INTRODUCTION:

Wastewater treatment is an important issue and several methods were applied to get desired results. Activated carbon adsorption is the significant process as sludge obtained is comparatively less but is not economically viable. Hence, several adsorbents were developed from natural resources like agricultural waste, mineral waste and Industrial waste by chemical treatments, physical treatments or both. Melia azedarach belongs to Meliaceae family and is a close relative of Indian neem, Azadirachta indica. It’s native to India¹ and known as ‘Dak’ tree locally. This deciduous tree flowers and fruits frequently and is a glorious sight to watch it with bunches of fruits hanging even after leaves fall. This is due to isoprene emission from this plant and it shed leaves to survive heat flecks². Azadirachtin³, benzene dicarboxylic acid, dimethyl ester, melianol, meliandiol⁴, melianoninol⁵, meliantriol, vanillin, vanillic acid, meliartenin⁶, toosendanin and tetranortriterpenol are some of the compounds extracted from Melia azedarach fruits. All of these compounds exhibited anti feedant and growth disruptive properties to many insect larvae and pests^{4, 7-9}.

When ethanolic extracts of melia azedarach and Azadirachta indica fruits were compared, melia azedarach extract showed better mortality rate to Aedes aegyptic larvae mosquito vector of dengue fever¹⁰.

Ma and Liu etal¹¹ filed an application for their new invention of bio fertilizer with insecticidal properties in which they mixed processed Melia azedarach seed kernel with organic compost. Whereas, an another application was filed by Zho etal¹² for their bio-fertilizer developed by mixing Melia azedarach fruit residue obtained from bio diesel and pharmaceutical industries with micro-organisms. A thorough study of the literature revealed that Melia azedarach fruits based adsorbents were not used in water treatment processes till date. Large amount of Melia azedarach fruits are available in this region and it is not used for any purpose and hence discarded by the municipal council with leaf litter. Hence the thought to utilize this material to develop a better adsorbent to treat waste water initiated this study. In addition to removing heavy metals from wastewater, this Melia azedarach based adsorbents may result in mosquitoes and pests free treated wastewater and thus can be safely released to water bodies. Residue or sludge obtained after adsorption process with wastewater can be safely utilized in small amounts as a bio-fertilizer as it has organic matter and natural insecticide. Moreover, it may help to neutralize soil acidity to some extent as Melia fruit contain higher calcium ions and alkalinity is the direct measure of calcium content¹³.

MATERIAL AND METHODS:

Adsorbents preparation:

About 5Kg of matured fallen fruits of Melia azedarach tree were collected from a park situated in Mohali, Punjab (India). Fruit pulp was removed by crushing and seed kernels were washed thoroughly with water. Air dried seed kernels were powdered in a mechanical mill and mixed with 1N H₂SO_4. This mixture was kept on a stirrer cum water bath for 6 hours maintained at 80°C. Later, this acid activated sample was filtered, washed repeatedly with tap water and finally with distilled water. Sulphuric acid free Melia azedarach powder was further dried in an electric oven for 4 hours at 100°C. Further cooled to room temperature and labelled as MA adsorbent and was stored in an air tight container. A portion of this MA adsorbent was mixed with 0.1N KOH solution and shaken for 30 minutes in a mechanical stirrer. After 30 minutes the slurry obtained was washed repeatedly with water till OH^- free filtrate was obtained and finally with distilled water. KOH treated MA adsorbent (hereafter, will be addressed as base treated MA adsorbent) was dried in electric oven at 100°C for 4 hours, cooled and stored in air tight container for further use. Samples were sieved to get uniform particle size.

Characterization of adsorbent samples:

MA and base treated MA samples were characterized by FTIR and SEM techniques to get an idea of functional groups present and surface morphology respectively. Humidity of washed seed kernels was determined by drying in an oven till constant weight was achieved. Sample was incinerated in a muffle furnace at 600° C for 5 hours to get ash content. Microprocessor based pH meter (Century, India) was used to measure pH of samples. Chemical Composition of MA Fruit adsorbent as determined by AAS and flame photometer is as under:-

Element	Mg/g	Analytical tool employed
Ca	3.2	AAS
Mg	3.7	Flame photometer
K	7.4	-do-
Na	0.1	-do-
Ash alkalinity 202 (C mol / Kg)

Adsorption studies:

All chemicals used in this study were of analytical grade and de-ionised water was used wherever necessary. Sodium hydroxide and Hydrochloric acid were used to maintain pH of solutions. 50 ml of metal solutions of different concentration range were taken in a series of 100 ml conical flasks. 100 mg of adsorbent samples were added to all conical flask solutions and closed with air tight stoppers. Blanks were also kept for reference purpose. Conical flasks were stirred in a shaker cum water bath and the temperature was set at 25°C. Samples were stirred for 120 min and the suspension was centrifuged. Clear solution obtained was analyzed in Atomic Absorption Spectrophotometer (ECIL, India) for metal concentration. Analyses were done in duplicate to get average values.

Desorption studies:

Metal laden adsorbents were filtered from metal solutions after adsorption experiments and washed with distilled water to remove unadsorbed metal ions. Desorption studies were carried out with 50 ml of distilled water at pH ranging from 3 – 8. Time period was adjusted slightly greater than the time at which equilibrium was achieved during adsorption experiments. Clear solution was analyzed in AAS for dissolved metal ion concentrations.

RESULTS AND DISCUSSION:

Presence of surface functional groups like carbonyl (1617.1cm^-1), carboxyl (1706 cm^-1 and 1106 cm^-1) and hydroxyl (3374.1cm^-1) in MA adsorbent was established by FTIR spectrum of MA adsorbent (Figure 1). SEM figures of MA adsorbent is shown given in Figure 2. Azadirachtin, benzene dicarboxylic acid, dimethyl ester, melianol, meliandiol, melianoninol, meliantriol, vanillin, vanillic acid meliartenin, toosendanin and tetranortriterpenol are some of the compounds extracted from Melia azedarach fruits. Melianol contain 2 OH^- groups and a double bond whereas, 2 OH^- groups, one aldehyde and an extended double bond in melianoninol molecules. Azadirachtin belongs to limonoids, a tetranortriterpenoid family. It has 3 –OH groups, 4 ketonic groups and one double bond. Vanillin is a phenol with an aldehyde and a –OCH₃ group. Vanillic acid is 4 – hydroxyl, 3 – methoxy, benzoic acid. FTIR spectrum of MA adsorbent reveal the presence of surface functional groups >=O, –OH^- and carboxylic acid (figure 1).

FTIR figures of MA adsorbent is shown in figure 1

Figure 2 SEM figure of MA adsorbent

Adsorption data obtained for the adsorption of Cu (II) ions on the surface of MA and base treated adsorbents were analyzed with Langmuir, Freundlich (figure 3) and Temkin (figure 4) isotherms. Freundlich isotherm is the best fit in both cases as R² values (Table 1) of linear plots is almost close to 1 (Figure 3). It has been observed that MA and base treated MA adsorbents adsorbed considerable amount of Cu (II) ions from aqueous solution. Contact time studies revealed that equilibrium was achieved well within 2 h and 24 h in the case of MA and base treated MA adsorbents respectively (figure 5). When the solution concentration was increased from 10 – 25 ppm and the adsorbent dose was kept at 100mg/50ml, percent Cu (II) removal increased from 94.4 –96.3%. It is very much clear that 100mg of adsorbent removed more than 90% metal ions at all concentrations (figure 6). Whereas, in the case of base treated MA adsorbent, 100mg of adsorbent removed 98.1% - 99.1% of the heavy metal ions when the metal solution initial concentration was maintained at the same range (10 – 25 ppm).

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Linear Langmuir plots, linear Freundlich plots and linear Temkin plots for the adsorption of Ni (II) ions on MA and base treated MA samples are shown in Figures 7, 8 and 9 respectively. Freundlich isotherm is the best fit for the adsorption of Ni (II) ions on both adsorbent samples (Table 1). When 100 mg of MA adsorbent was treated with 50 ml of Ni (II) solutions (5 – 20 ppm), percent Ni (II) removal increased from 68.88 – 86.43%. Equilibrium was achieved in about 2 h (figure 10) in both cases. On increasing adsorbent dose from 100 mg – 250 mg, percent metal ion removal increased from 91.51 – 94.42 %. Whereas, amount of Ni (II) ions adsorbed per gram of the adsorbent decreased from 6.1 – 3.78 mg (figure 12). Metal percent removal increased from 81.79 – 88.59% when 100 mg of base treated MA adsorbent was treated with 50 ml of Ni (II) solutions in the same concentration range. Equilibrium was achieved within 2 h (figure 11).

Figure 8

Figure 9

Figure 10

Figure 11

Ash alkalinity is the direct measure of Ca content of the material (13) Ash alkalinity was determined by titrating the acidified sample against the base (14) MA tree grows in alkaline soil. Leaves and Fruits withdraw soil nutrients especially cation and this makes the soil less alkaline. Soil nearer the roots of the tree become comparative more acidic and thus growing MA in alkaline soil is beneficial to soil desalination and acidification is a major task and both can achieved by growing this tree in alkaline soil and disposing desorbed adsorbent material in the acidic soil respectively.

Desorption studies revealed that percent desorption increased from about 45 – 99% for Cu (II) ions and from about 52 – 90% for Ni (II) respectively when pH was decreased from 8 – 3.

Lower pH increased positive charge on the adsorbent surface (15) and hence decreased negative sites available for adsorption. Moreover positively charged protons compete with metal cations and this increase desorption at lower pH values. Desorption was minimum at pH 5 and remained constant till pH 8 for both copper and nickel ions.

REFERENCES:

1. Nardo, E A B De, A S Costa and A L Lourence. Melia azedarach extract as an antifeedant to Bemisia Tabaci (Homoptera: Aleyrodidae). Florida Entomologist. 80 (1): 1997: 92 – 94.

2. Thomas D. Sharkey, Amy E. Wiberley and Autumn R. Donohue. Annals of Botony. 101 (1): 2008: 5 – 18.

3. Morgan, E. D.; Thornton, M. D. Azadirachtin in the fruit of Melia azedarach. Dep. Chem., Keele Univ., Keele/Staffs., UK. Phytochemistry (Elsevier) 12(2): 1973: 391-2.

4. Gu, Jingwen; Liu, Liding. Studies of the active components of fruits of Melia azedarach L. Tianran Chanwu Yanjiu Yu Kaifa. 8(4): 1996: 10-15.

5. Wang, Wenlu; Wang, Yi; Chiu, Shinfoon. The toxic chemical factors in the fruits of Melia azedarach and their bio-activities toward Pieris rapae. Kunchong Xuebao. 37(1): 1994: 20-4.

6. Carpinella, Maria C.; Giorda, Laura M.; Ferrayoli, Carlos G.; Palacios, Sara M. Antifungal Effects of Different Organic Extracts from Melia azedarach L. on Phytopathogenic Fungi and Their Isolated Active Components. Journal of Agricultural and Food Chemistry. 51(9): 2003: 2506-2511.

7. Andrade-Coelho Claudia A; Souza Nataly A; Gouveia Cheryl; Silva Vanderlei C; Gonzalez Marcelo S; Rangel Elizabeth F. Effect of fruit and leaves of Meliaceae plants (Azadirachta indica and Melia azedarach) on the development of Lutzomyia longipalpis larvae (Diptera: Psychodidae: Phlebotominae) under experimental conditions. Journal of medical entomology. 46(5): 2009: 1125-30.

8. Carpinella, Maria C.; Defago, Maria T.; Valladares, Graciela; Palacios, Sara M. Antifeedant and insecticide properties of a limonoid from Melia azedarach (Meliaceae) with potential use for pest management. Journal of Agricultural and Food Chemistry. 51(2): 2003: 369-374.

9. Ahmed, Qamar U.; Zaidi, S. M. K. R.; Khan, N. U.; Singhal, K. C. Exploration of the Potential Antifilarial Activity of the Fruit, Leaf and Stem Extracts of Melia azedarach Linn. on Cattle Filarial Parasite Setaria Cervi. Abstracts, 37th Middle Atlantic Regional Meeting of the American Chemical Society, New Brunswick, NJ, United States, May 22-25, 2005.

10. Wandscheer, Carolina B.; Duque, Jonny E.; da Silva, Mario A. N.; Fukuyama, Yoshiyasu; Wohlke, Jonathan L.; Adelmann, Juliana; Fontana, Jose D. Larvicidal action of ethanolic extracts from fruit endocarps of Melia azedarach and Azadirachta indica against the dengue mosquito Aedes aegypti.. Toxicon. 44(8): 2004: 829-835.

11. Ma, Yuxin; Liu, Lixin. Biological organic fertilizer with insecticidal functions. Faming Zhuanli Shenqing Gongkai Shuomingshu (2010), Patent written in Chinese. Application: CN 2009-10207892 20091102.

12. Zhou, Weibing; Min, Jiukang; Wu, Jincai; Wu, Lintao. Biofertilizer comprising chinaberry fruit residue generated during extraction and refining of allelopathic substance emulsifiable concentrate or chinaberry biodiesel and its preparation method. Faming Zhuanli Shenqing (2010). Patent written in Chinese. Application: CN 2010-10209867 20100625.

13. A. D. Noble and P. J. Randall (1999). Alkalinity effects of different tree litters incubated in an acid soil of N.S.W., Australia. Agroforestry Systems. 46 (2): 1999: 147-160.

14. Jarvis, S. C. and Robson, A. D. The effects of nitrogen nutrition of plants on the development of acidity in Western Australian soils. II Effects of differences in cation/anion balance between plant species grown under non-leaching conditions. Australian Journal of gricultural Research 34: 1983: 355-365.

15. Shekinah, P.; Kadirvelu, K.;, Kanmani, P.; Senthilkumar, P and Subburam, V. Adsorption of lead (II) from aqueous solution by activated carbon prepared from Eichhornia crassipes. J. Chem. Technol. Biotechnol., 77: 2002: 458 – 464.

Received on 05.07.2011 Modified on 09.08.2011

Asian J. Research Chem. 4(11): Nov., 2011; Page 1772-1776

Adsorbent	Regression constant (R²)
	Langmuir isotherm		Freundlich isotherm		Temkin isotherm
	Cu (II)	Ni (II)	Cu (II)	Ni (II)	Cu (II)	Ni (II)
Melia azedarach fruit adsorbent (MA)	0.8627	0.9341	0.9999	1	0.98	0.917
Melia azedarach fruit – Base treated adsorbent (MA base treated)	0.0097	0.8617	1	0.9998	0.9819	0.9261