I Heated Triton-x-100 stabilized Mg(OH)2 nanoparticles to gain MgO nanoparticles. This yields a gray color in the product not whitish MgO color. I heated the sample in a furnace to 500 degrees Celsius for four hours. Is it the burnt surfactant that gives rise to this color. But according to my knowledge Triton starts oxidizing at 230 Celsius and above 300 degrees most of the surfactants evapourates. Please help me out in this.
Synthesizing nanoparticles of magnesium oxide without surfactant. With the surfactant is gray of carbon. See the file.
Best regards.
I would first look at the cleanliness of your furnace. What else have you cooked in there? Decomposition of any surfactant will give rise to a darker color too - perhaps catalyzed by the Mg2+ . Not sure where you get your information that the surfactant evaporates at 300 C. Please indicate your source for this comment.
Synthesizing nanoparticles of magnesium oxide without surfactant. With the surfactant is gray of carbon. See the file.
Best regards.
Thank you very much. Appreciate it. Can't we remove the carbon by any means? I read that the thermal decomposition leaves the lipophilic component of Triton in the sample without decomposing.
The same source suggests the removal as "one can remove it completely from the fuel cell electrode whether in air or in nitrogen, in the case at 350~ or so and long time (above 30 min) heat treatment."
http://link.springer.com/article/10.1007/BF01107420
And I read in the following link
http://dowac.custhelp.com/app/answers/detail/a_id/2017/~/thermal-degradation-of-ethoxylated-nonionic-surfactants
Dear Kapila Elkaduwe,
Earlier, when I lived and worked in Russia, production of nano powders of MgO, were functioning in our company. We did not use any surfactants. The quality of the material is determined by only the precipitation regime. Nano powders get the perfect white.
However, if you think it necessary to use a surfactant in the synthesis, then you need to consider the following.
1. Structure of Triton-x-100 molecule contains carbon in the neo-structure and an aromatic ring. These structural elements lead to increased thermal stability and, consequently, to increase in temperature of decomposition and oxidation.
2. Surfactant molecules are on the surface of nano-particles, and some of them are inside the particles. This is due to the fact that the synthesis of magnesium hydroxide, in the initial stage, is formed a very developed pore structure.
These two factors in addition impede evaporation, thermal decomposition and oxidation of the surfactant due to diffusion processes. This leads to the formation of carbon particles, in the composition obtained magnesium oxide nanoparticles. To obtain the gray color of white material, enough to have a carbon content at the level of a few ppm.
From your situation is seen 2 outputs:
1. Rejection of the use of surfactants.
2. Increase the annealing temperature and the use of oxidative environment. 2. Increase the annealing temperature and the use of oxidative environment. For example, you can use a "fluidized bed", or to use high oxygen content in the furnace atmosphere.
With best regards
Professor Pavel Kudryavtsev
Dear all
Magnesium hydroxide Mg(OH)2 is considered as the precursor of MgO NPs. Mg(OH)2 and by stirring at room temperature for 3 hours, a mixture of aqueous solutions of magnesium nitrate, polyvinyl pyrrolidone, sodium bicarbonate and sodium hydroxide. Then Mg(OH)2 precipitate was filtered and dried at 800 oC for 1 hour. Then you ll calcinated at 3500 oC for 3 hours in a muffle furnace.
Dear Professor Pavel Kudryavtsev,
Thank you very much for the well elaborated reply. It helped me out a lot with my research. I feel that it is better to synthesis MgO nano particles without the use of surfactants.
Can the heating of the Mg(OH)2 nano particles lead to an agglomeration of some sort when converting to MgO?
Dear Raid Sahil Jawal,
Thank you for the reply. I will try out this method too.
@Kapila Yes, you will get aggregation of nanoparticles even at room temperature (solid-solid diffusion) and this will be increased the higher the temperature.
Dear Kapila,
Higher is solubility of the substance, the higher its agglomeration. Therefore, it may be better to go through the precipitation of carbonates and calcination at more than 800 ° C
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