Oxalic Acid

Also referred to as ethanedioic acid, oxalic acid occurs naturally in several dissimilar types of vegetables. It is a colorless chemical in its solid state. In its purified form, oxalic acid's appearance is similar to white crystalline substances. Both oral as well as topical application of oxalic acid is extremely toxic for the human body, because this chemical possesses corrosive and bleaching properties. However, these attributes of oxalic acid are useful for general cleaning and waste water application. Hence, this acid is commonly used for these purposes. Since this acid is highly toxic for the human body, it is necessary to wear gloves, protective glasses and appropriate clothing in order to avoid being exposed to this harmful chemical and prevent accidents.

However, people often ingest oxalic acid, though in very small amounts. This is because this acid occurs naturally in many foods including cucumbers, potato, broccoli and sprouts. This acid is present in more concentrated amounts as oxalates in the dark green, leafy vegetables. While these foods contribute to our overall health, they should always be taken in small amounts. Foods like broccoli and spinach are among the most widespread sources where these types of oxalates are found.

The corrosive property as well as the toxicity of oxalic acid can result in very harmful conditions for workers who deal with this chemical. Therefore, it is necessary to deal with this chemical in an open or well-ventilated place so that you can avoid accidents caused by inhaling this acid. In addition, it is essential to wear protective latex gloves with a view to avoid the skin being directly exposed to oxalate crystals.

The preparation of oxalic acid's salts from plants was known to people since 1745, when the noted Dutch physician and botanist Herman Boerhaave succeeded in isolating an oxalic acid salt from sorrel. By the time it was 1773, a Swiss scientist from Fribourg, Fran�ois Pierre Savary had successfully isolated oxalic acid from a salt found in sorrel.

A few years later, two Swedish chemists Torbern Olof Bergman and Carl Wilhelm Scheele created oxalic acid via a reaction between nitric acid and sugar in 1776. Scheele described the acid formed due to the reaction as s�cker-syra or socker-syra (sugar acid). By the time it was 1784, Scheele had demonstrated that the natural sources of oxalic acid and "sugar acid" form were the same. In 1824, Friedrich W�hler, a German chemist, was able to produce oxalic acid through a reaction between ammonia and cyanogens in an aqueous solution. In fact, the experiment undertaken by the German chemist can be considered as the first ever synthesis of any natural product.

By and large, it is now believed that a healthy human body is capable of disposing of oxalic acid at somewhat elevated dietary amounts with no difficulty. While oxalic acid is absorbed very poorly by the body and does not have any metabolic use, significant amounts of this chemical can be excreted readily. However, people enduring certain conditions have problems in eliminating oxalic acid from their body. Some of these conditions are usually genetic in nature and, to some extent they weaken the ability of these people's body to process oxalic acid. However, it is a fact that occasionally gout and stones do not have any relation whatsoever with oxalic acid.

For such individuals, oxalic acid is not the reason behind the problems faced by them. On the contrary, oxalic acid is the raw material for their problems. Therefore, it is important that such people should be cautious about regulating oxalic acid intake. This is something like people suffering from diabetes need to keep a tab on their sugar intake, although usually sugar is considered to be a risk-free substance.

Since oxalic acid is a toxic chemical, it needs to be handled very carefully. People who need to be extra cautious while handling oxalic acid or who should ideally stay away from using this chemical are those suffering from any type of kidney problems, including kidney stones, rheumatoid arthritis, gout, and specific types of unceasing vulvar pain.


Oxalic acid is considered to be the perfect chemical for various types of cleaning work. This chemical possesses bleach-like properties, making it ideal for sanitizing household items. At the same time, oxalic acid is also effective in getting rid of rust from a variety of dissimilar surfaces. You can use this chemical to remove stains on bathtubs, counters and kitchen sinks. However, this is a very toxic chemical and needs to be used with great caution. In present times, oxalic acid may be available in the form of a passive ingredient in several types of bleaches, cleaning products and detergents.

Occasionally, oxalic acid is employed in some mineral processing mechanisms. As this acid possesses bleaching properties, it can also be employed to sanitize equipment in several commercial environments. Oxalic acid is extensively used in factories and textile mills for its bleaching abilities and for coloring clothes. Sometimes, even medical companies also use this acid to sanitize specific chemicals or to dilute the chemicals further.

Similar to several other acids, oxalic acid is also an essential chemical for households, especially for cleaning various things. This acid can be used effectively to remove rust from various surfaces, in the form of a cleaning agent, to remove stain on wood work, in the form of a bleaching agent and many more purposes. Oxalic acid occurs naturally in many vegetables and plants like the rhubarb and buckwheat. Moreover, you can purchase this acid in its powdered form from home improvement depot in your neighbourhood. When you mix oxalic powder with water it forms into oxalic acid. When used in high concentrations, oxalic acid may prove to be highly hazardous. However, using it in moderate concentrations is considered to be safe as well as useful for various functions.

In fact, you can use oxalic acid in the form of a bleaching agent for wood as well as stone. When wood comes in contact with the elements, its color may sometimes change to grey. However, applying oxalic acid to old wood floor that have turned grey, it gets back its normal white color. In fact, oxalic acid is frequently used to prepare staining of old wooden floors. Moreover, this chemical is also employed by furniture manufacturers to remove heavy stained areas from wooden furniture in order to refinish them.

Application of oxalic acid is effective in removing food stains, ink and several other different types of stains. This chemical is considered to be a mild stain remover, as it removes the stain, but does not affect the surfaces negatively. The wood and other surfaces are left unharmed. Oxalic acid can be used to get rid of most types of stains present on wood, stone, linoleum, brick and even vinyl surfaces. Nevertheless, you should never use this acid in case the flooring is sealed. Using oxalic acid on such surfaces will damage the finishing of the flooring.

While oxalic acid can also be used to take away stains from various types of fabrics like cotton and linen, generally it will take plenty of time to do so. Hence, it is advisable that you go for dry cleaning of your fabrics.

In addition, oxalic acid is also employed to get rid of rusts, which are generally found on kitchen countertops and plumbing pipes. As a result, oxalic acid is widely used in various commercially available rust removers meant for tubs, sinks and those for taking away metal rust stains.

In addition to removing rust and stain and bleaching, oxalic acid is also used in developing photographic film in the form of a reducing agent. Oxalic acid can also be found employed in waste water treatment also because this chemical is effective in getting rid of calcium from waste water. Last, but not the least important, while polishing marble you can also use oxalic acid in the form of a grinding agent.

Side effects and cautions

Despite the various household and industrial use of oxalic acid, this chemical may prove to be harmful and cause negative side effects if one consumes foods containing high amounts of this substance. Even taking drugs with elevated concentration of oxalic may prove to be dangerous. Over a period of time, oxalic acid may accumulate in the body and form oxalate crystals. Later on, most oxalate crystals develop into kidney stones, resulting in a variety of complications. Some of the more acute health problems caused by oxalic acid include gastrointestinal (GI) disorders and kidney failure. Usually, such complications occur after undergoing specific types of surgeries.

People who take large amounts of vitamin C are more vulnerable to the negative effects of oxalic acid. This is mainly because inside our body vitamin C breaks down to release oxalic acid. Some of this oxalic acid my eventually build up in large amounts to form kidney stones later.

In its pure state, oxalic acid is extremely dangerous. It is not only toxic, but also corrosive and must always be handled cautiously. It is strongly recommended that you always wear gloves made from latex while adding the powdered acid to water, as it will be helpful in protecting your skin. In addition, it is also necessary to wear protective glasses as well as a dust mask, which will help in avoiding eye irritation and also to avoid the noxious fumes from entering your lungs. Before mixing the powdered oxalic acid with water ensure that you are in a well-ventilated area, it is always better if you do the mixing outdoors. If you ever accidentally swallow it, never try to induce vomiting. What you should do in such an instance is to immediately contact your physician or the poison control center in your neighbourhood.