Recovering of Disposed Nickel – Titanium Rotary Endodontic Files via Sulphuric Acid Leaching Treatments

Abstract

Nickel - titanium based alloys are widely used as a root canal files in dental canal treatment in endodontics. According to the Turkish Ministry of Health, approximately, two million root canal treatments were applied yearly in Turkey. Ni-Ti rotary files have been used for 80 % of these endodontic root canal treatments. Rotary files contain 55-60 wt.% nickel and 40-45 wt.% titanium. Ni-Ti endodontic files can be recovered by hydrometallurgy, which is an economical way, instead of treating them as medical waste. The aim of this study is to provide economical hydrometallurgical recycling of metallic wastes that cannot be recovered by direct melting. Nickel and titanium based endodontic rotary files were recovered via using different leaching techniques in high corrosive environments such as dissolution in concentrated acid, baking in sulfuric acid and hydrothermal treatment in concentrated sulfuric acid. The acid concentration, temperature and time parameters were optimized for concentrated sulfuric acid leaching in autoclave. The acid baking method is a simple system more efficient than the pure dissolution in acid. At the end of the hydroxide structures dehydration, TiO2 (anatase) and NiO powders were obtained. Moreover, under pressure within non-stirring autoclave the rotary file is completely dissolved with a cost-effective two-step process. Thus, an efficient recycling process has been created for waste Ni-Ti alloy tooth files.

Keywords

• endodontics Ni-Ti files
• recycling
• hydro-metallurgy
• root canal treatment

Endodontide Kullanılan Nikel-Titanyum Atık Eğelerin Sülfürik Asit Liçi İşlemleri ile Geri Kazanımı

Abstract

Nikel-titanyum esaslı alaşımlar endodontide dental kanal tedavisinde kök kanal eğesi olarak kullanılmaktadır. T.C. Sağlık Bakanlığı'na göre, Türkiye'de yılda yaklaşık iki milyon kök kanal tedavisi uygulanmakta ve bunların %80'inde Ni-Ti eğeler kullanılmaktadır. Eğeler ağırlıkça %55-60 nikel ve ağırlıkça %40-45 titanyum içerir. Ni-Ti endodontik eğeler tıbbi atık olarak değerlendirilmesinden, ekonomik bir yol olan hidrometalurji yöntemleri ile geri kazanılabilir. Nikel ve titanyum esaslı endodontik eğeler, konsantre asitte çözünme, sülfürik asitte pişirme ve konsantre sülfürik asitte hidrotermal işleme gibi yüksek korozif ortamlarda farklı liç teknikleri kullanılarak geri kazanılmıştır. Bu çalışmanın amacı, hidrometalurjik yöntemle doğrudan eritme ile geri kazanılamayan metalik atıkların ekonomik geri dönüşümünü sağlamaktır. Asit konsantrasyonu, sıcaklık ve zaman parametreleri otoklavda konsantre sülfürik asit liçi için optimize edilmiştir. Asitte pişirme yöntemi, asit çözeltisi liçinden daha verimli basit bir sistemdir. Hidrotermal işlemin sonunda ise meydana gelen hidroksit yapılarının dehidrasyonu sonucu TiO2 (anataz) ve NiO tozları elde edilmiştir. İlave maliyeti olmayan, otoklav içinde basınç altında ve karıştırılmaksızın eğeler tamamen çözülmüştür. Böylece kullanılmış atık Ni-Ti alaşımlı diş eğeleri için bir geri kazanım işlemi ortaya konulmuştur.

Keywords

• Endodontik Ni-Ti eğeler
• geri kazanım
• hidrometalurji
• kök kanal tedavisi

References

1. [1] Turkish Dental Association, Dental Treatment Statistics of 2014, (2014). http://www.tdb.org.tr/sag_menu_goster.php?Id=494 Accessed July 19, 2017.
2. [2] Ferreira A., Luersen M.A., Borges P.C., "Nickel-titanium alloys: A systematic review", Dental Press J. Orthod., 2012, 17(3): 71–82.
3. [3] Ryhänen J., Kallioinen M., Tuukkanen J., Junila J., Niemelä E., Sandvik P., Serlo W.," In vivo biocompatibility evaluation of nickel-titanium shape memory metal alloy: muscle and perineural tissue responses and encapsule membrane thickness", J. Biomed. Mater. Res., 1998, 41 (3): 481–8.
4. [4] Prasad P., Sam J., Kumar A., Kannan, "The effect of 5% sodium hypochlorite, 17% EDTA and triphala on two different rotary Ni-Ti instruments: An AFM and EDS analysis", J. Conserv. Dent.,2014, 17(3): 462-466.
5. [5] Thompson S.A.," An overview of nickel – titanium alloys used in dentistry", Int. Endod. J.,2000, 44 (14):297-310.
6. [6] Kai W.Y., Chang K.C., Wu H.F., Chen S.W., Yeh A.C., "Formation mechanism of Ni 2 Ti 4 Ox in NITI shape memory alloy", Materialia., 2019, 5: 100194.
7. [7] Elahinia M.H., Hashemi M., Tabesh M., "Progress in Materials Science Manufacturing and processing of NiTi implants: A review", Prog. Mater. Sci., 2012, 5(57): 911–946.
8. [8] Rotmann B., Lochbichler C., Friedrich B., "Challenges in Titanium Recycling - Do We Need a New Specification for Secondary Alloys?", EMC 2011, Düsseldorf, 1–15, (2011).

9. [9] Nickel Institute, Nickel Recycling, Nickel Inst. (2017). http://www.https//www.nickelinstitute.org/policy/nickel-life-cycle-management/nickel-recycling/ Accessed July 21, 2017.
10. [10] Grzmil B., Grela D., Kic B., "Formation of hydrated titanium dioxide from seeded titanyl sulphate solution", Chem. Pap.,2009, 2 (63): 217–225.
11. [11] Simka W., Kaczmarek M., Baron-Wiecheć A., Nawrat G., Marciniak J., Zak J., "Electropolishing and passivation of NiTi shape memory alloy", Electrochim. Acta.,2010, 55(7): 2437-2441.
12. [12] Eiselstain L.E., "Corrosion of Shape Memory and Superelastic Alloys",Br. J. Psychiatry, 1965, 479(111): 1009–1010.
13. [13] Shi Q., Zhang Y., Lui T., Huang J.,” Vanadium Extraction from Shale via Sulfuric Acid Baking and Leaching”, JOM, 2018, 70(10): 1972-1976.
14. [14] Meshram P., Abhilash J., Pandey B.D., Mankhand T.R., Deveci H.,” Acid baking of spent lithium ion batteries for selective recovery of major metals: A two-step process”, J IND ENG CHEM., 2016, 43: 117-126.
15. [15] Nesterov K.N., Smirnov K.M.,” Autoclave Leaching Of Rare-Earth Metals From Hydroxide Precipitate”, Metallurgist, 2018, 62 (1-2): 163-168.
16. [16] Jha M.K., Lee J.C., Kumari A., Choubey P.K., Kumar V., Jeong J., “Pressure leaching of metals from waste printed circuit boards using sulfuric acid”, JOM, 2011, 63 (8): 29–32.
17. [17] Baumann M., “Nickel-titanium: options and challenges”, Dent. Clin. N. Am., 2004, 48: 55-67.
18. [18] Habashi F.,” A short history of hydrometallurgy”, Hyromet., 2005: 79, 15-22.
19. [19] Kish J.R., Ives M.B., Rodda J.R., "Corrosion mechanism of nickel in hot, concentrated H2SO4", J. Electrochem. Soc., 2000, 147 (10): 3637-3646
20. [20] Thamaphat K., Limsuwan P., Ngotawornchai B.,”Phase Characterization of TiO2 Powder by XRD and TEM”, Kasetsart J. (Nat. Sci.), 2008, 42: 357–361.
21. [21] W. Zhang, Zhu Z., Cheng C.Y.,” Hydrometallurgy A literature review of titanium metallurgical processes”, Hydromet., 2011, 108: 177-188.
22. [22] Mohammadyani D., Hosseini S.A., Sadrnezhaad S.K.,“Characterization of Nickel Oxide Nanoparticles Synthesized Via Rapid Microwave-Assisted Route”, Int. J. Mod. Phys. Conf. Ser.,2012, 5: 270–276.
23. [23] Oncel, L., “Production of Ferronickel from Mill-scale via Metallothermic Process,” El-Cezerî Journal of Science and Engineering, 2020, 7 (2): 824-834.
24. [24] Subaşı M., Karataş Ç.,” A Review on Implants Made of Titanium and Titanium Alloys”, Journal of Polytechnic, 2012, 15(2): 87-103.
25. [25] Wódka J., Chmıelewskı T., ZıółkowskI B., "Pressure Leaching of Shale Ore", Physicochem. Probl. Miner. Process.,2007, 41: 349–364.
26. [26] Jiménez Correa M.M., Aliprandini P., Soares Tenório J.A., Crocce D., Espinosa R.," Precipitation of metals from liquor obtained in nickel mining", REWAS 2016: Towards Materials Resource Sustainability, Springer, Cham, 8 Downtown Nashville, Tennessee, (2016).
27. [27] Srinivasan V., Weidner J.W.," An Electrochemical Route for Making Porous Nickel Oxide Electrochemical Capacitors", J. Electrochem. Soc., 1997, 144 (8): 210–213.