INTRODUCTION:

As of now at least 20 metals are classified as toxic and half of these toxic metals are often discharged by a number of industrial processes and this can lead in turn to the contamination of fresh water and marine environment that cause risks to human health¹. Removal of heavy metals from waste water is a matter of serious concern due to their toxicity to various life forms. Heavy metals exists

in waste water of many industries such as metal plating, petroleum refining, wood preserving, mining operations, radiator manufacturing, pulp and paper industries, fertilizers and alloy industries, storage batteries industry etc². These heavy metals create health effects. The excessive intake of copper by man leads to several mucosal irritations, wide spread capillary damage, hepatic and renal damage central nervous problem³.

A number of acute chronic disorder such as itai- itai disease emphysema, hypertension, renal damage are associated with cadmium poisoning according to US Environmental protection agency, the maximum permissible limit for Pb in drinking water is 0.015 mg/liter, increase of this cause encenphalopathy and mental retardation. Arsenic affects the skin. It causes skin, lung, bladder and kidney cancer, neurological disorder and muscular weakness etc, chromium has both beneficial and detrimental properties. Cr (III) is essential in human nutrition while Cr (IV) causes lung cancer^{4,
42, 43, 101, 102, 112}.

As such there has been a great deal of research into finding cost effective methods for the removal of contaminants from waste water. So the investigation on the use of agricultural by-products for the removal of waste water has been on increase. The other reason for the use of these by-products is that, they are available at a little or no cost, naturally occurring, stable and require minimum maintenance or care¹²⁵.

The low cost agricultural by products such as rice husk^{5- 7} sugar cane bagasse^8-10, Teawaste¹¹, sawdust^{12, 116, 117, 124} coconut husk¹³, oil palm shell¹⁴, neem bark¹⁵ etc are used to remove toxic metals from waste water. some other low cost adsorbent as Dyetreated cassava Mesocarp¹⁶, coffee grounds, wool fibers, modified chitosan¹⁷ peanut skin, barks of trees and other cellulosic material¹², modified coconut pollen grains¹⁸, zeolite, activated carbon-zeolite composite are also used for the removal of heavy metals from waste water has been investigated by various researchers.

Cost is an important parameter for comparing the adsorbent materials and the high cost of activated carbon has promoted a search for cheaper substituentes. The expenses of the individual adsorbent depend upon the degree of processing required and local availabilities. The objective of this study is to contribute in the research for less expensive adsorbents and their utilization to remove heavy toxic metals which are in many case also pollution sources.

Different low cost adsorbents:

Sugarcane Bagasse:

Sugarcane bagasse is the waste product from sugar refining industry. Bagasse pitch is composed largely of cellulose, pentosan and lignin^9,62-65. It is used to remove Cd (II) and Pb (II) from waste water. The Pb (II) adsorption process follows Langmuir’s model and Cd (II) shows multilayer adsorption process. The carboxymethylated lignin of sugarcane bagasse can adsorb Pb (II) selectively under special conditions (pH = 6.0, temp. = 30⁰ c and ionic strength of 0.1 mol/dm³). It has been reported that removal of Cd (II) is found to increase with an increase in pH beyond 2 and at pH >8 the removal of Cd(II) is 100%.^13,66 reported that it shows 80 – 100% Cr(IV) removal from aqueous solution at an adsorbent dose of 0.8 g/ 50 ml, initial concentration of metal 20g/l and at pH value of 1. The data for Cd (II) removal follows Freundlich isotherm. The column operations showed 95.5% removal of Cu (II) from waste water. The best part of the sugarcane bagasse is, it can be regenerated in acid and the efficiencies decreased only after the fourth cycle of reuse. The acid treated sugarcane bagasse can be considered as a good alternative to remove toxic heavy metals from waste water of electroplating industries^{41, 66-75. 77}.

Rice Husk:

Rice husk is an agricultural waste material. Dry rice husk contain 70-80% of organic matter as lignin, cellulose and sugar etc^{7, 22, 23, 110, 118, 122}. In recent years attention has been made for utilization of unmodified and modified rice husk as an adsorbent for the Removal of Heavy Metals from Water/ Waste Water¹⁹. Rice husks were used for arsenic removal from water. Maximum adsorption occurred at 0.01 mol/l HNO₃,HCl, H₂SO₄ or HClO₄ using 0.1 g of adsorbent for 5.97×10^-3 mol/L of arsenic for 5 min. the process followed Freundlich isotherm at the concentration range from 8.7×10^-5 mol/L to 1.73×10^-3 mol/L of arsenic^{20, 81, 103}. Complete removal for both As (III) As (IV) was activated under the conditions: initial As concentration, 100 µg/L; adsorbent amount, 6 g; particle size, 780 and 510 µm; and pH, 6.5 and 6.0 respectively. Regeneration of the adsorbent is also possible (71–80%) with 1M of KOH []. It was reported that modified rice husk is a potentially useful material for the Removal of Heavy Metals as Cu (II) Pb (II) and from Water/ Waste Water. The removal of Cu and Pb was maximum when pH was increased from 2 to 3²⁶.²¹studied that phosphate treated rice husks show greater removal efficiency for Cd (II)^45-59 and the maximum adsorption (>90 %) was obtained at a pH value of 12. The activated carbon prepared by carbonization of rice husks with sulphuric acid followed by CO₂ activation, showed 88% removal of total Chromium and >99% of hexavalent chromium. Rice husks showed more Cr (IV) removal capacity than commercial carbon; those are 8.9 mg/g and 6.3 mg/g for rice husk and commercial carbon respectively³. Modified rice husk in the form of dyestuff treated husk show high removal capacity for Pb (II) and Cd (II) 99.8% and 92.2% respectably and for yellow stuffed treated husk the removal capacity for Pb (II) is 100% at the optimum conditions the Cr, Cu and Cd ions removal from waste water stated as 79% 80% and 85 % respectably^5,6. A combination of rice husk with maize cobes and sawdust is most effective for which the removal efficiency reached up to 98.15% for Pb at room temp. and the pH value from 4.5 to 6.5, the Pb removal reaches 99%²³. When rice husk is treated with tartaric acid it shows > 80% and 95% removal for Cu and Pb at pH value 2-3 respectably^{24, 60}.

Teawaste:

Teawaste is a natural adsorbent which is used for the removal of Pb and Cd from the industrial waste water^{81, 113}. The research is a batch scale experimental type and the analysis have performed by using different amounts of adsorbent with five different metal concentration in mixed combination and individually .these five different concentration are 5,10,15,30 and 100mg/liter, the experiment were performed using three different amounts of adsorbent which are 0.5, 1, and 1.5 g in single solution.

Table no. 1

S. No	Adsorbent amount in g	Concentration of solution used in mg/liter		Percentage removal of metals
S. No	Adsorbent amount in g	Pb	Cd	Pb	Cd
1.	0.5	5	5	94	60
		10	10	90	50
		15	15	87	55
		30	30	85	35
		100	100	80	30
2	1.0	5	5	100	78
		10	10	100	58
		15	15	100	50
		30	30	100	50
		100	100	90	40
3	1.5	5	5	100	80
		10	10	99	78
		15	15	98	68
		30	30	99	60
		100	100	99	50

It is represented that like the most other natural adsorbents tea waste is used in the treatment process of heavy metals and the treatment efficiency may be as high as 100 % by precise choosing of adsorbent amount¹¹. thereby it is possible to obtained maximum adsorption by grinding the adsorbent as 94% removal of lead from a 5mg/liter solution was possible by applying 0.5g tea waste and the removal is only 76% with 100mg/liter solution but on increasing the amount of tea waste to 1.5 g it was possible to increase the efficiency of adsorption to about 96.5% for 100 mg/liter solution¹².

The concentration of heavy metals have also and important effect on the result of this treatment. Teawaste is a cheap material so it is having a best utilization in the industrial waste water treatment plant. The efficiency of teawaste can be increases by its treatment with some chemicals such as acids and base^{25, 114}.

Chitin, chitosan and chitosan oil palm shell charcoal:

Chitin and chitosan are excellent natural adsorbents with high selectivity due to the following reasons.⁹⁷

1. Large no. of hydroxyl amino groups gives chitosan high hydrophilicity.

2. Primary amino provide high selectivity

3. The polymer chain of chitosan provide suitable configuration for efficient complectiation with metal ions²⁸.

As and other metal ions adsorbed by chitosan. Removal of As from contaminated water was also studied on chitosan chitin mixture at pH 7 the removal efficiency is maximum (0.13 µ equiv. As /g)^21,98.

A new composite bioadsorbent has been prepared by coating chitosan on oil palm shell charcoal among the many other low cost adsorbent identified ( Olin et all, 1996; Bailey et all. 1999; Bailey et all. 1997) chitosan has the highest capacity for several metal ions and oil palm shell has been succefully use to produce high quality activated carbon. Chitosan binds with both anionic and cationic species. The removal of Cr (VI) and As depending on the pH are known to exist as anions at pH 4^25,99.

To examine the effect of pH on the Cr removal efficiency the pH was varied from 1 to 9 where optimum metal removal efficiency occurs at pH 5 the removal efficiency for chitosan coated acid treated oil palm charcoal increase from 65% to 90% over pH range 1 to 5. The dependency of Cr adsorption on dose of adsorbent was studied by varying the amount of adsorbent from 1.5 to 30 g/liter while keeping the other parameters (pH, agitation speed contact time etc.) constant¹¹. It can be observed that removal efficiency increases with dose and it was about 86% at the dose of 13.5g/liter. The removal efficiency increased with an increase in contact time before equilibrium is reached, the Cr removal efficiency of chitosan coated acid treated beads (CCAB) increase from 60 to 90% when contact time increased from 30 to 180 min. and for the Cr removal efficiency of chitosan coated acid treated oil palm shell charcoal (CAOPSC) the contact time is 300 mints^21,100.

So it has been reported that use of chitosan coated oil palm shell charcoal and chitosan coated acid treated oil palm shell charcoal for r removal appeared to be ecofriendly technically feasible and low cost with high efficiency. The best part of this adsorbent is, it can be regenerated by using 0.1M NaOH and therefore can be reused^{14, 21}.

Dye treated Cassava Mesocarp:

^{27, 91, 76} studied the use of Dye treated Cassava Mesocarp shows that it is a good adsorbent for the removal of copper. Cassava Mesocarp was obtained from Cassava Mill factory then it is converted into chips and then sieved to powder having 0.40 and 0.63mm particle size^16,92. First the adsorption of Cu (II) has performed with un dyed cassava Mesocarp (UDCM) with particle size 0.40mm then it shows the adsorption of Cu (II) varying from 63-70mg/g from the contact time varying from 5 to 30 minute the different particle size of cassava Mesocarp have different removal efficiency as 0.40 mm particle size showed highest removal efficiency for metal ion than 0.6mm. The adsorption rate of metal ions on the dyed and undyed cassava Mesocarp with different particle size (0.40 and 0.63mm) is illustrated and the values are given in the table no. 2:

Table no.2

Time	UDCM (0.40mm)	Dye treated Cassava Mesocarp
	Cu(II) mg/g,	Cu(II) mg/g
	Particle size (0.40mm)	0.40mm, Particle size	0.63mm, Particle size
0	0	0.0	0.0
5	63	372.5	224.0
10	67.5	379.0	238.5
15	70	385.0	243.0
20	70	389.0	246.5
25	70	389.0	248.5
30	70	389.0	248.5

Where concentration of Cu solution = 10 mg/liter

The values (in table no. 2) show that efficiency of Cu (II) removal on dyed cassava Mesocarp is greater than un dyed cassava Mesocarp and the removal efficiency is also greater with 0.40mm than 0.63mm. It is clear from the above data that the removal efficiency also increased with increase in contact time. Another important factor used in describing the uptake capacity of metal ion on adsorbent is the hydrolysis constant pk_h. metal with smaller hydrolysis constant have increasing tendency to hydrolyses because of larger charge size fraction (Z²/r) and electronic structure (Huheey 1983) and the extent of hydrolysis of this metal indicates that it has greater hydrolysis capacity^{28,94, 106-109}.

Ulva Lactuca (Green Algae):

Ulva Lactuca (Green Algae) is found in Alexandria Egypt is another adsorbent for the removal of Cu (II) this algae was milled, sieved and it was labeled (GA) another part of algae were carbonized and was labeled (CGA)^{29, 93}.

Table no.3

Adsorbent Dose (g/liter)	Percentage of Cd removal
20	24.49%
70	71.47%
80	82.37%

According to table no. 3 the dose of adsorbent increses, the % of Cd removal also increases.

Table no. 4 shows the different adsorbents and their adsorption capacity for different heavy metal removal:

Table no. 4

S. No.	Type of Adsorbent	Adsorption capacity for metals					pH	Surface Area	particle size and does of adsorbent	Temp ^oC	Model used to calculate the adsorption capacity
S. No.	Type of Adsorbent	Cr	Cu	As	Cd	Pb	pH	Surface Area	particle size and does of adsorbent	Temp ^oC	Model used to calculate the adsorption capacity
1	Rice Husk	99%	-	100%	-	-	2-3	-	780 & 510 µm 6 g/lit	30	Freundlich
1.1	Rice Husk (water and HCl washed)	79%	80%	-	85%	-	2-3	-	-	37	Freundlich
1.2	Phosphate treated rice husk	-	-	-	90%	-	12	-	-	-	Freundlich
1.3	Dye stuffed rice husk (red)	39.7%	78.8 %	-	92.2%	98.8%	<5	-	-	30	Freundlich
1.4	Dye stuffed rice husk (yellow)	39.1%	70 %	-	83.3%	100%	<5	-	-	-	Freundlich
1.5	Tartaric acid modified rice husk	-	80 %	-	-	95%	2-3	-	-	20	Freundlich
1.6	Rice husk carbon	100%	-	-	99%	99%	2	-	-	37	Freundlich
1.7	Rice husk with maize cobe and saw dust	-	-	-	-	99%	4.5-6.5	-	-	25	Temkin
2	Sugar cane Bagasse	-	-	-	100%	80%	6-8	-	- 16 g/lit	30	Freundlich
	Raw Sugar Cane Bagasse	80-100%	-	-	-	-	1	-	-	30	Freundlich
3	Activated charcoal derived from coconut Shell	-	-	-	66%	-	6	630.8m²/g	-	30-40	Freundlich
3.1	Coconut husk carbon	-	-	146mg/g	-	-	12	206	-	30	Langmuir
3.2	Coconut shell carbon	-	-	2.1mg/g	-	-	5	1150-12508 m²/g	-	25	Langmuir
4	Tea waste	-	-	-	80%	100%	-	-	- 1.5 g/lit	30	-
5	Chitosan/Chitin	-	-	0.13 µEqu/g	-	-	7	-	-	25	-
5.1	Chitosan coated oil palm shell charcoal	65-92%	-	72	-	-	1-5	-	- 13.5 g/lit	25	-
6	Dye treated casaba Mesocarp	-	389 mg/g	-	-	-	2-3	-	0.40 mm	30	-
7	Green Algae (Ulva Lactuca)	-	62 %	-	-	-	5	-	-	25	Freundlich and Redlich-Peterson
7.1	Carbonated green algae	-	88 %	-	-	-	5-7	1.065 m²/g	-	25±1	Freundlich
8	Sago waste	-	75 %	-	-	95%	4-5.5	-	-	32	Langmuir and Freundlich
9	Coconut husk and palm pressed fibre	80%	-	-	-	-	2	-	-	20-25	Langmuir and Freundlich
10	Carbon prepared from Casurina Equisetifolia	65-80%	-	-	-	-	4	-	-	29	Freundlich
11	Raw Oil Palm Shell	-	-	-	90%	-	6-8	-	- 80 g/lit	28-31	Langmuir
12	Biochar ( Pine Wood Char)	-	-	1.20µg/g	-	-	3.5	2.73m²g	-	25	Langmuir
12.1	Oak wood Char	-	-	5.85 µg/g	-	-	3.5	2.04 m²g	-	25	Langmuir
12.2	Oak Bark Char	-	-	12.1 µg/g	-	-	3.5	25.4 mg	-	25	Langmuir
12.3	Pine Bark Char	-	-	12.15 µg/g	-	-	3.5	1.88 m²g	-	25	Langmuir

This study is limited to bath experiment only and the effect of various parameters on the removal of Cu (II) on to green algae (GA) and carbon green Algae was studied³⁰. This study shows that pH, adsorbent dose and the concentration of Cu (II) are important factor influencing heavy metal adsorption the maximum removal efficiency was 62% and 88% for GA and CGA respectively using 50mg/liter initial Cu concentration and 2g/liter adsorbent dose at the optimum pH value 5³¹. The maximum Cu (II) uptake capacity was 24.5 and 32.5mg/g for GA and CGA at pH 5. The maximum removal was 73% and 90% and it was attained in about 60 and 45 min for GA and CGA respectively keeping the other parameters constant. The process will follow Langmuir, Freundlich, Tempkin, Koble-Corrigan isotherm models. The application of adsorption of Cu (II) by GA and CGA had proved its efficiency in waste water treatment application^{31, 32}.

Sago waste:

Sago waste is used for adsorption of Pb and Cd. Sago waste is a waste product and pollutant which is used to remove Pb and Cu from waste water. For this adsorption process the effective pH range found to be 4 to 5.5 for both the metals. The equilibrium data for both metals fitted for both the Langmuir and Freundlich Isotherm and show that the sago waste had a greater adsorption capacity for Pb (46.6mg/g) than Cu (12.4mg/g)^{33,
90,104, 105, 111}.

Coconut husk carbon and activated charcoal derived from coconut shell:

It is studied that the removal of Cr from water/waste water by coconut husk and palm pressed fibber and the investigation shows that the process is limited to batch study only. For both the adsorption the optimum pH for maximum removal (>80%) is at 2^{13, 61,79}. Another method for Cr (IV) removal by carbon prepared from Casurina Equisetifolia leaves were studied by Rangnathan, K. (2000), the adsorption studies show that 65 to 80% removal of Cr (IV)^{34, 123}. Coconut husk carbon is also used for waste water studied by³⁵ it can remove 142 mg/g As from waste water.

The coconut shell active charcoal was prepared by pulverizing the coconut shell into the powders this activated charcoal^{109, 120-121} derived from coconut shell having characteristics as surface area 630.80 m²/ g, porosity 0.50ml/g, pH 6, imperigation ratio 0.5 and temperature 30-40 ⁰C is used for the removal of Cd (II) this studies is limited to batch study only and the adsorption increases with the increase in contact time and it is clear from above data when the adsorption process is done with these characteristics the removal of Cd (II) is 66% from water^36,38.

Raw oil Palm Shell:

^{4, 119} studied that Raw oil palm shell seems to be quite feasible for the removal of Cd (II) from the waste water. The adsorption of Cd (II) on raw oil palm shell is highly pH dependent. The maximum adsorption of Cd (81.63%) is observed at pH value 10. If the lower initial concentration of Cd (II) is 10 to 20mg/liter, the raw oil palm shell absorbs the Cd (II) up to 90% at pH value 6 and contact time of six hours. The adsorption equilibrium data followed Langmuir isotherm.^{78, 87} The removal efficiency also depends upon adsorbent dose with initial Cd (II) concentration of 50 mg/liter which is as follows:

Biochar:

Biochar is a byproduct from fast wood/bark pyrolysis it is investigated as adsorbent for the removal of As, Cd and Pb^{38,
40, 95, 115}. Oak bark Oak wood Pine bark and pine wood chars was obtained from fast pyrolysis and has been characterized. The adsorption studied performed at different temperatures, pH values in the batch mode, the maximum adsorption occurs at a pH range of 3-4 for As, 4-5 for Pb and 4-5 for Cd. The equilibrium data were modeled with the help of Langmuir and Frendlich equation. As (III) removal followed the order pine wood char (1.2µg/g) < oak wood char (5.85 µg/g) < Oak bark char (12.1µg/g) <pine bark char (12.15 µg/g)^39,96.

CONCLUSION:

The heavy metals such as Pb, Cr, Cu, As and Cd have been serious pollutants of water since Roman times, these have been major water pollutants come from industrial waste water. A review of various agricultural and industrial by-products as adsorbents presented herein shows a great potential for the removal of heavy metals from wastewater. Adsorption is a useful tool for controlling the extent of heavy metals from waste water. In this review the low cost adsorbents are presented for the removal of heavy metals. Some adsorbent shown in this paper have equal or greater removal capacities than activated carbon and also have low cost than activated carbon. The adsorption capacity of different adsorbents is dependent on the type of adsorbent investigated, size of adsorbents nature of waste water treated, pH values, and amount of adsorbent and concentration of heavy metals in water/waste water. The use of commercially available activated carbon for the removal of the heavy metals can be replaced by the utilization of low cost effective and easily available, agricultural and industrial by products as adsorbent.

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47. M. Rozainee, S.P. Ngo, A.A. Salema, K.G. Tan, M. Ariffin, Z.N. Zainura “Effect of fluidising velocity on the combustion of rice husk in a bench-scale fluidised bed combustor for the production of amorphous rice husk ash”Bioresource Technology, Volume 99, Issue 4, March 2008, Pages 703.

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52. César Ricardo Teixeira Tarley, Sérgio Luis Costa Ferreira, Marco Aurélio Zezzi Arruda “Use of modified rice husks as a natural solid adsorbent of trace metals: characterisation and development of an on-line preconcentration system for cadmium and lead determination by FAAS” Microchemical Journal, Volume 77, Issue 2, August 2004, Pages 163-175.

53. K. G. Mansaray, A. E. Ghaly “Thermal degradation of rice husks in nitrogen atmosphere” Bioresource Technology, Volume 65, Issues 1-2, July-August 1998, Pages 13-20

54. A.L.G. Gastaldini, G.C. Isaia, N.S. Gomes, J.E.K. Sperb “Chloride penetration and carbonation in concrete with rice husk ash and chemical activators” Cement and Concrete Composites, Volume 29, Issue 3, March 2007, Pages 176-180

55. Muhammad Shoaib Ismail, A. M. Waliuddin “Effect of rice husk ash on high strength concrete” Construction and Building Materials, Volume 10, Issue 7, October 1996, Pages 521-526.

56. Runping Han, Dandan Ding, Yanfang Xu, Weihua Zou, Yuanfeng Wang, Yufei Li, Lina Zou “Use of rice husk for the adsorption of congo red from aqueous solution in column mode” Bioresource Technology, Volume 99, Issue 8, May 2008, Pages 2938-2946.

57. Vimal Chandra Srivastava, Indra Deo Mall, Indra Mani Mishra “Characterization of mesoporous rice husk ash (RHA) and adsorption kinetics of metal ions from aqueous solution onto RHA” Journal of Hazardous Materials, Volume 134, Issues 1-3, 30 June 2006, Pages257-267.

58. Yupeng Guo, Jingzhe Zhao, Hui Zhang, Shaofeng Yang, Jurui Qi, Zichen Wang, Hongding Xu “Use of rice husk-based porous carbon for adsorption of Rhodamine B from aqueous solutions” Dyes and Pigments, Volume 66, Issue 2, August 2005, Pages 123-128.

59. E.I. El-Shafey “Sorption of Cd(II) and Se(IV) from aqueous solution using modified rice husk” Journal of Hazardous Materials, Volume 147, Issues 1-2, 17 August 2007, Pages 546-555.

60. Vimal Chandra Srivastava, Indra Deo Mall, Indra Mani Mishra “Removal of cadmium(II) and zinc(II) metal ions from binary aqueous solution by rice husk ash” Colloid sand Surfaces A Physicochemical and Engineering Aspects, Volume 312, Issues 2-3, 15 January 2008, Pages 172-184.

61. Francisco W. Sousa, Marcelo James Sousa, Isadora R.N. Oliveira, André G. Oliveira, Rivelino M. Cavalcante, Pierre B.A. Fechine, Vicente O.S. Neto, Denis de Keukeleire, Ronaldo F. Nascimento “Evaluation of a low-cost adsorbent for removal of toxic metal ions from wastewater of an electroplating factory”
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62. Wilson S. Peternele, Ana A. Winkler-Hechenleitner, Edgardo A. Gómez Pineda “Adsorption of Cd(II) and Pb(II) onto functionalized formic lignin from sugar cane bagasse” Bioresource Technology, Volume 68, Issue 1, April 1999, Pages 95-100.

63. N. Syna, M. Valix “Assessing the potential of activated bagasse as gold adsorbent for gold–thiourea” Minerals Engineering, Volume 16, Issue 6, June 2003, Pages 511-518.

64. Vimal C. Srivastava, Mahadeva M. Swamy, Indra D. Mall, Basheswar Prasad, Indra M. Mishra “Adsorptive removal of phenol by bagasse fly ash and activated carbon: Equilibrium, kinetics and thermodynamics” Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 272, Issues 1-2, 5 January 2006, Pages 89-104.

65. Vidya S. Batra, Sigita Urbonaite, Gunnar Svensson “Characterization of unburned carbon in bagasse fly ash” Fuel, Volume 87, Issues 13-14, October 2008, Pages 2972-2976.

66. Abd El-Aziz A. Said, Adriane G. Ludwick, Heshmat A. Aglan “Usefulness of raw bagasse for oil absorption: A comparison of raw and acylated bagasse and their components” Bioresource Technology, Volume 100, Issue 7, April 2009, Pages 2219-2222.

67. V.K. Gupta, Suhas “Application of low-cost adsorbents for dye removal” – A review Journal of Environmental Management, Volume 90, Issue 8, June 2009, Pages 2313-2342.

68. Tzong-Horng Liou “Development of mesoporous structure and high adsorption capacity of biomass-based activated carbon by phosphoric acid and zinc chloride activation” Chemical Engineering Journal, In Press, Corrected Proof, Available online 16 December 2009.

69. “Liliana Giraldo-Gutiérrez, Juan Carlos Moreno-Piraján ”Pb(II) and Cr(VI) adsorption from aqueous solution on activated carbons obtained from sugar cane husk and sawdust” Journal of Analytical and Applied Pyrolysis, Volume 81, Issue 2, March 2008, Pages 278-284.

70. C.A. Cardona, J.A. Quintero, I.C. Paz “Production of bioethanol from sugarcane bagasse: Status and perspectives Bioresource Technology”, In Press, Corrected Proof, Available online 28 November 2009.

71. Dhiraj Sud, Garima Mahajan, M.P. Kaur “Agricultural waste material as potential adsorbent for sequestering heavy metal ions from aqueous solutions” – A reviewBioresource Technology, Volume 99, Issue 14, September 2008, Pages 6017-6027.

72. J. Guo, A.C. Lua “Surface Functional Groups on Oil-Palm-Shell Adsorbents Prepared by H₃PO₄ and KOH Activation and their Effects on Adsorptive Capacity” Chemical Engineering Research and Design, Volume 81, Issue 5, May 2003, Pages 585-590.

73. Osvaldo Karnitz Júnior, Leandro Vinícius Alves Gurgel, Rossimiriam Pereira de Freitas, Laurent Frédéric Gil “Adsorption of Cu(II), Cd(II), and Pb(II) from aqueous single metal solutions by mercerized cellulose and mercerized sugarcane bagasse chemically modified with EDTA dianhydride (EDTAD)”
Carbohydrate Polymers, Volume 77, Issue 3, 11 July 2009, Pages 643-650.

74. Leandro Vinícius Alves Gurgel, Rossimiriam Pereira de Freitas, Laurent Frédéric Gil “Adsorption of Cu(II), Cd(II), and Pb(II) from aqueous single metal solutions by sugarcane bagasse and mercerized sugarcane bagasse chemically modified with succinic anhydride
Carbohydrate Polymers”, Volume 74, Issue 4, 21 November 2008, Pages 922-929.

75. G. McKay, M. El Geundi, M.M. Nassar “Equilibrium studies during the removal of dyestuffs from aqueous solutions using Bagasse pith” Water Research, Volume 21, Issue 12, December 1987, Pages 1513-1520.

76. David William O’Connell, Colin Birkinshaw, Thomas Francis O’Dwyer “Heavy metal adsorbents prepared from the modification of cellulose: A review”Bioresource Technology, Volume 99, Issue 15, October 2008, Pages 6709-6724.

77. Umesh K. Garg, M.P. Kaur, Dhiraj Sud, V.K. Garg “Removal of hexavalent chromium from aqueous solution by adsorption on treated sugarcane bagasse using response surface methodological approach” Desalination, Volume 249, Issue 2, 15 December 2009, Pages 475-479

78. A.A. Abia, E.D. Asuquo “Kinetics of Cd²⁺ and Cr³⁺ Sorption from Aqueous Solutions Using Mercaptoacetic Acid Modified and Unmodified Oil Palm Fruit Fibre” (Elaeis guineensis) Adsorbents Tsinghua Science and Technology, Volume 12, Issue 4, August 2007, Pages 485-492.

79. Dinesh Mohan, Kunwar P. Singh “Single- and multi-component adsorption of cadmium and zinc using activated carbon derived from bagasse—an agricultural waste” Water Research, Volume 36, Issue 9, May 2002, Pages 2304-2318.

80. Umesh K. Garg, M.P. Kaur, V.K. Garg, Dhiraj Sud “Removal of hexavalent chromium from aqueous solution by agricultural waste biomass” Journal of Hazardous Materials, Volume 140, Issues 1-2, 9 February 2007, Pages 60-68.

81. Sai Krishna Reddy Yadanaparthi, David Graybill, Ray von Wandruszka “Adsorbents for the removal of arsenic, cadmium, and lead from contaminated waters” Journal of Hazardous Materials, Volume 171, Issues 1-3, 15 November 2009, Pages 1-15.

82. Alok Mittal, Lisha Kurup, Jyoti Mittal “Freundlich and Langmuir adsorption isotherms and kinetics for the removal of Tartrazine from aqueous solutions using hen feathers” Journal of Hazardous Materials, Volume 146, Issues 1-2, 19 July 2007, Pages 243-248.

83. Amit Bhatnagar, Mika Sillanpää “Utilization of agro-industrial and municipal waste materials as potential adsorbents for water treatment- A Review” Chemical Engineering Journal, In Press, Accepted Manuscript, Available online 18 January 2010.

84. S.A. Sayed, A.M. Zayed “Investigation of the effectiveness of some adsorbent materials in oil spill clean-ups” Desalination, Volume 194, Issues 1-3, 10 June 2006, Pages 90-100.

85. S. Larous, A.-H. Meniai, M. Bencheikh Lehocine “Experimental study of the removal of copper from aqueous solutions by adsorption using sawdust”Desalination, Volume 185, Issues 1-3, 1 November 2005, Pages 483-490.

86. Ibrahim Kula, Mehmet Uğurlu, Hamdi Karaoğlu, Ali Çelik “Adsorption of Cd(II) ions from aqueous solutions using activated carbon prepared from olive stone by ZnCl₂ activation”Bioresource Technology, Volume 99, Issue 3, February 2008, Pages 492-501.

87. Jia Guo, Aik Chong Lua “Characterization of adsorbent prepared from oil-palm shell by CO₂ activation for removal of gaseous pollutants”Materials Letters, Volume 55, Issue 5, August 2002, Pages 334-339.

88. C. Namasivayam, R. T. Yamuna “Adsorption of chromium (VI) by a low-cost adsorbent: Biogas residual slurry”Chemosphere, Volume 30, Issue 3, February 1995, Pages 561-578.

89. Parul Sharma, Pushpa Kumari, M.M. Srivastava, Shalini Srivastava “Removal of cadmium from aqueous system by shelled Moringa oleifera Lam. seed powder” Bioresource Technology, Volume 97, Issue 2, January 2006, Pages 299-305.

90. K. Kadirvelu, M. Kavipriya, C. Karthika, N. Vennilamani, S. Pattabhi “Mercury (II) adsorption by activated carbon made from sago waste” Carbon, Volume 42, Issue 4, 2004, Pages 745-752

91. M. Horsfall Jr., A.A. Abia, A.I. Spiff “Kinetic studies on the adsorption of Cd²⁺, Cu²⁺ and Zn²⁺ ions from aqueous solutions by cassava (Manihot sculenta Cranz) tuber bark waste”Bioresource Technology, Volume 97, Issue 2, January 2006, Pages 283-291.

92. A. A. Abia, M. Horsfall Jr., O. Didi “The use of chemically modified and unmodified cassava waste for the removal of Cd, Cu and Zn ions from aqueous solution” Bio-resource Technology, Volume 90, Issue 3, December 2003, Pages 345-348.

93. Sarabjeet Singh Ahluwalia, Dinesh Goyal “Microbial and plant derived biomass for removal of heavy metals from wastewater” Bio-resource Technology, Volume 98, Issue 12, September 2007, Pages 2243-2257.

94. M. Horsfall Jr, A. A. Abia “Sorption of cadmium(II) and zinc(II) ions from aqueous solutions by cassava waste biomass (Manihot sculenta Cranz)”Water Research, Volume 37, Issue 20, December 2003, Pages 4913-4923.

95. Bruno O. Dias, Carlos A. Silva, Fábio S. Higashikawa, Asunción Roig, Miguel A. Sánchez-Monedero “Use of biochar as bulking agent for the composting of poultry manure: Effect on organic matter degradation and humification”
Bioresource Technology, Volume 101, Issue 4, February 2010, Pages 1239-1246.

96. Zhengang Liu, Fu-Shen Zhang “Removal of lead from water using biochars prepared from hydrothermal liquefaction of biomass” Journal of Hazardous Materials, Volume 167, Issues 1-3, 15 August 2009, Pages 933-939.

97. R. A. A. Muzzarelli, N. Frega, M. Miliani, C. Muzzarelli, M. Cartolari “Interactions of chitin, chitosan, N-lauryl chitosan and N-dimethylaminopropyl chitosan with olive oil” Carbohydrate Polymers, Volume 43, Issue 3, November 2000, Pages 263-268.

98. Marguerite Rinaudo “Chitin and chitosan: Properties and applications”Progress in Polymer Science, Volume 31, Issue 7, July 2006, Pages 603-632.

99. Majeti N. V. Ravi Kumar “A review of chitin and chitosan applications” Reactive and Functional Polymers, Volume 46, Issue 1, November 2000, Pages 1-27.

100. Ke-Jin Hu, Jin-Lian Hu, Kwok-Ping Ho, Kwok-Wing Yeung “Screening of fungi for chitosan producers, and copper adsorption capacity of fungal chitosan and chitosanaceous materials” Carbohydrate Polymers, Volume 58, Issue 1, 1 October 2004, Pages 45-52.

101. Nalini Sankararamakrishnan, Awantika Dixit, Leela Iyengar, Rashmi Sanghi “Removal of hexavalent chromium using a novel cross linked xanthated chitosan” Bioresource Technology, Volume 97, Issue 18, December 2006, Pages 2377-2382.

102. L.P Christov, B van Driessel, C.A du Plessis ”Fungal biomass from Rhizomucor pusillus as adsorbent of chromophores from a bleach plant effluent” Process Biochemistry, Volume 35, Issues 1-2, October 1999, Pages 91-95.

103. Anjali Gupta, Vivek Singh Chauhan, Nalini Sankararamakrishnan ”Preparation and evaluation of iron–chitosan composites for removal of As(III) and As(V) from arsenic contaminated real life groundwater” Water Research, Volume 43, Issue 15, August 2009, Pages 3862-3870.

104. Sai Krishna Reddy Yadanaparthi, David Graybill, Ray von Wandruszka”Adsorbents for the removal of arsenic, cadmium, and lead from contaminated waters” Journal of Hazardous Materials, Volume 171, Issues 1-3, 15 November 2009, Pages 1-15.

105. “K. Kadirvelu, M. Kavipriya, C. Karthika, N. Vennilamani, S. Pattabhi “Mercury (II) adsorption by activated carbon made from sago waste” Carbon, Volume 42, Issue 4, 2004, Pages 745-752.

106. M.S. Ray “Adsorption principles, design data and adsorbent materials for industrial applications: A Bibliography “(1967–1997) Studies in Surface Science and Catalysis, Volume 120, Part 1, 1999, Pages 977-1049.

107. K. G. Mansaray, A. E. Ghaly “Determination of kinetic parameters of rice husks in oxygen using thermo gravimetric analysis” Biomass and Bioenergy, Volume 17, Issue 1, July 1999, Pages 19-31.

108. Sumrerng Ruk zon, Prinya Chindaprasirt, Rattana Mahachai “Effect of grinding on chemical and physical properties of rice husk ash” International Journal of Minerals, Metallurgy and Materials, Volume 16, Issue 2, April 2009, Pages 242-247.

109. Tarun Kumar Naiya, Pankaj Chowdhury, Ashim Kumar Bhattacharya, Sudip Kumar Das “Saw dust and neem bark as low-cost natural biosorbent for adsorptive removal of Zn(II) and Cd(II) ions from aqueous solutions” Chemical Engineering Journal, Volume 148, Issue 1, 1 May 2009, Pages 68-79.

110. Neeta Sharma, Kulwinder Kaur, Sumanjit Kaur “Kinetic and equilibrium studies on the removal of Cd²⁺ ions from water using polyacrylamide grafted rice (Oryza sativa) husk and (Tectona grandis) saw dust” Journal of Hazardous Materials, Volume 163, Issues 2-3, 30 April 2009, Pages 1338-1344.

111. P.C. Mishra, R.K. Patel “Removal of lead and zinc ions from water by low cost adsorbents” Journal of Hazardous Materials, Volume 168, Issue 1, 30 August 2009, Pages 319-325.

112. “Removal of toxic metal Cr(VI) from aqueous solutions using sawdust as adsorbent: Equilibrium, kinetics and regeneration studies”Chemical Engineering Journal, Volume 150, Issues 2-3, 1 August 2009, Pages 352-365

113. Leandro Vinícius Alves Gurgel, Laurent Frédéric Gil “Adsorption of Cu(II), Cd(II) and Pb(II) from aqueous single metal solutions by succinylated twice-mercerized sugarcane bagasse functionalized with triethylenetetramine” Water Research, Volume 43, Issue 18, October 2009, Pages 4479-4488.

114. Amit Bhatnagar, Mika Sillanpää “Utilization of agro-industrial and municipal waste materials as potential adsorbents for water treatment—A review” Chemical Engineering Journal, In Press, Corrected Proof, Available online 18 January 2010.

115. S.P. Sohi, E. Krull, E. Lopez-Capel, R. Bolbn “A Review of Biochar and Its Use and Function in Soil” Advances in Agronomy, Volume 105, 2010, Chapter Chapter 2, Pages 47-82.

116. Tarun Kumar Naiya, Pankaj Chowdhury, Ashim Kumar Bhattacharya, Sudip Kumar Das “Saw dust and neem bark as low-cost natural biosorbent for adsorptive removal of Zn(II) and Cd(II) ions from aqueous solutions” Chemical Engineering Journal, Volume 148, Issue 1, 1 May 2009, Pages 68-79.

117. S.D. Khattri, M.K. Singh “Removal of malachite green from dye wastewater using neem sawdust by adsorption” Journal of Hazardous Materials, Volume 167, Issues 1-3, 15 August 2009, Pages 1089-109.

118. K.Y. Foo, B.H. Hameed “Utilization of rice husk ash as novel adsorbent: A judicious recycling of the colloidal agricultural waste”Advances in Colloid and Interface Science, Volume 152, Issues 1-2, 30 November 2009, Pages 39-47.

119. A.A. Abia, E.D. Asuquo “Kinetics of Cd²⁺ and Cr³⁺ Sorption from Aqueous Solutions Using Mercaptoacetic Acid Modified and Unmodified Oil Palm Fruit Fibre(Elaeis guineensis) Adsorbents” Tsinghua Science and Technology, Volume 12, Issue 4, August 2007, Pages 485-492.

120. O.S. Amuda, A.A. Giwa, I.A. Bello “Removal of heavy metal from industrial wastewater using modified activated coconut shell carbon”Biochemical Engineering Journal, Volume 36, Issue 2, 15 September 2007, Pages 174-181.

121. Osei-Wusu Achaw, George Afrane “The evolution of the pore structure of coconut shells during the preparation of coconut shell-based activated carbons” Microporous and Mesoporous Materials, Volume 112, Issues 1-3, 1 July 2008, Pages 284-290.

122. D.H. Lataye, I.M. Mishra, I.D. Mall “Pyridine sorption from aqueous solution by rice husk ash (RHA) and granular activated carbon (GAC): Parametric, kinetic, equilibrium and thermodynamic aspects” Journal of Hazardous Materials, Volume 154, Issues 1-3, 15 June 2008, Pages 858-870.

123. Rumi Chand, Kenji Narimura, Hidetaka Kawakita, Keisuke Ohto, Takanori Watari, Katsutoshi Inoue “Grape waste as a biosorbent for removing Cr(VI) from aqueous solution” Journal of Hazardous Materials, Volume 163, Issue 1, 15 April 2009, Pages 245-250.

124. S.D. Khattri, M.K. Singh “Removal of malachite green from dye wastewater using neem sawdust by adsorption” Journal of Hazardous Materials, Volume 167, Issues 1-3, 15 August 2009, Pages 1089-1094.

125. V.K. Gupta, Suhas “Application of low-cost adsorbents for dye removal – A review” Journal of Environmental Management, Volume 90, Issue 8, June 2009, Pages 2313-2342.

Received on 14.07.2011 Modified on 14.08.2011

Asian J. Research Chem. 4(9): Sept, 2011; Page 1432-1439