Total dissolved solids (TDS)
What is total dissolved solids(TDS)?
When a salt is dissolved in water,the positively charged ions are attracted by oxygen atoms of water molecules and negatively charged ions are attracted by hydrogen atoms of water molecules is called dissolvation.the measurement of total dissolved ions are called total dissolved solids.
In this process,water called as solvent and salt called as solute.
Do you know?
We are daily drinking dissolved solids.our drinking water contains dissolved solids such as sodium,chloride,etc. which are necessary to maintain our body.drinking dissolved solids less water is unhealthy.except pure water of H2O molecules,every water has a particular amount of dissolved solids.dissolved ions are recovered as a salt by evaporating water content.
Viscosity of water is increase with increase in TDS value.
Range of total dissolved solids in various water.
*Drinking water or RO(Reverse osmosis) water containing the value of 20 to 500mg/l of total dissolved solids which are necessary for healthy life.
*Lake water,river water contains the value higher than drinking water range from 1000mg/l.
*Sea water contains very higher amount of total dissolved solids from 40000mg/l to a lakh or more.
*Reagent grade water such as distilled water and millipore water have no or very lesser amount of total dissolved solids.
There are 3 methods for determination of total dissolved solids.they are
1)Gravimetric method.
2)Conductivity cell method.
3)Calculation method.
Determination of sodium in water.
1)Gravimetric method for determination of total dissolved solids.
Determination of total dissolved solids(TDS).
AIM:
To determine the amount of total dissolved solids(TDS) present in water.
PRINCIPLE:
It is an gravimetric method of determination of total dissolved solids (TDS) in which the water sample containing evaporating dish is placed on hot water bath at a particular temperature.after the evaporation of all water molecules or dried,the evaporating dish to be placed in oven.the remaining content in the dish will be total dissolved solids(TDS). then the evaporation dish to be weighed.difference between the empty weight and after weight of that dish is the value of total dissolved solids.
APPARATUS REQUIRED:
1)Evaporating dish(200ml capacity).
2)Standard volumetric flask(100ml capacity).
3)Hot water bath.
4)Oven.
5)Weighing balance.
PROCEDURE:
Dry the evaporating dish in oven at 105 or 180 degree celcius for an hour.then transfer into dessicator and then weighed.note that empty weight of dish.filter the sample using filter paper and pour an aliquot of sample and place on hot water bath at a temperature of about 90 degree celcius.should not let the sample to boil.after the dish become dried,keep it to in oven at a temperature of 105 or 180 degree celcius.then again transfer to dessicator and take weight.note that as final weight.place that dish again in oven to get concordant value.
CALCULATION:
TDS = (W2 - W1) × 10^6 / S.v
TDS - Total dissolved solids.
W2 - Final weight of dish.
W1 - Empty weight of dish.
10^6 - For gram to mg and mg/l conversion.
S.v - Sample volume.
EXAMPLE CALCULATION:
W1 = 77.15327g
W2 = 77.15568g
TDS = ( 77.15568 - 77.15327 ) × 10^6 / 100 = 24.1mg/l.
Determination of Sulphate and sulphite in water.
2)Conductivity cell method for determination of total dissolved solids.
See here for the procedure of using and calibration of conductivity cell.the electrical conductivity meter also having the advantage of seeing value of total dissolved solids by simply dipping the electrode in sample.
3)Calculation method for determination of total dissolved solids.
From the value of electrical conductivity of water,multiply it by 0.50 or 0.60 to get the nearest value of total dissolved solids.the range is varying by differ in countries or continents.
Total suspended solids (TSS)
What is total suspended solids(TSS)?
The particles or solids which are not dissolved in water called total suspended solids.
Our drinking water contains very lesser amount of suspended particles which are invisible to eyes.they are below 0.1 Nephelometric unit.reagent grade water contains zero suspended solids and waste water contains high amount of suspended solids.
Determination of Nitrate and nitrite in water.
Determination of total suspended solids (TSS).
AIM:
To determine the amount of total dissolved solids(TDS) present in water.
PRINCIPLE:
Sample is filter through a filter paper which does not allow any suspended particles to penetrate through it.by filtering with filtration apparatus,it is great way to do process quickly and effective.the filter paper is dried in oven at a particlular temperature to evaporate the water content then weighed.the difference between the initial weight and final weight of the filter paper is noted as total suspended solids.
APPARATUS REQUIRED:
1)Filtration apparatus and vacuum pump.
2)Measuring cylinder.
3)Weighing balance.
4)Whatman filter paper (47mm diameter).
5)Oven.
PROCEDURE:
Dry the Whatman filter paper in oven at 105 degree celcius.then cool in dessicator and take empty weight.place the filter paper over filtration apparatus.apply vaccume and pour the sample.during filtration the suspended solids trapped in filter paper.after the filtration is complete,keep the filter paper in to oven at 105 degree celcius for an hour.then transfer to dessicator and take final weight.repeat the same procedure for concordant value.
Determination of total hardness in water.
CALCULATION:
Calculation of total suspended solids (TSS) is same as the calculation of totals dissolved solids (TDS).
TSS = (W2 - W1) × 10^6 / S.v
TSS - Total Suspended solids.
W2 - Final weight of filter paper.
W1 - Empty weight of filter paper.
10^6 - For gram to mg and mg/l conversion.
S.v - Sample volume.
EXAMPLE CALCULATION:
W1 = 0.88732g
W2 = 0.95463g
TSS = (0.95463 - 0.88732) × 10^6 / 200 = 336.55mg/l.
DIFFERENCE BETWEEN TOTAL DISSOLVED SOLIDS(TDS) AND TOTAL SUSPENDED SOLIDS (TSS):
*Total dissolved solids in water are invisible to eyes.but total suspended solids are visible to eyes.
*Total dissolved solids are got by evaporation after filtration of water.total suspended solids are got by filtering of water.
SIMILARITIES BETWEEN TOTAL DISSOLVED SOLIDS AND TOTAL SUSPENDED SOLIDS:
*Both are water parameters.
*Value of total dissolved solids increase with increase in value of total suspended solids.
*The value of total dissolved solids and total suspended solids are directly proportional to the odour of natural water.
*If a water contains suspended solids.it also contain dissolved solids in nature.
*Both causing colour difference in water.
*Both are measured in gram or milligram.
*Both are decrease by dilution.
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