Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/207

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    Citation - WoS: 23
    Citation - Scopus: 23
    Pressure-Induced Amorphization of MOF-5: A First Principles Study
    (Wiley-VCH Verlag GmbH, 2018) Erkartal, Mustafa; Durandurdu, Murat; Erkartal, Mustafa; Durandurdu, Murat; 0000-0001-5636-3183; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; 01. Abdullah Gül University; 02.07. Malzeme Bilimi ve Nanoteknoloji Mühendisliği; 02. Mühendislik Fakültesi
    Amorphous metal-organic frameworks (MOFs) and the amorphization of crystalline MOFs under mechanical stimuli are attracting considerable interest in last few years. However, we still have limited knowledge on their atomic arrangement and the physical origin of crystalline-to-amorphous phase transitions under mechanical stimuli. In this study, ab initio simulations within a generalized gradient approximation are carried out to investigate the high-pressure behavior of MOF-5. Similar to the previous experimental findings, a pressure-induced amorphization is observed at 2 GPa through the simulations. The phase transformation is an irreversible first order transition and accompanied by around 68% volume collapse. Remarkably, the transition arises from local distortions and, contrary to previous suggestions, does not involve any bond breaking and formation. Additionally, a drastic band gap closure is perceived for the amorphous state. This study has gone some way towards enhancing our understanding of pressure-induced amorphization in MOFs.
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    Citation - WoS: 6
    Citation - Scopus: 7
    Synergistic Effect of Organic Acid on the Dissolution of Mixed Nickel-Cobalt Hydroxide Precipitate in Sulphuric Acid Solution
    (Edp Sciences S A, 2019) Kursunoglu, Sait; Kursunoglu, Sait; 0000-0002-1680-5482; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; 01. Abdullah Gül University
    The synergistic effect of an organic acid on the dissolution of nickel and cobalt from a mixed nickel-cobalt hydroxide precipitate (MHP) in sulphuric acid solution was studied. The effects of sulphuric acid concentration, the type of organic acid, leaching time, leaching temperature and stirring speed on the dissolution of the metals were experimentally investigated. It was observed that there is no beneficial effect of leaching temperature and stirring speed on the dissolution of the metals from the used MHP product which contains 37.7% Ni, 2.1% Co and 5.6% Mn. It was found that citric acid was more effective than oxalic acid for the dissolution of nickel and manganese, whereas oxalic acid was more effective than citric acid for the dissolution of cobalt. The addition of oxalic acid into the leaching system, however, affected the dissolution of nickel negatively because nickel precipitate as nickel oxalate. Therefore, the use of citric acid as synergist for sulphuric acid leaching of MHP product is more promising. After 60 min of leaching, 90.9% Ni, 84.2% Co and 98.1% Mn were dissolved under the following conditions: 0.75 M sulphuric acid, 2 g citric acid, 1/10 solid-to-liquid ratio, 400 rpm stirring speed and 30 degrees C temperature. The experimental results demonstrate that the addition of citric acid as a synergist for sulphuric acid leaching of a MHP product provides beneficial effect for the dissolution of nickel, cobalt and manganese.