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Theory

Heavy metals are a major concern in the treatment of water due to theirs toxic and other

detrimental effects these materials can produce. In general, heavy metals are considered to be the

following elements such as copper (Cu), zinc (Zn), cadmium (Cd), mercury (Hg), lead (Pb),

chromium (Cr), and arsenic (As). The presence of heavy metals in a waste stream can interfereand destroy the effectiveness or normal waste treatment operations. The heavy metals can kill the

necessary bacteria that will affect the activated sludge secondary treatment plants. The heavy

metals in water can make it unsuitable for many uses such as drinking or process uses where

high degree purities are required.

The presence of heavy metals in waste water can be determined by using inductive

coupled plasma (ICP). With reference to World Health Organization (WHO), the water can be

decided whether is potable or not.

The World Health Organization (WHO) has stipulated the level of heavy metals allowedin drinking water as following below:

Heavy metal Maximum concentration of heavy metals allowed in

drinking water (mg/L or ppm)

Arsenic 0.01

Cadmium 0.003

Chromium 0.05

Copper 2.0

Lead 0.01

Mercury 0.001

Zinc 3.0

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The most common calibration technique options for ICP measurements are calibration

standard. It is assumed that the calibration is linear. This means that the standard and sample

elemental concentration give an instrumental response that is described by the equation for a

straight line. Theoretically, the correlation coefficient of all metals is equal to one.

Table 1 : Pearson correlation of heavy metals from effluent wastewater sample in three years

Apparatus & Materials

100 ppm of stock solutions of ZnCl2.2H2O

Electronic analytical balance

Inductively Coupled Plasma (ICP)

Automatic pipettes

Volumetric flasks

Procedure

A) Sample Preparation

1. 0.0208 g of zinc (Zn) was weighed by using electronic analytical balance and then diluted

with distilled water to get 100 ppm of Zn stock solution.

2. Zinc was dissolved using distilled water and transferred into 100 mL volumetric flask.

3. The solution was diluted to the mark with distilled water and was shaken well.

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4. Automatic pipette was used to measure 50, 25, 12.5, and 3.125 mL of Zn stock solution

respectively to prepare 100, 50, 12.5, 6.25 ppm of standard solutions.

B) Handling ICP

1. The cooling unit is turned on for ten minutes.

2. The tubing is pulled up and the levers were flipped corresponding to the tubing.

3. The argon gas is turned on for ten minutes. Firstly, the gas at the tank is turned on, then

the wall, followed by the bench at the top.

4. The probe is placed into distilled water and the ICP is turned on.

5. On the desktop, ICP Expert is clicked.

6. The button that looks like a lock with electricity is pressed. This turns on the plasma. The

plasma is allowed to heat up for 15 minutes.

7. While waiting for the plasma to heat up, worksheet is selected from the main index

window.

8. new is selected, followed selecting quantitative for the experiment. A name for theworksheet is typed and save button is clicked.

9. The box with the hand, pencil and paper is clicked. This will open the method editor and

the element page. If the periodic table is not visible, choose the periodic table from the

method table from the editor view.