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Evaluation of two different methods to synthesize cobaltaluminate spinel
Shiva Salem,Seyyed Hamid Jazayeri,Federica Bondioli,Ali Allahverdi,Mansoor Shirvani 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.6
The aim of this research is to study the efficiency of both microwave-hydrothermal and combustion methods to synthesize CoAl2O4 spinel. To attain the objectives, precursor solutions of CoCl2·2H2O and AlCl3·6H2O were applied to prepare cobalt aluminate spinel by a microwave-hydrothermal method and the effects of pH (4, 8 and 12), residence time (1 and 2 h), and temperature of the digestion system (190 and 220 oC) on the properties of final powders were studied. Moreover, mixed solutions of Al(NO3)3·9H2O, Co(NO3)2·6H2O and glycine were used as a precursor in the combustion synthesis method and the effect of different molar ratios of fuel to nitrate (0.36, 0.56) and calcination temperatures (800, 1000 oC) were evaluated. The powders obtained were characterized by XRD, XPS, SEM, TEM, FT-IR and UV-Vis. The results show that CoAl2O4 spinel is not formed by the microwave-hydrothermal method under the variable conditions studied, while the combustion synthesis method is capable of producing nano-particles of CoAl2O4 spinel and according to the results of TEM and Scherrer’s equation most of the particles have sizes less than 100 nm.
Shiva Salem 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.3
In this investigation, the normal nano-crystalline cobalt-aluminate spinel has been successfullysynthesized by the combustion technique. In order to study the colorant behavior of powders after heattreatment, quantitative and qualitative experiments such as color spectroscopy, X-ray and Ramanspectroscopy were applied. Transmission electron microscopy technique was used to estimate theparticle size and observe the morphology of pigments. The green powder was identified as an inversespinel structure whereas a normal spinel corresponding to blue color was produced at highertemperatures. For obtaining powder with the high colorant efficiency, it is better to carry out calcinationat 1000 ℃.
Shiva Salem,Amin Salem,Aylin Agha Babaei 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.23 No.-
The nano-porous adsorbents were initially produced by acid treatment of natural clay. The effects of some important factors such as acid type, concentration and residence time were evaluated on porous structure of adsorbent. A reduction about 2.7 A˚ was observed in the distance of montmorillonite layers due to replacement of hydrogen ions in the presence of sulfuric acid. The number of nano-pores, 12 nm, was preferable for removal of contaminations from spent engine oil, depending on the activation agent type in the treatment process. The results are very promising for reduction of adsorbent content in the regeneration of waste lubricant oil.
Amir Hossein Razm,Amin Salem,Shiva Salem 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.4
γ-Alumina powders were produced from the calcination of pseudo-boehmite for scavenging anionic blue (RS 150), and red (RB 133) dyes. The effects of calcination temperature, soaking time, pH, and nanoparticle dosage on dye adsorption were investigated to fabricate a reusable adsorbent. The mentioned dyes can be efficiently adsorbed over the γ-alumina nanoparticles if the calcination conditions, and pH are identified correctly. The powder calcined at 700 °C within 30 min inherently exhibited a high affinity towards blue dye at pH 5.0, while the proper adsorption towards red dye was achieved at pH 2.0. The maximal blue, and red dye adsorption capacities were determined to be 303, and 417 mg L−1, respectively. Although the calcination of boehmite at 1,000 °C led to the higher chemical resistance, the specific surface area significantly decreased from 202 to 126 m2 g−1, causing a significant drop in the adsorption of blue dye due to an increase in pore diameter, 6 nm. Importantly, the adsorptive performance of produced powder was stable with ten times thermal regeneration. Based on results obtained for the treatment of industrial textile wastewater, the fabricated γ-alumina powder is promising material to adsorb the anionic dyes.