International Journal of Pharma Sciences
Vol. 3, No. 4 (2013): 289-290
Research Article
Open Access
ISSN: 2320-6810
Reduction in the amount of KMnO4 used in getting
rid of Manganese in ground water
Alaa Ahmed Mohamed*
Chemist, Sohage Water Company, Sohage, 82611, Egypt
* Corresponding author: Alaa Ahmed Mohamed; e-mail: [email protected]
Received: 15 June 2013
Accepted: 30 June 2013
Online: 25 July 2013
ABSTRACT
Chemical treatment of water in the process of getting rid of manganese and iron is the use of (KMNO4) in the
oxidation of iron, manganese and convert them all (iron and manganese) from soluble to insoluble form easily
remove by filtration. This process cost much some places with high concentrations of iron and manganese can
not afford, leading to lock and chemical processing units. We will make the same operation with the same
efficiency and at lower cost through the use of physical characteristics of the material used (KMNO4) as it
increases oxidative effect of (KMNO4) when you raise the pH.
Keywords: KMnO4, water treatment, ground water, iron, manganese
INTRODUCTION
Iron, and to a lesser degree manganese, are some of the
most abundant elements in the earth’s crust. They are
found in waters emanating from soil leaching and
industrial pollution. These elements pose no danger to
human health or to the environment. But they cause
esthetic and organoleptic inconveniences. Iron and
manganese gives water colour that can stain linen and
sanitary appliances. Iron and manganese, when not
eliminated, could be progressively oxidized in the
distribution network giving water colour, taste, smell,
turbidity and favouring the development of
microorganisms with serious consequences for users.
In surface or ground waters, one finds iron and
manganese in different chemical forms (dissolved,
precipitated, free or complexed) in variable
concentrations [1]. They may be present in
concentrations of the order of 2 to 5 mg/L of iron and
0.5 to 2 mg/L of manganese [2] or that are markedly
higher and capable of attaining 20 mg/L iron and 5
mg/L manganese [3]. The methods of iron and
manganese removal from water consist of transforming
the dissolved forms (Fe2+ and Mn2+) by oxidation, into
precipitates (Fe(OH)3 and MnO2) followed by
filtration. Oxidation can be carried out using powerful
chemical oxidants like oxygen, chlorine, chlorine
dioxide, ozone or potassium permanganate [4] or
biologically [5]. The objective of this work was to study
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a process for found way to reduce the costs of remove
(Fe2+ and Mn2+).
Iron and Manganese Oxidation
A primary use of permanganate is iron and manganese
removal. Permanganate will oxidize iron and
manganese to convert ferrous (2+) iron into the ferric
(3+) state and 2+ manganese to the 4+ state. The
oxidized forms will precipitate as ferric hydroxide and
manganese hydroxide [6]. The precise chemical
composition of the precipitate will depend on the
nature of the water, temperature, and pH.
The classic reactions for the oxidation of iron and
manganese are:
3Fe2+ + KMnO4 + 7H2O3Fe(OH)3(s) + MnO2(s) + K+
+ 5H+
3Mn2+ + 2KMnO4 + 2H2O5MnO2(s) + 2K+ + 4H+
These reactions show that alkalinity is consumed
through acid production at the rate of 1.49 mg/L as
CaCO3 per mg/L of Fe+2 and 1.21 mg/L as CaCO3 per
mg/L of Mn+2 oxidized. This consumption of alkalinity
should be considered when permanganate treatment is
used along with alum coagulation, which also requires
alkalinity to form precipitates.
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Alaa Ahmed Mohamed / Int J Pharma Sci. 2013, 3(4): 289-290
The potassium permanganate dose required for
oxidation is 0.94 mg/mg iron and 1.92 mg/mg
manganese [7]. In practice, the actual amount of
potassium permanganate used has been found to be
less than that indicated by stoichiometry. It is thought
that this is because of the catalytic influence of MnO2
on the reactions [8]. The oxidation time ranges from 5
to 10 minutes, provided that the pH is over 7.0 [9].
Hence the following attempt was made to reduce the
amount of potassium permanganate by PH adjustment
by NaOH.
0.2 ML KMNO4 (0.01 M) + 0.5 ML NaOH (1N) in 1litre
of ground water (0.91 ppm MN+2) after the addition it
was found that the concentration of Mn+2 is
(0.20ppm).
MATERIALS AND METHODS
In the classic reaction of potassium permanganate to
remove Mn+2 the numbers of moles is
3Mn2+ 2KMnO4
Figure 1. Batches in different conditions
That mean when the concentration of (Mn+2) is 1.2
ppm that mean we need 0.0023 g KMnO4 for one liter
that mean 2.3 Kg per m3. The price of KMnO4 is about
140 Egyptian pounds and it seems to be high cost for
daily process.
CONCLUSION
The following attempt was made. pH adjustment by
NaOH when we increase pH not more than 8.5 the
ability of KMNO4 to oxidation increase. Alkaline
conditions enhance the capability of potassium
permanganate to oxidize organic matter; however, the
opposite is true for its disinfecting power. Typically,
potassium permanganate is a better biocide under
acidic conditions than under alkaline conditions [10].
It can be concluded from the study that the amount of
KMnO4 can be reduced using the methodology
described here. We used to remove the Fe+2 and Mn+2
in ground water by addition of NaOH to increase pH
which increases the ability of KMnO4 to oxidise.
REFERENCES
RESULTS AND DISCUSSION
Results obtained by addition of KMNO4 in 1 liter
ground water
Table 1. Batches in different conditions
No of
batches
Added
1N
NaOH (ml)
Added 0.1 M
KMnO4 (ml)
pH
value
1
2
3
4
5
6
0
0
0
0
1
1
0
1
0.5
0.5
0.25
0.25
7.13
7.12
7.14
7.12
8.5
8.5
Concentration
of Mn+2 (in
ppm)
1.2
0.35
0.62
0.75
0.15
0.19
After the reaction the pH value decreased. These
reactions show that alkalinity is consumed through acid
production at the rate of 1.49 mg/L as CaCO3 per mg/L
of Fe+2 and 1.21 mg/L as CaCO3 per mg/L of Mn+2
oxidized. From the above results, it is evident that when
we increase pH the amount of KMnO4 decreased and
the process to remove Mn+2 was achieved (the higher
limit of Mn+2 in water is 0.4 ppm).
But the amount of NaOH was quite high and hence the
following attempt was made.
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