Chemistry of Detergents and Surfactants

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Questions and Answers

What primary chemical is released from acid mine drainage?

Calcium bicarbonate

Potassium sulphate

Sulphuric acid (correct)

Sodium chloride

What is the recommended maximum concentration of total dissolved solids (TDS) in water for safety?

800 mg/L

150 mg/L

300 mg/L (correct)

600 mg/L

Which of the following metals is considered nephrotoxic?

Zinc

Sodium

Lead (correct)

Iron

What impact do sediments have on aquatic ecosystems?

Block sunlight and reduce photosynthetic rate Signup and view all the answers

Which anion is commonly found in dissolved salts in water?

Chloride Signup and view all the answers

Which of the following metals is known for its extreme toxicity in higher doses?

Cadmium Signup and view all the answers

What is a consequence of siltation in water bodies?

Blocked sunlight reaching aquatic plants Signup and view all the answers

What is a significant risk posed by heavy metals in industrial waste waters?

Induction of tumors and mutations Signup and view all the answers

Why is CaCO3 chosen to express the degree of hardness in water?

It is a primary standard with a molecular weight of 100. Signup and view all the answers

What role does the pH play in the EDTA titration method?

It affects the formation of stable complexes with Ca2+ and Mg2+. Signup and view all the answers

What happens at the endpoint of the titration using EDTA?

The color changes from wine red to blue due to EBT. Signup and view all the answers

Which buffer solution is used to maintain the pH during the EDTA method?

NH4Cl and NH4OH Signup and view all the answers

What indicates the presence of calcium and magnesium ions in the EDTA method's initial stages?

A wine red solution. Signup and view all the answers

What is the significance of EBT in the EDTA titration method?

It acts as an indicator by changing color. Signup and view all the answers

What defines the alkalinity of water?

The tendency of water to accept H+ ions to neutralize acids. Signup and view all the answers

What is the main purpose of the EDTA method in water analysis?

To estimate the hardness of water accurately. Signup and view all the answers

What is the primary active ingredient in detergents that serves as a cleansing agent?

Surfactants Signup and view all the answers

Which surfactant was commonly used in synthetic detergents until the early 1960s?

Alkylbenzene sulphonate (ABS) Signup and view all the answers

What is eutrophication primarily caused by?

Excessive plant nutrients like nitrogen and phosphorus Signup and view all the answers

What pH value is maintained during chlorination to prevent dissociation of HOCl?

6.5 Signup and view all the answers

What condition is commonly referred to as 'blue baby syndrome'?

Methaemoglobin anemia Signup and view all the answers

Which species is predominantly formed at a pH of 6.5 during chlorination?

Dichloramine Signup and view all the answers

Which of the following statements about surfactants is true?

Surfactants can produce foam in rivers and sewage treatment plants. Signup and view all the answers

What is the term used for chlorine that is combined with other substances in water?

Combined chlorine Signup and view all the answers

What happens to algae after an algal bloom occurs in water bodies?

They decompose, leading to reduced dissolved oxygen levels. Signup and view all the answers

How do certain bacteria in the intestines affect nitrates in water?

They transform nitrates into toxic nitrites. Signup and view all the answers

In which stage does the amount of residual chlorine begin to increase during chlorination?

Stage II Signup and view all the answers

What do inorganic chemicals and minerals in water bodies generally include?

Trace elements and organometallic compounds Signup and view all the answers

What happens to all added chlorine during Stage I of the chlorination process?

It is consumed for oxidizing reducing substances. Signup and view all the answers

What undesirable compounds may form during the chlorination process, leading to bad odor?

Chloro-organic compounds Signup and view all the answers

How does combined chlorine compare to free chlorine in terms of effectiveness?

Less effective Signup and view all the answers

What is the role of chloramines formed during chlorination?

They act as a disinfectant reserve. Signup and view all the answers

What is primarily achieved during secondary treatment of wastewater?

Removal of dissolved or colloidal organic material Signup and view all the answers

Which of the following is NOT a commonly used approach for secondary treatment?

Chemical precipitation Signup and view all the answers

What is a disadvantage of trickling filters in wastewater treatment?

High construction cost Signup and view all the answers

During the activated sludge process, what is primarily generated by the agitation and aeration of wastewater?

Aerobically active microorganisms Signup and view all the answers

What is the typical range of BOD reduction achieved by trickling filters?

60% to 85% Signup and view all the answers

What factor does NOT influence the efficiency of trickling filters?

Depth of the filter bed Signup and view all the answers

In the activated sludge process, what is the primary function of activated sludge?

To act as a source of microorganisms Signup and view all the answers

Which types of wastewater are trickling filters particularly used for?

Industrial wastewater from particular sectors Signup and view all the answers

Study Notes

Detergents

Detergents contain surfactants, which reduce water's surface tension, allowing penetration into surfaces for effective cleaning.
Typical detergent formulations consist of 10-30% surfactants, with the remainder being polysulfate salts and other ingredients.
Surfactants can cause foaming in water bodies even at low concentrations (1 ppm), potentially affecting taste and oxygen absorption.
Alkylbenzene sulfonate (ABS), a non-biodegradable surfactant, has been largely replaced by linear alkyl sulfonate (LAS), which is biodegradable.

Plant Nutrients and Eutrophication

Essential chemicals for plant growth include nitrogen, phosphorus, and potassium, which can lead to algal blooms in water bodies.
Eutrophication occurs when excess nutrients cause algae to decompose, depleting dissolved oxygen and creating health hazards in aquatic environments.
Consequences of eutrophication include shallower, warmer lakes and the transformation of lakes into marshes.

Inorganic Chemicals and Heavy Metals

Inorganic pollutants in water include salts, minerals, acids, and heavy metals like cadmium, chromium, and lead, which are harmful in high concentrations.
Acid mine drainage results from mining operations, releasing sulfuric acid and metals into local waters, causing ecological damage.
Concentration of total dissolved solids (TDS) should be kept below 500 mg/L for safe drinking; WHO recommends a range from 50 to 300 mg/L.
Heavy metals can cause various health issues, including kidney damage and carcinogenesis.

Sediments

Sediments consist of soil, sand, and mineral particles washed into waterways, which can block sunlight, decrease photosynthesis, and increase water treatment costs.
Sedimentation reduces the storage capacity of reservoirs and can lead to increased turbidity in water bodies.

Water Hardness

Water hardness primarily results from calcium and magnesium concentrations and is expressed in terms of CaCO3 equivalents.
Estimation of water hardness using the EDTA method relies on complexometric titration to form stable complexes with metal ions.

EDTA Method for Hardness

Involves titration of water samples with EDTA in the presence of EBT indicator, where the color changes from wine red to blue at the endpoint.
Maintains pH through an ammonia buffer to ensure accurate complexation during titration.

Alkalinity in Water

Alkalinity measures water's ability to neutralize acids and is influenced by various chemical species present.
The chlorination process manages pH levels to ensure effective disinfection by optimizing the formation of stable chloramines.

Break Point Chlorination

Chlorine disinfection of water occurs in stages: initial consumption by impurities, followed by chloramine formation until free disinfectant is available.
Understanding the relationship between chlorine dosage and residual chlorine is crucial for effective water treatment.

Secondary Treatment of Wastewater

Secondary treatment addresses remaining organic materials in wastewater through biological processes like coagulation and anaerobic digestion.
Common methods of secondary treatment include trickling filters, activated sludge processes, and oxidation ponds.

Trickling Filters

Composed of rocks or coarse materials where microorganisms decompose waste, achieving BOD removal efficiency of 65-85%.
Advantages include simplicity and improved effluent quality, while disadvantages include sensitivity to temperature and high construction costs.

Activated Sludge Process

A versatile method involving the aeration of wastewater mixed with activated sludge, leading to high-quality effluent with low BOD levels.
Utilizes microorganisms for effective organic matter breakdown and occupies less area compared to trickling filters.

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Description

Explore the science behind detergents and surfactants, the essential components that make cleaning agents effective. Understand how surfactants function to lower water surface tension and enhance cleaning performance. This quiz delves into the composition, roles, and properties of these cleansing agents.