Requirements Chemical Oxygen Demand ( COD ) in wastewaterTo determine the amount of organic matter in the water can do a test
faster than the BOD test , yaiut by chemical reaction of a substance
called oxidants COD test
Chemical Oxygen Demand ( COD ) is the amount of oxygen required for the relationship existing materials in the water can be oxidized through chemical reactions . In this case the relationship of organic material is oxidized by potassium bichromat or K2Cr2O7 is used as a source of oxygen ( oxidizing agent ) . The oxidation of organic material relationship will follow the following reaction :
Cr2O72 - CaHbOc + + H + → CO2 + H2O + Cr3 +
Organic substances ( yellow) ( green color )
The reaction needs a catalyst warm-up and also the addition of silver sulfate ( Ag2SO4 ) fatherly accelerate the reaction . If the organic waste material is estimated there are elements that can interfere with the reaction of chloride the mercury sulfate should be added to the disorder menghilamhkan ( Ward , 1995) .
chloride can be annoying because it will come oxidized by potassium binhromat according to the following reaction :
6C 1 - + + + 14-15 Cr2O72 - H + → 3 Cl 2 + 2 Cr3 + + 7H2O
With the addition of mercury sulphate ( HgSO4 ) in the sample , senelum addition of other reagents . Chloride ions join to form mercury chloride ions , according dibaawah reaction is :
Hg2 + + 2 C1 - → HgC12
With the presence of Hg2 + ions , the concentration of C1 - ions becomes very small and does not interfere with the oxidation of organic substances in the COD test .
To ensure that almost all the oxidized organic matter discharged K2Cr2O7 oxidising agent remaining after refluxing . Terisa K2Cr2O7 in solution which is used to determine how much oxygen has been used up . The rest of K2Cr2O7 is determined by titration with ferrous ammonium sulfate ( FAS ) , in which the reaction takes place is as follows :
6 Fe2 + + + 14-15 Cr2O72 - H + → Fe 3 + + 6 + + 7 H2O 2Cr3
Ferroin indicator used to determine the endpoint of the titration is when the color green - blue solution turned brown - red . residual K2Cr2O7 in the blank solution is K2Cr2O7 early , as expected form does not contain organic substances which can be oxidized by K2Cr2O7 ( Alaerts , 1987) .
COD measurements are based that almost all organic materials can be oxidized to carbon dioxide and water with the help of a strong oxidizing agent ( potassium bichromat / K2Cr2O7 ) role in acidic conditions . By using potassium bichromat as an indicator , estimated at about 95 % -100 % organic ingredients can be oxidized ( Effendi , 2003) .
COD test typically produce oxygen demand values higher than the BOD test because the ingredients are stable against biological reactions and microorganisms can participate oxidized in the COD test . For example , cellulose is often not measured by BOD test as difficult oxidized through biochemical reactions , but can be measured through COD test ( Fardiaz , 1992) .
The color of water solution environments lack the organic material before oxidation reaction is yellow . After the oxidation reaction is complete it will turn green . The amount of oxygen needed fatherly towards oxidation reactions of organic materials is equal to the amount of potassium bichromat used in the oxidation reaction , which means more oxygen is needed . This means that the water is polluted by more and more environment relationship material . organic ( Ward , 1995)
According to the decision of Minister of Environment No. Kep - 03/MENLH/18/2010 states that the maximum levels of COD that are allowed for domestic wastewater for industry is 100 mg / l .
Chemical Oxygen Demand ( COD ) is the amount of oxygen required for the relationship existing materials in the water can be oxidized through chemical reactions . In this case the relationship of organic material is oxidized by potassium bichromat or K2Cr2O7 is used as a source of oxygen ( oxidizing agent ) . The oxidation of organic material relationship will follow the following reaction :
Cr2O72 - CaHbOc + + H + → CO2 + H2O + Cr3 +
Organic substances ( yellow) ( green color )
The reaction needs a catalyst warm-up and also the addition of silver sulfate ( Ag2SO4 ) fatherly accelerate the reaction . If the organic waste material is estimated there are elements that can interfere with the reaction of chloride the mercury sulfate should be added to the disorder menghilamhkan ( Ward , 1995) .
chloride can be annoying because it will come oxidized by potassium binhromat according to the following reaction :
6C 1 - + + + 14-15 Cr2O72 - H + → 3 Cl 2 + 2 Cr3 + + 7H2O
With the addition of mercury sulphate ( HgSO4 ) in the sample , senelum addition of other reagents . Chloride ions join to form mercury chloride ions , according dibaawah reaction is :
Hg2 + + 2 C1 - → HgC12
With the presence of Hg2 + ions , the concentration of C1 - ions becomes very small and does not interfere with the oxidation of organic substances in the COD test .
To ensure that almost all the oxidized organic matter discharged K2Cr2O7 oxidising agent remaining after refluxing . Terisa K2Cr2O7 in solution which is used to determine how much oxygen has been used up . The rest of K2Cr2O7 is determined by titration with ferrous ammonium sulfate ( FAS ) , in which the reaction takes place is as follows :
6 Fe2 + + + 14-15 Cr2O72 - H + → Fe 3 + + 6 + + 7 H2O 2Cr3
Ferroin indicator used to determine the endpoint of the titration is when the color green - blue solution turned brown - red . residual K2Cr2O7 in the blank solution is K2Cr2O7 early , as expected form does not contain organic substances which can be oxidized by K2Cr2O7 ( Alaerts , 1987) .
COD measurements are based that almost all organic materials can be oxidized to carbon dioxide and water with the help of a strong oxidizing agent ( potassium bichromat / K2Cr2O7 ) role in acidic conditions . By using potassium bichromat as an indicator , estimated at about 95 % -100 % organic ingredients can be oxidized ( Effendi , 2003) .
COD test typically produce oxygen demand values higher than the BOD test because the ingredients are stable against biological reactions and microorganisms can participate oxidized in the COD test . For example , cellulose is often not measured by BOD test as difficult oxidized through biochemical reactions , but can be measured through COD test ( Fardiaz , 1992) .
The color of water solution environments lack the organic material before oxidation reaction is yellow . After the oxidation reaction is complete it will turn green . The amount of oxygen needed fatherly towards oxidation reactions of organic materials is equal to the amount of potassium bichromat used in the oxidation reaction , which means more oxygen is needed . This means that the water is polluted by more and more environment relationship material . organic ( Ward , 1995)
According to the decision of Minister of Environment No. Kep - 03/MENLH/18/2010 states that the maximum levels of COD that are allowed for domestic wastewater for industry is 100 mg / l .
No comments:
Post a Comment