Preparation of nano-MgO using ultrasonic method and its characteristics

Abstract

Introduction The alteration of the bulk electronic structure of nanosized materials causes change in the total energy of the system, so that, ignoring entropy considerations, it will thermody-namically stabilize the reduced scale system relative to that of normal bulk crystals. Such alterations may change the most energetically stable form of a particular material, as when small nanoparticles or nanodimensional layers adopt a crystal structure different from that of the normal bulk material. The surface area to volume ratio (S/V) and the specific surface area of a system are inversely proportional to particle size. Both S/V and specific surface area increase drastically for particles less than 100 nm in diameter. Reduction of the system size may change the chemical reactivity and physical properties such as electrical, thermal, optical and magnetic characteristics [1, 2]. Due to their different physical and chemical properties, nano-structured materials have received increasing attention in various fields of science and technology [3-5]. A variety of physicochemical methods, including metal evaporation [6], spray pyrolysis [7], sol-gel [8], hydrothermal synthesis [9] and electrochemical methods [10], have been used to produce nanometer-sized materials. Recently, the sonochemical methods have been shown to be very promising in the preparation of a variety of materials with nanometer dimensions, including nanochalcogenides [11, 12], metallic nanoparticles [13, 14] and nano-sized metal oxides [15, 16]. These materials possess improved magnetic properties [17], energy storage capacities [18-20] and photocatalytic [21] and catalytic properties [22]. 15 Abstract: MgO is an important inorganic material, which can be used in many aspects, such as catalyst , toxic-waste remediation agent, adsorbent, and others. In order to make use of MgO, nano-MgO was prepared by ultrasonic method using Mg (CH 3 COO) 2 .2H 2 O as precursor, NaOH aqueous solution as precipitant in this paper. Effect factors on MgO nano-particle size were investigated. Characteristics of samples were measured by TGA, XRD, TEM, and others techniques. The results showed that the size of nano-MgO about 4 nm could be obtained under the following conditions (ultrasonic time 20 min, ultrasonic power 250 W, titration rate of NaOH 0.25 mL/min, NaOH concentration 0.48 mol/L, calcinations temperature 410 °C, calcination time 1.5 h, heating rate of calcination 5 °C/min). It was a very simple and effective method to prepare nano-MgO.

Nanosize MgO as antibacterial agent: preparation and characteristics

“…Characteristics measurement of CaO nanoparticles were described previously in our group (Shi et al, 2012;Tang and Shi, 2008;. TGA measurements were carried out using a Netzsch STA 409 apparatus.…”

“…With prolonged calcination time, the process will be achieved completely. The crystal size grows for long times at high calcination temperatures (Shi et al, 2012;Tang and Shi, 2008). Thus, large size nanoparticles can be obtained.…”

“…Thus, through controlling calcination temperature and calcination time, nano-MgO with different sizes could be obtained. (Shi et al, 2012;Tang and Shi, 2008). In order to get smallest size particles, the calcination temperature was about 410 °C and calcination time was 1.5 h.…”

“…When the heating rate of calcination is very fast, aggregation of nano ZnO happens more easily, due to urgent collapse of the intermediate. When the heating rate of calcination is low, nano MgO exists for a long time at high calcination temperatures, which will decrease production efficiency (Shi et al, 2012;Tang and Shi, 2008). So, an optimized heating rate of calcination must exist.…”

“…MgO can be obtained mainly by thermal treatment of magnesium hydroxide or carbonate (Aramendia et al, 1996;Xu et al, 2001), and, more recently, by the sol-gel method (Choi and Hwang, 2000;López et al, 1998) and sonication method (Tang and Shi, 2008). In the sol-gel procedure, the fabrication of nanocrystalline and nanoparticulate metal oxides involves synthesis from methoxides or alkoxides of the metals followed by controlled drying or dehydration under vacuum (Stark et al, 1996;Znaidi et al, 1996;Koper et al, 1996).…”