Why Sulfates in Washing Powders are Harmful?

Washing powders and detergents, which you can find in the assortment on Shoppok,  are similar to soaps because they have a water-soluble ionic end in their molecule and a nonpolar end that displaces oils. Detergents have the advantage, over soaps, of forming water-soluble calcium and magnesium sulfates, so they do not form clots when used with hard water. Furthermore, since the corresponding acid of the acidic alkyl sulfates is strong, their salts (detergents) are neutral in the water.

Why Sulfates in Washing Powders are Harmful

Fig: Why Sulfates in Washing Powders are Harmful

Detergents are products that are used for cleaning and are basically made up of a surfactant that acts by modifying the surface tension, reducing the adhesion force of the particles (dirt) to a surface; by phosphates that have a water softening effect and flocculate and emulsify dirt particles, and some other component that acts as a solubilizer, bleach, bactericide, perfumes, optical brighteners (dyes that give clothes a clean appearance), etc.

Synthetic detergents contain surfactant substances that aid in penetration, soaking, emulsification, dispersion, solubilization, and foaming. All of this occurs at the solid-liquid and liquid-liquid interfaces.

Most synthetic detergents are persistent pollutants because they are not easily broken down by bacterial action. Detergents that are not biodegradable are called hard detergents and degradable ones, soft detergents.

The main surfactant used in detergents is a derivative of alkylbenzene sulfonates, such as sodium dodecylbenzene sulfonate (C12H25-C6H4-SO3Na) which can make the detergent hard (non-biodegradable, persistent pollutant) or soft (biodegradable, biodegradable pollutant), depending on the type of branches it has.

A large number of detergents are sodium aryl alkyl sulfonates having the general formula R-C6H4-SO3Na, that is, they are salts of aromatic sulfonic acids with a long alkyl chain. If the chain is branched, it cannot be degraded by microorganisms, which is why they are said to be persistent, and cause great problems of water pollution in lakes, rivers, and underground reservoirs. Aryl Alkyl Sulfonates that have straight chains are biodegradable.

The use of surfactant compounds in the water, when they are thrown into lakes and rivers, causes a decrease in the solubility of dissolved oxygen in the water, which makes aquatic life difficult and also, as they remove the fat from the feathers. A waterfowl causes insulating air to escape from between feathers and get wet, which can cause death from cold or drowning, much like oil spills in the sea.

Detergents are synthetic chemicals that are used in large quantities for domestic and industrial cleaning and that act as water pollutants when discharged into wastewater.

The polluting power of detergents is manifested in aquatic plants, inhibiting the photosynthesis process, causing the death of aquatic flora and fauna. In fish it causes injuries to the gills, making it difficult for them to breathe and causing death.

Polyphosphate Detergents:

A component of solid detergents is the metaphosphate called sodium tripolyphosphate, Na5P3O10, which contains the ion (O3 P-O-PO2-O-PO3) 5-. The triphosphate ion is very useful because it forms soluble complexes with calcium, iron, magnesium, and manganese ions, removing the stains they cause on clothing and helping to keep dirt particles in suspension so that they can be easily removed by washing.

Phosphate additives in detergents such as sodium tripolyphosphate are called phosphate builders and they have three functions, first, they act as bases making the wash water alkaline (high pH), which is necessary for detergent action; secondly, phosphates react with calcium and magnesium ions in hard water in a way that they do not act with detergent, and thirdly, they help keep fats and dust in suspension, making it easier for them to be eliminated.

Sodium (Na4P2O7) or potassium pyrophosphate is used in liquid detergents because it hydrolyzes into the phosphate ion (PO43-) at a slower rate than sodium tripolyphosphate.

Phosphate-based detergents have a destructive effect on the environment by accelerating the eutrophication or eutrophication process of lake and river waters. As the use of phosphate detergents has created very serious problems in the water, some countries have banned the use of detergents of this type.

Water with Detergent and Algae:

Liquid and powder detergents after being used in domestic and industrial cleaning are thrown into sewers and become a source of water pollution.

Algae are aquatic plants that can be perceived as blue-green silt on the surface of stagnant waters. Algae, like other plants, store energy through the process of photosynthesis so they require sunlight to consume carbon dioxide and release oxygen. Like other plants, algae also need other inorganic nutritive chemicals such as potassium, phosphorus, sulfur, and iron.

The amount of algae that a certain body of water, such as a lake, can support depends on the inorganic nutrients it can provide, and the accumulation of these elements depends on the amount of salts carried by the different streams of water into the lake. Algae grow rapidly when the amount of nutrients is abundant and can cover the surface of the water with thick layers, and as some algae die they become food for bacteria.

As bacteria consume oxygen to decompose algae, they cause the decrease in oxygen to reach a level that is unable to support other forms of life, which is essential so that the ecosystem does not disappear. For example, where there are fish such as bass and perch that are useful to humans, they diminish or disappear, they give way to other forms of lifeless less useful to humans such as catfish, leeches, and worms that feed on garbage.

Eutrophication and Its Control:

In relatively calm waters, such as lakes and ponds, aquatic plants proliferate due to the presence of nutritive elements such as nitrates and phosphates that act as fertilizers. The main sources of nutrients are sewage and agricultural runoff that originate from the massive growth of algae and lilies, which generates large amounts of plant masses on the waters and their subsequent accumulation on the banks. When plants die, for their decomposition they consume the oxygen dissolved in the water causing anaerobic conditions.

Eutrophication or eutrophication (from the Greek eú, well, and trophé, food) is a natural aging process of stagnant or slow-flowing water with excess nutrients and that accumulates decomposing plant matter at the bottom. Plants take over the lake into a swamp and then it dries up. The problems begin when man pollutes lakes and rivers with excess nutrients that accelerate the eutrophication process, which causes the accelerated growth of algae, the death of fish, and other aquatic flora and fauna, generating anaerobic conditions.

The eutrophication process results from the use of phosphates and nitrates as fertilizers in agricultural crops, organic matter from garbage, phosphate-based detergents, which are washed or thrown into rivers and lakes are a very problem. Severe for stagnant waters near urban or agricultural centers. During warm seasons, the overload of these chemical products, which serve as nutrients, generates the accelerated growth of plants such as algae, cyanobacteria, water lilies, and duckweed, which, when they die and are decomposed by aerobic bacteria, cause oxygen depletion dissolved in the surface layer of water and cause the death of different types of aquatic organisms that consume oxygen, in the waters of lakes and rivers. The eutrophic lake is a shallow lake with little content of dissolved oxygen but rich in nutrients and organic matter.

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