FIELD OF INVENTION
This invention relates to a process for the decontamination of toxic heavy metal's [Pb (II), Cd (II), Ni (II), Cr (III) and Cr (VI)] polluted ground water as well as water discharged from leather, electroplating and related industries like those involved in manufacture of Ni-Cd batteries. The present invention explores the sorption capacity of seed powder of Leucaena leucocephala Lam. for metals from water bodies.
BACKGROUND OF INVENTION
The quality of water is of vital concern for mankind since it is directly linked with human welfare. It is particularly vulnerable to contamination from discharge of waste by various industries among which heavy metals are the most important components. Metal ions may enter the food chain and get magnified through bioaccumulation, thereby increasing the magnitude of the problem. In view of their high toxicity, environment mobility, non-biodegradability and stability, their removal becomes an absolute necessity. The decontamination of metal bearing wastewater is a pressing environmental concern.
An increasing awareness and concern about the environment motivated research has been developed for new efficient technologies that would be capable of treating inexpensively waste water polluted by heavy metals. This search brought newly emerging eco-friendly techniques to the foreground of scientific interest as a potential basis for the design of novel water treatment processes. Bio-sorption of heavy metals is, thus, one of the most promising and tangible alternatives to traditional methodologies, removing toxic metals from water bodies. Bio-sorption is one such important phenomenon, which is based on one of the twelve principles of Green Chemistry "Use of renewable resources". Bioremediation involves processes that reduce overall treatment cost through the application of agricultural residues which are particularly attractive as they lessen reliance on imported water treatment chemicals, negligible transportation requirements and offer genuine, localized and appropriate solutions to water quality problems. Regeneration of the biosorbent further increases the cost effectiveness of the process thus warranting its future success.
PRIOR ART
Over a few decades, scientific community is developing concerted efforts for the treatment and removal of these toxicants in order to combat this problem. A large number of physico-chemical methods such as reduction, direct precipitation, ion exchange, reaction with silica, solvent extraction, reverse osmosis and flocculation (with various synthetic coagulants such as aluminium, ferric salts, soda ash, polymers etc) have been developed for their abatement from water at point of use, entry and for co-water system. However, the application of such processes is often restricted because of technical or economic constraints viz. unpredictable metal ion removal, high material costs and generation of toxic sludge that is often more difficult to manage. Research findings have raised strong doubts and explored several drawbacks in the synthetic coagulants based removal processes like Alzheimer's disease, carcinogenic effects of alum and problem associated with residual iron salts.
The limitations of existing technologies can be listed herein below:

• Disposal of the contaminated chemical sludge.
• Consumption of electricity and chemicals.
• Frequent replacement of filters, which is quite expensive.
• Possibility of Alzheimer's disease and Carcinogenic effects (Aluminium salts).
• Severe other health problems (Iron salts).
In the past, plants such as Moringa oleifera (Sharma et al.,Kumari et al), Samoa indica (Srivastava et al), Sunflower stalks (Sun and Shi), Magnifera indica seeds (Ajmal et al.), Pine bark (Asheh and Duvunjak), Rice husk (Khalid et al.,), Cone biomass (Ucun et al.,) Cocoa shells (Meunier et al.), Lechuguilla (Gonzalez et al.,), Jutefibers (IShukla and Roshan) have been known to exhibit significant biosorption properties.
Further, reference may be made to the following publications:
1. The publication "Metal transfer ratio of Leucaena leucocephala an
experimental study using the solids of Industrial areas of Korangi and Landhi,
Karachi" Syed Atiqur Rehman et al. 2007 discusses biosorption of heavy
metals such as Fe, Cu, Zn and Cr by the plant.
2. The paper "Growth and uptake of Cd and Zn by Leucaena leucocephala in
reclaimed soils as affected by NaCl salinity" H Mohamed Helal et al.
Journal of Plant Nutrition and Soil Science, Vol 162m No. 6 pp. 589-592,
1999, discloses uptake of Cd and Zn by the Plant from saline solids of Bangar
area of Egypt.
3. The paper "Effect of fly-ash on metal composition and physiological
responses in Leucaena, L" Meenu Gupta et al. Environmental Monitoring and
Assessment Vol 61, No. 3, April, 2000 disclosed accumulation of Fe, Zn, Cu,
Man from fly-ash rich soils.
The above cited three references are devoted to the uptake and distribution of metals by the roots, shoots and leaves of plant and thus indicating the metal uptake capacity by the plant from the contaminated soil i.e. Phytoremediation of toxic metals.
OBJECTS OF THE INVENTION
The primary object of the present invention is to propose a process for the decontamination of toxic heavy metal's [Pb (II), Cd (II), Ni (II), Cr (III) and Cr (VI)] polluted ground water as well as water discharged from leather, electroplating and related industries like those involved in manufacture of Ni-Cd batteries which is eco-friendly and cost effective.
Another object of the present invention is to propose a process for the decontamination of toxic heavy metal's [Pb (II), Cd (II), Ni (II), Cr (III) and Cr (VI)] polluted ground water as well as water discharged from leather, electroplating and related industries like those involved in manufacture of Ni-Cd batteries which is simple and fast technique for low and high volume of less and highly contaminated water.
Further object of the present invention is to propose a process for the decontamination of toxic heavy metal's [Pb (II), Cd (II), Ni (II), Cr (III) and Cr (VI)] polluted ground water as

well as water discharged from leather, electroplating and related industries like those involved in manufacture of Ni-Cd batteries which is having toxicant removal efficiency [In case of single metal ion solution upto 99 %, while in case of multi metal ion solution upto 95%].
Another object of the present invention is to propose a process for the decontamination of toxic heavy metal's [Pb (II), Cd (II), Ni (II), Cr (III) and Cr (VI)] polluted ground water as well as water discharged from leather, electroplating and related industries like those involved in manufacture of Ni-Cd batteries which is simple, cost effective (reusability of biomass) and domestic technique (Bucket treatment) for low volume of water while as a pretreatment step for larger volume and highly contaminated water.
Final object of the present invention is to propose a process for the decontamination of toxic heavy metal's [Pb (II), Cd (II), Ni (II), Cr (III) and Cr (VI)] polluted ground water as well as water discharged from leather, electroplating and related industries like those involved in manufacture of Ni-Cd batteries which is quite effective in decontaminating toxic metals with the help of finely powdered seed material.
STATEMENT OF THE INVENTION
According to this invention there is provided a process for the decontamination of toxic heavy metal's [Pb (II), Cd (II), Ni (II), Cr (III) and Cr (VI)] polluted ground water as well as water discharged from leather, electroplating and related industries like those involved in manufacture of Ni-Cd batteries comprising steps of-
• Washing of seeds ofLeucaena leucocephala Lam. with water
• Drying the clean seeds followed by powdering and
• Sieving to obtain powder used as biosorbent.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from the ensuing
description when read in conjunction with the accompanying drawings and wherein:
Fig. 1 shows : IR Spectra of Untreated LLSP
Fig. 1 (a) shows IR Spectra of Pb (II) treated LLSP
Fig. 1 (b) shows IR Spectra of Cd (II) treated LLSP
Fig. 1 (c) shows IR Spectra of Cr (VI) treated LLSP
Fig. 1 (d) shows IR Spectra of Cr (III) treated LLSP
Fig. 1 (e) shows IR Spectra of Ni (II) treated LLSP
Fig. 2 shows SEM of Untreated LLSP
Fig. 2 (a) shows SEM Pb (II) treated LLSP
Fig. 2 (b) shows SEM Cd (II) treated LLSP
Fig. 2 (c) shows SEM Cr (VI) treated LLSP
Fig. 2 (d) shows SEM Cr (III) treated LLSP
Fig. 2 (e) shows SEM Ni (II) treated LLSP
DETAILS DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS AND DATA REPRESENTED IN TABLES

This invention provides process for the decontamination of toxic heavy metal's [Pb (II), Cd (II), Ni (II), Cr (III) and Cr (VI)] polluted ground water, for which seeds of Leucaena leucocephala Lam. are collected preferably in the month of March to September. The seeds are washed repeatedly with water to remove dust and impurities. This is followed by drying at 40-65°C for 24-48 hours. Thereafter, the dry seeds are powdered and finally sieved through mesh of size 50-500m preferably 105 m. The seed powder thus obtained is used as biosorbent, which is effective enough to achieve the objects of the present invention. The biosorption refers to the property of biomasses to bind heavy metals from water bodies.
1. Biosorption and Analytical procedures
Sorption studies using standard practices were carried out in batch experiments as functions of biomass dosage (0.5 to 8g), contact time (5 to 60 min), metal concentration (1 to 200ppm), particle size (50 to 500m) and pH (1 to 8.5). The solutions of Pb (II), Cd (II), Ni (II), Cr (III) and Cr (VI) comprised of lead nitrate, cadmium nitrate, nickel sulphate, chromium chloride and potassium dichromate were
taken into separate Erlenmeyer flasks. After pH adjustment, a required quantity of biosorbent was added and finally metal bearing suspension was allowed to settle. The residual biomass sorbed with metal ion was filtered using Whatman 42 filter paper. Filtrate were collected and subjected for metal ion estimation using Atomic Absorption Spectroscopy (AAS). Percent metal sorption in single metal ion solution as well as multi metal ion solution by the sorbent was computed using the equation:
(Equation Removed)
where, C0 and Ce are the initial and final concentration of metal ions in the solution.
The tables indicating % sorption of single metal ion solution [1b, 2b, 3b, 4b and 5b] and multi metal ion solution [6b] are enclosed herewith
Statistical analysis
Batch experiments were conducted in replicates (N=5) and data represent the mean value. Mean values, correlation coefficients, standard deviation were calculated using (SPSS+TM Statistical package, 1983). For the determination of inter group mean value differences, each parameter was subjected to the student's t - test for significance level (p<0.05). The tables indicating sorption of single metal ion solution (Dm) [la, 2a, 3a, 4a and 5a] and multi metal ion solution (m) [6a] are enclosed herewith:
2. Regeneration of biomass
Desorption studies help in regeneration, recycling of used biosorbent and recovery of metals from metal loaded biosorbent which in turn may reduce operational cost and protect the environment.
In order to assess the reusability of LLSP, desorption studies (batch process) were conducted to restore the biomass as a function of concentration (0.01 - 1.0 M) of different stripping agent [Soft acid: Citric acid, Hard acid: Hydrochloric acid and Nitric acid]. Metal loaded biosorbent obtained from our sorption experiments, were transferred to Erlenmeyer flask and shaken with 1 to 20 ml of each acid for 10 to 60 min. The filtrate was analyzed for

desqrbed metal. The desorption / sorption behavior clearly indicates that the present biosorbent can be used successfully three times after regeneration for the sorption of metals from aqueous system. The tabulation indicating desorption [7a, 8a and 9a] and sorption [7b, 8b and 9b] are enclosed herewith.
Metal-Biosorbent interactions which are found to be responsible for observed biosorption behavior has been further highlighted on the basis of the records of IR spectrum, Scanning Electron Micrographs of the Native and Metal treated biosorbent and some other relevant studies.
3. Fourier Transform Infrared Spectroscopy (FTIR)
In order to gain better insight into the surface functional groups of the biosorbent that might be involved in metal sorption, FTIR analysis in solid phase was performed using a Fourier Transform Infrared Spectrometer (FTIR- 8400, Shimadzu). Spectra of the sorbent before and after metal sorption were recorded. The same has been indicated in the accompanying figures 1-le.
Infrared values [IR]
Adsorption band Untreated Pb (II) Cd (II) Cr (VI) Cr(III) Ni
(II)
[IR] LLSP
NH3+ 3289.77 3293.23 3291.51 2926.68 3289.87 3287.93
Stretching
coo-
Stretching 1396.66 1456.47 1457.73 1456.43 1389.87 1456.72
4. Scanning Electron Microscopy (SEM)
Surface morphology was studied with Scanning Electron Microscope (Steroscan 360, Cambridge Instruments, U.K). The Scanning Electron Micrograph (SEM) of untreated (native) and metal treated (exhausted) at bar length equivalent to 200 Dm, working voltage 20 KV with 200x magnification were recorded. The same has been shown in the accompanying figures 2-2e.
• Spherical type clusters in UNTREATED LLSP with pore area: 9.12 µm2.
• Dense agglomerated, etched dendrite type morphology in Pb (II), Cd (II), Cr (VI),
Cr (III) and Ni (II) TREATED LLSP with pore area: 2.74 µm2, 2.23 µm2, 1.27 µm2,
1.12 µm2 and 1.09 µm2 respectively.
5. BET Surface area analysis
The surface area of the biosorbent was measured using a Micrometrics ASAP - 2010 BET surface area analyzer.
Surface area of the LLSP is 5.17 m2/g determined with BET surface area analyzer
6. Sorption isotherms

The experimental data for the sorption of metal ions by the LLSP over the studied concentration range processed in accordance with the two of the most widely used adsorption isotherms: Freundlich and Langmuir isotherm describing the adsorption phenomenon.
The classical freundlich equation is given below
(Equation Removed)
where, q is the heavy metal adsorbed on the biosorbent (mg/g dry weight); Ce is the final concentration of metal (mg/1) in the solution; Kf and n are the characteristic constants.
The classical Langmuir equation is given below;
(Equation Removed)
where, Ce is the equilibrium concentration, qe is the amount adsorbed of metal at equilibrium,
Qo and b are the Langmuir constants related to adsorption capacity and energy of adsorption
respectively.
The biosorption capacity (Kf and Q0) and biosorption intensity/energy (1/n and b) were estimated from the slope and intercept of the Freundlich and Langmuir isotherms.
7. Regeneration of biomass
The desorption behavior clearly indicates that the present biosorbent can be used successfully atleast three times after regeneration for the sorption of metals from aqueous
system.
8. Kinetics experiments
To determine the kinetics of sorption of metal onto LLSP, Lagergren plots were obtained at initial metal concentration. LLSP (0.5 to 8g) was suspended in 100 to 500ml of the metal solutions of known initial sorbate concentration at different pH, where maximum sorption was recorded. The mixture was continuously stirred using a magnetic stirrer. Samples were withdrawn at predetermined time intervals in the range of 10 to 40 minutes, filtered and analyzed for residual metal concentration.
EXAMPLE
For the process of the decontamination of toxic heavy metal's [Pb (II), Cd (II), Ni (II) Cr (III) and Cr (VI)] polluted water, seeds of Leucaena leucocephala Lam. were collected in the month of April. The seeds were washed with running water three times followed by drying at 65°C for 24 hours. Then, the dry seeds were powdered and sieved through mesh of size 105 m to obtain powder used as biosorbent.
This sorption property of the seed of the plant Leucaena leucocephala has been explored and can be used as bio cakes or biofilters for instant, domestic, fast, low cost and ecofriendly green method for the purification of water specially for rural and remote areas of the country, which is need of the day.

Table 7a Desorption of single metal [25 mg/L: Pb (II), Cd (II), Cr (III) and Ni (II); 50 mg/L: Cr (VI)] ions from Leucaena leucocephala Seed Powder (LLSP) using 0.5 M of Citric acid.

(Table Removed)
Table 7b: Sorption of single metal [25 mg/L: Pb (II), Cd (II), Cr (III) and Ni (II), 50 mg/L: Cr (VI)] ions on regenerated biomass.

(Table Removed)
Table 8a: Desorption of single metal [25 mg/L: Pb (II), Cd (|l), Cr (III) and Ni (II); 50 mgA.: Cr (VI)] ions from Leucaena /ewcocephala Seed powder (LLSP) using 0.05 M of Hydrochloric acid.
(Table Removed)

Table 8b: sorption of single metal [25 mg/L: Pb( II), Cd (II), Cr (III) and Ni (II); 50mg/L:]Cr(VI) ions on regenerated biomass.

(Table Removed)
Table 9a: Desorption of multi metal [25 mg/L: Pb (II), Cd (II), Cr (III) and Ni (jl); 50 mg/L: Cr (VI)] ions frorn Leucaena leucocephala Seed Powder (LLSP) using 0.05M of Nitric acid.

(Table Removed)
Table 9b; Sorption of single metal [25 mg/L: Pb (II), Cd (II), Cr (III) and Ni (II); 50 mg/L: Or (VI)] ions on regenerated biomass.

(Table Removed)
Table 1a: Soluble Pb (II) ion concentration (uM) after adsorption on Leucaena leucocephala Seed Powder (LLSP) as functions of contact time and biomass dosage at volume (200 ml), particle size (105µ) and pH (6.5).

(Table Removed)
aNumber in parenthesis represent soluble metal concentrations in µM.,
bStandard deviation values of replicate (N=5) determinations.
Mean difference Dnitial Pb (II) loaded (uM) versus soluble Pb (II) (µM)] as functions of
Time "significance (p< 0.10), "insignificance (p> 0.10).
Metal concentration 'significance (p< 0.01), sinsignificance (p> 0.01).
Biomass dosage 'significance(p<0.01), insignificance (p> 0.01).
Table 1b: Sorption efficiency (%) of Leucaena leucocephala Seed Powder (LLSP) for Pb (II) ion as functions of metal concentration, contact time and biomass dosage at volume (200 ml), particle size (105 µ) and pH (6.5),

(Table Removed)
Table 2a: SoIuble CD (II) ion concentratioir (µM) after adsorption on Leucaena leucocephala Seed Powder (LLSP) as functions of contact time and biomass dosage at volume (200 ml), particle size (105µ) and pH (6.5).

(Table Removed)
aNumber in parenthesis represent soluble metal concentrations in µM.,
b Standard deviation values of replicate (N=6) determinations.
Mean difference [initial Cd (II) loaded (uM) versus soluble Cd (II) (µM)] as functions of
Time "significance (p< 0.10), "insignificance (p> 0.10).
Metal concentration 'significance (p< 0.01), "insignificance (p> 0.01).
Biomass dosage "significance (p< 0.01), insignificance (p> 0.01).

Table 2b : Sorption efficiency (%) of Leucaena leucocephala Seed Powder (LLSP)
for Cd (II) ion as functions, of metal concentration, contact time and biomass
dosage at volume (200ml) particle size (105 µ) and pH (6.5).

(Table Removed)
Table 3a: Soluble Cr (VI) ion concentration (µM) after adsorption on Leucaena leucocephala Seed Powder (LLSP) as functions of contact time and biomass dosage at volume (200 ml), particle size (105µ) and pH (2.5).

(Table Removed)
aNumber in parenthesis represent soluble metal concentrations in µM.,
b Standard deviation values of replicate (N=6) determinations.
Mean difference pnitial Cr (VI) loaded (µM) versus soluble Cr (VI) µM)J as functions of
Time "significance (p< 0.10), "insignificance (p> 0.10).
Metal concentration 'significance (p> O.10). sinsignificance (p> 0.01).
Table 3b : Sorption efficiency (%) of Leucaena leucocephala Seed Powder (LLSP) for Cr (VI) ion as functions of metal concentration, contact time and biomass dosage at volume 1200 ml), particle size (105 u) and pH (2,5).
(Table Removed)
Table 4a: Soluble Cr (III) ion concentration (µM) after adsorption on Leucaena leucocephala (LLSP) as functions of contact time and biomass dosage at volume (200 ml), particle size (105 µ) and pH (6.5).

(Table Removed)
aNumber in parenthesis represent soluble metal concentrations in pM.,
b Standard deviation values of replicate (N=5) determinations.
Mean difference [initial Cr (III) loaded (pM) versus soluble Cr (III) (µM)] as functions of
Time 'significance (p< 0.10), "insignificance (p> 0.10).
Metal concentration 'significance (p< 0.01}, sinsignificance (p> 0.01).
Table 4b : Sorption efficiency (%) of Leucaena leucocephala Seed Powder (LLSP) for Cr (III) ion as functions of metal concentration, contact time and biomass dosage at volume (200 ml), particle size (105 µ) and pH (6.5).

(Table Removed)
Table 5a: Soluble Ni (II) ion concentration (µM) after adsorption on Leucaena leucocephala Seed Powder (LLSP) as functions of contact time and biomass dosage at volume (200 ml), particle size (105 µ) and pH (6.5).

(Table Removed)
a Number in parenthesis represent soluble metal concentrations in µM.,
b Standard deviation values of replicate (N=5) determinations.
Mean difference [initial Ni (II) loaded ftiM) versus soluble Ni (II) µM)] as functions of
Time "significance (p< 0.10), "insignificance (p> 0.10).
Metal concentration 'significance (p< 0.01), "insignificance (p> 0.01).
Biomass dosage 'significance (p< 0.01), insignificance (p> 0.01).

Table 5b : Sorptiori efficiency (%) of Leucaena leucocephala Seed Powder (LLSP) for Ni (II) ion as functions of metal concentration, contact time and biomass dosage at volume (200 ml), particle size (105µ) and pH (6.5).
(Table Removed)
Table 6a: Soluble multi metal [Cd (II), Cr (III) and Ni (II)] ions concentration (µM) after adsorption on Leucaena leucocephala Seed Powder (LLSP) as a function of contact time at optimum biomass dosage (4-0 g), volume (200 ml), particle size (105µ) anld pH (6.5).

(Table Removed)
aNumber in parenthesis represent soluble metal concentrations inµM-.
b Standard deviation values of replicate (N=5) determinations.
Mean value difference [initial Cd (II), Cr (III) and Ni (II) loaded versus soluble Cd (II), Cr (III) and
Ni (II) (µM)] as functions of metal concentration; "significant (p<0.05), "Insignificant (p>0.05).
contact time; "significant (p<0.05), "insignificant (p>0.05).

Tabte 6b: Sorption efficiency (%) of Leuceana feucocephata Seed Powder (LLSP) Cd (II), Cr {111) and Ni (II)] ions as functions of metal concentration and contact time at optimum biomass dosage (4.0 g). volume (200 ml), particle size (105µ) and pH (6,5).

(Table Removed)
It is to be noted that the present invention is susceptible to modification, adaptations changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-

WE CLAIM:
1) A process for the decontamination of toxic heavy metal's [Pb (II), Cd (II), Ni (II),
Cr (III) and Cr (VI)] polluted ground water as well as water discharged from leather,
electroplating and related industries like those involved in manufacture of Ni-Cd
batteries comprising steps of-
• Washing of seeds of Leucaena leucocephala Lam. with water
• Drying the clean seeds followed by powdering and
• Sieving to obtain powder used as biosorbent.

2) A process as claimed in claim 1 wherein the drying is carried out at 40-65°C for 24-
48 hours.
3) A process as claimed in claim 1 or 2 wherein the sieving is done through mesh of
size 50- 500 µm preferably 105 µm.
4) A process for the decontamination of toxic heavy metal's [Pb (II), Cd (II), Ni (II),
Cr (III) and Cr (VI)] polluted ground water as well as water discharged from leather,
electroplating and related industries like those involved in manufacture of Ni-Cd
batteries substantially as herein described and illustrated.