SEPİOLİT-KİTOSAN KOMPOSİTLERİNİN SENTEZİ ve BU KOMPOZİT İLE SULU ÇÖZELTİLERDEN Cr(VI) ADSORPSİYONUNUN İNCELENMESİ

Öz

Birçok doğal veya ticari adsorbanlar, boyalar, ağır metaller ve diğer kirleticilerin çevreden uzaklaştırılması için adsorpsiyon işlemlerinde yaygın olarak kullanılmıştır. Doğal adsorbanlar, düşük maliyetli ve bol bulunmaları nedeniyle, çoğunlukla tercih edilmektedir. Ayrıca, yeni kaynaklar doğal adsorbanlardan daha verimli adsorbanlar geliştirilebileceğini açıklamıştır. Bu doğal adsorbanları daha verimli hale getirmenin yollarından biri de kompozitler hazırlamaktır. Kitosanın yapısında bulunan hidroksil (-OH) ve amino (-NH2) grupları ağır metallerle bağ yapabilme potansiyeline sahip adsorbanlar elde edilmesini sağlar. Killer, adsorpsiyon çalışmalarında genelde sık kullanılmasıyla birlikte, pratik kullanımlarda agregasyon ve koagülasyon gibi hidrodinamik özellikleri etkileyen olumsuzluklar ile karşılaşılır. Bu olumsuzluklar, killerin kitosan polimerleri ile oluşturduğu kompozitlerin kullanımı ile bertaraf edilebilir. Bu çalışmada ticari sepliolit kili ve kitosan ile kompozit bir adsorban (SK) hazırlanmıştır ve kompozit boncukları (SK) FTIR analizi yapılarak karakterize edilmiştir. Sulu çözeltiden Cr(VI) iyonlarının adsorpsiyonunda (SK) kompoziti kullanılmıştır. Cr(VI) adsorpsiyonuna, pH, adsorban miktarı, adsorbat konsantrasyonu ve temas süresi gibi parametrelerin etkisi araştırılmıştır. Freundlich, Langmuir, Scatchard ve Dubinin-Radushkevich (D-R) adsorpsiyon izoterm modelleri adsorpsiyon dengesinin analizi için kullanılmıştır. Adsorpsiyon işlemi Langmuir ve Scatchard adsorpsiyon izotermlerine uymuştur. Kompozitin Cr(VI) adsorpsiyonu için adsorplama kapasitesi, Scatchard adsorpsiyon izotermi verilerinden hesaplanmıştır. Sepiolit ve SK kompoziti sırasıyla 3.11; 61.048 mg/g maksimum adsorpsiyon kapasitesi ile krom (VI) iyonlarını uzaklaştırmıştır (25 C, pH 2, temas süresi 60 dakika, adsorban miktarı 0.04 g). SK kompozitinin krom (VI) uzaklaştırılmasında etkin bir şekilde kullanılabileceği sonucuna varılmıştır.

Anahtar Kelimeler

• Adsorpsiyon,İzoterm,Kitosan,Kompozit,Krom(VI),Sepiolit kili

Synthesis of Sepiolite-Chitosan Composites and Investigation of Cr(VI) Adsorption from Aqueous Solution by Using This Composite

Öz

Many natural or commercial adsorbents have been commonly used for the removal of dues, heavy metals, and other pollutants from the environment. Due to low-cost and abundance of natural adsorbents, they are mostly preferred. Moreover, new sources have indicated that more efficient biosorbents from natural adsorbents. One of the ways to make these natural adsorbents more efficient is preparation of composites. The hydroxyl (-OH) and amino (-NH2) groups present in the structure of chitosan provide a binding capacity for the adsorbent to remove heavy metals. Clays, on the other hand, are usually used in adsorption processes and negativities affecting hydrodynamic properties such as aggregation and coagulation are encountered in practice. These negativities can be removed by using composites prepared from clays with chitosan polymer. In this study, a composite adsorbent was prepared from sepiolite clay and chitosan (SK) and FTIR analysis of composite beads was carried out. Then SK composite was used for the removal of Cr(VI) ions from aqueous solutions. The effects of parameters such as pH, adsorbent amount, adsorbate concentration and contact time were investigated for Cr(VI) adsorption. Scatchard and Dubinin-Radushkevich (D-R) adsorption isotherm models were used for the analysis of adsorption equilibrium. For adsorption process, Scatchard adsorption was well fitted to the data of adsorption. It was determined that sepiolite and SK composite removed Cr(VI) ions respectively 3.11 and 61.048 mg/g with maximum adsorption capacity (25 C, pH 2, contact time 60 minutes, 0.04 g adsorbent amount ). It was concluded that SK composite can be effectively used for Cr(VI) removal from aqueous solutions.

Anahtar Kelimeler

• Adsorption,Isotherm,Chitosan,Composite,Chromium(VI),Sepiolite Clay

Kaynakça

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