This paper presents the results for contribution of determining the manganese from waters and steel. Manganese, due to its properties, cannot be found but in acid waters and usually associated with iron. In small amounts, the manganese is a necessary nutrient above all as activator of certain enzymes. In large amounts, though, coming from contaminated waters , the manganese is noxious and may cause brain damage l. It is considered that drinking water should not contain more than 0,1 ppm manganese. From the studies carried out , the tiobis-β-naftolul dissolved in etilic alcohol or isobutilic alcohol may be used to determine the Mn (II) ion , under certain conditions as described in the paper. To determine manganese (II) in water, a photometric extraction method has been developed. The method is new, useful and accurate and enables determining Mn in surface, underground and fishery waters

Lucica ORAC

Olga MITOSERIU

Stela CONSTANTINESCU

The Annals of “Dunarea de Jos” University of Galati Fascicle IX Metallurgy and Materials Science

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FO N D ATĂ
19 76
 
 
THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 2 – 2007, ISSN 1453 – 083X 
 
 
 
 
STUDY AND RESEARCHE REGARDING BINARING  
SISTEM WITH TIOBIS - β – NAFTOL  
 
Olga MITOSERIU, Stela CONSTANTINESCU,  
Lucica ORAC 
“ Dunarea de Jos” University of Galati 
email: stelaconstantinescu@email.ro 
 
ABSTRACT 
 
This paper presents the results for contribution of determining  the manganese 
from waters and steel. Manganese, due to its properties, cannot be found but in acid 
waters and usually associated with iron. In small amounts, the  manganese is a 
necessary nutrient above all as activator of certain enzymes. In large amounts, 
though, coming from contaminated waters , the  manganese is noxious and may 
cause brain damage l. It is considered that drinking water should not contain more 
than 0,1 ppm manganese. From the studies carried out , the tiobis-β-naftolul 
dissolved in etilic  alcohol or isobutilic  alcohol may be used to determine the  Mn 
(II) ion , under certain conditions as described in the paper. To determine 
manganese (II) in water, a photometric extraction  method has been developed. The 
method is new, useful and accurate and enables determining Mn in surface , 
underground and fishery waters.   
 
KEYWORDS: manganese, tiobis-β-naftolul, waters, photometric extraction  
method 
 
 
1.Introduction 
 
Finding efficient extraction agents is one the 
major research directions  in the  field of extraction  
process chemistry. From an anlytical point of view, 
the metal ion extraction systems using organic 
reactants are higly important. The chelate polyketides 
agents containing  acid and coordination groups in 
their molecule  are the most widely used  for this 
purpose. Metal separation by means of etheric 
sulphide organic compounds is, however, less studied  
than other classes of compounds.[1] Researches have 
revealed that certain substances from tiobisphenol 
class can be used as remarkable reactants  for the 
separation of metals by extraction. Thus,  di-β- 
naftolmonosulphide has groups of–OH in its  
molecule, with  mobile hydrogen and   etheric 
sulphide which, under favorable conditions,  produces 
donor-acceptor bounds  therefore it can form complex 
combinations.  
The literature  only points out to  combinations 
reached by  ions Ca(II) and  Ba(II) [2], Pb(II) [3], 
Cu(II) [4] and alkaline  metals. [5,6,7,8] 
 Di-β-naftolmonosulphide, dissolved in a 
suitable organic solvent, non-miscible with water, 
extracts the metal ions from the water environment, 
thus proving to be a very good extracting agent.  
2.The extraction mechanism 
 
Di-β-naftolmonosulphide is a poor-acid 
organic  ligand . Dissolved into organic solvents such 
as higher alcohols, it is able to form with ion Mn(II) 
extractable soluble green species. To study the 
extraction  mechanism a calculation model was used 
and applied to the chelate extraction system.[9,10,11] 
In a first approximation, the extraction  balance 
may be written as: 
  ( )[ ] [ ]aq00naq HnHRnmMRn)HR(mM ++ +−⋅↔+     (1)  
 
Symbols  0 and ap  represent the compounds in 
organic-phase and water –phase respectively . 
As to the balance this can be written as : 
 
[ ] [ ]
[ ] [ ]m0aqn
n
aq0
ex HRM
HHR)nm(MRn
K +
+⋅−⋅
=          (2) 
 
For the case under study the authors suggest: 
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FO N D ATĂ
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 2 – 2007, ISSN 1453 – 083X 
 
 
- Under the conditions provided the metal 
ion does not form significant amounts of  acid-
compounds; 
- Concentration of species M(OH), 
formed by  auxiliary balances, becomes neglijible due 
to the more stable chelate MRn, and its extraction in 
organic phase; 
- Concentration of  species MRn in water 
phase and those of the intermediate water species are 
also small and therefore neglijible. 
By denoting D the repartition coefficient , and  
by applying logarithms and differential calculation to  
equation (2) with respect to  pH, we have: 
0( )
lg
HR
D n
pH
⎡ ⎤∂
=⎢ ⎥∂⎣ ⎦
                                           (3) 
 
Relation (3) enables determination of  n,  i e 
the cathion charge and implicitly the form of thre  
species where the metal ion in water phase is to be  
found.  
The graphic illustration is performed in the  
coordinates lgD- pH,  while keeping  constant the  
concentration of the reactant HR. 
At the  pH where an extraction of  50% lgD=0 
is obtained we shall  have: 
                              
50% 0
1 lg lg[ ]ex
mpH K HR
n n
= −
      (4) 
 
From the graphic  pH50% - lg[HR]0  the value of  
m can be determined. 
When the variation of the metal ion  
concentration influences the repartition coefficient, 
some polymer species are assumed to be in organic 
phase.
 
This balance is expressed by the equation: 
( )[ ] [ ]aq0x10naq HnHRnmMRn)HA(mM ++ +−⋅↔+                                                      (5) 
Where x is the number  of  monomer units in the polymer phase. 
 
For the repartition  coefficient, we have: 
                              [ ]
[ ] [ ]
1
1
0
0
0
1;[ ] 1
x x
x
n
aq xn
aq
M
M
xM
D D
M
M
x
−
+
+
⎧ ⎫⎪ ⎪
⎨ ⎬
⎪ ⎪⎩ ⎭= =
⎛ ⎞⎡ ⎤ ⎜ ⎟⎣ ⎦ ⎝ ⎠
                                      (6)
By applying a logarithm and re-arranging the terms in the extraction constant relation, we have: 
                           
0
1 1lg lg lg lg lgex
xD K n pH m HA x M
x x
−
= + + + +          (7)
At the pH where extraction is 50%  M0 =M  
total/1 therefore: 
                                          
[ ]
0,
50% 1
lg
X
total HR
pH x
M nx
⎡ ⎤∂ −
= −⎢ ⎥
∂⎢ ⎥⎣ ⎦
                           (8) 
The graphic representation  under coordinates 
lgD Vs–pH50% at different  metal concentrations shall 
have, in some areas, strainght lines. From the slope of 
this line it can be calculated the x value .[12] 
 
2.Experimental 
 
The experiments were carried out using  an 
organic phase -water phase ratio =1:2. The  pH was 
varied by different buffer solutions (NH4OH + 
NH4Cl). Funnels were stirred  for 20 minutes; after 
the balance had become stable, the water solution was 
analyzed to determine the pHl (with a pH-meter MV-
S4) and  the concentration M(II) ( complexonometric 
titration in the presence of ascorbic acid, using violet 
pirocatehine as indicator). The ion strength was still 
present with solution of KNO3 1m. 
 
3.Rezults and discussions 
 
The experimental results concerning the variation 
of the repartition coefficient depending on the pH 
value are presented in fig.1. Applying the 
mathematical quantitative approach to the described 
extraction procedure the slope of the straight lines of 
n=1,92≈ 2 is obtained. The  n value , even at this  pH, 
is consistent with the second oxidation state of the 
manganese; this takes part in the complexion reaction 
with di-β- naftolmonosulphide as a Mn2+ species and 
complexes two ligand molecules. The occurence of a 
family of straight parallel lines in the lgD-pH graphic, 
for different  ligand concentrations, indicates  the 
possibilitity of solvating the complex compound 
consisting of two reactive molecules. From the 
graphic illustration under coordinates pH50%  -  lgCHR  
(fig.2), we get a straight line from which slope  we 
can calculate  m ≈ 3.  
-  64  -
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 2 – 2007, ISSN 1453 – 083X 
 
 
 
The species extracted will add a ligand molecule  which can be written as: 
                                                            [MnR2• HR]    
     
8
8,2
8,4
8,6
8,8
9
9,2
9,4
-2,3 -2,2 -2,1 -1,9
lg CHR
pH
 5
0%
 
 
Fig.1. Extraction Mn(II) with di - β- naftol 
lgCHR upon Mn(II) extraction 
Fig.2. Variation of  pH50% with monosulphide 
CMn=const., CHR=variable 
 
 
Experimental researches performed, while 
keeping the reactive concentration constant, at 
different metal ion  concentrations, were focused on 
the variation of the repartition  coefficient depending 
on the  pH of the water phase. Within the 
concentration range concerned , 4•10-4 - 6•10-4 mol 
Mn2+/ 1, the repartition  coefficients do not   depend 
on the initial  concentration of the Mn2+ ion which 
indicates the absence of the polymerization of the 
species extracted in organic phase (fig.3. ) 
Therefore, the di-β-naftolmonosulphide, dissolved in 
isobutilic alcohol forms with  Mn2+ ion a green  
combination, extractable in non water medium. 
 
The extraction balance is described by the following chemical equation: 
( ) ( ) ++ +⋅↔+ aq0214202213200214202aq H2SOHCSOHCMnSOHC3nM                                     (9) 
 
-0,8
-0,6
-0,4
-0,2
0
0,2
0,4
0,6
0,8
8,78 8,88 8,98 9,03 9,12 9,2 9,3
pH
lg
 D
 
Fig.3. Extraction Mn(II) with  
 di- β- naftolmonosulphide: 
 CMn= variable; CHR=const. 
 
Based on the studies carried out  the optimum 
extraction conditions have been established ( wave 
length , pH,  reactive concentration, extraction time , 
influence of foreign ions) and an efficient method of 
determining the manganeese from waters was finally 
reached.  
The following  way of working is 
recommended: in a  separating funnel of 50 ml,  10ml 
reactive solution is poured into  1• 10-2 mol/l  
isobutilic alcohol, 10 ml buffer solution of  pH 10 
(clorura de amoniu- ammoniac) and V ml solution to 
be analyzed are poured. After 5 min stirring , phases 
are separated  and the water layer is removed.  
The extract in isobutlic alcohol is brought to 
level in a  measuring flask of 25 ml. With higher 
Mn2+ concentrations, it is recommended to repeat 
extraction.  
-  65  -
FO N D ATĂ
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 2 – 2007, ISSN 1453 – 083X 
 
 
To remove water traces, the extract is filtered 
through cutton or a layer of anhydrous Na2SO4.  
The absorbance of solutions flasks 
supplemented with isobutilic alcohol was measured  
after 30 minutes. 
The variation of  absorbance versus the Mn2+   
ion concentration  results in  a linear  dependence, in a 
very large range of [Mn2+](Table1). 
 
Table 1. Processing the  experimental results to verify Lambert- Beer law 
CMn•10-2 
mol/litru 
xi 
A560 
 
yi 
xi2 • 108 Xiyi • 104 
A 
calculate 
Yi 
(yi - Yi)• 103 (yi - Yi)2 • 106 
1 0,072 1 0,072 0,073 -1 1 
2 0,145 4 0,290 0,145 0 0 
3 0,220 9 0,660 0,218 2 4 
4 0,290 16 1,160 0,290 0 0 
5 0,362 25 1,810 0,363 -1 1 
6 0,435 36 2,610 0,436 -1 1 
7 0,508 49 3,556 0,508 0 0 
8 0,582 64 4,656 0,581 1 1 
 
 
 
 
y = 0,5 • 10-4 + 0,0726 • 104 x 
ysup = 2,88 • 10-3 + 0,0726 • 104 x 
yinf = - 2,88 • 10-3 + 0,0726 • 104 x 
 
where: 
y- absorbance 
x – concentration CMn 
 
 
5. Conclusion 
 
- Di–β-naftolmonosulphide, organic polydentat  
ligand , can be used as an efficient extract agent in the 
extract process chemistry; 
- The Mn2+ ion reacts with di–β-  
naftolmonosulphide resulting in a green compound, 
extractible in  organic water non-miscible solvents, 
such as high alcohol; 
 
- When  isobutilic alcohol is used as solvent in the concentration range  concernd , at pH 8-10, the 
extraction balance of  Mn2+, is written as:   
( ) ( ) ++ +⋅↔+ aq0214202213200214202aq H2SOHCSOHCMnSOHC3nM                                     10 
 
- The extraction procedure depends on the pH 
of the water phase, the ligant  concentration in  
organic phase and the stirring time. Under certain 
conditions, the extraction can be carried out  
quantitatively. 
 
References 
 
[1]. Mitoşeriu O., Doctor’s degree thesis, Jassy Polytechnic 
Institute, 1980 
[2]. Mitoseriu O., Constantinescu S., sa., Metode moderne de 
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[10]. Mitoseriu O. , Musat V. , Popescu M., Benea L., Bodiu V., 
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Study And Researche Regarding Binaring Sistem With Tiobis - β – Naftol

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Study And Researche Regarding Binaring Sistem With Tiobis - β – Naftol

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