ISSN 2456-0235

International Journal of Modern Science and Technology


​​February-March 2021, Vol. 6, No. 2-3, pp. 43-68. 

​​Biosorption of toxic metals from leachate using Pleurotus pulmonarius

J. D. Nanev*, I. S. Eneji, R. A. Wuana, A. U. Itodo
Federal University of Agriculture, Department of Chemistry, P.M B 2373 Makurdi, Benue State, Nigeria.

​​*Corresponding author’s


The biosorption of Pb2+, Cd2+, Cr6+, Ni2+ and Co2+ by Pleurotus polmonarius from municipal open solid waste leachate was investigated to evaluate its effectiveness for removing toxic metals.. The composite leachate samples were analyzed for some physicochemical parameters. The results were obtained  as colour, smell, pH,  total solids,  total volatile solids, suspended solids, total dissolved solids, COD, BOD5, COD/BOD5 ratio are light brown, Malodorous, 7.79±0.02, 5993±33.0 mg/L, 228±8.5 mg/L, 887±6.5 mg/L, 12168±22.1 mg/L, 868±0.12 mg O2/L, 373±0.002 mg O2/L and 0.43, respectively while the toxic metals in the leachate were determined using AAS and their concentrations (mg/g)  for Pb, Ni, Co, Cr and Cd were 0.461±0.0010, 0.0845±0.0004, 0.2045±0.0009, 0.5211±0.0011 and 0.1565±0.0010 respectively. The biosorbent was modified and its physico-chemical properties were determined by measuring the bulk density (356.33 kg/m3), surface area (27.75 m2/g), total pore volume (0.0213 cm3/g) and pore size (1.187 nm), pH (7.32), point of zero charge pHpzc (6.40). The SEM analysis showed some cylindrical pores of various sizes on the surface of the biosorbent. The FTIR spectroscopic analysis showed the following functional groups were on its surfaces  O-H, N-H, C-H, C=N, N=N, C=C, H-O-H, C=O, C-CH3, S-O, -NH2 and C-O. Proximate analysis of biosorbent showed that crude protein content was (15.75±0.04%), moisture content (2.65±0.01%). Crude lipid (10.35±0.06%), ash content (7.32±0.01%), crude fibre (6.60±0.0 %) and carbohydrate (57.33±0.02%). The effect of contact time, initial toxic metal ion,  pH,  biosorbent dosage, temperature were carried out in batches mode. The experimental data were tested with eight experimental models.  The thermodynamic experiments were also conducted. The results from the biosorption studies proved that the biosorbent can be an effective, alternative low-cost biosorbent for the removal of toxic metal ions from leachate.

Keywords: Biosorption; Leachate; Toxic metals; Biosorbent.


  1. Abbas S.T., Mustafa, M.A, Raheem, A.Z. Adsorption of Pb2+ and Zn2+ ions from oil wells onto activated carbon produced from rice husk in batch adsorption process. Journal of Chemistry and Pharmacological Research 2013;4(5):240-250.
  2. Ali, S., Sardar, K., Hameed, S., Afzal, S., Fatima, S., Shakoor, B.M,. Tauqeer, H.M. Heavy Metals Contamination and what are the Impacts on Living Organisms. Greener Journal of Environmental Management for Public Safety 2013;(2):172-179.
  3. Ahmed, A.T.A., Mandal, S., Chowdhury, D.A., Tareq, A.R.M., Rahman, M.M. Bioaccumulation of some Heavy Metals in Ayre Fish (Sperata Aor Hamilton, 1822), Sediment and Water of Dhaleshwari River in Dry season. Bangladesh. Journal of. Zoology 2012;40(1):147-153
  4. Raikwar, M.K., Kumar, P., Singh, M., Singh, A. Toxic Effect of Heavy Metals in Livestock Health. Veterinary. World 2008; 1(1):28-30.
  5. Aguoru, CU and Alu, C.A. Studies on Solid Waste Disposal and Management Methods in Makurdi and its Environs North Central Nigeria. Greener Journal of Environmental Management and Public Safety 2015;4(2): 19-27.
  6. Kansal, A  Solid Waste Management Strategies for India, Indian Journal of Environmental Protection 2012;22(4):444-448.
  7. Tchobanoglous, G., Theisen, H. and Vigil, S. A. Integrated Solid Waste Management Engineering Principles and Management Issues. 1st ed. New York: McGraw-Hill; 2009.
  8. Sulayman, M., Khaiwal R., Dahiya, R. P., Chandra, A. Leachate Characterization and assessment of groundwater pollution near municipal solid waste landfill site. Centre for Energy Studies, IIT Delhi. 2012. 
  9. Appel C, Ma L. Heavy metals in the environment concentration, pH and surface charge effects on Cd and Pb sorption in three tropical soils. Journal of Environmental Quality 2012;21(3):581-589.
  10. Salman, H., Ibrahim, M., Tarek, M., Abbas, H. Biosorption of Heavy Metals: A Review. Journal of Chemical Science and Technology 2014;3(6):45-49.
  11. Shweta, K., Nupur, M. and Pradeep, B. Mushroom as a Product and their Role in Mycoremediation. Springer Open Journal, 2014;2014:2-7.
  12. Arbanah, M., Miradatul Najwa, M.R and Ku Halim, K.H. Biosorption of Cr(III), Fe(II), Cu(II), Zn(II) Ions from Liquid Laboratory Chemical Waste by Pleurotus ostreatus. InternationalJournal of Biotechnology for Wellness Industries 2012;1:152-162
  13. Eneji, I.S., Julian N and Sha’Ato R. Kinetics and Thermodynamic Study of Aqueous Adsorption of Cd2+ and Pb2+ Ions on Activated Carbon from Nymphaea ampla (Water Lily) Roots. Science and Technology Journal 2016;1(2):456-465.
  14. Pandey, A.K., Jamaluddin, A.K., Awasthic, A. Journal of Environ. Sci. Comp. Sci. Eng. Technol. 2013;2:385-393.
  15. Mathialagan, T, Viraraghavan, T , Cullimore, D.R. Water Quality Research Journal of Canada 2003;38:499-514.
  16. Peter, T. O and Tolulope, A. O. Proximate Analysis and Chemical Composition of Cortinarius Species. European Journal of Advanced Research in Biological and Life Sciences. 2015; 3 (3): 2056-5984.
  17. Agnew, J.M. and Leonard, J.J. Literature Review-the Physical Properties of Compost. Compost Science and Utilization 2003;11:238-264.
  18. American Water Works Association (AWWA) Standards for Granular Activated Carbon NSI/AWWA  B604-90 Denver Co. 2014.
  19. Boldizsar, N., Carmen, M., Andrada M., Cerasella I., Barbu-Tudoran L. and Cornelia M. Linear and Nonlinear Regression analysis for Heavy Metals Removal using Agaricus Bisporus Macrofungus. Arabian Journal of Chemistry 2014;2:181-198.
  20. AOAC. Official Methods of Analysis 16th Edition, Association of Official Analytical Chemists, Washington DC. 2013.
  21. Onyeike, E.N.; Olungwe, T., Uwakwe, A. A. Effect of Heat Treatment and Defatting on the Proximate Composition of Some Nigerian Local Soup Thickeners. Food Chemistry 1995;53:173-175.
  22. Ho, Y.S  Review of Second-Order Models for Adsorption Systems. Journal of Hazardous Materials 2011;136:681.
  23. Agay, K.A., Mahendra, S.K., Chandrashekhar, P.P and Ishwardas, L.M. Langmuir, Freundlich and BET adsorption Isotherm Studies for zinc ions onto Coal fly ash. International Journal of Application of Innovation in Engineering and management. 2014;3:64-71.
  24. Mahmooda, T., Toufique, S., Nitin, M. and Majumder, D. R. Bioremediation of Xenobiotics: Use of Dead Fungal Biomass as Biosorbent. International Journal of Research in Engineering and Technology 2014;3:565-570.
  25. Okwulehie, I. C., Urama J and Okorie, D. O. Chemical Composition and Nutritional Value of Mature and Young Fruiting-Bodies of Pleurotus Pulmonarius Produced On Andropogon Gayanus Straw and Khaya Ivorensis Sawdust. Journal of Pharmacy and Biological Sciences 2014;3(9):2319-767.
  26. Cheung P.C.K. Mini-review on edible mushrooms as source of dietary fiber: preparation and health benefits. – Food Science and Human Wellness 2013;2:162–166.
  27. Taye, V. F., Clement, O. O., Bamidele, J. A., Anthony, K. O. Evaluation of yield, biological efficiency and proximate composition of Pleurotus species cultivated on different wood dusts. Czech Mycology 2018;70(1):33–45.
  28.  Ayodele, S.M. and Okhuoya, J.A., Nutrition of cultivated Psathyrella atroumbonata. Pegler, a Nigeria edible mushroom. Journal of Science 2009;105(4): 158-159.
  29. Adejumo, T.O., Coker, M.E and Akinmoladun, V.O. Identification and Evaluation of Nutritional Status of some Edible and Medicinal Mushrooms in Akoko Area, Ondo State, Nigeria. International Journal of Current Microbiology and Applied Sciences 2015;4(4):1011-1028.
  30. Ibe C.C., Osuji1 C.N., Akunna, O., Nwabueze, E.U and Ahaotu, E.O. Proximate Composition and Antioxidant Activity of Eleven Selected Wild Edible Nigerian Mushrooms. International Journal of Agriculture and Biosciences 2013;2(5):181-184.
  31. Kalmis, E; Yildiz, H.; Ergonul, B.;Kalyoncu, F. And Solak, M. H. Chemical composition and nutritional value of a wild edible ectomycorrhizal mushroom, Tricholoma anatolicum. Turkey Journal of Biology 2011;35:627-633.
  32. Valverde M.E., Hernández-Pérez T., Paredes-López O. Edible mushrooms: improving human health and promoting quality life. International Journal of Microbiology 2015;2015:376387.
  33. Okhuoya, J.A., Okogbo, F.O. Induction of sclerotia of Pleurotus tuberregium (fr) Sing.On various farm waste product. Academic Science 2014;71:1-3.
  34. Mattilla PS, Vannanen P, Kinko K, Heiki A, Jalava T. Basic composition and amino acid contents of mushrooms cultivated in Finland. Journal of Agricultural and Chemical Science 2010;5(4):6419-6422.
  35. Stamets, P. Growing Gourmet and Medicinal Mushrooms, 3rd edn.Ten Speed Press, Berkeley. 2013.
  36.  Wani, B.A., Bodha, RH., Wani A.H. Nutritional and medicinal importance of mushrooms. Journal of Medicinal Plants Resources 2010;4(24):2598-604.
  37. Patil, A.S., Ahmed, S.A., Telang, S.M., Baig, M.M.V. The nutritional value of Pleurotus ostreatus (Jacq: Fr) Kumm. cultivated on diffrent lignocellulosic agrowastes. Innovation Romanian Food Biotechnology 2012;7:66-76.
  38. Colak A., Özlem F., Sesli, E.  Nutritional composition of some wild edible mushrooms. Turkish Journal of Biochemistry 2016;34(1):25-31.
  39. Parisa, M., Helmi, J., Mohammad, S., Roslinda, M., Nor, Z. O and Hesham, A. E. The Edible Mushroom Pleurotus spp.: I. Biodiversity and Nutritional Values. International Journal of Biotechnology for Wellness Industries 2015;4:67-83.
  40. Familoni T.V., Ogidi C.O., Akinyele B.J., Onifade A.K. Evaluation of yield, biological efficiency and proximate composition of Pleurotus species cultivated on different wood dusts. Czech Mycology 2018;70(1):33–45.
  41. Deepalakshmi, K., Mirunalini, S. Pleurotus ostreatus: an oyster mushroom with nutritional and medicinal properties. Journal of Biochemical Technology 2014; 5(2):718-26.
  42. Hossain, M.S., Alam, N., Amin, S.R., Basunia, M.A., Rahman, A. Essential fatty acid contents of Pleurotus ostreatus, Ganoderma lucidum and Agaricus bisporus. Bangladesh. Journal of Mushroom. 2013; 1(1):1-7.
  43. Madu P. C. and Lajide L. Physicochemical characteristics of activated charcoal derived frommelon seed husk. Journal of Chemical and Pharmaceutical Research 2013;5(5):94-98.
  44. Ekpete, O.A., Horsfall M. Jnr., and Tarawou, T. Potentials of fluted pumpkins and commercial activated carbons for phenol removal in aqueous systems. Journal of Engineering and applied Science. 2010;5(9), 39-47.
  45. Modak, J.M and Natarajan, K.A. Biosorption of metals using nonliving biomass-A Review. Mineral Metallurgical Process. 2015;12:189-196.
  46. Augustine, E. O., Yuh-Shan, H. Effect of temperatures and pH on methyl violet biosorption by Mansonia wood sawdust. Bioresource Technology 2008;99:5411–5417.
  47. Hu, Z.H.  Chen, H.  Ji, F.  Yuan, S.J.  Removal of Congo Red from Aqueous Solution by Cattail Root, Journal of Hazard Materials. 2010;173:292-297.
  48. Ceci, S.C., Lidia, M. A., Marli, T. A. M., Meire C. N. A. Physiochemical analysis and centesimal composition of Pleurotus ostreatus mushroom grown in residues from the Amazon. Food Science and Technology 2011;31:2. 
  49. Al-Degs, Y. S., El-Barghouthi, M. I., Issa, A. A., Khraisheh, M. A., and Walker, G. M. Sorption of Zn(II), Pb(II), and Co(II) using natural sorbents: Equilibrium and kinetic studies. Water Resources. 2016, 40, 2645-2658.
  50. Karthikeyam, G. and Ilango, S.S. Adsorption of Cr6+ on Activated Carbons Prepared from Indegineous Materials. E-J Chem. 2008;5(4):666-678
  51. Chang, S. T. and Miles, P. G (2013). Mushrooms. Cultivation, Nutritional Value, Medicinal. Food Science and Technology, 38:2.
  52. Das, K. Diversity and conservation of wild mushrooms in Sikkim with special reference to Barsey Rhododendron Sanctuary. An international Journal of Environment and Biodiversity (NeBIO). 2010;1(2):1-13
  53. Okoro, I. O. and Achuba, F. I. Proximate and mineral analysis of some wild edible mushrooms. African Journal of Biotechnology 2012;11(30):7720-7724.
  54. Sugundevi, S.R., Sathishkumar, M., Shanthi, V., Kadiruvalu, K. and Pattabhi, S. Removal of Direct T-blue-R from Aqueous Solution onto Carbonized Sugarcane Bagasse Waste. Indian Journal of Environmetal Protection 2012;22:500-505.
  55. Guonying, L., Zuofa, Z., Huijuan, P and Leifa, F. Effect of Physical Modification of Mushroom (A. chaxingu) Powders on their Physical and Chemical Properties. Food Science and Technology Research 2014;20(4):731-738.
  56. Antima, K., Singh, A. K., Ajit,  J. Utilization of waste material (Part II): DMAC (De oiled mustard cake), as an efficient adsorbent for the removal of metal cutting fluids from aqueous medium/industrial waste water.International Journal of Engineering and Technical Research 2015; (3)12:2454-4698.
  57. Cao L, Zheng W, Zhao X. Distribution and evolution of organic matter phases during biochar formation and their importance in carbon loss and pore structure. Chemical Engineering Journal 2014; 250(15):240-247.
  58. Bohli, T.H., Ouademi A., Fiol N and Villaescusa I. Uptake of  Cd2+ and Ni2+ Metal Ions from Aqueous Solutions by Activated Carbons Derived from  Waste Olive Stones. International Journal of Chemical Engineering and Applications 2012;3(4):232-236.
  59. Guo, Z.R., Zhang, G.M., Fang, J.D., Dou, X.D. Enhanced Chromium Recovery from Tanning Wastewater. Journal of Clean Production. 2010, 14: 75-79.
  60. Silverstein, R. M. Bassler, G. C. Morrill, T. C. Spectrometric Identification of Organic Compounds, IV Ed., John Wiley and Sons Publication, New York. 2013.
  61. Adebejo, M. O and Frost, R. L. Infrared and 13-C Mass Nuclear Magnetic Resonance Spectrosacipic Study of Acetylation of Cotton, Spectrochim. Acta. A. 2004, 60, 449-453.
  62. Jiuzhou, D., Feng, C., Jinhu, J., Weiwei, Z., Heng, X. Biosorption of Lead(II) in Aqueous Solution by Spent Mushroom Tricholoma lobayense. Water Environmental Research. 2012, 84: 291.
  63. Suseem, S. R. and Mary, S. A. Biosorption of Heavy Metals Using Mushroom Pleurotus eous.Journal of Chemical and Pharmaceutical Research. 2014, 6 (7): 2163-2168.
  64. Devlina, D., Vimala, R., Nilanjana, D. Screening of Macrofungi for the Removal of Ag (I) and Zn (II) Ions from Aqueous Environment. Journal of Pharmaceutical, Biological and Chemical Sciences 2014;322.
  65. Reddy, D.H.K., Seshaiah, K., Reddy, A.V.R., Lee, S.M. Optimization of Cd (II), Cu (II) and Ni (II) biosorption by chemically modified Moringa oleifera leaves powder. Carbohydrate Polymer 2012;88:1077-1086.
  66. Das, K. Diversity and conservation of wild mushrooms in Sikkim with special reference to Barsey Rhododendron Sanctuary. An international Journal of Environment and Biodiversity 2012;1(2):1-13.
  67. Vimala, R., Das, N. Journal of Hazard Materials. 2009, 168: 376-382.
  68. Azza, M.A., Nabila, S.A., Hany, H.A.G., Ali, R.K Relevance of isotherm models in biosorption of pollutants by agricultural by products, Journal of Environment and Chemical Engineering. 2013, pp. 2398-2414.
  69.  Setshedi, K., Ren, J., Aoyi, O., Onyango, M.S. Removal of Pb (II) from Aqueous Solution using Hydrotalcite-like Nanostructured Material, International Journal of Physical Science. 2012, 7: 63–72.
  70. Kanawade, S.M., Gaikwad, R.W.  Removal of Dyes from Dye Effluent By Using Sugarcane Bagasse Ash as an Adsorbent, International Journal of Chemical Engineer. 2011, 2(3): 202–206.
  71. Wang, L.  Zhang, J.  Wang, A. Fast removal of Methylene blue from Aqueous Solution by Adsorption onto Chitosan-g-poly (acrylic acid)/Attapulgite composite, Desalination. 2011, 266: 33–39.
  72. Sarkar, K., Banerjee, S.L., Kundu, P.P. Removal of Anionic Dye in Acid Solution by Self Crosslinked Insoluble Dendronized Chitosan, Hydrological Current Research. 2012, 3: 133. 
  73. Cossich, E.S., Tavares, C.R.G., Ravagnani, T.M.K. Biosorption of Chromium (III) by Sargassu sp Biomass. Available from http// 0717-3458. Electronic Journal Biotechnology. 2017, 5(2): 133-140.
  74. Lamrood P.Y., Ralegankar S.D. Biosorption of  Cu, Zn, Fe, Cd, Pb and Ni by non-treated biomass of some edible musrooms. Asian Journal of Experimental Biological Sciences. 2013, 4(2): 192.
  75. Weber, W. J., Morris, J. C. Kinetics of adsorption of Zn (II) ions bioremediation from aqueous solution using unmodified and EDTAmodified maize cob. Ecl. Quim. Sao Paulo. 1963, 32(1), 33-42.
  76. Pant, K. K. and Sing, T. S. Equilibrium, Kinetics and Thermodynamics Study for Adsorption of As (II) Ions on Activated Alumina. Separation and Purification Technology. 2014, 3:139-147.
  77. Allen, S. J., Mckay, G., Khader-Khy. Intraparticle Diffusion of Basic Dye during Adsorption onto Sphagnum Peat. Journal of Environmental Pollution. 2009, 50: 39-50
  78. Das, B., Mondal, N K. Calcerous Soils as a New Adsorbent to Remove Lead from Aqueous Solution: Equilibrium, Kinetics and Thermodynamic Studies. University Journal of Environment and Research Technology 2011:1(4);515-530.
  79. Itodo, A.U. Derived Low Cost Biosorbent as Water Decolourizer. Research Journal of Pharmacy, Biology and Chemical Science. 2010;2(1):693-700.
  80. Alau, V., Gimba C., Agbaji, B.E., Abechi, S.E. Kinetic and Equilibruim Studies on the Selective Removal of Heavy Metals by Neem seed and Husks using Column Adsorption Studies. Der Chemica sinica. 2015;6(3):76-82
  81. Badmus, M., Audu, T., Anyata, B. Removal of Lead Ion from Industrial Wastewaters by Activated Carbon Prepared from Periwinkle Shells (Typanotonus fuscatus). Turkish Journal of Engineer Environmental Science 2012;31:251-263.
  82. Dawodu, F. A., Akpomie, G. K., Ogbu, I. C.. Application of Kinetic Rate Equations on the Removal of Copper(II) ions by Adsorption unto “Aloji” kaolinite Clay Mineral. International Journal of Multidisciplinary Science and Engineering. 2012;3(10):2045-2051
  83. Abuh, M. A., Akpomie, G. K.., Nwagbara, N. K., Abia-Bassey, N., Dape, I., Ayabie, B. U. Kinetic Rate Equations Application on the Removal of Copper (II) and Zinc (II) by Unmodified Lignocellulosic Fibrous Layer of Palm Tree Trunk-Single Component System Studies. International Journal of Basic and Applied Science 2016;1: 800.
  84. Anbalagan K and Juliet J.C. Adsorption of Cr (VI) ion onto activated amla dust: Adsorption isotherms and kinetics. Indian Journal of Chemical Technology 2004;43: 45-50.
  85. Ghorbani, M.  Eisazadeh, H. Ghoreyshi, A.A. Removal of Zinc ions from Aqueous Solution using Polyaniline Nanocomposite Coated on Rice Husk, Iranian Journal of Energy and Environment 2012;3:66-71.
  86. Weber, T.W and Chakraborti, R.K. Pore and Solid Diffusion Models for Fixed-Bed Adsorbers, Journal of American Institute of Chemical Engineers 1974;20:228-238.
  87. Dunnick, J.K., Elwell, M.R., Radovsky, A.E., Benson, J.M., Hahn, F.F., Nikula, k.J., Barr E.B., Hobbs C.H. Comparative Carcinogenic Effects of Nickel Subsulfide, Nickel oxide, or Nickel Sulfate hexahydrate Chronic Exposures in the Lung. Cancer Research 2013;55(22):5251.
  88. Conrad, K., Hansen, H.C.B. Sorption of Zinc and Lead on Coir. Bioresource Technology 2016;98:89-97.
  89. Abdel-Halim, E.S.,  Abou-Okeli, A., Hashem, A. Adsorption of Cr(VI) oxy-anions onto modified wood pulp. Polymer-Plastics Technology and Engineering 2006;45:71-76.
  90. Dada, A.O, Olalekan, A.P, Olatunya, A.M., Dada, O. Langmuir, Freundlich, Temkin and Dubinin–Radushkevich Isotherms Studies of Equilibrium Sorption of Zn2+ Unto Phosphoric Acid Modified Rice Husk. IOSR Journal of Applied Chemistry. 2012;3(1):38-45
  91. Samarghandi M R., Hadi M., Moayedi S and Barjasteh Askari F. Two parameter isotherms of methyl orange sorptionby pinecone derived activated carbon. Journal of Chemical Science and Technology 2009; 9(6):35-40.
  92. Barakat M A. New trends in removing heavy metals from industrialwastewater. Arabian Journal of Chemistry 2011;4:361-377.
  93. Marimuthu, V. Pollution Abatement by Activated Nano Materials derived from Natural Plants and Minerals, Thesis submitted to Bharathidasan university, Thiruchirappalli. 2013. pp179.
  94. Matthew A. A., Adedoyin A. A.,  Johnson F. A.,  Oluwayemisi T. A. Isotherm, Kinetic, and Thermodynamic Studies of Lead (II) Biosorption by Streblus asper. 2014.
  95. Zhao, M., Duncan, J. R., Van Hille, R. P. Removal and Recovery of Zinc from Solution and Electroplating Effluent using Azolla Filiculoides. Water Research. 2013, 33(6): 1516-1522.
  96. Claudia, M.S and Mariana F Fungal Biomass for Cu (II) Uptake from Aqueous systems. Polish Journal of Environmental Studies. 2012, 21: 1831-1839.
  97. Gupta VK, Suhas.  Application of low-cost Adsorbents for Dye removal-A review. Journal of Environmental Management. 2009, 90: 2313-2342.
  98. Wei, C., Xiaoping Z.,  Mairambek, M., Zihao, W. Sorption of Perfluorooctane Sulfonate and Perfluorooctanoate on Polyacrylonitrile fiber derived Activated Carbon Fibers: in Comparison with Activated Carbon. The Royal Society of Chemistry 2017;7:927–938.
  99. Schineider, RM., Cavalin CF., Barros, MASD., Tereves, C.R.G. Adsoption of Chromium ions in Activated Carbon. Chemical Engineering Journal 2015;132: 355.
  100.  Shirashkumar, H., Maqdoom, F and Milind, U. Removal of Copper (ii) from Aqueous Solution and Waste Water by Prosopis juliflora leaf powder by Adsorption. International Journal of Application or Innovation in Engineering and Management 2013;2:3.
  101. Wang, J. Biosorption of copper (II) by chemically modified biomass of Sacchromyces cerevisiae. Process Biochemistry. 2012;37:847–850.