1. INTRODUCTION:

Dyes and pigments are becoming inseparable components of modern industrial man’s day to day life and the industries based on them, both on manufacturing and application sides, are being increasingly established ^1-3. The effluents from these industries possess substantial amounts of the Dyes^{4, 5}. Majority of the synthetic Dyes are non-degradable in nature and are stable to light, heat and oxidizing agents⁶. Hence, increasing amounts of these synthetic Dyes are being detected with the progress of the time in the water bodies near to the industries. The accumulation of synthetic toxic Dyes in water bodies is alarming as they are toxic to aquatic life and furthermore, they affect the photosynthetic activity due to their color⁷.

Brilliant green is a cationic Dye and is widely used in paper and textile industries⁸. It is used in the manufacture of green ink and is used as pH indicator and also as biological strain, dermatological agent, veterinary medicine, and an additive to poultry feed to inhibit propagation of mold, intestinal parasites and fungus⁹.

The Dye is detrimental to human health and causes gastrointestinal problems, vomiting, diarrhea, nausea and dermatological problems ^9-11.

In view of the toxicity of the Dyes, increasing interest is being envisaged by researchers in developing methods to remove Dyes from polluted waters. Various methods based on Electro-kinetic coagulation, ion-exchange, membrane filtration, electrochemical oxidation and photo-catalytic degradation process have been tried but these methods have one or the other disadvantage and a universally acceptable and eco-friendly method, is still evading the researchers^12-19. Coagulation methods have sludge disposal problem¹⁴ while Ion-exchange and Membrane separation methods are costly though effective²⁰. The conventional biological decomposition methods are not effective ¹⁹.

In the recent past, increasing interest is being devoted in evolving procedures using bio-adsorbents derived from flora and fauna materials, either in their native form or modified, in controlling the Dyes in polluted waters^{8,9, 24- 50}. These bio-processes are proving to be potential alternative to the existing methods of detoxification from industrial discharges/polluted waters and are stimulating continuous and expanding research in this field. Orange peel²², banana pith ²⁵, bottom ash^26-28, deoiled soya⁹, rice husk²⁹, kaolin⁸, bentonite clay ³⁰, neem leaf powder ^{31, 32}, powdered activated sludge³³, perlite³⁴, powdered peanut hull³⁵ , natural and modified clays like sepiolite³⁶, zeolite³⁷, bamboo dust³⁸, coconut shell³⁹ , groundnut shell³⁸ , rice straw⁴⁰, duck weed⁴¹, sewage sludge⁴² , saw dust carbon⁴³, agricultural waste and timber industry waste carbons⁴⁴ and gram husk⁴⁵, have been explored as adsorbents for the removal of Dyes from wastewaters.

In the present work, activated bio-adsorbents derived from leaves and barks/stems of some plants have been explored for their sorption abilities towards Brilliant Green Dye from the waste waters by optimizing various physicochemical parameters such as pH, time of equilibration and sorbet concentrations and further, the developed methodologies have been applied for some industrial samples.

2: MATERIALS AND METHODS:

(A) CHEMICALS:

All chemicals used were of analytical grade.

Stock solution of Brilliant Green Dye:

50 ppm of Brilliant Green solution was prepared by dissolving a requisite amount of A.R. grade Brilliant Green Dye in double distilled water. It was suitably dilute as per the need.

(B) ADSORBENTS:

Powders of leaves, stems and their ashes of various plants were tried for the removal of Brilliant Green from synthetically prepared simulated waters by optimizing various physicochemical parameters viz., pH, concentration of sorbent and time of equilibration. It was observed that the sorbents derived from leaves and stems of Ficus religiosa, Prosopis cineraria and Hibiscus rosa-sinensis had affinity towards the Dye.

A: Ficus religiosa

B: Prosopis cineraria

C: Hibiscus rosa-sinensis

Fig No. 1: Plants showing affinity towards Brilliant Green Dye

Ficus religiosa is a large dry season-deciduous tree grows up to 30 meters with a large trunk diameter and it has cordate shaped leaves with a distinctive extended tip and it grows well in India. It belongs to Moraceae family. It has many recognized medicinal properties. It is used in various traditional medicines in curing asthma, diabetes, diarrhea, epilepsy, gastric problems, and inflammatory disorders. It has religious sanctity and has the status of demi-god in Hindu, Jain and Buddhist religious texts.

Prosopis cineraria:

is a species of flowering tree in the pea family, Fabaceae. It is native to arid portions of South Asia. It is a versatile species, providing fodder, fuel for timber and shade besides affecting the soil improvement and sand dune stabilization. It is commonly used in dry land agro forestry in India. It is used in the preparation of some skin ointments.

Hibiscus rosa-sinensis:,

is an evergreen flowering shrub belongs to Malvaceae family and is grown throughout tropics and subtropics and is native to Asia. It is well accepted that the leaves and flowers of Hibiscus rosa-sinesis have hair growth promoting and anti-graying properties. In traditional medicine, the leaves of the plant are used in fatigue and skin diseases. Fresh root juice of the plant is given for gonorrhea and powder root for menorrhagia and further it is reported that the plant parts have therapeutic using in curing epilepsy, leprosy, bronchial catarrh and diabetes ^51-54.

The leaves and stems/barks of Ficus religiosa, Prosopis cineraria and Hibiscus rosa-sinensis were freshly cut from the plants, washed with tap water, then with distilled water and then sun dried. The dried materials were powdered to a fine mesh of size: < 75 microns and activated at 105^o C in an oven and then employed in this study. Further these leaves and stems/barks were burnt to ashes and these ashes were also used in this work.

(C) ADSORPTION EXPERIMENT:

Batch system of extraction procedure was adopted^55-57. Carefully weighted quantities of adsorbents were taken into previously washed 1 lit/500 ml stopper bottles containing 500 ml/250 ml of Brilliant Green Dye solution of predetermined concentrations. The various initial pH values of the suspensions were adjusted with dil HCl or dil NaOH solution using pH meter. The samples were shaken vigorously in mechanical shakers and were allowed to be in equilibrium for the desired time. After the equilibration period, an aliquot of the sample was taken for the determination of Brilliant Green Dye using Spectrophotometric method. The Dye has λmax at 628 nm and obeys Beers-Lamber’s law at low concentrations. The O.D. measurements were made at the said λmax using UV-Visible Spectrophotometer (Systronics make). The obtained O.D value for un-known solution was referred to standard graphs (drawn between O.D and concentration) prepared with known concentrations of Brilliant Green by adopting method of Least Squares.

The sorption characteristics of the said adsorbents were studied with respect to the time of equilibration, pH and sorbent dosage. At a fixed sorbent concentration, the % removal of Brilliant Green from sample waters was studied with respect to time of equilibration at various pH values. The results obtained were presented in the Graph Nos. A: 1-12. To fix the minimum dosage needed for the maximum removal of the Brilliant Green Dye for a particular sorbent at optimum pH and equilibration times, extraction studies were made by studying the % of extraction with respect to the sorbent dosage. The results obtained were presented in the Graph Nos. B: 1-3.

(D) EFFECT OF OTHER IONS (INTERFERING IONS):

The interfering ions chosen for study were the common ions present in natural waters viz. Sulphate, Fluoride, Chloride, Nitrate, Phosphate, Carbonate, Calcium (II), Magnesium (II), Copper(II), Zinc(II) and Nickel (II). The synthetic mixtures of Brilliant Green and of the foreign ions were so made that the concentration of the foreign ion was maintained at fivefold excess than the Dye concentrations as cited in the Table: 1. 500ml of these solutions were taken in stopper bottles and then correctly weighted optimum quantities of the promising adsorbents (as decided by the Graph Nos. A and B) were added. Optimum pH was adjusted with dil. HCl or dil. NaOH using pH meter. The samples were shaken in shaking machines for desired optimum periods and then small portions of the samples were taken out, filtered and analyzed for Brilliant Green. % of extraction was calculated from the data obtained .The results were presented in the Table: 1.

(E) APPLICATIONS OF THE DEVELOPED BIO-SORBENTS:

The adoptability of the methodology developed with the new bio-sorbents derived from Ficus religiosa, Prosopis cineraria and Hibiscus rosa-sinensis in this work for removing the Dye, is tried with some real sewage/effluent samples collected from some Dyeing industries at Hyderabad and Mangalore. For this purpose, samples were collected from effluents of industries and the samples were analyzed for actual amounts of Brilliant Green Dye and samples were fed with known amounts of Brilliant Green Dye.

Then these samples were subjected to extraction for the Dye using the bio-sorbents developed in this work at optimum conditions of extraction as given in the Table 2. The results obtained were presented in the Table 2.

3: RESULTS:

Leaves, stems/barks and their ashes of Ficus religiosa, Prosopis cineraria and Hibiscus rosa-sinensis have been found to have affinity towards Brilliant Green Dye. The extractability of Brilliant Green Dye has been studied with respect to various physicochemical parameters such as pH, time of equilibration and sorption concentration and the results obtained are presented in the Graph No.A: 1-12 and Graph No. B: 1-3. The following observations are significant:

1. Time of equilibration:

Percent of extractability increases with time for a fixed adsorbent at a fixed pH and after certain duration, the extractability remains constant (vide Graph Nos. A: 1-8). As for example, in the case of powder of leaves of Ficus religiosa, % of extraction of Brilliant Green Dye has been found to be 10.3% at 15min, 20.4% at 30 min , 31.0% at 45 min , 40.6% at 60 min, 60.1% at 75 min, 75.1% at 90 min or above at pH:2; 42.1% at 15 min, 60.6% at 30 min, 73.2% at 45 min, 85.4% at 69 min, 87.2% at 75 min, 90.2% at 90 min and 100% at and above 105 min at pH: 6; 49.0% at 15 min, 65.3.0% at 30 min, 80.3% at 45 min, 90.1% at 60 min, 92.3% at 75 min, 95.4% at 90 min and 100.0% at and above 105 min at pH: 8; 60.1% at 15 min, 75.3% at 30 min, 85.2% at 45 min, 95.4% at 60 min, 97.1% at 75 min, 98.6% at 90 min and 100% at and above 105 min at pH:10 (vide Graph No. A: 1). The same trend is found in other sorbents of our present study (vide Graph Nos. A: 2-12).

2.Effect of pH:

Percentage of extraction of Brilliant Green Dye is found to be pH sensitive. Extraction of Brilliant Green Dye has been found to be almost ‘nil’ or marginal at pH: 1 and below but substantially increased with increase in the pH conditions of extraction. As for example in case of powders of Ficus religiosa leaves, the maximum extractability has been found to be 2.5% at 1.0 N HCl; 3.0 % at pH: 1; 75.1% at pH: 2; 95.3% at pH: 4; 100% at pH: 6; 100% at pH 8 and above, at 105 minutes of equilibration and with sorbent dosage of: 1.0 g/500 ml (vide Graph No.A:1; B: 1). With the ash of leaves of Ficus religiosa, the % of extraction has been found to be 0.5% at 1.0 HCl, 2.5% at pH: 1; 60.7% at pH: 2; 80.4% at pH: 4; 85.6% at pH: 6 and 100% at pH: 8 and 10 after an equilibration time of 90 minutes with a sorbent concentration of 0.5 gm/500ml (vide Graph No.A:2 and B: 1). With stem powder of Ficus religiosa, 100% extractions has been observed throughout the pH range : 2 to 10 after an equilibration time of 30 min while with its ash, even 15 minutes of agitation time has been found to be sufficient to remove completely the Dye in the said pH range with the sorbent concentration of 0.5 gm/500ml (Graph No.A:3 and 4; B:1)

Plant materials derived from Prosopis cineraria have shown good sorption characteristics towards Brilliant Green with the increase of pH. With the leaves powder, the maximum extraction of the Dye has been found to be 0.7% at pH:0, 0.8% at pH:1, 100% at pH:4 and above after an equilibration time of 30 minutes with the sorbent dosage of 1.0gm/500ml while with the ashes of leaves, % of maximum extraction has been found to be 0.3% at pH:0, 0.9% at pH:1, 100% at pH: 4 and above after an equilibration time of 20 minutes with the sorbent dosage of 0.5 gm/ 500ml (vide Graph Nos. A: 5 and6; B:2). With the stem powder and its ashes also, the trend of complete removal of the Dye at pH: 2 and above at optimum conditions of time of agitation and sorbent concentration as cited in the Graph Nos. A:7 and 8 and B: 2, has been observed.

With the sorbents pertaining to Hibiscus rosa-sinensis, the complete removal of the Dye has been observed above pH: 2 at optimum conditions of time of agitation and sorbent concentration (vide Graph Nos. A: 8-12 and B: 3).

3. Time of equilibration:

With the bio- sorbents of the present study, the equilibration time needed for maximum extractability of Brilliant Green Dye has found to be less for ashes than with the raw powders of leaves or stems. In the case of Ficus freligiosa, the optimum equilibration time has been found to be 105 minutes for the leaves powders while it is 90 minutes with its ashes; 30 minutes for powders of stems while 15 minutes only with its ashes. With plant materials of Prosopis cineraria, the optimum time has been found to be: 30 minutes for leaves powder while 20 minutes for its ashes; 30 minutes for stems powder while 15 minutes only for its ashes. With Hibiscus rosa-sinensis plant, the equilibration time for maximum extraction of the Dye at optimum pH and sorbent dosage has been found to be: 30 minutes for leaves or stem powder while 15 minutes for their ashes (vide Graph Nos. A: 1-12).

4. Sorbent Concentration: The optimum bio-sorbent concentration required for maximum extractability of the Brilliant Green Dye is found to be less for ashes than raw powders. Sorbent concentration of 1 gm/500 ml is needed for leaves powders of Ficus religiosa, and Prosopis cineraria while 0.5 gm/500 ml is sufficient with their ashes; 0.5 gm/500ml for stems powders of the same plants while 0.25 gm/500ml with their ashes (vide Graph Nos. B:1and2).

In the case of Hibiscus rosa-sinensis, the leaves or stems powders needs 0.5 gm/500ml of the sorbent concentration while it has been reduced to 0.25 gm/500 ml with their ashes (vide Graph No.: B:3 ). It is interesting to note that at the optimum conditions of pH and agitation time, very small amounts of sorbents have been found to be effective in removing completely the said Dye from synthetically prepared simulated waters.

5. Interfering Ions:

The interference of common ions present in natural waters such as Sulphate, Phosphate, Chloride, Carbonate, Fluoride, Calcium, Copper, Iron, Zinc and Magnesium ions, on the extraction of the Dye with the sorbents developed in this work from simulated waters has been studied at the optimum conditions of extractions as cited in the Table No. 1. It is observed that anions have envisaged marginal effect (vide 3 to 7 Columns of the Table No.1). Cations namely, Ca²⁺, Mg²⁺ and Cu²⁺have interfered to some extent while Fe²⁺ and Zn²⁺ have synergistically maintained the complete extraction of the Dye (vide 8 to 12 Columns of the Table No.1).

4. DISCUSSIONS:

For a thorough understanding of the sorption mechanism of these bio-adsorbents, surface morphological studies using such modern instruments like X-ray Photo Electron Spectroscopy (XPS), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscope (SEM) and Energy Dispersive Spectrum (EDS) in addition to the classical elemental chemical analysis before and after the sorption of the Brilliant Green Dye species on the bio-sorbent surface, are needed. It is beyond the aims of this work.

However, a rough nature of sorption characteristic may be accounted from the pH-dependent dissociation of surface functional groups namely –OH or –COOH present in the biomaterials pertaining to leaves or stems or barks. As pH increases, the dissociation of the functional groups increases imparting negative charge to the surface and so the surfaces thus charged negatively has electrostatic thrust for positively charged ions.

Brilliant Green Dye being a cation especially in the pH range 2 to 10, is glued to the surface resulting in the increase in the % of extraction.

Ashes are the oxides of some heavy metals containing large amounts of silica. The ashes, contains ‘-OH’ groups and ‘–O-’. The observed behaviors of extractability as pH varies may be understood in the same lines as described in the case of raw leaves or stem powders. In fact, in the literature it is reported that the silica possesses cation exchanging nature^58-60and this supports the proposed logic for the observed behavior.

Adsorbent and its concentration	Maximum Extractability at optimum conditions	% of Extractability of Brilliant Green Dye in presence of fivefold excess of (50 ppm) interfering ions at optimum conditions: Conc. of Brilliant Green Dye: 50 ppm
Adsorbent and its concentration	Maximum Extractability at optimum conditions	SO₄^2-	PO₄^3-	Cl^-	CO₃^2-	F^-	Ca²⁺	Cu²⁺	Fe²⁺	Zn²⁺	Mg²⁺
Leaves powder of Ficus religiosa	100.0%; pH: 8; 105 minutes; sorbent conc.: 1.0 g/500 ml	98.0	98.0	100.0	99.5	100.0	95.2	92.5	100.0	100.0	93.0
Leaves Ash of Ficus religiosa	100.0%; pH:8;90 min; Sorbent conc.: 0.5g/500 ml	97.4	99.5	100.0	98.3	99.0	93.5	90.0	100.0	100.0	92.5
Stem powders of Ficus religiosa	100.0%; pH:8; 30 minutes; Sorbent conc.:0.5 g/500 ml	99.2	97.5	100.0	100. 0	98.5	93.0	91.0	100.0	100.0	91.6
Stems ash of Ficus religiosa	100.0%;pH:8, 15 miutes; Sorbent conc.: 0.25 g/500ml	100.0	98.5	100.0	100. 0	97.5	91.5	92.0	100.0	98.0.	90.5
Leaves powder of Prosopis cineraria	100.0%; pH:8; 30 minutes; Sorbent conc.: 1.0 g/500 ml.	99.0	97.5	100.0	97.4	96.0	90.1	90.0	100.0	96.0	87.9
Leaves Ash of Prosopis cineraria	100.0%; pH:8; 20 minutes; 0.5 gm/500 ml	98.5	98.6	100.0	100. 0	98.5	89.0	92.0	100.0	98.0	91.5
Bark powders of Prosopis cineraria	100.0%; pH:8; 30 minutes; Sorbent Conc.: 0.5 g/500 ml	100.0	99.5	100.0	100. 0	97.5	88.1	91.0	100.0	97.0	92.0
Bark ash of Prosopis cineraria	100.0%; pH:8; 15 minutes; Sorbent Conc.: 0.25 g/500ml	98.8	98.2	100.0	100. 0	96.5	93.2	93.0	100.0	98.0	93.0
Leaves powder of Hibiscus rosa-sinensis	100.0 %; pH: 8; 30 minutes; Sorbent conc.:0.5 g/500 ml.	99.0	95.5	99.0	98.0	98.0	92.5	89.0	100.0	95.0	88.5
Leaves Ash of Hibiscus rosa-sinensis	100.0%; pH:8; 15 minutes; Sorbent Conc..: 0.25 g/500 ml	97.5	97.8	100.0	99. 0	98.5	91.5	91.0	100.0	96.0	87.5
Stem powders of Hibiscus rosa-sinensis	100.0%; pH:8; 30 minutes; Sorbent Conc.: 0.5 g/500 ml	98.3	99.0	100.0	97.9	99.0	90.5	89.0	100.0	97.5	88.5
Stems ash of Hibiscus rosa-sinensis	100.0%; pH:8; 15 minutes; Sorbent Conc.: 0.25 g/500 ml	100.0	97.8	100.0	100. 0	99.2	93.2	94.2	100.0	98.0	90.5

Table No.2: % of Extractability of Brilliant Gree Dye from Different Industrial Effluents with Bio-Sorbents Developed in this Work

Bio-Sorbent	% of Extractability of Brilliant Green Dye
Bio-Sorbent	Sample 1: Fed with 20.0 ppm of Brilliant Green Dye	Sample 2 Fed with 35.0 ppm of Brilliant Green Dye	Sample 3 Fed with 40.0 ppm of Brilliant Green Dye	Sample 4 Fed with 45.0 ppm of Brilliant Green Dye	Sample 5 Fed with 60.0 ppm of Green Dye
Leaves powders of *Ficus religiosa* :at pH: 8; Equilibration time: 105 minutes; sorbent conc.: 1.0 g/500 ml	94.5	93.0	92.0	92.5	96.0
Leaves ashes of *Ficus religiosa* :at pH:8; Equilibration time: 90 min; Sorbent conc.:0.5g/500 ml	93.0	91.5	91.5	92.5	92.0
Stem powders of *Ficus religiosa:*:at pH:8; Equilibration time: 30 minutes; Sorbent concentration: 0.5 g/500 ml	92.0	92.0	91.5	93.0	93.5
Stems ash of *Ficus religiosa:*:at pH:8; Equilibration time:15 minutes; sorbent concentration: 0.25 gm/500 ml	96.0	92.1	96.5	95.0	94.0
Leaves powders of *Prosopis cineraria:* :at pH:8; Equilibration time: 30 minutes; sorbent concentration: 1.0 g/500 ml	88.0	89.2	94.5	93.5	96.5
Leaves ash of *Prosopis cineraria* :at pH:8; Equilibration time: 20 minutes; sorbent concentration:0.5 g/500 ml.	92.0	87.2	97.0	91.0	89.6
Barks powder of *Prosopis cineraria:*at pH:8; Equilibration time: 30 minutes; sorbent concentration: 0.5 g/500 ml.	93.0	92.5	98.0	92.0	90.0
Barks ash of *Prosopis cineraria* :at pH:8; Equilibration time: 15 minutes; sorbent concentration: 0.25 g/500 ml.	91.5	90.5	97.0	93.6	91.2
Leaves powder of *Hibiscus rosa-sinensis:* pH: 8; Equilibration time: 30 minutes; Sorbent conc.: 0.5 g/500 ml.	89.2	87.5	96.0	92.6	90.5
Leaves Ash of *Hibiscus rosa-sinensis: at pH:8; Equilibration time:* 15 minutes; Sorbent Conc..: 0.25 g/500 m	88.5	86.9	93.0	91.0	92.1
Stem powders of *Hibiscus rosa-sinensis: at pH:8; Equilibration time:* 30 minutes; Sorbent Conc.: 0.5 g/500 ml	90.5	90.0	91.0	88.5	92.5
Stems ash of *Hibiscus rosa-sinensis: at pH:8: Equilibration time:* 15 minutes; Sorbent Conc.: 0.25 g/ 500 ml	93.5	93.4	90.5	87.5	93.5

The decrease in the rate of adsorption with the progress in the equilibration time may be due to the more availability of adsorption sites initially and are progressively used up with time due to the formation of adsorbate film on the sites of adsorbent and hence, the decrease in sorption capability of the adsorbent with the increase in the time.

The observations made with respect to the interfering ions are interesting to note. Anions have not interfered with the extraction of the Brilliant Green Dye at the optimum conditions of extraction as cited in the Table 1 but some cations like Ca²⁺, Mg²⁺ and Cu²⁺have shown interference. This is excepted because the negatively charged surface at the high pH values show less affinity towards anions. The cations like Ca²⁺, Mg²⁺ and Cu²⁺compete with cationic Dye for sorption sites on the sorbents resulting inference. But this is not found in the case of Zn²⁺ and Fe²⁺ because the Zn²⁺ ion forms negatively charged zincate at the high pH resulting no affinity towards the sorbent while Fe²⁺ gets precipitated as its hydroxide at high pH conditions of extraction and thus resulting precipitate also adsorbs or traps the Dye effecting the complete removal.

5: APPLICATIONS:

The methodologies developed in this work have been tested with respect to the real samples of diverse nature, collected from the sewages/effluents of Dyeing industries which are fed with varying quantities of the Brilliant Green Dye. The results have been presented in the Table No: 2.

The results reflect the remarkable success of the developed procedures in removing Brilliant Green Dye at optimum conditions of pH, equilibration time and sorbent dosage as give in the Table No.2. Percentage of removal of Brilliant Green Dye is found to be between: 92.0% to 96.0% with leaves powder of Ficus religiosa and 91.5% to 93.0% with their ashes; 92.0% to 93.5% with stems powder of Ficus religiosa and 92.1% to 95.05% with their ashes; 88.0% to 96.5% with the leaves powders of Prosopis cineraria and 89.6% to 97.0% with their ashes; 90.0% to 98.0% with the stem powder of Prosopis cineraria and 90.5% to 97.0% with their ashes. With the plant materials pertaining to Hibiscus rosa-sinensis, the % of removal of the Dye has been found to be: 87.5% to 96.0% for leaves powder and 86.0% to 93.0% with their ashes; 88.5% to 92.5% with stems powder and 87.5% to 93.5% with their ashes.

6: CONCLUSSIONS

1. Leaves, stems/barks and their ashes of Ficus religiosa, Prosopis cineraria and Hibiscus rosa-sinensis have been found to have strong affinity towards Brilliant Green Dye at high pH values of extraction.

2. % of removal of Brilliant Green Dye also depends on sorbent concentration and time of equilibration.

3. The conditions for the maximum extraction of Brilliant Green Dye from simulated waste waters at minimum dosage and equilibration time have been optimized.

4.The optimum sorbent concentration and time of agitation needed for the maximum removal of Brilliant Green Dye is less for the ashes than with the raw powders of the plant materials.

5. Fivefold excess of common anions ions present in natural waters, have not interfered the extractability of Brilliant Green Dye at optimum conditions of pH, equilibration time and sorbent concentration. Cation like Ca²⁺, Mg² and Cu²⁺have shown some interference but while Fe²⁺ and Zn²⁺ have synergistically maintained the maximum extraction of the Dye.

6. We claim 100% of extraction of Brilliant Green Dye with the sorbents derived from Ficus religiosa, Prosopis cineraria and Hibiscus rosa-sinensis from simulated waters at high pH conditions of extraction and with small amounts of sorbent concentrations: 0.25 g/500 ml in some sorbents, 0.5/500 ml in some other sorbents and 1.0 g/500 ml in other sorbents as shown in Graph No. B: 1-3

7. The methods developed have been found to be remarkably successful in removing the Brilliant Green Dye from industrial effluents as detailed in Table No: 2.

7. ACKNOWLEDGEMENT:

The authors thank UGC for financial aid.

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Received on 04.10.2012 Modified on 19.10.2012

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