Effect of process parameters on the morphology and adsorption properties of nanocrystalline boehmite/Uticaj procesnih parametara na morfologiju i adsorpcione osobine nanokristalnog bemita

• Published in: Hemijska industrija Vol. 68; no. 3; p. 357
• Main Authors: Obrenovic, Zoran, Nikolic, Ljubica M, Filipovic, Radislav, Milanovic, Marija, Stjepovic, Ivan
• Format: Journal Article
• Language: English
• Published: Association of Chemical Engineers of Serbia 01.05.2014
• Subjects: Adsorption; Aluminum oxide; Chemical properties; Identification and classification
• ISSN: 0367-598X; 2217-7426
• DOI: 10.2298/HEMIND130404060O

In the last decade, exploration of transition alumina phases with good adsorption properties has attracted a great research interest from both a fundamental and a practical point of view. The transition phases of alumina are metastable polymorphs of aluminum oxide formed through the thermal dehydration of aluminum trihydroxide and aluminum oxyhydroxide. Powder X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and low-temperature nitrogen absorption studies were employed to trace the formation of the transition phases of alumina. In this work transition alumina powders were synthesized starting from sodium aluminate solution prepared from Bayer liquor. The neutralization of sodium aluminate solution was performed with the use of sulphuric acid, while glucose was added in the starting solution. In this way, the single phase nanocrystalline boehmite was obtained. As-synthesized boehmite powders have high surface area (above 360 [m.sup.2]/g) and the average crystallite size less than 5 nm. The results showed that the properties of the powders (structure, morphology) are strongly influenced by the initial pH value of sodium aluminate solution, as well as by the duration of neutralization step. Keywords: Sodium aluminate * Nanocrystalline boehmite * Neutralization * Morphology of particles * Specific surface area * Pore volume * Pore size distribution Dobijanje razlicitih prelaznih faza [Al.sub.2][O.sub.3] dobrih adsorpcionih osobina poslednjih decenija privlaci veliku paznju istrazivaca kako sa aspekta istrazivanja tako i sa aspekta primene ovih materijala. Prelazne [Al.sub.2][O.sub.3] faze predstavljaju metastabilne polimorfne oblike alumine koje nastaju pri dehidrataciji aluminijum-hidroksidnih (gibsita i bajerita) ili aluminijum-oksihidroksidnih prahova (bemita). U ovom radu sintetisan je nanokristalni bemit polazeci od rastvora natrijum-aluminata, dobijenog u Bajerovom postupku. U procesu neutralizacije sumpornom kiselinom, podesavanjem procesnih parametara i dodatkom glukoze, dobijen je nanokristalni bemit, prosecne velicine kristalita ispod 5 nm i specificne povrsine iznad 360 [m.sup.2]/g. Za analizu faznog sastava, strukture i morfologije dobijenih prahova primenjene su sledece metode: rentgenska difrakcija, XRD, Furije transformisana infracrvena spektroskopija, FT-IR, skenirajuca elektronska mikroskopija, SEM i niskotemperaturna adsorpcija azota. Rezultati su pokazali da je, bez obzira na uslove sinteze, a uz koriscenje glukoze, moguce dobiti nanokristalni bemitni prah, na relativno niskoj temperaturi. Pri tome je pokazano da karakteristike praha (struktura i morfologija) zavise od pH vrednosti polaznog rastvora kao i od vremena trajanja reakcije neutralizacije. Kljucne reci: natrijum-aluminat, nanokristalni bemit, neutralizacija, morfologija cestica, specificna povrsina, zapremina pora, raspodela pora po velicini. Dostupno na Internetu sa adrese casopisa: