[01] Samir B. Eskander, Radioisotope Department, Egyptian Atomic Energy Authority, Giza, Egypt. [02] Talat A. Bayoumi, Radioisotope Department, Egyptian Atomic Energy Authority, Giza, Egypt.

Cesium-137 and cobalt-60 are major radionuclides detected in various categories of radioactive waste streams generated due to the peaceful applications of nuclear technology in our life. Both are γ emitters. Cs-137(γ= 0.662 MEV) is extremely soluble alkaline, highly radiotoxic and long lived element with half-life of 30.5 years. Co-60(T1/2 = 5.25 years) has two gamma energy peaks at 1.17 and 1.33 MEV. The two radioisotopes reported to have immense applications in medicine, industry, agriculture, research and others. Hence, the generated liquid waste streams spiked with ¹³⁷Cs and /or 60Co need adequate treatment before their release to the environment. During recent years biosorption has gained imperative credibility because of its good performance and low cost. The present work puts forward an effective green chemistry approach to radioactive liquid waste treatment. Spent Black Tea leaves (the dregs), (SBT), have been used as biosorbent for removal of these two radionuclides from their waste simulate solutions at bench scale laboratory experiments. This study aims at evaluating the efficiency of the non–costed SBT as biosorbent for Cs-137 and /or Co-60 from hazard radioactive waste streams. The factors assumed to affect the sorption capacity and determine the suitability SBT as biosorbent for these two radiocontaminants e.g. contact time, biomass dosage, and temperature of the surrounding…were evaluated. Based on the data obtained it is recorded that ~ 90% of the radiocobalt and more than 80% of radiocesium added were removed from the waste simulate stream by the SBT at concentration 150g/L, after one week, at pH value ~ 5.4 and at ambient temperature (25±5ºC). Therefore, the present study recommends spent black tea dregs as a cost effective and an easily available biosorbent, substituted for the conventional carbon based sorbents, for radiocontaminants removal.

Biosorption, Radioactive Waste Solution, Cobalt-60, Cesium-137, Spent Black Tea

[01] Chen, Y., Wang, J., “Removal of radionuclide Sr²⁺ ions from aqueous solution using synthesized magnetic chitosan beads” Nuclear Engineering and Design 242 (2012) 445–451. [02] Ghattas, N.K., Eskander, S.B., Bayoumi, T.A., Shatta, H.A.,” Chemical treatment of secondary waste solutions resulting from wet oxidative degradation of spent ion-exchange resins”. Isotope and Radiation Research, 37, (2005) 211-219. [03] Ojovan, M.L., Lee, M.E.” An introduction of nuclear waste immobilization.” Elsevier Ltd .2014. [04] Wattel, P.K., Basu, S.” Radioactive waste management .Practices in India: Achievements and Challenges’. Science and cuture.Vol79, Nos 1-2, 45-51, 2013. [05] Food and Agriculture Organization of the United Nations. FAOSTAT. http://faostat3.fao.org/home/index.html#DOWNLOAD [06] Ramesh, S. T., Gandhimathi, R., Elevarasi, T. E., Isai, T. R., Sowmya, K., Nidheesh, P. V. “Comparison of methylene blue adsorption from aqueous solution using spent tea dust and raw coir pith”. Global NEST Journal, Vol 16, No 1, pp 146-159, 2014. [07] Duran, C., Ozdes, D., Gundogdu, A., Imamoglu, M., Senturk, H. B. “Tea-industry waste activated carbon, as a novel adsorbent, for separation, preconcentration and speciation of chromium.” Anal Chim Acta 688(1):75–83, (2011). [08] Parab, H., Joshi, S., Shenoy, N., Verma, R., Lali, A., Sudersanan, M. “Uranium removal from aqueous solution by coir pith: equilibrium and kinetic studies”. Bioresour. Technol. 96:1241–1248, (2005). [09] Bursali, E. A., Merdivan, M., Yurdakoc, M. “Preconcentration of uranium (VI) and thorium (VI) from aqueous solutions using low-cost abundantly available sorbent”. J. Radioanal. Nucl. Chem. 283:471–476, (2010). [10] Kutahyali, C., Eral, M. “Sorption studies of uranium and thorium on activated carbon prepared from olive stones: kinetic and thermodynamic aspects”. J. Nucl. Mater. 396:251–256, (2010). [11] Aksu, Z., Isoglu, I. A. “Removal of copper (II) ions from aqueous solution by biosorption onto agricultural waste sugar beet pulp”. Process Biochem., 40: 3031-3044, (2005). [12] Zuorro, A., Lavecchia, R., Medici, F., Piga, L., “Spent Tea Leaves as a Potential Low-cost Adsorbent for the Removal of Azo Dyes from Wastewater”, Chemical Engineering Transactions. Vol. 32, (2013). [13] Fazal, A., Rafique, U., “Severance of Lead by Acetylated and Esterified spent Camellia sinensis Powder”. American Journal of Environmental Engineering, 3(6): 288-296 (2013). [14] Fazal, A., Rafique, U., “Biosorption of Cadmium on Spent Tea: Green Chemistry Approach”. Journal of Water Sustainability, Volume 2, Issue 4, 259–270. December (2012). [15] Hand book of spectroscopy, Vol. I. Edited by Gauglitz, G. and Vo-Dinh, T. Wiely VCH Verlag-Germany, (2003). [16] Boonamnuayvitaya, V., Sae-ung, S., Tanthapanichakoon, W. “Preparation of activated carbons from coffee residue for the adsorption of formaldehyde”. Sep. Purif. Technol, 42:159–168, (2005). [17] Refas, A., Bernardet, V., David, B., Reinert, L., Bencheikh, Lehocine M., Dubois, M., Batisse, N., Duclaux, L.” Carbons prepared from coffee grounds by H₃PO₄ activation: characterization and adsorption of methylene blue and Nylosan Red N-2RBL.” J. Hazard. Mater. 175:779–788, (2010). [18] Sag, Y., Aktay, Y. “Mass transfer and equilibrium studies for the sorption of chromium ions onto chitin”. Process Biochemistry 36, 157–173. (2000). [19] Fazal, A., Rafique, U. “Mechanistic Understanding of Cadmium Sorption by Sulfonated and Esterified Spent Black Tea”. Intern.l J. of Chem. and Environ. Eng., Vol. 3, No. 4, (2012). [20] Cho, H. C., D. Oh and K. Kim, “A study on removal characteristics of heavy metals from aqueous solution by fly ash”. J. Hazard. Mater., 127(1-3), 187-195 (2005). [21] Ahluwalia, S. S, Goyal, D. “Removal of Heavy Metals by Waste Tea Leaves from Aqueous Solution ‘.Engineering in Life Sciences, Volume 5, Issue 2, pages 158–162, April, (2005). [22] Aksu, Z.” Equilibrium and kinetic modeling of cadmium (II) from aqueous by C. vulgaris in a batch system: effect of temperature”. Separation and Purification Technology 21, 285–294. (2002). [23] Bai, S. R., Abraham, T. E.”Biosorption of Cr (VI) from aqueous solution by Rhizopus nigricans”. Journal of Scientific & Industrial Research 57, 806–816. (1998). [24] Thilagavathy, P., Santhi.T.”Sorption of toxic Cr (VI) from aqueous solutions using treated Acacia nitoica leaf as adsorbent: Single and Binary System”. Bio-Resources (8), 2, 1813-1830, (2013).