INTRODUCTION:

Ammonia is present in waste waters due to incomplete biological degradation of nitrogenous matter present in wastes waters. It is toxic to human beings and animals causing various health disorders such as headache, insomnia, nausea, diarrhoea, a failure in glucose tolerance in animals and human beings ^1-9 and it attacks the cardiac tissues ^10,11 and also causes metabolic toxicity by interfering with energy metabolism in the brain¹². Ammonia presence even in very low concentrations affects the aquatic life as it is a strong cell poison and damage to the gills of fish. Further, it presence in waters causes the “eutrophication” of lakes which results in depletion of dissolved oxygen in water bodies and consequential loss of valuable aquatic species due to decrease in dissolved oxygen⁷.

The maximum limit of ammonia set by the European Association for drinking water is approximately 0.5 ppm and also a guide level is given as 0.05 ppm^{13, 14}. Therefore the removal of ammonia from wastewaters assumes importance.

Many methods based on Air stripping, ion exchange, biological nitrification and de-nitrification^15-21 and Microwave radiations are reported in literature^21-25. New concepts of microbial treatment processes for the removal of ammonia have been discussed by Schmidt I et al (2003)²⁶.

M.S. Çelik et al (2001) studied the removal of ammonia by natural clay minerals using fixed and fluidized bed column reactors²⁷. These methods have one or other disadvantage, a universally acceptable, eco-friendly and economically sustainable methods are still eluding the researcher.

The use bio-sorbents derived from bio-materials for the removal of polluting ions offer a potential alternative to the conventional methods of detoxification^28-32. Duck weeds²⁸, neem products²⁹and low cost agricultural wastes ^30,32 have been explored for their surfaction activity in the removal of ammonia from polluted waters.

In the present work an attempt is made to explore the sorption potentialities of some bio-sorbents derived from bio-materials in removing the ammonia from polluted waters by studying the sorption characteristics of the bio-sorbents under various physicochemical parameters such as pH, sorbent concentration and time of equilibration and further, the developed methodologies have been applied for natural and industrial polluted samples.

MATERIALS AND METHODS:

(A) Chemicals: All chemicals used were of analytical grade.

1. 500 ppm stock solution of Ammonia was prepared by dissolving suitable amounts of Ammonium chloride in double distilled water and is suitably diluted as per the need.

2. Nessler’s reagent: 35gs of Potassium Iodide and 4% Mercuric Chloride were dissolved in 100 ml of double distilled water with constant stirring until a slight red precipitate remains. To this, solution of NaOH (120 gms of NaOH + 250 ml of double distilled water ) was added and made up to 1 lit with double distilled water .A little more Mercuric Chloride solution was added until there was a permanent turbidity . The mixture was allowed to stand for one day and decant from the sediment. The solution was kept in stoppered dark colored bottle.

(B) Adsorbents:

A thorough probe has been made to find ammonia sensitive bio-materials. It is noticed that leaves and their ashes of Tamarindus indicia, Emblica officinalis and Ficus Religiosa have been found to have affinity towards ammonia and hence, the methodologies presented here, pertain to these sorbents only.

A: Tamarindus Indicia

B: Emblica officinalis

C: Ficus religiosa

Fig 1: Plants showing affinity towards Ammonia

Tamarindus indica belongs to the family Fabaceae and is found widely in tropical and sub-tropical countries especially in India and South Africa. The tamarind tree besides producing edible and pod-like fruits which are used extensively in cuisines around the world, its products are used in traditional medicine and metal polish.

Emblica officinalis is a deciduous tree of the family Phyllanthaceae and it is a natural, efficacious antioxidant with the richest natural source of Vitamin C.

Ficus religiosa belongs to the Moraceae or mulberry family and has cordate shape leaves with a distinctive extended drip tip and it has edible fruit of the same name. This tree has religious sanctity in Buddhist, Jain and Hindu religions. This tree bio-materials are used in the preparation of some traditional medicines.

Sorbent Preparation:

The leaves of Tamarindus indicia, Emblica officinalis and Ficus religiosa were cut, washed with tap water, then with distilled water and then sun dried. The dried materials were powdered to a fine mesh of size < 75 µ and activated at 105⁰ C for 4 hrs. in an oven and then these were employed in this work. Further, the leaves of the said plants were burnt to ashes and their ashes were also used as sorbents in this work.

(C) Adsorption experiment:

Batch system of extraction procedure was adopted [33-35]. Carefully weighted quantities of adsorbents were taken into previously washed l lit/500 ml stopper bottles containing 500ml/250ml of Ammonium Chloride 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 in mechanical shakers for a desired period and after the equilibration period; an aliquot of the sample was taken for Ammonia determination. Ammonia was determined by using Nessler’s method spectrophotometrically [36].

(D) Estimation of Ammonia:

An aliquot amount of ammonium chloride solution was taken in a 50 ml volumetric flask. To it 1ml of Nessler’s reagent was added, mixed well and was allowed to stand at least 10 min at room temp in a diffused light. The solution was diluted to the volume and mixed well. Optical Density of the orange-brown color was measured at 525 nm against a reagent blank using U.V and visible Spectrophotometer (of Systronics make). Thus obtained O.D value was referred to standard graph (drawn between O.D and Concentration) prepared with known amounts of ammonia to find concentration of unknown solutions.

(E) Effect of Interfering Ions:

The interfering ions chosen for study were the common ions present in natural waters, viz., Sulphate, Nitrate, Chloride, Phosphate, Fluorides, Carbonate, Calcium, Magnesium, Copper, Zinc and Nickel. The synthetic mixtures of Ammonia and one of the interfering ions were so made that the concentration of the interfering ions maintained at five fold excess than the ammonium ion concentration. 500 ml of these solutions were taken in stopped bottles and then correctly weighed optimum quantities of the promising sorbents were added. Optimum pH was adjusted with dil. HCl or dil. NaOH using pH meter. The samples were shaken in shaking machines for the desired optimum periods and then the samples were filtered and analyzed for Ammonia. % of extraction was calculated from the data obtained. The results are presented in the Table No. 1.

(F)Applications of the developed bio-sorbents:

The adoptability of the methodology developed with the new bio-sorbents in this work for removing ammonia is tried with some real sewage/effluent samples of some industries and natural samples.

Table No: 1: Effect of interfering Ions on the Extractability of Ammonia with different Bio-sorbents:

S. No	*Adsorbent and its concentration*	*Maximum Extractability at optimum conditions*	*% of Extraction of Ammonia in presence five fold excess of interfering ions at optimum conditions:* *Conc. of ammonia: 50 ppm at pH:5*
S. No	*Adsorbent and its concentration*	*Maximum Extractability at optimum conditions*	*SO₄^2-*	*NO₃^2-*	*Cl^-*	*PO₄^3-*	*F^-*
1	Powder of *Tamarindus indicia* leaves: 2.0 gm/lit	93.0%; pH:5, 240 min	87.0 %	88.2%	91.2%	92.0%	90.0%
2	*Ashes of Tamarindus indicia* leaves ; 1.5gm/lit	97.0% pH:5, 180 min	93.1%	94.0%	95.0%	96.1%	92.0%
3	Powder of *Emblica officinalis* leaves: 1.75gm/lit	88.0%; pH:5, 210 min	89.8%	82.4%	83.7%	86.8%	85.1%
4	*Ashes of Emblica officinalis* leaves ; 1.5gm/lit	92.0% pH:5, 180 min	84.6%	85.2%	86.6%	87.2%	91.8%
5	Powder of **Ficus Religiosa** leaves: 1.75gm/lit	84.0%; pH:5, 210 min	78.2%	80.0%	82.8%	83.2%	83.9%
6	*Ashes of* **Ficus Religiosa** leaves ; 1.25gm/lit	90.0% pH:5, 150 min	81.3%	82.8%	84.4%	87.7%	89.6%

Table No: 1: Cont….

S. No	*Adsorbent and its concentration*	*Maximum Extractability at optimum conditions*
S. No	*Adsorbent and its concentration*	*Maximum Extractability at optimum conditions*	*CO₃^2-*	*Ca²⁺*	*Mg²⁺*	*Cu²⁺*	*Zn²⁺*	Ni²⁺
1	Powder of *Tamarindus indicia* leaves: 2.0 gm/lit	93.0%; pH:5, 240 min	88.5%	72.5%	70.0%	60.0%	63.0%	64.3%
2	*Ashes of Tamarindus indicia* leaves ; 1.5gm/lit	97.0% pH:5, 180 min	89.5%	73.1%	69.0%	61.5%	63.6%	64.1%
3	Powder of *Emblica officinalis* leaves: 1.75gm/lit	88.0%; pH:5, 210 min	82.3%	70.1%	66.8%	65.6%	63.2%	65.3%
4	*Ashes of Emblica officinalis* leaves ; 1.5gm/lit	92.0% pH:5, 180 min	88.0%	72.4%	69.2%	67.6%	62.1%	60.8%
5	Powder of **Ficus Religiosa** leaves: 1.75gm/lit	84.0%; pH:5, 210 min	80.3%	70.8%	61.3%	72.8%	71.2%	66.2%
6	*Ashes of* **Ficus Religiosa** leaves ; 1.25gm/lit	90.0% pH:5, 150 min	84.6%	70.9%	67.5%	73.2%	61.2%	69.2%

Table No.2: % of Extractability of Ammonia in Diverse Samples

Bio-sorbents	% of Extraction of Ammonia in diverse Samples (actual Conc. of Ammonia is shown in parenthesis)
	Sample:1: Sugar Factory effluents at Tadepalligudem in A.P. (21.5 ppm)	Sample:2: Dairy farm effluents in Guntur,A.P. (14.5 ppm)	Sample:3: Paper pulp Industry at Rajahmundry, A.P. (12.5 ppm)
		Sample:2: Dairy farm effluents in Guntur,A.P. (14.5 ppm)
Powder of *Tamarindus indicia* leaves concentration: 2.0 gms/lit	87.0 %	86.2%	82.2%
*Ashes of Tamarindus indicia* leaves concentration:1.5gms/lit	88.8%	87.4%	83.6%
Powder of *Emblica officinalis* leaves concentratio:1.75 gms/lit	84.2%	81.7%	81.2%
*Ashes of Emblica officinalis* leaves concentration:1.5gms/lit	85.7%	84.8%	83.2%
Powder of Ficus Religiosa* leaves* concentratio:1.75gms/lit	86.1%	83.0%	80.5%
*Ashes of* **Ficus Religiosa** leaves concentration:1.25gms/lit	80.2%	88.6%	85.5%

Table No.2: Cont….

Bio-sorbents	% of Extraction of Ammonia in diverse Samples (actual Conc. of Ammonia is shown in parenthesis)
	Natural polluted Lake samples: in Bapatla mandalam of A.P.
	Sample-4 (21.5ppm)	Sample-5 (18.5 ppm)	Sample-6 (15.8ppm)
Powder of *Tamarindus indicia* leaves concentration: 2.0 gms/lit	86.8%	85.4%	84.2%
*Ashes of Tamarindus indicia* leaves concentration:1.5gms/lit	88.1%	86.0%	85.5%
Powder of *Emblica officinalis* leaves concentratio:1.75 gms/lit	83.0%	82.0%	89.1%
*Ashes of Emblica officinalis* leaves concentration:1.5gms/lit	84.5%	83.2%	81.5%
Powder of Ficus Religiosa* leaves* concentratio:1.75gms/lit	80.4%	81.7%	83.2%
*Ashes of* **Ficus Religiosa** leaves concentration:1.25gms/lit	84.6%	84.3%	86.9%

For this purpose, samples were collected from the effluents of Paper pulp industry at Rajahmundry, Sugar industry at Tadepalligudem and Dairy form at Guntur in Andhra Pradesh. Further, three samples were collected at different polluted lakes in Bapatla mandalam of Guntur District of Andhra Pradesh.

Then these samples were subjected to extraction for Ammonia using the bio-sorbents developed in this work at optimum conditions of pH, equilibration time and sorbent concentration. The results obtained were presented in the Table 2.

RESULTS AND DISCUSSIONS:

The extraction characteristics of leaves and their ashes of Tamarindus indicia, Emblica officinalis and Ficus religiosa towards Ammonia at varying physicochemical parameters such as pH, time of equilibration and sorption concentration are presented in the Graph No. A: 1-3; B: 1-3; C: 1-3 and in Table No. 1and 2. The following points may be noted:

1. Time of equilibration:

Extraction of Ammonia increases with time of equilibration for a fixed adsorbent and at a fixed pH and after certain duration of equilibration, the extraction remains constant, i.e. an equilibrium state is reached (vide Graph No’s: A: 1-3). For example, with activated leaves powder of Tamarindus indicia as adsorbent, the percentage of extraction at pH: 5 is found to be 38.1% at 30 min of equilibration, 49.2% at 60min, 58.3% at 90min, 67.2% at 120min, 75.0% at 150min, 82.5% at 180 min, 89.3% at 210 min and 93.0% at 240 min or above (vide Graph No. A: 1.a). Similarly, with activated leaves powder of Emblica officinalis, the percentage of extraction at pH: 5 is found to be 45.1% at 30 min of equilibration,53.4% at 60 min, 62.1% at 90 min,70.2% at 120 min, 76.2% at 150 min, 81.3% at 180 min, 88.0% at 210 min or above (vide Graph No. A: 2.a). At pH: 5, percentage of extraction has been found to be 39.2% at 30 min of equilibration, 48.1% at 60 min,55.3% at 90 min,63.1% at 120 min,70.1% at 150 min,78.2% at 180 min,85.0% at 210 min or above for activated leaves powder of Ficus Religiosa (vide Graph NO A: 3.a). Similar observations have been found with the ashes of above activated leaves and the results are presented in Graph Nos. A: 1.b, 2.b and 3.b.

2. pH sensitivity:

Removal of Ammonia is found to be pH sensitive and is increasing with decrease in the pH at optimum conditions of time of equilibration and sorbent concentration extraction (Graph No. B: 1-3). With the leaves powders of Tamarindus indicia as adsorbent, the maximum extractability is found to be: 65.0 % at pH: 10; 71.0% at pH: 9; 79.0% at pH: 8; 83.0% at pH: 7; 86.0 % at pH: 6; and 93.0% at pH: 5 at equilibration time of 240 min and sorbent conc. of 2 gm/l , while with the ashes of Tamarindus indicia leaves , the maximum % of extraction is found to be 72.0% at pH:10; 76.0% at pH:9; 84.3% at pH:8; 87.4% at pH:7; 90.0 at pH:6 and 97% at pH:5 at equilibration time of 180 min and sorbent conc. :1.5 g/l.(Vide Graph No B: 1).

Similar results are found with the other sorbents of interest. At optimum conditions of time of equilibration and sorbent concentration, % of removal of Ammonia at equilibration pHs of 10, 9, 8, 7,6 and 5 has been found to be respectively 62.7%, 66.2% , 73.8% , 76.8% , 80.8% and 88.0% with the activated leaves powder of Emblica officinalis and 66.1%, 72.5%, 80.3%, 82.4%, 85.1% and 92.3% with their ashes as adsorbent(Vide Graph No B:2); 58.8% 64.3% 70.1% 73.6%; 76.5% and 85.0%. with sorbents derived from Ficus Religiosa leaves powder and 60.1% , 70.4% , 75.2% , 78.7% , 82.2% , and 90.0% with their ashes (Vide Graph No B:3).

3. Time of equilibration:

The equilibrium time needed for maximum extractability of ammonia has found to be less for ashes than with the raw powders of leaves at optimum conditions of extraction as cited in the Fig. A: 1-3; B: 1-3 and Table No.: 1. The optimum extraction time is found to be 240 min for sorbents pertaining to leaves of Tamarindus indicia but only 180 min with their ashes; 210 min with leaves of Emblica officinalis but 180 min only with their ashes; 210 min with leaves powders of Ficus Religiosa but 150 min with their ashes.

4. Sorbent Concentration:

The optimum bio-sorbent concentration required for maximum extractability of the ammonia is found to be less for ashes than raw powders at optimum conditions of pH and time of equilibration. Sorbent concentration of 2.0 gm/lit is needed for leaves powders of Tamarindus Indicia, but only 1.5gm/lit is sufficient with their ashes at optimum pH:5 and equilibration time: 240 min for leaves powder and 180 min for ashes of leaves (vide Graph No: C-1). The optimum sorbent dosage is found to be 1.75gm/lit for Emblica officinalis leaves powders while 1.5gm/lit for their ashes at optimum conditions of equilibration (vide Graph No::C-2). With Ficus Religiosa leaves powders, the optimum sorbent dosage is found to be 1.75gm/lit while with their ashes is found to be 1.25g/lit at the optimum conditions of equilibration (vide Graph No::C-3).

5. Effect of Interfering Ions:

The interference of common ions present in natural waters, namely Chloride, Fluoride, Sulphate, Phosphate, Carbonate, Calcium, Magnesium, Copper, Zinc and Nickel ions have been studied with the successful adsorbents at optimum conditions of pH: 5 and time of equilibration and sorbent concentration for extractions of Ammonia as cited in the Table 1. Cations viz.,, Ca²⁺, Mg²⁺, Cu²⁺, Zn²⁺and Ni²⁺are interfering with the % of extraction to some extent while Anions of the present study viz., Chlorides, Fluorides, Sulphate, Phosphate and Carbonates are found to have marginal affect on the % of extractability of Ammonia under optimum experimental conditions.

DISCUSSIONS:

With the available data, it is not possible to propose sound theoretical grounds for each observation as further probe is needed on the surface morphology. It is beyond the aims of this work. The surface of the sorbents derived from plant materials, has potential –OH groups and their dissociation is pH sensitive. At high pH values, the dissociation of –OH groups impart negative charge to the surface and thereby a thrust for cations prevails on the surface. But as the pH decreases, the -OH groups dissociation is less favored and are even protinated endowing positive charge to the surface which manifests in the thrust for anions at the surface at low pHs.

Ammonia exists in aqueous solution as either ammonium ion (NH₄⁺) or ammonia gas depends upon the pH of the solution. Below pH: 9.25, the predominant species is NH₄⁺ and above pH: 9.25, ammonia, NH_3, is considerable. In the present work, studies are made in the pH range from 5 to 10.

As pH decreases from 10 to 5, the equilibrium shifts towards the formation of more and more NH₄⁺ species, and thus formed positively charged species get exchanged to the sorbents and thereby progressively increasing the % of extraction. At high pH values, the predominant species is NH₃and the species being neutral is uninfluenced by the electrostatic thrusts prevailing on the surface of the sorbent and hence, % of extraction decreases.

APPLICATIIONS:

The methodologies developed were applied to the real samples of diverse nature, and the results were presented in the Table No: 2. It can inferred from the results that the procedures developed are remarkably successful. % removal of Ammonia is found to be: 60.0% to 92.0% with leaves powder of Tamarindus indicia and 61.5% to 96.1% with their ashes; 63.2% to 89.8% with leaves powder of Emblica officinalis and 60.8% to 91.8%with their ashes; 61.3% to 83.9% with the leaves powder of Ficus Religiosa and 61.2% to 89.6% with their ashes.

CONCLUSIONS:

a) Leaves and their ashes of leaves of Tamarindus Indicia, Emblica officinalis and Ficus religiosa have been probed for their sorption abilities towards Ammonia from synthetically prepared waste waters.

b) Extraction conditions such as pH, sorbent dosage and time of equilibration have been optimized for the maximum removal of Ammonia.

c) We claim more than 84% removal of Ammonia with the bio-sorbents of interest from simulated waters at optimum conditions of extractions.

d) Fivefold excess of common cations like Ca²⁺, Mg²⁺, Cu²⁺, Zn²⁺and Ni²⁺are interfering with the % of extraction to some extent while Anions of the present study viz., Chlorides, Fluorides, Sulphate, Phosphate and Carbonates are found to have marginal affect.

e) The minimum sorbent dosage and time of equilibration needed for the maximum removal of Ammonia is found considerably less for ashes than for powders of leaves

f) The procedures developed are found to be remarkably successful with some real sample of industrial effluents and polluted lakes.

ACKNOWLEDGEMENT:

The authors thank UGC for financial aid for conducting this research work.

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Received on 10.03.2014 Modified on 30.03.2014

Asian J. Research Chem. 7(5): May 2014; Page 513-521