D. Liao, W. Zheng, X. Li, Q. Yang, X. Yue et al., Removal of lead(II) from aqueous solutions using carbonate hydroxyapatite extracted from eggshell waste, J. Hazard. Mater, vol.177, pp.126-130, 2010.
DOI : 10.1016/j.jhazmat.2009.12.005

S. H. Jang, B. G. Min, Y. G. Jeong, W. S. Lyoo, and S. C. Lee, Removal of lead ions in aqueous solution by hydroxyapatite/polyurethane composite foams, J. Hazard. Mater, vol.152, pp.1285-1292, 2008.
DOI : 10.1016/j.jhazmat.2007.08.003

¸. S. Raita, N. Cornil?, V. Danacu, P. Rosu, and F. Barbuceanu, Histological researches concerning the pancreas in Struthio camelus Anatomia, Histol. Embryol, vol.43, pp.74-75, 2014.

S. L. Iconaru, A. M. Prodan, C. S. Turculet, M. Beuran, R. V. Ghita et al., Enamel Based Composite Layers Deposited on Titanium Substrate with Antifungal Activity, J. Spectroscop, p.4361051, 2016.
DOI : 10.1155/2016/4361051

URL : http://downloads.hindawi.com/journals/jspec/2016/4361051.pdf

R. W. Gillham and R. S. ;-o'hannesin, Enhanced degradation of halogentaed aliphatics by zero-valent iron, Ground Water, vol.32, pp.958-967, 1994.
DOI : 10.1111/j.1745-6584.1994.tb00935.x

P. Biswas and C. Y. Wu, Nanoparticles and the Environment, Critical Review Paper. J. Air Waste Manag. Assoc, vol.55, pp.708-746, 2005.

D. W. Elliott and W. X. Zhang, Field assessment of nanoscale bimetallic particles for groundwater treatment, Environ. Sci. Technol, vol.35, pp.4922-4926, 2000.
DOI : 10.1021/es0108584

I. Suciu, C. Vârlan, B. Dimitriu, . Sorit, O. ?u et al., Biocompatibility Study of Several Esthetic Dental Restorative Materials. Rom. Biotechnol. Lett, vol.21, pp.11438-11442, 2016.

D. Predoi, M. V. Predoi, S. L. Iconaru, M. Ech-cherif-el-kettani, D. Leduc et al., Ultrasonic Measurements on ? Cyclodextrin/Hydroxyapatite Composites for Potential Water Depollution, Materials, vol.10, p.681, 2017.
URL : https://hal.archives-ouvertes.fr/hal-01919431

S. Raita, N. Cornil?, V. D?nacu, C. Belu, B. Georgescu et al., Morphological studies on the liver in Struthio camelus, Anatomia. Blackwell Verlag GmbH Ana. Histol. Embryol, vol.43, pp.74-75, 2014.

A. M. Prodan, M. Beuran, C. S. Turculet, M. Popa, E. Andronescu et al., In vitro evaluation of glycerol coated iron oxide nanoparticles in solution, Rom. Biotechnol. Lett, vol.23, pp.13901-13908, 2018.

C. S. Turculet, A. M. Prodan, I. Negoi, G. Teleanu, M. Popa et al., Preliminary evaluation of the antifungal activity of samarium doped hydroxyapatite thin films, Rom. Biotechnol. Lett, vol.23, pp.13927-13932, 2018.

S. Zamani and E. Salahi, Mobasherpour, I. Removal of Nickel from aqueous solution by nano hydroxyapatite originated from Persian Gulf corals, Can. Chem. Trans. 2013, vol.1, pp.173-190

R. Zhu, R. Yu, J. Yao, D. Mao, C. Xing et al., Removal of Cd 2+ from aqueous solutions by hydroxyapatite, Catal. Today, vol.139, pp.94-99, 2008.

S. K. Milonji´cmilonji´c, Comments on "factors influencing the removal of divalent cations by hydroxyapatite, J. Hazard. Mater, vol.162, pp.1588-1589, 2009.

S. L. Iconaru, M. Motelica-heino, R. Guegan, M. V. Predoi, A. M. Prodan et al., Removal of Zinc Ions Using Hydroxyapatite and Study of Ultrasound Behavior of Aqueous Media, Materials, vol.11, 1350.
URL : https://hal.archives-ouvertes.fr/insu-01856087

T. Suzuki, T. Hatsushika, and Y. Hayakawa, Synthetic hydroxyapatites employed as inorganic cation-exchangers, J. Chem. Soc. Faraday Trans, vol.77, pp.1059-1062, 1981.

S. S. Gupta and K. G. Bhattacharyya, Kinetics of adsorption of metal ions on inorganic materials: A review, Adv. Colloid Inter. Sci, vol.162, pp.39-58, 2011.

D. Natale, F. Erto, A. Lancia, A. Musmarra, and D. , A descriptive model for metallic ions adsorption from aqueous solutions onto activated carbons, J. Hazard. Mater, vol.169, pp.360-369, 2009.

A. Erto, F. Di-natale, D. Musmarra, and A. Lancia, Modeling of single and competitive adsorption of cadmium and zinc onto activated carbon, Adsorption, vol.21, pp.611-621, 2015.

Y. Suzuki and Y. Takeuchi, Uptake of a few divalent heavy metal ionic species by a fixed bed of hydroxyapatite particles, J. Chem. Eng. Jpn, vol.27, pp.571-576, 1994.

T. Suzuki, K. Ishigaki, and M. Miyake, Hydroxyapatites as inorganic cation exchangers. Part 3: Exchange characteristics of lead ions (Pb 2+ ), J. Chem. Soc. Faraday Trans, vol.80, pp.3157-3165, 1984.

C. E. Martínez and M. B. Mcbride, Aging of coprecipitated Cu in alumina: Changes in structural location, chemical form, and solubility, Geochim. Cosmochim. Acta, vol.64, pp.1729-1736, 2000.

L. Borum, O. C. Wilson, and . Jr, Surface modification of hydroxyapatite, Part II. Silica. Biomaterials, vol.24, pp.3681-3688, 2003.

C. S. Ciobanu, L. V. Constantin, and D. Predoi, Structural and physical properties of antibacterial Ag-doped nano-hydroxyapatite synthesized at 100 C, Nanoscale Res. Lett, vol.6, 2011.
URL : https://hal.archives-ouvertes.fr/hal-00849703

C. S. Ciobanu, S. L. Iconaru, P. Le-coustumer, L. V. Constantin, and D. Predoi, Antibacterial activity of silver-doped hydroxyapatite nanoparticles against gram-positive and gram-negative bacteria, Nanoscale Res. Lett, vol.7, p.324, 2012.

C. S. Ciobanu, S. L. Iconaru, C. L. Popa, M. Motelica-heino, and D. Predoi, Evaluation of samarium doped hydroxyapatite, ceramics for medical application: Antimicrobial activity, J. Nanomater, vol.849216, 2015.
URL : https://hal.archives-ouvertes.fr/insu-01160556

C. S. Ciobanu, E. Andronescu, and D. Predoi, Bet and Xrd Studies on the Hydroxyapatite and Europium Doped Hydroxyapatite, Dig. J. Nanomater. Biostruct, vol.6, pp.1239-1244, 2011.

C. S. Ciobanu, S. L. Iconaru, F. Massuyeau, L. V. Constantin, A. Costescu et al., Synthesis, structure, and luminescent properties of europium-doped hydroxyapatite nanocrystalline powders, J. Nanomater, 2012.

C. S. Ciobanu, S. L. Iconaru, P. Le-coustumer, and D. Predoi, Vibrational Investigations of Silver-Doped Hydroxyapatite with Antibacterial Properties, J. Spectrosc, p.471061, 2013.

C. S. Ciobanu, E. Andronescu, A. Stoicu, O. Florea, P. Le-coustumer et al., Influence of Annealing Treatment of Nano-Hydroxyapatite Bioceramics on the Vibrational Properties, Dig. J. Nanomater. Biostruct, vol.6, pp.609-624, 2011.
URL : https://hal.archives-ouvertes.fr/hal-00849507

C. S. Ciobanu, S. L. Iconaru, C. L. Popa, A. Costescu, M. Motelica-heino et al., Porous Methyltrimethoxysilane Coated Nanoscale-Hydroxyapatite for Removing Lead Ions from Aqueous Solutions, J. Nanomater, p.361061, 2014.
URL : https://hal.archives-ouvertes.fr/insu-01052573

A. Slósarczyk, Z. Paszkiewicz, and C. Paluszkiewicz, FTIR and XRD evaluation of carbonated hydroxyapatite powders synthesized by wet methods, J. Mol. Struct, pp.657-661, 2005.

A. Costescu, C. S. Ciobanu, S. L. Iconaru, R. V. Ghita, C. M. Chifiriuc et al., Fabrication, Characterization, and Antimicrobial Activity, Evaluation of Low Silver Concentrations in Silver-Doped Hydroxyapatite Nanoparticles, J. Nanomater, 2013.

I. R. Cusco, F. Guitian, S. De-aza, and L. Arttis, Differentiation between Hydroxyapatite and ?-Tricalcium Phosphate by Means of p-Raman Spectroscopy, J. Eur. Ceram. Soc, vol.18, pp.1301-1305, 1998.

S. Brunauer, P. H. Emet, and E. Teller, Adsorption of Gases in Multimolecular Layers, J. Am. Chem. Soc, vol.60, pp.309-319, 1938.

E. P. Barrett, L. G. Joyner, and P. P. Halenda, The determination of pore volume and area distributions in porous substances. I. Computations from nitrogen isotherms, J. Am. Chem. Soc, vol.73, pp.373-380, 1951.

L. M. Cozmuta, A. M. Cozmuta, A. Peter, C. Nicula, E. B. Nsimba et al., The influence of pH on the adsorption of lead by Na-clinoptilolite: Kinetic and equilibrium studies, vol.38, pp.269-278, 2012.

M. Zhang, C. C. Jin, L. H. Xu, and T. Ding, Effect of temperature, salinity, and pH on the adsorption of lead by sediment of a tidal river in east China, Proceedings of the 2012 International Conference on Biomedical Engineering and Biotechnology, pp.28-30, 2012.

A. Malek and S. Farooq, Comparison of isotherm models for hydrocarbon adsorption on activated carbon, AIChE J, vol.42, pp.3191-3201, 1996.

I. Langmuir, The constitution and fundamental properties of solids and liquids, J. Am. Chem. Soc, vol.38, pp.2221-2295, 1916.

E. Bulut, M. Ozacar, and I. A. Sengil, Adsorption of malachite green onto bentonite: Equilibrium and kinetic studies and process design, Micropor. Mesopor. Mater, vol.115, pp.234-246, 2008.

M. C. Ncibi, Applicability of some statistical tools to predict optimum adsorption isotherm after linear and non-linear regression analysis, J. Hazard. Mater, vol.153, pp.207-212, 2008.

K. Vijayaraghavan, T. V. Padmesh, K. Palanivelu, and M. Velan, Biosorption of nickel(II) ions onto Sargassum wightii: Application of two-parameterand three parameter isotherm models, J. Hazard. Mater, vol.133, pp.304-308, 2006.

S. Kundu and A. K. Gupta, Arsenic adsorption onto iron oxide-coated cement (IOCC): Regression analysis of equilibrium data with several isotherm models and their optimization, Chem. Eng. J, vol.122, pp.93-106, 2006.

S. J. Allen, G. Mckay, and J. F. Porter, Adsorption isotherm models for basic dyea dsorption by peat in single and binary component systems, J. Colloid Interface Sci, vol.280, pp.322-333, 2004.

I. Langmuir, The adsorption of gases on plane surfaces of glass, mica and platinum, J. Am. Chem. Soc, vol.40, pp.1361-1403, 1918.

Y. S. Ho, C. T. Huang, and H. W. Huang, Equilibrium sorption isotherm for metal ions on tree fern, Process. Biochem, vol.37, pp.1421-1430, 2002.

Y. S. Ho, Selection of optimum sorption isotherm, Carbon, vol.42, pp.2115-2116, 2004.

J. He, S. Hong, L. Zhang, F. Gan, and Y. S. Ho, Equilibrium and Thermodynamic parameters of adsorption of merhylene blue onto rectorite, Fresen. Environ. Bull, vol.19, pp.2651-2656, 2010.

D. P. Minh, N. D. Tran, A. Nzihou, and P. Sharrock, Hydroxyapatite gel for the improved removal of Pb 2+ ions from aqueous, Solution Chem. Eng. J, vol.232, pp.128-138, 2013.
URL : https://hal.archives-ouvertes.fr/hal-01632393

H. M. Freundlich, Over the adsorption in solution, J. Phys. Chem, vol.57, pp.385-471, 1906.

A. W. Adamson and A. P. Gast, Physical Chemistry of Surfaces, 1997.

K. Y. Foo and B. H. Hameed, Insights into the modeling of adsorption isotherm systems, Chem. Eng. J, vol.156, pp.2-10, 2010.

J. Zeldowitsch, Adsorption site energy distribution, Acta Phys. Chim. URSS, vol.1, pp.961-973, 1934.

E. Voudrias, F. Ytianos, and E. Bozani, Sorption Description isotherms of Dyes from aqueous solutions and Waste Waters with Different Sorbent materials, Global Nest, Int. J, vol.4, pp.75-83, 2002.

S. Mohan and J. Karthikeyan, Removal of lignin and tannin color from aqueous solution by adsorption on to activated carbon solution by adsorption on to activated charcoal, Environ. Pollut, vol.97, pp.183-187, 1997.

S. Goldberg, Equations and Models Describing Adsorption Processes in Soils, Chemical Processes in Soils

, Soil Science Society of America, p.489, 2005.

K. Sangeetha, G. Vidhya, G. Vasugi, and E. K. Girija, Lead and cadmium removal from single and binary metal ion solution by novel hydroxyapatite/alginate/gelatin nanocomposites, J. Environ. Chem. Eng, vol.6, pp.1118-1126, 2018.

Y. Xu and F. W. Schwartz, Lead immobilization by hydroxyapatite in aqueous solutions, J. Contam. Hydrol, vol.15, pp.187-206, 1994.

H. Z. Mousavi and S. R. Seyedi, Kinetic and equilibrium studies on the removal of Pb (II) from aqueous solution using nettle ash, J. Chil. Chem. Soc, vol.55, pp.307-311, 2010.

W. Zheng, X. Li, Q. Yang, G. Zeng, X. Shen et al., Adsorption of Cd(II) and Cu(II) from aqueous solution by carbonate hydroxylapatite derived from eggshell waste, J. Hazard. Mater, vol.147, pp.534-539, 2007.

X. M. Zhan and X. Zhao, Mechanism of lead adsorption from aqueous solutions using an adsorbent synthesized from natural condensed tannin, Water Res, vol.37, pp.3905-3912, 2003.

S. M. Mousa, N. S. Ammar, and H. A. Ibrahim, Removal of lead ions using hydroxyapatite nano-material prepared from phosphogypsum wast, J. Saudi. Chem. Soc, vol.20, pp.357-365, 2016.

E. G. Hafsteinsdóttir, D. Camenzuli, A. L. Rocavert, J. Walworth, and D. B. Gore, Chemical immobilization of metals and metalloids by phosphates, Appl. Geochem, vol.59, pp.47-62, 2015.

Q. Peng, J. Guo, Q. Zhan, J. Xiang, B. Liu et al., Unique Lead Adsorption Behavior of Activated Hydroxyl Group in Two-Dimensional Titanium Carbide, J. Am. Chem. Soc, vol.136, pp.4113-4116, 2014.

A. Günay, A. Arslankaya, and I. Tosun, Lead removal from aqueous solution by natural and pretreated clinoptilolite: Adsorption equilibrium and kinetics, J. Hazard. Mater, vol.146, pp.362-371, 2007.

M. Vila, S. Sandra-sánchez-salcedo, and M. Vallet-regí, Hydroxyapatite foams for the immobilization of heavy metals: From waters to the human body, Inorg. Chim. Acta, vol.393, pp.24-35, 2012.

Q. Y. Ma, S. J. Traina, T. J. Logan, and J. Ryan, In situ lead immobilization by apatite, Environ. Sci. Technol, vol.27, pp.1803-1810, 1993.

M. R. Gandhi and G. N. Meenakshi, Removal of copper(II) using chitin/chitosan nano-hydroxyapatite composite, Int. J. Biol. Macromol, vol.48, pp.119-124, 2011.

W. Liang, L. Zhan, L. Piao, and C. Rüssel, Lead and copper removal fromaqueous solutions by porous glass derived calcium hydroxyapatite, Mater. Sci. Eng. B, vol.176, pp.1010-1014, 2011.
DOI : 10.1016/j.mseb.2011.05.036

Z. Zhang, M. Li, W. Chen, S. Zhu, N. Liu et al., Immobilization of lead and cadmium from aqueous solution and contaminated sediment using nano-hydroxyapatite, Environ. Pollut, vol.158, pp.514-519, 2010.
DOI : 10.1016/j.envpol.2009.08.024

A. Corami, S. Mignardi, and V. Ferrini, Cadmium removal from single-and multi-metal (Cd + Pb + Zn + Cu) solutions by sorption on hydroxyapatite, J. Colloid Interface Sci, vol.317, pp.402-408, 2008.
DOI : 10.1016/j.jcis.2007.09.075

Z. Yang, Z. Fang, L. Zheng, W. Cheng, P. E. Tsang et al., Remediation of lead contaminated soil by biochar-supported nano-hydroxyapatite, Ecotoxicol. Environ. Saf, vol.132, pp.224-230, 2016.
DOI : 10.1016/j.ecoenv.2016.06.008

Z. Yang, Z. Fang, P. E. Tsang, J. Fang, and D. Zhao, In situ remediation and phytotoxicity assessment of lead-contaminated soil by biochar-supported nHAP, J. Environ. Manag, vol.182, pp.247-251, 2016.

M. P. ?or?evi´c?or?evi´c, J. Maleta?ki´cmaleta?ki´c, N. Stankovi´cstankovi´c, B. Babi´cbabi´c, K. Yoshidab et al., In-situ immobilization of Sr radioactive isotope using nanocrystalline hydroxyapatite, Ceram. Int, vol.44, pp.1771-1777, 2018.