Introduction
The aim of this report is to present a peer review critique on Simulation of adsorption of gold nanoparticles carried by gas ascending from the Earth’s interior in alluvial cover of the middle–lower reaches of the Yangtze River, the article published by J. J. Cao, X. Y. Hu, Z. T. Jiang, H. W. Li and X. Z. Zou in Geofluids in 2010.
The research initiated by the article authors was aimed at the determination of the possibilities for the gas-carried gold extraction from the surficial alluvial cover (Cao et el. 438). In particular, the authors touched upon the problem of endogenous processes which influence the minerals formation as well as the metals nanoparticles carriage and stated the hypothesis about the high degree of adsorption of gold nanorparticles by certain minerals in the surficial sediments.
The previous research and observations proved that gold nonoparticles are frequently carried by the gases formatting in the Earth magma and ascending through the rocks under the impact of pressure. In addition, the results of previous research shown that the majority of the concealed gold deposits can be mostly found in the layers of sedimentary rocks and surficial sediments.
The layer of the surficial sediments, which can be described as the combination of minerals resulted from the wind and water influence on the surface of the Earth, represents an interesting field for study. The urgency of the research presented in Simulation of adsorption of gold nanoparticles carried by gas ascending from the Earth’s interior in alluvial cover of the middle–lower reaches of the Yangtze River is connected to the scarce observations and investigation of the gold nanoparticles lying in the surficial sediments.
Materials and methods
In general, the processes of mineral formation on the Earth can be divided into two groups: the endogenous processes, which derive from the Earth magma resulting in the gas and water solutions, as well as the exogenous processes characterized by the impact of the external energy and proceeding on the surface of lithosphere.
Geologists classify the processes from both groups further. As regards the processes studied by the authors of the article, we can state that they concentrated their attention on the pneumatolytic process or the process of minerals formation from the ascending gases. This process relates to the endogenous group of processes.
“Metal nanoparticles attract strong interest both because they open up a new field in fundamental science and because of their potential technological applications” (“Gold nanoparticles”, par.2)
In order to test the hypothesis stated in the research the authors used the method of scientific experiment. They tested a sample of alluvium for the gold nanoparticles adsorption.
“Adsorption is the process through which a substance, originally present in one phase, is removed from that phase by accumulation at the interface between that phase and a separate (solid) phase” (Armenante par.1).
The sample was extracted from the alluvial cover of the middle–lower reaches of the Yangtze River (Cao et el. 439). The term of the alluvial cover can be briefly explained as surficial sediments in the river areas. After that, the geochemical method was applied with the purpose of gold nanoparticles extraction (Cao et el. 439).
The gold nanoparticles were generated by means of the usage of 2.5 ml of 1% aqueous HAuCl4 solution placed in a 250 ml graduated flask to which the high-purity water was added and that substance had been boiled for 10 min before trisodium citric acid; the reagent applied for gold nanoparticles, was added (Cao et el. 439).
The addition of the reagent allowed proving the formation of gold nanoparticles. “In any adsorption process the material being adsorbed is simply but effectively removed from one phase and transferred to another phase” (Armenante par.11)
In case of the research presented in the article the gold nanoparticles were used as the adsorbed material and the alluvium sample as the adsorbent. “The driving force for adsorption is the reduction in interfacial (surface) tension between the fluid and the solid adsorbent as a result of the adsorption of the adsorbate on the surface of the solid” (Armenante par.7).
The researchers also constructed the apparatus for simulation of the gold nanoparticles transfer by the ascending gases of the alluvium (Cao et el. 439). The scheme of the apparatus has been presented in the article. Then, the TEM (transmission electronic microscope) analysis was used to determine whether the substances contained in the alluvium sample adsorbed the gold nanoparticles (Cao et el. 439). The conclusions from the TEM analysis were supported by the images and were presented in the article.
Data analysis and conclusions
The analyzed TEM images showed that gold nanoparticles had been absorbed by hematite which presented the highest degree of absorbtivity (Cao et el. 441). In addition, the adsorption of gold nanoparticles had been observed by kaolinite, halloysite, and goethite (Cao et el. 438).
First of all, the results of the research allowed making a conclusion that the minerals from alluvial cover of the middle–lower reaches of the Yangtze River adsorb the gold nanoparticles. It can be claimed that there is a real possibility for extracting the gold nanoparticles from the surficial alluvial cover sediments (Cao et el. 444).
Secondly, the obtained results proved the effectiveness of the geochemical method for the discovery of gold nanoparticles (Cao et el. 444).
Overall, the results of the research can be used for further development of leaching methods of gold extraction (Cao et el. 444).
Critique
The article Simulation of adsorption of gold nanoparticles carried by gas ascending from the Earth’s interior in alluvial cover of the middle–lower reaches of the Yangtze River can be characterized as the valuable contribution to the global geological knowledge base.
The authors of the article used innovative approaches to the gold nanoparticles generation and simulation of their carriage by the ascending gases. Generally speaking, we can explain their approaches as artificial representation of the geological process using scientific methods. Furthermore, the results of their research advanced the methods of gold nanoparticles extraction.
The article is interesting and useful for studying. Although it is enriched with the specific terminology and can be difficult for in-depth understanding of the methods applied without any basic knowledge of the physical and chemical processes, the language and the structure of the article make it easier for understanding. In addition, the authors clearly described their conclusions allowing us to determine whether the results of their research were useful.
Taking into account, that the gold nanoparticles can be used in cancer therapy, the new methods of their extraction can save lives of many people suffering from this very often intractable disease. That is why medicine will surely be one of the major applicants of the developed method. The type of alluvial cover which contains the substances representing effective adsorbents for gold nanoparticles should be extracted not only in the region of the Yangtze River but in other parts of the world as well.
In summary, we can conclude that the article Simulation of adsorption of gold nanoparticles carried by gas ascending from the Earth’s interior in alluvial cover of the middle–lower reaches of the Yangtze River can be used as the scientific material for further research on the topic as well as educational material for the students majoring in Geology.
Works Cited
Armenante, P. M. n.d., Adsorption. n.d. Web.
Cao, J.J., Hu, X.Y., Jiang, Z.T., Li, H.W. and X. Z. Zou. ” Simulation of adsorption of gold nanoparticles carried by gas ascending from the Earth’s interior in alluvial cover of the middle–lower reaches of the Yangtze River.” Geofluids 10 (2010): 438-436. Print.
Gold nanoparticles. Web.