Zinc ions Biosorption from aqueous solutions by bark ...

International Journal of Chemtech Applications Vol. 2; Issue 1; Page 1-7 ZINC IONS BIOSORPTION FROM AQUEOUS SOLUTIONS BY ACACIA RADDIANA BARK Talhi M. Fouzi1, Cheriti Abdelkrim1*, Agha Leila1, Belboukhari Nasser2 1) 2)

Phytochemistry & Organic Synthesis Laboratory Bioactive Molecules & Chiral Separation Laboratory University of Bechar, 08000, Bechar Algeria

ABSTRACT Biosorption of Zn(II) from aqueous solutions by Saharan biomass was studied in batch mode in different conditions. Saharan tree Acacia raddiana bark was evaluated as a new biosorbent for removal of Zinc ions from aqueous solution. Effect of operating conditions, like initial metal concentration, pH and temperature, on zinc biosorption were investigated. Equilibrium at 25ºC was reached after 5 h and zinc cations biosorption in excess of 78% was obtained at pH 6. The relation between the chemical composition of the bark part of Acacia raddiana (polyphenol, saponin, terpenoids, carbohydrates...). Keywords: Biosorption, Heavy metal, Zinc, Acacia raddiana, Arid area

1. INTRODUCTION Increasing concentration of heavy metals in waters is mainly due to effluent discharges from industries. Knowledge about toxicological effects of heavy metals on the environment and in drinking water is well recognized and therefore, it is inevitable to search for different methods to reduce water pollution [1-3]. Due to their persistence in nature and to the increased susceptibility to disease in man and animal (hepatic, kidney, nerves and the immune system damage and block functional vital groups…..), it becomes essential to study new and alternative technologies to remove trace metals from wastewaters. Conventional wastewater treatment including sludge separation, chemical precipitation, electrochemical process, membrane separation, reverse osmotic treatment, ion-exchange and solvent extraction are often expensive, require high energy, have low selectivity and are impractical when they are used to treat the wastewaters with heavy metal ions amount lower than 100 mg l-1 [4-6]. Environmental contamination by the zinc heavy metal, arises as a result of many industrial activities, such as the electroplating, metallurgical industry, tannery operations, chemical manufacturing, and it uses in matches, photographic materials, fuels, and printing processes [7]. In the Dangerous Substances Directive (2006/11/EC) of the European Union, zinc has been registered as a List 2 Dangerous Substance, with Environmental Quality Standards being set at 40 μg l−1 for estuaries and marine waters and at 45–500 μg l−1 for fresh water depending on water hardness. The maximum allowable level of zinc in drinking water considered safe by the World Health Organisation is 5 mg l−1 [8, 9]. Zinc toxicity primarily affects the gastrointestinal system followed by circulatory, renal, and neurological disturbances [8, 10, 11]. The conventional methods for Zn(II) removal from industrial effluents usually include chemical precipitation, chemical oxidation or reduction, ion exchange, filtration, electrochemical treatment, reverse osmosis, membrane technologies, and recovery by evaporation. However, these methods are ineffective or expensive, and are not eco-friendly [7, 12, 13]. Biosorption of heavy metals from aqueous solutions is a relatively new technology for the treatment of industrial wastewater, which utilizes naturally occurring biomass derived from waste materials. The major advantages of biosorption technology are its effectiveness in reducing the concentration of heavy metal ions to very low levels and the use of inexpensive 1

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International Journal of Chemtech Applications Vol. 2; Issue 1; Page 1-7 biosorbent. Thus, several approaches have been studied and developed for the effective removal of heavy metals using biosorbents like peat, fly ash, algae, soya bean, hulls leaf mould, sea weeds, coconut husk, sago waste, peanut hull, hazelnut, bagasse, rice hull, sugar beet pulp, plants biomass and bituminous coal. It has also been observed that these biosorbents need further modifications to increase the active binding sites and also made them readily available for sorption [1, 14-19]. Algeria, with more than 34 million inhabitants, is located in a semi arid region, and is increasingly confronted with the problem of the scarcity of water. The country is characterized by irregular rainfall with a generally variable pattern of distribution and the major environmental issues include: soil erosion from overgrazing and other poor farming practices; desertification; dumping of raw sewage, petroleum refining wastes, and other industrial effluents is leading to the pollution of rivers and coastal waters [20]. Continuing our effort on the valorization of Algerian Sahara plants as biomaterials for the biosorption of toxic heavy metals from water [18, 19], We present here our results on the use of the locally available Sahara tree Acacia raddiana. Thus, the objective of this study was to utilize Acacia raddiana bark as an adsorbent for removal of zinc ion from aqueous solution. Effect of operating conditions like initial metal concentration, pH and temperature, on zinc biosorption were investigated. The relation between the phytochemical composition (polyphenol, saponin, terpenoids, carbohydrates...) of the plants and the percent of adsorption for zinc ion was examined. Thus, biosorption of Zn(II) occurs as a result of ion exchange or complex formation between metal ions and functional groups (hydroxyl, amine, carboxyl...) on the cell surface of the biomass derived from the Saharan tree Acacia raddiana bark. 2. MATERIALS AND METHODS 2.1. Biosorbent preparation Bark of tree Acacia raddiana used in this work was collected from Saoura desert (South, Algeria) in March 2010. The biomass was washed with distilled water several times to remove soil-associated particles and water soluble materials. The dried bark, ground in a mortar to powder and sieved into a size ranging from 125 to 250 m, was stored in a desiccator until use for the biosorption process [19]. 2.2. Biosorption studies Experiments were performed to determine the effect of various parameters (contact times, initial metal concentration, pH and temperature) on the biosorption of Zn2+ onto Acacia raddiana bark. All chemicals used in this study were of analytical grade and solutions were prepared using double distilled water. Zn2+ solution was prepared by dissolving zinc sulphate (ZnSO4.7H2O) in distilled water. HNO3 and NH4OH solutions were used to adjust the solution pH. The pH was measured using Hanna pH meter at the beginning and at the end of the experiments. Batch experiments were carried out by shaking 100 mg of biosorbent mixed with 100 ml of zinc sulfate solution of known concentration in 200 ml Erlenmeyer flasks stirred at constant speed in a magnetic shaker. After, the solid was removed by filtration through a filter paper (Whatman GF/A). Blank runs, with only the sorbent in 100 mL of double distilled water, were conducted at similar conditions, to understand the pH change of solution during sorption experiments. The equilibrium metal concentration in the filtrates as well as in the initial solution was analyzed using atomic adsorption spectrophotometer (Perkin Elmer Analyst 700). Each experiment was carried out in duplicate.

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International Journal of Chemtech Applications Vol. 2; Issue 1; Page 1-7 3. RESULTS AND DISCUSSION The identification of the physico-chemical interactions between active sites on the adsorbent and metallic species, and the quantification of metal removed according to different mechanisms (physical adsorption, ion exchange, complexation, chelation, surface microprecipitation) is an intriguing target that would allow the precise description of the effect of the environmental factors. Thus, the biosorption capacity is governed by a series of properties, such as pore and particle size distribution, specific surface area, cation exchange capacity, pH, surface functional groups, and temperature [1, 21]. Firstly, we noted that biosorbed zinc ion concentrations increased with time and reached equilibrium after 5 h for all initial zinc ion concentrations tested. As shown in Table 1, an increase of time up to 24 h did not show notable effects. Table1: Variation of biosorbed Zn(II) concentration with time for different initial concentrations, pH 6, T = 25 ± 0.1 °C Initial Zn2+ concentration C0 (mg l -1) 50 100 150 200 250 300

Biosorbed Zn2+ concentration , qe (mg Zn2+. g biomass-1) Time (h)

1

2

3

4

5

6

7

24

25 58 71 74 77 82

33 64 79 82 85 90

37 70 85 86 89 94

39 74 89 90 93 98

41 78 93 94 97.5 102

41 78 93 94 97.5 102

41 78 93 94 97.5 102

41 78 93 94 97.5 102

3.1. Effect of initial copper ions concentration Important parameters in biosorption of heavy metal ions are the equilibrium solid phase metal ion concentration. Zn(II) concentrations were varied between 50 and 300 mg l-1 at constant pH 6.0. Table 2 summarizes data on variations of percent removal and the final zinc ion concentrations with initial Zn2+ concentrations. Zinc ion percent removal decreased from 82% to 34% and the final Zn2+ concentration increased from 9 mg l-1 to 198 mg l-1 when the initial Zn2+ concentration was raised from 50 mg l-1 to 300 mg l-1. At low initial Zn2+ concentrations, such as 50 mg l-1 and 150 mg l-1, the majority of zinc ions were biosorbed onto binding sites on Acacia raddiana bark surfaces and adsorption sites took up the available metal more quickly. However, at high initial zinc ion concentrations, such as 250 mg l-1 and 300 mg l-1, a large fraction of binding sites on biomass surfaces were occupied by zinc ions and metals need to diffuse into the biomass surface by intra-particular diffusion and greatly hydrolyzed ions will diffuse at a slower rate [12]. This biosorption characteristic indicates that the surface saturation is dependent on the initial metal ion concentrations. 3.2. Effect of pH The pH of the solution is the most important parameter that in the biosorption process can significantly influence the removal of heavy metals [1, 18, 19]. Following the previously mentioned experimental conditions a 100 mg/L zinc ions solution was treated at pH values from 3 to 7. Table 3 shows that removal of Zn(II) by the Acacia raddiana bark increased with pH. 3


International Journal of Chemtech Applications Vol. 2; Issue 1; Page 1-7 Table 2: Variation of percent Zn(II) removal with the initial concentration at the end of 5h pH 6, T = 25 ± 0.1 °C Initial Zn2+ concentration C0 (mg l -1) 50 100 150 200 250 300

Final Zn2+ concentration C (mg l -1) 9 22 57 106 152.5 198

Biosorbed Cu2+ concentration qe (mg g -1) 41 78 93 94 97.5 102

Percent Zn2+ removal 82 78 62 47 39 34

Table 3: Effects of initial pH on percent Zn(II) removal concentration. Initial Zn2+concentration C0 = 100 mg l-1, T = 25 ± 0.1 °C, 5h

pH 3 4 5 6 7

Final Zn2+ concentration C (mg l-1) 92 68 29 22 31

Percent Zn2+ removal 8 32 71 78 69

The greatest increase in the biosorption rate of zinc ions on the Acacia raddiana bark was observed at pH 6. At lower pH, H+ ions compete with Zn2+ for the exchange sites in the system. The heavy metal cations are completely released under extreme acidic conditions. At pH (3 - 7) species formed in solution are adsorbed through electrostatical interaction at the surface of the biomass. As the pH decrease, the surface of the Acacia raddiana bark exhibits an increasing positive characteristic. H+ ions, present at a high concentration in the reaction mixture, compete with Zn2+ ions for the biosorption sites reducing uptake of zinc cation. At around pH 6, zinc cations, would be expected to interact more strongly with the negatively charged binding sites in the sorbent [19, 22]. 3.3. Effect of temperature Keeping all other parameters constant temperature was varied from 25ºC to 60ºC. Table 4 shows that the removal of Zn2+ depends on temperature. The sorption of zinc cations increased slightly with the increase in temperature up to 30ºC and then started decreasing. The temperature higher than 50ºC caused a change in the texture of the biomass and thus reduced its sorption capacity. Usually the physical sorption reaction is exothermic and preferred at lower temperature [18, 19, 22].

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International Journal of Chemtech Applications Vol. 2; Issue 1; Page 1-7 Table 4: Biosorption quantity of Zn2+ onto Acacia raddiana bark at different temperature Initial Zn2+concentration C0 = 100 mg l-1, pH 6, 5h

T °C 25 30 40 50 60

Final Zn2+ concentration C (mg l-1) 22 22 45 68 81

Percent Zn2+ removal 78 78 55 32 19

3.4. Chemical Characterization of Acacia’s bark Acacia is a cosmopolitan genus containing in excess of 1350 species that together with the African and the Middle Eastern monotypic genus. In Algerian Sahara, Acacia raddiana is a medium umbrella-shaped tree 4-15 m tall, with round irregular crown and reddish bark. This Saharan tree provide food and shelter for many desert animals and is a major source of livestock feed and firewood for the native people [23-25]. This specie is reported to tolerate annual precipitation of 10-100 mm, arid climates with temperatures as high as 50 ºC and alkaline soils. The tree has been recommended for reclaiming dunes. Gum from the tree is dispensed in water and used to treat ocular affections, jaundice, anthelmintic, antidiarrhoea, asthma and pulmonary diseases. Seeds, entire or powdered, are taken as antidiarrhoeic, vermifuge and dusted onto skin. Dried powdered bark used as disinfectant, for healing wounds and is a good source of tannin and used in tanning [23-27]. In a previous study, we reported the phytochemical screening of the bark’s Acacia and the presence an important quantity of polyphenolic compounds (Flavonoids, Tannin) and another natural substances such as: tritepenoids saponin, cellulose, hemicellulose and lignin [28]. It’s known that these natural compounds present in the cell wall are the most important sorption sites. Therefore, the important of these natural compounds is that they contain hydroxyl, carboxylic, carbonyl, groups which are potential binding sites for the sequestration of metal ions [29]. In another hand, polysaccharides are important components of the cell wall of bark’s tree containing ionisable functional groups such as carboxyl, phosphoric, amine, and hydroxyl groups. They can constitute up to 40% of the dry matter and have a great affinity for divalent cations [30-32]. 4. CONCLUSIONS Biosorpion of zinc ions from aqueous solution onto Acacia raddiana bark was investigated as functions of important parameters, such as contact time, concentrations of adsorbate (Zn2+ ions), solution pH and temperature. In the light of experimental results obtained and their evaluation, the Saharan biomass of Acacia raddiana bark could be used as an efficient and low cost biosorbent for the removal of Zn(II) ions from aqueous solutions in excess of 78%. The process of biosorption has nearly reached equilibrium in 5 hours and the biosorption of metals was pH and temperature dependent, respectively optimal pH was 6 and temperature was 25-30ºC. Finally, additional work will be required in order to determine the biosorption of other heavy metals ions, and to determine the mechanism of zinc biosorption by this eco-friendly biomaterial.

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International Journal of Chemtech Applications Vol. 2; Issue 1; Page 1-7 ACKNOWLEDGEMENT The authors would like to express their gratitude to the MESRS – Algeria-, for the financial support REFERENCES [1] Cheriti A., Talhi M.F., Belboukhari N., Taleb S. (2011), “Copper ions biosorption properties of biomass derived from Algerian Sahara plants”, Chapter 16 in “ Expanding issues in desalination”, Ning R. Y. (Ed.), InTech, Croatia. [2] Ahluwalia, S.S., Goyal, D., (2007), Biores. Technol. 98, 2243-2257. [3] Demirbas A., (2008), J. Hazard. Mat.157, 220-229. [4] Wang X.-S., Qin Y., (2005), Process Biochem. 40(2), 677-680. [5] Rangsayatorn N., Pokethitiyook P., Upatham E.S., Lanza G.R., (2004), Environ. Int. 30, 57-63. [6] Meunier N., Laroulandie J., Blais J.F., Tyagi R.D., (2003), Biores. Technol. 90, 255-263. [7] Norton L., Baskaran K., McKenzie T., (2004), Adv. Environ. Res. 8, 629-635. [8] Mishra V. , Balomajumder C., Agarwa V. K., (2010), Water Air Soil Pollut. 211, 489500. [9] Perez Marın A. B., Aguilar M. I., Ortu J. F. , Meseguer V. F., Saez J., Llorens M., (2010), J. Chem. Technol. Biotechnol. 85, 1310-1318 [10] Roney N., Smith V., Cassandra W., Osier M., Paikoff S. J., (2005) “Toxicological profile of zinc”, Agency for Toxicology and Disease Registry. [11] Simon H. B., Wbbertaman A., Wanger D., Tomaska L., Malcolm H., (2001) “Environmental health criteria, Zinc”, World Health Organization, Geneva. [12] Jin-Ho J., Sedky H.A., Sang-Eun O., (2010), Intern. Biodeter. Biodeg. 64, 734-741. [13] Tsekova, K., Todorova, D., Ganeva, S., (2010), Intern. Biodeter. Biodeg. 64, 447-451. [14] Prasad M.N.V., Freitas H., (2000), Environm. Pollu. 110, 277-283 [15] Chubar N., Carvalho J.R., Correia M.J-N., (2004), Colloids Surf. A: Physicochem. Eng. Aspects 230, 57-65. [16] Villaescusa I., Martinez M., Miralles N., (2000), J. Chem. Technol. Biotechnol.75, 1-5. [17] Al-Qodah Z., (2006), Desalination 196, 164-176. [18] Cheriti A., Talhi M.F., Belboukharia N., Taleb S., Roussel C., (2009), Desalination and Water Treatment 10, 317-320 [19] Talhi M.F., Cheriti A., Belboukharia N., Agha L., Roussel C. (2010), Desalination and Water Treatment 21, 323-327. [20] Sekkoum K., Talhi M.F., Cheriti A., Bourmita Y., Belboukhari N., Boulenouar N., Taleb S. (2012) “Water in Algerian Sahara: Environmental and Health impact”, Chapter 10 in “Advancing Desalination”, Ning R. Y. (Ed.), InTech, Croatia. [21] Naja G., Volesky B., (2011) “ The mechanism of metal cation biosorption” , Chapter 3 in P. Kotrba et al. (Eds.), “Microbial Biosorption of Metals”, Springer Science [22] Nuhoglu Y. , Oguz E., (2003), Process Biochemistry 38, 1627-1631. [23] Cheriti A., (2000) “Plantes médicinales du sud ouest algérien : Ethnopharmacologie“, CRSTRA, Alger. [24] Cheriti A. Belboukhari N., Hacini S., (2004), Ir. J. Pharm. Res. 3(2), 51 [25] Cheriti A., Belboukhari N., Sekkoum K., Hacini S., (2006), J. Algerien des regions arides 5, 07-10. [26] Bellakhdar, J., (1997) “La pharmacopée marocaine traditionnelle. Médecine arabe ancienne et savoirs populaires“, IBIS Press, Paris. [27] Ibn Baytar D., (1992) “El djamia limoufradet el Adouia wa Aghdia”, Ed Dar el koutob Elmia, Beirut. 6


International Journal of Chemtech Applications Vol. 2; Issue 1; Page 1-7 [28] Belhadjadji Y., (2007) “ Contribution à l’étude phytochimique de l’Accacia radiana savi” mémoire de Magister, Université de Bechar. [29] Rao Popuri S., Jammala A., Naga K.V. Reddy S., Abburi K., (2007), Electr. J. Biotechno.10(8), 63-68. [30] Mar Areco M., Santos Afonso M., (2010), Colloid. Surf. B: Biointerfaces 81, 620–628. [31] Liu H., Fang H.H.P., (2002), Biotechnol. Bioeng. 80, 806–811. [32] Fourest E., Canal C., Roux J.C, (1994), FEMS Microbiol. Rev. 14, 325–332.

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