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

Öz

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.

Anahtar Kelimeler

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

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

Öz

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.

Anahtar Kelimeler

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

Kaynakça

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