use just a little bit several times a year and don't find it really that bad. I have an iron filter for my house and the postassium permaganate (sp?) sometimes stains my hands and I will sometimes wash my hands with a solution of the oxalic acid. I also soak my filter injector in it to clean it. It works well. Barkeeper's Friend cleansing powder also has oxalic acid in it and I used it just lask week to scrub on my hands to help remove some rust stains. Maybe I just live dangerously!!!