INTRODUCTION:

More than 10,000 dyes have been widely used in textile, paper, rubber, plastics, leather and cosmetic, pharmaceutical, and food industries [1]. Methylene blue (MB) is cationic dyes. MB will cause increased heart rate, vomiting, shock, Heinz body formation, cyanosis, jaundice, quadriplegia, and tissue necrosis in humans [2]. Today as a commercial plant, tamarind is grown on a large scale in different parts of the world like India, Tropical America, South Florida, Bermuda, etc, In India there are special tamarind orchards producing 275,500 tons of tamarind annually. Pollution of the aqueous environment by dyes due to the release of dye containing effluents in to the water bodies from various textile industries is one of the most serious environmental issues of the century. There are may harmful effects to the environment especially to the aquatic systems due to the dye mixed wastewater coming from the textile industry.

There effects include increase in the level of BOD and COD, carcinogenic effects, mutagenic changes to organisms, light penetration etc, they also results in the serious health hazards because of their accumulation in the food chain.

Some of the common methods for industrial waste water treatment includes Ozonation, Membrane Filtration, Ion exchange, Phytoremidiation etc., Out of all these methods, adsorption was found to be the most popular water remediation process and can be utilized by any textile industry without much investment.

Many biosorbents were available for the process and in this work Tamarind seeds which are abundant in India is chosen. In most areas people generally dump these seeds as waste therefore here an attempt had been made to collect tamarind seeds from house hold and is finally proved as a biosorbent.

MATERIALS AND METHODS:

Stock metal solutions of Methylene dye were prepared by dissolving 1 gm of Methylene dye in 1000 ml of distilled water. The stock solutions were diluted to obtain working solutions of desired concentrations.

Biosorption Experiments:

All the experiments in this study were performed in 250-mL Erlenmeyer flasks containing 100 mL dye solutions. The biosorbent selected for this work i.e., Tamarindus indica was collected ,then dried in normal sunlight and made in to powder .The powder was classified in to 100 and 150 mesh size by using Taylor standard screen analysis. To study the effect of biomass weight, Samples containing 0.2,0.4,0.6,0.8 and 1.0 of biomass was taken and is mixed in the working solution .for this purpose 1000 ml of working solution was taken in 250 ml capacity Erlen meyer flasks. the flasks with varying biomass wts were inserted in to orbital shaker and were agitated at a speed of 120 r.t.m at room temperature for 1 hr.

After 1 hr, the solution was filtered using whatman filter paper .the filtered papers colected were analysed using AAS. Percentage removal of dye by Tamarindus indica was determined according to the formula

* 100

where

R = % od dye adsorbed by Tamarindus indica

C₀ = Initial dye concentration (mg/L)

C_t = Final concentration at time t (ppm)

metal uptake at equilibrium can be determined using the formula

q= V

where

q = metal uptake in mg (dye) g^-1 biomass

V=volume of metal containing solution in contact with the biosorbent in L

Ci = Initial concentration of dye in the solution mg/ L

Ce = Final concentration of dye in the solution mg/L

x= Amount of Tamarindus indica added on dry basis in g.

RESULTS AND DISCUSSIONS:

Effect of initial dye concentration:

Different dye concetrations were selected 20,40,60,80 and 100 mg/L to study the biosorption capacity of Tamarindus indica.1 g/L of Tamarindus indica was contacted with a solution bearing a dye concetration of 20,40,60,80 and 100 mg/L. Variation in dye adsorption capacity with increase in the initial dye concentration was clearly indicated in the figure 1.

Increase in the dye concentration increases the dye adsorption due to the increase in the mass transfer resistqne between the solid and aqueous phase.

Table 1;

Dye concentration (mg/L) Ci	Dye uptake (mg/g) q
0	0
20	1.26
40	3.45
60	6.65
80	7.89
100	10.2

Fig 1: - Effect of initial dye concentration on its uptake by Tamarindus indica (Time - 60 min , dosage = 1 g/L)

Effect of contact time:

Effect of contact time starting from 0 min up to 60 min is studied and it was proved that at 60 min equilibrium has been achieved and further contacting does not result in much variation in dye uptake values .Variation in dye uptake values with contact time is shown in fig 2.

Table 2

Time	Dye uptake (mg/g) q
0	0
10	2.5
20	3.89
30	6.22
40	7.34
50	9.3
60	10.2

Fig - 2 : Effect of contact time on its uptake by Tamarindus indica (100 mg/L initial concentration, 1g of biosorbent).

Effect of biosorbent dosage:

Dosage of biosorption influences adsorption process and the potential of the biosorbent in removing the dye with its varying dosage is studied. Since metal uptake q is the ratio of meta in mg to the biomass dosage, q decreases with increase in the dosage of the biomass from 0-1g. The concentration difference existing between the adsorbate and the adsorbent might be the reason for the decrease in the metal uptake q (mg/g)[3]. So adsorption of metals increases with the increase in biosorbent dosage value due to the available surface area with large no of active sites [4].

Table 3:

Biosorbent dosage (g)	Metal uptake q (mg/g)
0	85.9
0.2	75.2
0.4	58.5
0.6	39.2
0.8	38.2
1.0	10.2

Fig 3: - Effect of biosorbent dosage on methylene blue uptake(q)

Kinetic studies:

Adsorption mechanism can be easily understand by the kinetic studies. In literature we can find no of models for studying the adsorption kinetics .in the present study,we are concentrating on pseudo first order and pseudo second order kinetic models.

Pseudo first order kinetic equation is given as

Therefore from the above equation we can say that if the biosorption process follows a plot drawn between ln (qe - qt) vs t should be a straight line [5].

Pseudo second order kinetic equation is given as

Where qe and qt are the amount of metal adsorbed at equilibrium and time t (min) in mg/g, respectively and k1 (min-1) and k2 (g mg-1 min-1) are the pseudo first order and pseudo second order reaction rate constants .

From the above equation ,we can say that if the biosorption process follows the pseudo - second order rate equation ,a plot drawn between t/qt vs t should be linear with slope = 1/qe and intercept = 1/k₂ qe²[6].

The kinetic studies data was obtained for the initial dye concentration of 100 mg/L and the data obtained were fitted using both kinetic models such as pseudo first order and pseudo second order kinetic models.

Table 4:

t	qt	qe(exp)	ln(qe-qt)	t/qt
0	0	10.2	2.322388	#DIV/0!
10	2.5	10.2	2.04122	4
20	3.89	10.2	1.842136	5.141388
30	6.22	10.2	1.381282	4.823151
40	7.34	10.2	1.050822	5.449591
50	9.23	10.2	-0.03046	5.417118
60	10.2	10.2	#NUM!	5.882353

Fig 4 : pseudo first order kinetic model

Fig :5 pseudo second order kinetic model.

The results of kinetic studies were discussed in table 5. The obtained data is taken as a dye concentration of 100 mg/L with a bio sorbent dosage of 1 g/L. The parameters k₁,k₂,R², and qe (cal) for both pseudo first order kinetics and pseudo second order kinetics were studied and compared . From the table it was clear that pseudo first order kinetic model is well suited with the experimental data obtained .Since the coefficient of determination R2 value for pseudo first order kinetics is very much closer to unity compared to pseudo second order kinetics and also the difference between qe cal and qe exp value is lower in case of pseudo first order kinetic model compared to pseudo second order kinetic model.

REFERENCES:

1. S. Mondal, “Methods of dye removal from dye house effluent an overview,” Environmental Engineering Science, 25(3); 2008:383–396.

2. R. Ahmad and R. Kumar, “Adsorption studies of hazardous malachite green onto treated ginger waste,” Journal of Environmental Management,91(4); 2010:1032–1038.

3. Kadirvelu, K.; Thamaraiselvi, K.; Namasivayam, C: Removal of heavy metals from industrial wastewaters by adsorption onto activated carbon prepared from an agricultural solid waste. Bioresour. Technol. 76; 2001: 63–65.

4. Alyüz, B.;Veli, S.: Kinetics and equilibrium studies for the removal of nickel and zinc from aqueous solutions by ion exchange resins. J. Hazard. Mater. 167; 2009: 482–488.

5. Gaber Edris, Yahia Alhamed , Abdulrahim Alzahrani - Biosorption of Cadmium and Lead from Aqueous Solutions by Chlorella vulgaris Biomass: Equilibrium and Kinetic Study Arabian Journal for Science And Engineering .39(1);2014:87-93.

6. Flávio André Pavan , Ana Cristina Mazzocato , Yoshitaka Gushikem Removal of methylene blue dye from aqueous solutions by adsorption using yellow passion fruit peel as adsorbent. Bioresource technology,99(8),2007,3162-3165.

Received on 28.04.2017 Modified on 31.05.2017

Research J. Pharm. and Tech. 2017; 10(8): 2557-2560.

DOI: 10.5958/0974-360X.2017.00452.8

Dye	Pseudo first order kinetic model				Pseudo second order kinetic model
Methylene Blue	qe (exp)	qe (cal)	k₁	R²	qe (cal)	k₂	R²
Methylene Blue	10.2	18.725	0.4251	0.9399	1.346	0.3893	0.628