Citric Acid: A Versatile Natural Acid for Everyday Use

What is Citric Acid:

Citric acid, a weak organic acid, naturally occurs in citrus fruits like lemons and limes. The food and beverage industry commonly uses it as a preservative, flavor enhancer, and pH adjuster. Besides its culinary uses, citric acid also effectively removes limescale and stains in household cleaning products.

Physical Properties

Citric acid, with the chemical formula C₆H₈O₇, is a tricarboxylic acid, meaning it contains three carboxyl (COOH) groups. These properties give it the following characteristics:

Acidity: Citric acid, a weak acid, has pKa values of around 3.1, 4.8, and 6.4 for its three carboxyl groups. These values reflect its ability to donate protons (H⁺ ions) in solution, contributing to its role as a pH adjuster.
Solubility: Citric acid dissolves readily in water, making it useful in various aqueous solutions. It also dissolves in ethanol and slightly in ether.
Chelation: Citric acid acts as a chelating agent, binding with metal ions like calcium and magnesium to form stable, water-soluble complexes. This property proves particularly useful in cleaning products and water softening.
Crystalline Structure: In its solid form, citric acid appears as colorless or white crystalline powder, typically as a monohydrate (C₆H₈O₇·H₂O).
Decomposition: When heated above 175°C (347°F), citric acid decomposes, releasing carbon dioxide and water, and forming other compounds such as aconitic acid.
Reactivity: Citric acid reacts with bases to form salts known as citrates. For example, reacting citric acid with sodium hydroxide yields sodium citrate, a commonly used food additive and anticoagulant.

Citric acid serves a wide range of uses in both industrial applications and everyday life. Here’s a breakdown:

Industrial Uses:

Food and Beverage Industry:

Preservative and Acidulant: Manufacturers use citric acid as a preservative in many food and beverage products. It regulates pH levels, preventing microbial growth and extending product shelf life.
Flavor Enhancer: Due to its tart taste, citric acid adds a sour flavor to candies, soft drinks, fruit juices, and other food products.

Cleaning Products:

Limescale Remover: Industrial cleaning products use citric acid to remove limescale, water stains, and rust. It also appears in descaling products for washing machines and dishwashers.
Metal Cleaning: Citric acid cleans and polishes metal surfaces, acting as a rust and corrosion remover.

Cosmetic and Pharmaceutical Industry:

pH Regulator: Citric acid adjusts and stabilizes pH levels in cosmetics (shampoos, skin creams, soaps) and pharmaceutical products (medications and vitamins).
Preservative: It preserves the stability and extends the shelf life of cosmetic and pharmaceutical products.

Water Treatment:

Chelating Agent: Citric acid binds with heavy metals in water treatment processes, aiding in water purification and reducing water hardness.

Everyday Uses:

Cooking and Food Preparation:

Flavor Enhancer: People use citric acid in homemade foods and beverages (like homemade lemonade or candies) to add a sour taste.
Preservative: It serves as a natural preservative in homemade jams, jellies, and pickles.

Cleaning:

Natural Cleaner: Citric acid cleans limescale, water stains, and soap scum on household surfaces, especially in bathrooms and kitchens.
Descaling Agent: It removes limescale and buildup in dishwashers and washing machines.

Personal Care:

DIY Cosmetics: Citric acid balances pH and acts as a preservative in homemade shampoos, soaps, and bath bombs.
Skincare: It exfoliates in DIY face masks.

Dietary Supplements:

Here are some tips for cleaning in your daily life:

Limescale Removal from Bathroom Fixtures:

How to Use: First, dissolve 1-2 tablespoons of citric acid in a cup of warm water. Next, apply the solution to limescale-affected faucets, showerheads, and other surfaces. Then, let it sit for 10-15 minutes. Finally, scrub with a brush or sponge and rinse thoroughly with water.

Descaling Kettles and Coffee Makers:

How to Use: To begin, mix 1-2 tablespoons of citric acid with a liter of water. Pour the solution into the kettle and bring it to a boil. After that, let it sit for 15-20 minutes. Then, empty the kettle and rinse it thoroughly with clean water. For coffee makers, pour the solution into the water reservoir and run a full brewing cycle without coffee. Finally, rinse thoroughly with clean water.

Washing Machine Cleaning:

How to Use: Start by adding 6-8 tablespoons of citric acid directly into the empty washing machine drum. Then, run a hot wash cycle to remove limescale and detergent buildup. After the cycle, run an additional rinse cycle to ensure all citric acid is flushed out.

Rust Removal from Tools and Metal Surfaces:

How to Use: Initially, mix 2-3 tablespoons of citric acid with enough water to submerge the rusty items. Soak the items in the solution for several hours or overnight. After soaking, remove the items, scrub off the loosened rust with a brush, and rinse and dry thoroughly.

Cleaning Glass and Mirrors:

How to Use: First, mix 1 tablespoon of citric acid with 500 ml (about 2 cups) of water in a spray bottle. Then, spray the solution onto glass and mirrors. Finally, wipe with a microfiber cloth or paper towel to achieve a streak-free shine.

Where to Buy?

You can buy citric acid from hardware stores or online marketplaces such as Amazon or eBay.