Adsorption of Thymol Blue and Erythrosine-B on MWCNTs Functionalized by N-( 3-nitrobenzylidene )-N '-trimethoxysilylpropyl-ethane-1 , 2-diamine Equilibrium , Kinetics and Thermodynamic Study

We have accomplished a synthesized of an adsorption material through anchoring N-(3nitro-benzeyliden)-N-trimethoxysilylpropylethan-1,2-diamin onto multi-wall-carbon nanotube. The systems were established via SEM and FT-IR techniques. Then, it was used for removing the ultra-sound-assisted for Thymol Blue (TB) and Erythrosine-B (EB).The pH dependency and initial dyes concentration, sonication time and adsorbent’s dosage for the removing percentage of Thymol Blue and Erythrosine-B which have investigated by CCD or Central-Composite Designing. It was exhibited that the Thymol Blue and Erythrosine-B adsorption follows, while the Langmuir models explain the equilibriums variables.


INTRODUCTION
Dyes and pigments have been released in the waste-waters from textiles, papers, rubbers, plastics, leathers, cosmetics, foods, and drug industries 1 .These dyes make allergic dermatitis 1 , skins irritation, cancers and mutations in living 1,2 organism.It also causes eyes burn, which might be reason for permanent injuries to the eye's human and animal also.. Discharge 1,2 of a dye into waters sources threaten the water supplies and qualities due to irr-efrangible 2 under harshest condition, toxicities, accumulations and magnifications throughout 3 the foods chain 2,3 .The high colored's effluents not only cause damages for living but human being via producing mutagenic 3 effects 3 .
Dye generally has a complex aromatics structure which makes them stables and difficulty for decomposing.The dye presents in wastewater 3 absorbs sunlight's leading to decreasing in the efficiencies of photo-synthesis in the aquatic plant due to reducing lights penetration 4 .
Among various types of dye including anionic 4 , cationic 5 (basically dye), and non-anion (disperse 5 dye), the positive ion is the most toxic dyes 5 .Among various methods of dye's removal from aqueous solutions such as membrane 6 separation 6 are important.For the chemical oxide materials the adsorption techniques are known as an important methods for dye removal 7,8 .
Thymol Blues, belongs to tri-phenylmethane 7 groups, have biological activities same stains agents.The TB 8 dyes are also used for pH indicators in analytical chemistries.Inhalation leads to respiratory 8 tract exposures and subsequently 8 .Skin Contacts may causes irritations with redness 8 and pain 9 .
Erythrosine-B is a water-soluble xanthenes class of dye.It is extremely used as colorant 9 in foods, textiles, drugs and cosmetics 10 .In high dose it cause several types 9,10 of allergies 10 , thyroid activity, carcinogenicities, DNA damages, and neurotoxicity's behavior in the human 9 and animal.The photo-chemicals and bio-chemicals degradations of the erythrosine 10 are not suggested because for formation toxic by-products 10 .Adsorptions are the best techniques 11 for removing of toxics and noxious 12 impurity in comparison 12 to other conventional 13 protocols same as chemical coagulation 12,13 , ion exchanges, electrolysis of electrolytes, biological 13 treatment which are related to advantages 14 .Adsorption technique 12 also have a lot of efficiencies for the removing pollutant which are highly stables in biological degradations process through economically 14 mild pathways [11][12][13] .Of those methods 14 , nanomaterial's based adsorbent is highly recommended for dye pollutant removal 14,15 .The suitable figures 15 of merit in multi components dye system removing are based on development 15 of novel 16 methods which permits 15 its accurate simultaneous 15,16 determination of mixture.The encounters difficulty is serious peak overlapping 16 that subsequently 17 impossible for its direct determination in the mixtures using general equations like Beer-Lamberts.Derivatives spectroscopies efficiently are applicable 17 for resolving absorption peak overlaps through its separations and corrections of background interference 16 .These methods are based on searching 18 the wavelength which able to accurate 18 and repeatable 17 monitoring for each specie in the complexes without no interferences from the other targets compounds 16,17 .The classical optimization of protocols failed for giving useful information of interactions between several variables 17 .Central composites design or CCD 18 under surface methodologies can be applied 18 for handling of both variable involving and response without suffers above-mentioned 19 draw backs.These approaches enable us for making a suitable predicative models for applying several factor even in the presence 19 of complexes interaction for describing and finding the best optimized condition with less times elapsed 18,19 .
In this Paper, MWCNT has been modified with N-(3-nitro-benzylidene)-N-tri methoxy silylpropyl-ethane1, 2diamine as the best adsorbents using FTIR and SEM.This adsorbent was used for the ultrasound-assisted removal of Thymol Blue and Erythrosine-B from aqueous solutions.The influences of variables initial Thymol Blue and Erythrosine-B as well as its interaction were investigated under response surface methodology 19 .

Materials and instruments
Thymol Blue and Erythrosine-B supply from Merck in Germany.The stocks solution 20 of one hundred mg/l for every dyes were getting dissolutions of ten milligram of which in 100 milliliter double distilled waters, separately and are suitable dilute 20 on performing for obtain worked solution with desired concentration 21 .R, N-(3-(tri meth oxysilyl)-propyl) ethylene diamine (TSPED) and 2-nitrobenzaldehyde (NBA) was purchased through SigmaAldrich.Multi-walled carbon nanotube was supplied via RiedelDeHean and other reagents 22 was used for analytical grades in the Merck Company 22 .The pH/Ion-meter was used for the pH measurement.Dye Thymol Blue and Erythrosine-B concentration was determined using Jasco UVVis spectrophotometric model V530, at wave-length of 430 nm and 580 nm, respectively 23 .
The ultrasonic 24 bath including heating systems were used at frequencies 60Hz and power 130W.The morphologies of the NBATSPEDMWCNT were studied by SEM Hitachi, model S4160.The FTIR spectrophotometer for compound was recorded on the JASCO680" instrument in areaof 380-4200 cm −1 using potassium bromide pellets with molratio 1: 100 for the sample of potassium bromide the software MINITAB version 6.2.4.4 were used for experiment designing and its subsequent regression analysis 24 .

Preparation of NBATSPED-MWCNT
At first step, tri methoxy silylpro pylethylene diamines support on MWCNT-(NH2-MWCNT) were synthesized through the reactions of 1.85 ml N-(3-(tri methoxysilyl)-propyl) ethylene diamine and 0.15 gramm MWCNT in 20 milliliter of dichloromethan under reflux at forty degree in the oil bath for twenty four hours.Then, the obtained solids were filtered.The products were filtered, washed with fifty milliliters of C2H5OH, double distilled water and then dried in oven for 10 h 50 oC .These step are presented in the Fig. 1.

Ultra-sounded-assist a-multicomponent adsorb of Thymol Blue (TB) and Erythrosine-B (EB) on to NBATSPED-MWCNT
The batches process using NBA..MWCNT in presence of ultrasounds were applied for binaries adsorption of Thymol Blue and Erythrosine-B.The vessels were immersed in the ultrasonic baths for four minutes at room temperature and then the solution was centrifuged.

Adsorption equilibrium study
The equation and parameter of the isotherm of the research has been reported in Tables 1 and 2, respectively [20][21][22][23][24][25][26] .which support the achievements for optimum value 30 .The principles and applications of desirability functions for the best predications of real behaviors of adsorptions system were pointed out previously 30 .The desirability's profile indicates the predicted level of variable, which produce the most desirable responses.

Analysis of central composite designing
ANOVA was performed for obtaining information of the most important variable and its possible interaction (Table 5).Generally, they applied for the model of 11.16 and 8.48 of TB and EB respectively.The value calculated of the determination coefficient are R 2 0.96 and 0.94 for TB and EB respectively.The removal percentage of for TB and EB has been calculated.Therefore, the following semi-empirical expression applies for models of the removal percentage (R%) for TB and EB respectively 36 .
For making other assessments on the applicability 37 of the model, the predicted and observed value of the removal percentages of TB and EB dye on NBATSPED-MWCNT were compared in (Fig. 3).

RESULTS AND DISCUSSTON
Based on theoretical calculation for comparison to experimental data the references have been considered  .And based the experiments results and approaches of related works this work has been investigated  .

Characterization of adsorbents
The FT-IR spectrums of NBASPEDMWCN (Fig. 2b), exhibits absorption peaks at 1715 cm -1 correspond to the stretching modes of vibrations for carbonyl group.The broad peak at 1086 cm -1 could assign to carbon oxygen stretching from phenolic, alcohlic, etherics group.These peaks can be assigned to the OH groups of moistures and carboxylic groups 34 .The aromatic 35 C=C stretching are observed at 1459 cm -1 .The FT-IR spectrums (Fig. 3b.) displays the new peaks as a weak shoulders at 2931 cm -1 , which correspond to a stretching modes vibration for C-H bond in propyl 35 groups.

Statistical analysis
Central composites are designed as the most applicable types of RSM were applies for modeling and optimizing of concentrations for TB (X 1 ) and EB (X 2 ),pH(X 3 ),amounts of adsorbent (X4) and (X5) on the ultrasonic-assisted 36 adsorption of TB 37 and EB 38 dye through NBATSPED-MWCNT 38 .5 independent variable was set at five level at which the R% of TB and EB dye as response were determined and exhibit in the Tables four and five.Analysis of the variance or ANOVA 38 were performed for evaluating the important 35 and effectives terms for modeling of the response based on F-test and p-values [36][37][38] .

Response surface methodologies
Fig ( 3a, b) exhibits the removal percentages change versus the adsorbents dosages.The positive increasing in the dyes removal percentages with

Fig. 5 .
Fig. 5. Profiles for predication data and desirability functions for removing percentages of TB and EB.

Table . 6: Several isotherms including the correlation coefficient calculation dyes adsorption over NBATSPED-MWCNT
38creasing in the adsorbent masses can be seen.Significant38diminishes in removal percentages at lower amounts of NBTSPEDMWCN are at attributes to higher ratio of dyes molecules.