Sudan is applied to colour merchandises nutrient and are man-made industrial, used in plastics, oil and waxes. However, the dye should be within the safety bound set by the nutrient ordinances. In this work, a simple method was proposed for survey of surface assimilation of the Sudan ( III ) by utilizing activated C. Activated C was found effectual for up taking the dye with maximal capacity of 7.8 mg/g at 40 oC where the undermentioned experimental conditions maintained at mass of C 0.2 g, volume of solution 50 milliliter, dye concentration scope 10-50 mg/L with participle diameter 300-500 ?m. The surface assimilation informations of Sudan ( III ) were modeled utilizing Langmuir and Ferundlich isotherms. The theoretical account parametric quantities were found to be 1.7 ( KL ) , 7.8 mg/g ( qm ) , 0.8557 ( R2 ) and 1.37 ( N ) , and 0.8620 ( R2 ) which were obtained at 40 oC. The activated C was proved to be a perfect absorbent for Sudan ( III ) as indicated from the distribution coefficient value ( 9.9 L/g ) and this value was reported at the undermentioned conditions: 10 mg/L dye, 0.2 g C mass, 3 yearss agitation, and pH 8.5.
Thermodynamic surveies indicated that Sudan ( III ) surface assimilation onto activated C was an exothermal procedure and spontaneously at 293, 303 and 313 K. The values of free Gibbs energy ( ?G ) were -4.8, -4.9 and -5.0 KJ/mol severally. The enthalpy value of surface assimilation was -2.4 KJ indicate a physiosorption procedure. The procedure occurred with positive information.
Sudan dye is classified of azo dye was used for variant field in industrial and scientific applications ( colourising of fuel and staining for microscopy ) [ 1,2 ] . Sudan dyes in figure ( 1.1 ) are man-made industrial, used in plastics, oil and waxes [ 3 ] . Because of this colour low cost and available [ 4 ] . Man-made organic colorants, have a group ( -N=N- ) . The international Agency for Research on malignant neoplastic disease ( IARC ) classified sudan dyes as category 3 carcinogens [ 5,6 ] . In some European states sudan dyes have been found in nutrient merchandises such as chili pulverization to mime. sudan dyes have been found in six 100 merchandises in UK such as fish sauce, noodle soup, Worchester sauce and pizza. The sensing bound of sudan dyes is 0.5-1 mg/kg [ 7 ] .
Figure1.1. Chemical construction of Sudan III
Sudan dyes have different techniques to be used for their separation and designation. The traditionally analytical techniques for the finding of the sudan dyes include solid-phase spectrophotometry [ 8,9,10 ] , HPLC-Fluorimetry [ 11 ] , thin bed chromatography [ 12 ] , capillary cataphoresis [ 13 ] , HPLC coupled with photo-diode array [ 14 ] , UV-visible [ 15 ] , chemiluminescence [ 16 ] and MS [ 17,18,19,20,21 ] .
The finding of sudan dyes by utilizing conventional methods is hard because of high-cost instruments and time-consuming pretreatment technique separations, such as equipment such as liquid and gas chromatography are non available for little research labs due to their high cost.
The application of activated C is investigated in this work. The studied dye is sudan ( III ) . This dye has a broad application. Effect of experimental conditions such as initial dye concentration, C mass, agitation clip, pH, salt and temperature were studied.
The consequence of intervention clip, initial dye concentration, C mass, pH, salt and temperature was determined by gauging the distribution coefficient ( Kd ) of dye between solid stage and aqueous solution. The value of ( Kd ) was merely estimated utilizing Equation ( 1 ) , [ 22 ] .
Kd = qe/Ce ……………………………… ( 1 )
Where kd, qe, and Ce, and are distribution coefficient ( L/g ) , surface concentration of dye ( mg/g ) , and concentration of dye remaning in solution after clip ( T ) or at equilibrium ( mg/ L ) severally. The value of qe can be calculated from Equation ( 2 ) :
qe= ( C0-Ce ) V/ m ……………………… ( 2 )
Where C0, V, and m are initial dye concentration ( mg/ L ) , volume of solution ( L ) and mass of extractant ( g ) severally. A big Kd ( & A ; gt ; & A ; gt ; 1.0 mg/g ) signifies a high affinity between dye and the extractant.
The purpose of work survey surface assimilation of the Sudan dye ( III ) in methyl alcohol by utilizing activated C Effect of experimental conditions such as initial dye concentration, C mass, agitation clip, pH, salt and temperature were studied.
All stuffs used in this research were analytical class reagents and used as received without any farther purification: The dye sample of Sudan ( III ) was obtained from Lobal Chemie ( India ) . Methanol from Sigma- Aldrich Chemie ( Germany ) . Activated C was purchased from Nen Tech Ltd ( UK ) . Sodium Hydroxide and sodium chloride from Lobal Chemie ( India ) . Hydrochloric acid from Riedel-de Haen.
UV-Visible spectrophotometer ( SP-300, Optima, Japan ) for computation of dye concentration, Samples were shaken and thermostated utilizing Wise Bath ( Daihan scientific, Korea ) shaker. pH was measured utilizing ( Lovibond pH-meter, Germany ) . Multitudes were accurately measured ( ±0.0001 g ) utilizing Wiggen Hanser. Samples were stirrer utilizing Magnetic scaremonger Wigen Hauser.
Adsorption of Sudan ( III ) dye
The surface assimilation belongingss for dye were studied utilizing batch-Equilibrium technique in the undermentioned mode: A certain sum of activated C at specific diameter ( 300-500 µm ) was contacted with 50 milliliters dye solution and the mixture was agitated to make equilibrium. The equilibrium dye concentration was detected utilizing the standardization graph Figure ( 3.1 ) . Consequence of C mass, dye concentration, solution sourness, ionic strength, and temperature on Sudan ( III ) dye surface assimilation was investigated. As shown in Figure ( 3.2-3.7 ) .
2.3.1 The consequence of clip on dye
The equilibrium clip for dye surface assimilation was determined as following: Different dye solutions were agitated for different periods ( 1-8days ) . The staying dye concentration in each solution was determined. The undermentioned variables were maintained: mass of C = 0.2g, temperature = 25 oC, volume of solution = 50 milliliter, initial concentration 35 mg/L, pH = 8.5 and atom diameter = 300 – 500µm. As shown in Figure ( 3.2 ) .
2.3.2 Effect of adsorptive mass on dye remotion
Different multitudes of activated C ( 0.10-0.35 g ) were assorted with 50-mL of 35 mg/L dye solution. The mixtures were agitated for 3 twenty-four hours. The undermentioned variables were maintained: pH = 8.5, temperature = 25 oC, volume of solution =50 milliliter, and atom diameter =300-500 µm. As shown in Figure ( 3.3 ) .
2.3.3 Adsorption isotherm finding
Adsorption isotherm of Sudan ( III ) by activated C was recorded at different temperatures. A fixed sum of activated C was added to put of dye solutions of variable degrees ( 10-50 mg/L ) . The mixtures were agitated until equilibrium. The undermentioned variables were maintained: agitation clip = 3 yearss, mass of C = 0.2 g, temperature = 25 oC, volume of solution = 50 milliliter, pH=8.5 and atom diameter =300 – 500µm. As shown in Figure ( 3.4 ) .
2.3.4 Effect of ionic strength on dye
Different solutions of Sudan ( III ) of variable ionic strengths were prepared and agitated with activated C for 3 yearss. The staying dye concentration in each solution was determined. The staying dye concentration in each solution was determined. The sum of dye removed was calculated in each instance. The undermentioned variables were maintained: mass of C = 0.2 g, temperature = 25 oC, volume of solution = 50 milliliter, initial concentration 35 mg/L, pH=8.5 and atom diameter = 300 – 500µm. As shown in Figure ( 3.5 ) .
2.3.5 Effect of solution pH on dye
Different solutions of Sudan ( III ) dye were prepared at different pH conditions: 1, 3, 10, and 12. The mixtures were carefully agitated for 3 yearss. The staying dye concentration in each solution was determined. The undermentioned variables were maintained: mass of C = 0.2 g, temperature = 25 oC, volume of solution = 50 milliliter, contact clip = 3 yearss, initial concentration 35 mg/L, and atom diameter = 300-500 µm. As shown in Figure ( 3.6 ) .
2.3.6 Effect temperature on dye
Adsorption isotherm of Sudan ( III ) dye was recorded at different temperatures ( 20, 30, and 40 oC ) . The undermentioned variables were maintained: agitation clip = 3 yearss, mass of C = 0.2 g, initial concentration=35mg/L, temperature = 25 oC, volume of solution = 50 milliliter, pH=8.5 and atom diameter = 300 – 500µm. As shown in Figure ( 3.7 ) .
Result and treatment
Adsorption belongingss of the activated C
The surface assimilation belongingss of the activated C toward Sudan ( III ) were studied by finding of dye concentrations staying in solution utilizing spectrophotometer after constructing up analytical standardization curve for Sudan ( III ) .
Linear standardization curve was obtained for dye utilizing a clean sample and a series of standard samples in the scope of 1.0-8.0 mg L-1. The standardization graph Figure ( 3.1 ) was obtained by plotting optical density values against dye concentration. A additive standardization graph was obtained with R2 = 0.9887 and this graph were repeated every hebdomad for more truth. The standardization secret plan was carried out at 510 nanometer, the wavelength at the maximal soaking up of the dye ( ?max ) .
Figure ( 3.1 ) . Calibration curve of Sudan ( III ) in methyl alcohol ( ?max. = 510 nanometer )
3.2 The consequence of clip on dye
Adsorption of dye by the activated C 0.2g was determined as mentioned earlier over long period of clip ( 1-8 ) yearss, pH = 8.5, T = 25 oC and initial concentration of 35 mg/L. The consequences of these experiments are shown in Figure ( 3.2 ) .
Figure ( 3.2 ) Dye consumption by the activated C as a map of contact clip
Consequence of agitation clip on dye extraction at 35mg/L is shown in figure ( 3.2 ) . As the contact clip addition, the surface assimilation of Sudan ( III ) increases to go about steady after 3 yearss. The distribution value was somewhat changed after that clip. Consequently, the optimal agitation clip was selected to be three twenty-four hours. As can be noted, the uptake procedure is favourable after the twenty-four hours figure four where Kd is higher than integrity.
3.2. Consequence of C mass on dye uptake
The consequence of changing mass of activated C on dye consumption was studied utilizing batch process in the scope: 0.10 – 0.35 g. the sorption capacity profile is illustrated in Figure ( 3.3 ) .
Figure ( 3.3 ) Dye uptake as a map of C weight
The distribution value has been decreased by increasing C mass from 0.1 to 0.35 g and somewhat changed after that mass. Consequently, the optimal mass of activated C was maintained at 0.2 g.
3.3. Consequence of dye concentration
Consequence of dye surface assimilation was at different initial concentrations of Sudan ( III ) ( 10-50 mg/L ) while maintaining the other variables at: T = 25 oC, contact clip 3 yearss, pH = 8.5, C mass = 0.2 g, and solution volume = 50 milliliter. The distribution values were calculated at each concentration and presented in Figure ( 3.4 ) .
Figure ( 3.4 ) Effect concentration of dye on Kd.
The extent of Sudan ( III ) surface assimilation was studied over a broad concentration scope ( 10-50 mg/L ) . As can be noted Figure ( 3.4 ) , the Kd value is significantly decreased as concentration increased. For illustration, the Kd value was extremely decreased from 9.98 to2.47 when dye degree increased from 10 to 50 mg/L. Consequently, the values of Kd will be much larger than 9.98 at lower initial dye concentration because the staying dye concentration ( Ce ) will be really little. [ 23 ] .
3.4. Consequence of ionic strength on dye surface assimilation
The consequence of Sudan ( III ) surface assimilation by activated C at different ionic strength values was studied utilizing batch process and ionic strength scope: 0.5-3.0 mol/L NaCl. Figure ( 3.4 ) presents the informations.
Figure ( 3.4 ) Consequence of solution ionic strength on Sudan ( III ) uptake
The surface assimilation of activated C has been well decreased when the salt is introduced to the mixture. The distribution values were decreased when the salt degree become more than 0.5 M. A figure of intermolecular forces have been suggested to explicate the collection between dye molecules in solutions and these forces include van der Waals forces, ion-dipole forces, and dipole-dipole forces which occur between dye molecules in the solution. These forces found to be more favourable when salt is added to the dye solution. The salt ions force dye molecules to aggregate and migrate toward C surface [ 23 ] .
3.5. pH-dependence of dye sorption by activated C
The consequence of dye consumption at variable pH values ( 1-12 ) was studied and the informations were given in Figure ( 3.5 ) .
Figure ( 3.5 ) : Consequence of solution pH on extent of dye distribution value
The surface assimilation of Sudan ( III ) by activated C was affected when pH was changed. The alteration in Sudan ( III ) uptake with solution pH is explained harmonizing to following mechanisms:
1 ) Electrostatic interaction between the protonated surface at pH 3 of activated C and negatively charged dye molecule.
2 ) Hydrophobic interactions between the activated C and the hydrophobic portion of dye molecule. The big decrease in C surface assimilation at basic medium can be attributed to the electrostatic repulsive force between negatively charged activated C ( due to surface assimilation of OH- ions on the surface ) and the deprotonated dye molecule [ 23 ] .
3.6. Consequence of Temperature on dye surface assimilation
The surface assimilation isotherms were determined for dye at different temperatures ( 20 oC, 30 oC, 40 oC ) in the concentration scope 10 – 50 mg/L. Adsorption consequences are presented in figure ( 3.6 ) .
Figure ( 3.6 ) Adsorption isotherms of dye on activated C at different temperatures.
Adsorption of Sudan ( III ) by activated C was studied at different temperatures ( 20, 30 and 40 & A ; deg ; C ) and surface assimilation isotherms were presented in Figure ( 3.7 ) . The Kd of the dye was increased by increasing temperature ; nevertheless, this addition is dependent on the initial concentration. This indicates that temperature has a higher consequence on Kd but at lower concentration and little consequence at higher concentration. The high surface assimilation at higher temperature may be attributed to increased incursion of dye inside micropores at higher temperatures or the creative activity of new active sites.
3.6.1. Analysis of surface assimilation isotherms by Langmuir and Ferundlich theoretical accounts
The surface assimilation informations were modeled by utilizing Langmuir and Ferundlich isotherms. The Langmuir theoretical account ( homogenous sorption ) was chosen for the appraisal of the maximal surface assimilation capacity matching to the impregnation of the polymer surface utilizing the linearized signifiers of Langmuir isotherms:
Kd = qe/Ce = qmK – Kqe ………………….. ( Linear signifier I ) ……………….… ( 3 )
1/qe = ( 1/ ( qmKL ) ) 1/Ce + 1/qm ………..… ( Linear form II ) …..………….… ( 4 )
Ce/qe = 1/ ( qmK ) + ( 1/qm ) Ce …………..…… ( Linear signifier III ) … … … … … …… ( 5 )
Therefore, a secret plan of ( qe / Ce ) against ( qe ) should be a consecutive line with incline = – K and an intercept = qm K for Langmuir signifier ( I ) , a secret plan of 1/qe versus 1/Ce gives a consecutive line of incline ( 1/qmK ) and intercept 1/ ( qm ) for Langmuir signifier ( II ) , a secret plan of Ce/qe against Ce should be a consecutive line with incline = 1/qm and an intercept = 1/ ( qmK ) for Langmuir signifier ( III ) where Kd is the distribution coefficient, KL is a changeless related to the adsorption/desorption energy, and qm is a maximal surface assimilation capacity upon complete impregnation of the clay surface. On the other manus, The Freundlich theoretical account ( heterogenous sorption ) is an empirical equation used to gauge the surface assimilation strength of the dye towards the clay utilizing the linearized signifier of the Freundlich isotherm:
log qe = log KF + 1/n log Ce… … … … … … … … … … … … … … … … … … … … … … .. ( 6 ) .
A secret plan of log qe versus log Ce gives a consecutive line with a incline of 1/n and intercept of log KF. Were KF and Ns are the Freundlich invariables, the value of n indicates the affinity of the metal towards the clay [ 24 ] .
The theoretical accounts were presented in Figure ( 3.7 and 3.8 ) .
Figure ( 3.7 ) : Langmuir mold for surface assimilation informations at different temperatures
Figure ( 3.8 ) : Mold of surface assimilation informations by Freundlich theoretical account at different temperatures
As can be noted form the Figures above, Ferundlich theoretical account was more representative for Sudan ( III ) surface assimilation as can be noted from R2 values. For Langmuir theoretical account and at all temperatures, R2 values were in the scope 0.6982 – 0.8900 while for other theoretical account better R2 values were obtained: 0.8620-0.9995.
The estimated parametric quantities ; qm, Kl, n, Kf and qmax of surface assimilation isotherms were calculated from the intercepts and the inclines of the corresponding additive secret plans for dye surface assimilation onto the activated C at different temperatures. The value of these parametric quantities with their correlativity coefficients ( R2 ) is given in Tables ( 3.1 ) at optimal experimental conditions.
Table ( 3.1 ) : Langmuir and Ferundlich parametric quantities.
T ( oC )
T ( oC )
The correlativity coefficients ( R2 ) were determined for each isotherm utilizing simple additive arrested development method. The Langmuir and Freundlich have different correlativity coefficients for showing the information as shown in the old Tables ( 3.1 ) . So we can reason that there is type of sorption on the adsorbent, heterogenous sorption. The n values for surface assimilation of Sudan ( III ) were all more than integrity, which reflects the favourable surface assimilation of the dye over the studied temperatures ( 20-40 oC ) . Furthermore, the surface of activated C is known to be extremely heterogenous and the energies of active sites are extremely variable, which would besides be given to do the values of n more than integrity [ 24 ] .
3.7. Thermodynamic parametric quantities of surface assimilation
Thermodynamic parametric quantities were determined utilizing the distribution coefficient, Kd ( qe/Ce ) which depends on temperature. The alteration in free energy ( ?G ) , enthalpy ( ?H & A ; deg ; ) and entropy ( ?S & A ; deg ; ) associated to the surface assimilation of Sudan ( III ) were all calculated utilizing equations ( 7-8 ) :
?G & A ; deg ; = ?H & A ; deg ; – T ?S & A ; deg ; ……………………………….. ( 7 )
Where R is the cosmopolitan gas invariable ( 8.314 J/mol K ) and T is temperature ( K ) .
ln Kd = ?S & A ; deg ; /R – ?H & A ; deg ; /RT ………………………….. ( 8 )
Harmonizing to the above equations, ?H & A ; deg ; and ?S & A ; deg ; maps can be calculated from the incline and intercept of the secret plan of ln K versus 1/T ; severally. This is represented in Table ( 3.2 ) and in Figure ( 3.9 ) .
Table ( 3.2 ) : Thermodynamic maps for the surface assimilation of 35 mg/L Sudan ( III ) onto activated C.
?H & A ; deg ; ( kJ/mol )
?S & A ; deg ; ( J/mol.K )
?G ( kJ/mol )
Figure ( 3.9 ) : Plots ln Kd versus 1/T for Sudan ( III ) .
The surface assimilation procedure was exothermal for Sudan ( III ) where ?H & A ; deg ; has negative value for surface assimilation procedure ( -2.4 kJ/mol ) , which means that the desiccation energy is lower than the surface assimilation energy. The positive values of information for dye may be due to some structural alterations in the adsorbate and adsorbent during the surface assimilation procedure from aqueous solution onto the adsorbent. In add-on, positive value of ?S & A ; deg ; indicates the increasing entropy at the solid-liquid interface during the surface assimilation of dye on the adsorbent. The free Gibbs energy alteration calculated for surface assimilation of dye lessenings as the temperatures addition, indicates that the interaction are thermodynamically favourable. We can reason the surface assimilation of dye is self-generated.
Activated C was found an effectual adsorbent for Sudan ( III ) from solution. The maximal surface assimilation value of Sudan ( III ) was 7.8 mg/g. Adsorption of Sudan ( III ) lessening as mass of C additions and figure lessening with temperature. The procedure of Sudan ( III ) surface assimilation was found self-generated at 20, 30, and 40 0C.
Adsorption of Sudan ( III ) on activated C was more favourable at acidic conditions. Kd value was 15.42 at pH 1. The surface assimilation of Sudan ( III ) was improved at lower content of NaCl.
Adsorption isotherms of Sudan ( III ) on activated C were more fitted to Freundlich equation than to Langmuir equation. Consequently, heterogenous active site was available for Sudan ( III ) surface assimilation.