Question

1. How pH of so is evaluated? Does soil pH upset plant growth experiment? Why KCl is used in pH meter? How will you formulate 0.1 M solution of KOH? What is pH of electrode storage solution? 2. What is the use of point of zero charge of any adsorbent? What is its use in electrochemistry? What are the dissimilarities between zeta potential and point of zero charge? 3. What are the varieties of fats in food? In what way are fats categorized? Describe the working of soxtec foss 2055 & its different units? 4. What is advance oxidation process? What are the main advantages and disadvantages of Advanced Oxidation process? Differentiate between oxidation & reduction using suitable chemical reactions? How do you tell if a reaction is oxidation or reduction? 5. How does a UV VIS spectrophotometer work? What is the Beer Lambert law used for? What are the constituents, principle and applications of UV Vis- Spectrophotometer? 6. What is meant by activated sludge process? What is the difference between primary and secondary sludge? An activated-sludge system is to be used for secondary treatment of 15,000 m3/d of municipal wastewater. After primary clarification, the BOD is 170 mg/L, and it is desired to have not more than 25 mg/L of soluble BOD in the effluent. A completely mixed reactor is to be used, and pilot-plant analysis has established the following values: hydraulic detention time )-10 d yield coefficient (Y)-0.5 kg/kg, kd-0.05 d-1. Assuming an MLSS concentration oj 4500 mg/L and an underflow concentration of 12,000 mg/L from the secondary clarifier, determine the volume of the reactor

Answer 1

Ans 1) pH of soil can be measured by using pH meter and placing it in soil : liquid mixture in a ratio of 1 : 2.5 for soil with high organic matter because these soil absorbs a significant amount of water.The liquid can b distilled water or 1M KCl solution.Before measuring pH it is necessary to calibrate pH meter.

To maintain a constant potential of Ag/AgCl electrode in pH meter , an electrolyte solution is needed which has sufficient chloride ions and which has neutral pH.To achieve this , KCl solution is needed.

0.1M KOH solution can be formulated as ,

w = S V M /1000

where, S = molarity

V = Volume

M =Molar mass of KOH

w = weight of KOH required

Storage solution has a pH of 7.0

Ans 2) The point of zero charge is the pH at which the surface of absorbent is globally neutral .Below this value, surface is positively charged and above this, it is negatively charged.It is used to make  surface charge positive or negative.

In electrochemistry , potential at point of zero charge is a potential of electrode at which one of the charge defined is zero.The potential of zero charge  is used to determine absolute electrode potential of given electrolyte.

Difference between zeta potential and point of zero charge are as follows:

Zeta potential	Point of zero charge
Potential difference between surface of solid particle immersed in conducting liquid and bulk of liquid	It is a concept related to phenomenon related to adsorption which tells about the condition when electrical charge density on surface is zero
It indicates the stability of colloidal dispersion	It indicates about the electrical charge density on surface of absorbent

Ans 3) There are four variety of fats in food :

1) Saturated fats

2) Poly-saturated fats

3) Mono saturated fats

4) Trans-fats

Categories of fats are saturated fats and unsaturated fats

Soxtec 2055 is the new generation of extraction systems.It can handle upto six samples at a time .The system consist of extraction unit and a control unit. The sample which is to be analyzed is weighted into thimbles and inserted in extraction unit.The solvent is added in closed system.The cups are heated by electrical heating plate .It has four step boiling process which consist of boiling, rinsing, recovery and pre- drying. The system is flexible and suitable for wide variety of food

Ans 4) Advance oxidation process(AOP) are a set of treatment procedures which are designed to remove organic materials in water and wastewater by oxidation through reaction with OH^- .Following are the advantages of  AOO :

1) They can effectively eliminate organic compound

2) It virtually reacts with almost every aqueous pollutant therefore AOPs can remove many organic contaminent at the same time

3) It can also remove some heavy metals

4) In some AOPs , disinfection can also be achieved

Following are the disadvantages of AOPs :

1) Cost is very high

2) In some cases, pre-treatment of wastewater is required which increases cost and are technically demanding

Oxidation is a loss of electrons or hydrogen atoms or gain of oxygen atoms and reduction is gain of electrons or hydrogen atoms or loss of oxygen atoms.For example:

2ZnO + C --> 2Zn + CO₂

In above reaction one substance is oxidize and other get reduced as:

Zn⁺ + e^- --> Zn (Gained electron so it is reduced)

C --> C⁺² + 2e^- ( Loss electron so it is oxidized )

To tell if the reaction is oxidation or reduction first balance the equation and notice its charge if it losses electron then it is oxidized and if it gain electron then it is reduced