Evaluation and Data Analysis of sol-gel method with acids to determine most effective sol-gel method

Synthesizing nanocomposite materials using sol-gel methodology is a cheap and effective method for creating quality U3O8 particles. To some degree acids can influence the synthesis of the nanoparticles by catalyzing the reaction. This paper presents important details comparing different acids used as catalysts in nanocomposite synthesis versus time manipulation to determine if an acid catalyst is necessary for the synthesis of U3O8/SiO2 nanocomposites.


INTRODUCTION
Nanoparticles are small particles with critical dimensions ranging from 1 to 100 nm. Additionally, these particles are composed of interfacial layers. Materials constructed as nanostructures provide novel performance and new properties. Hence, with each new property constructed, each material will contain unique characteristics and critical length associated with the desired material. 1 Solid nanoparticles form crystal structures through a specific arrangement of atoms. They have a long-range order which stems from the regularity of crystal arrangement extending through the crystal. 1 The periodic table contains numerous elements leaving scientists with the daunting task to construct nanoparticles each day. This experiment will solely focus on the nano construction of the rare earth metal, uranium.
Uranium is number 92 on the periodic table. It is considered a rare earth metal, located in the actinide series. Due to this element containing natural characteristics in earth one can infer uranium can provide positive benefits for the earth due to its structure and ability to donate ions. Currently, uranium compounds are being studied more closely due to their potentiality in benefiting environmental safety in maximizing the utilization of limited sources. [2][3][4] Upon studying uranium, the uranium framework contains linear structure ions and donor ions, through this characteristic one can confirm the donor atoms from the organic ligands will display uranyl equatorial positions which give rise to clusters, 1D chains, or 20 layers. [5][6][7][8][9][10] The challenge with this element stems from the element displaying different physical and chemical properties existing in four different oxidation states of +3, +4, +5, +6. The oxidation states of +3 and +5 are very stable, leading this earth metal to exist in oxidation phase UO2, U3O8, and U3O11.
This study aims to discuss the proper methodology for synthesizing U3O8 using the silica gel matrix for enhanced catalysis reactions in an aqueous environment at atmospheric pressure, provide the proper techniques on creating simple cost-effective composites, with the addition of acetic acid (CH₃COOH), Hydrochloric acid (HCl) and standard no acid to create a homogenous mixture after heat treatment was conducted on uranyl acetate for final confirmation; the protocol with the two acids can aid in providing homogenous mixture similar to no acid catalysis.

Sol-gel synthesis
The regents used in the following experiments were methanol purchased from Fisher scientific, tetramethyl orthosilicate (TMOS), uranyl acetate, oxalic acid, sodium hydroxide, hydrochloric acid, phenolphthalein, and de-ionized nano pure water (DI water) filtered in-house using a Millipore system. All glassware used in these experiments were thoroughly washed and oven dried unless noted.

Synthesis of U3O8/SiO2 Nanocomposites
The synthesis of U3O8/SiO2 nano composites was achieved with a solution containing 10 mL of TEOS, 0.6389 g uranyl acetate (UO2(CH3COO2)2•2H2O) and 3.5 mL of DI water. After, 2methyoxyethanol C3H8O2 was added to the solution and stirred for 20 minutes. The resulting preparation was aged for 72 h. The sample was then dried at 100° C for 4 h. In this work a material weight of 1.0556 g of material was calcinated under an N2 atmosphere for 4h.

Synthesis of U3O8/SiO2 Nanocomposites with acetic acid CH3COOH
The synthesis of U3O8/SiO2 nanocomposites with CH3COOH was achieved with a solution containing 0.6389 g uranyl acetate (UO2(CH3COO2)2•2H2O), 3.5 mL of DI water, 2methyoxyethanol C3H8O2 and 1.0 mL of catalysis added to the solution and stirred for 20 minutes. The resulting preparation was aged for 72 h. After it, the sample was dried at 100°C for 4 hours. In this work a material weight of 1.0556 g of material was calcinated for 4h under an N2 atmosphere for 4h. Samples grown under basic catalysis with different time intervals values are: 1h, 2h and 4h.

Synthesis of U3O8/SiO2 Nanocomposites with Hydrochloric acid (HCL)
The synthesis of U3O8/SiO2 nanocomposites with HCl was achieved with a solution containing 0.6389 g uranyl acetate (UO2(CH3COO2)2•2H2O), 3.5 mL of DI water, 2methyoxyethanol C3H8O2, and 1.0 mL of catalysis added to the solution and stirred for 20 minutes. The resulting preparation was aged for 72 h. After it, the sample was dried at 100°C for 4 h. In this work a material weight of 1. 0556 g of material was calcinated for 4 h under an N2 atmosphere for 4h. Samples grown under basic catalysis with different time intervals values are: 1h, 2h, and 4h.

Synthesis of Pure U3O8 (C4H6O6U)
The synthesis of pure U3O8 was achieved with 1.0930 g of pure (UO2(CH3COO2)2•2H2O) calcinated for 4h under an N2 atmosphere for 4h. Samples prepared in this manner serve as the control.

Characterization of sol-gel samples
FTIR measurements are presented in the figures below. conclusions are obtained with Fourier Transform infrared (FITR) instrumentation. This spectrum produces a profile of the sample thus creating a distinctive fingerprint which is then used to scan various known and unknown samples. FTIR is essential for detecting functional groups and characterizing covalent bonding information. There are many references of IR frequencies for various functional groups. This characterization is beneficial to the research because it allows for visualization and identification of any impurities in samples, and for indicating the absence or presence of nanocomposite production without impurities.
In the sol-gel process, the conversion of monomers to colloidal solutions creates an integrated polymer network. By adding strong acids to the sol-gel technique this creates a strong interconnected network. The goal of the experiment was to compare the two acids and prove if interconnection improved within the sol-gel samples. In the image below, the control was pure uranium salt. The Pure uranium salt confirms the solvent used was not contaminated and picked up both Silica and OH bonds which are standard.

FIGURE1.
Background spectrum shows pure uranium acetate, C4H6O6U, confirming pure sample, and acts as control of the experiment.

CONCLUSION
Although one can create uranium oxide using different methodology, this paper confirms sol gel synthesis can produce U3O8/SiO2 nanocomposites. Based on the above data, one can conclude using standard conditions with the absence of hydrochloric acid and acetic acid as catalysis present can produce homogeneous nanocomposites. One can use this cheap and costeffective synthesis method and add to further application ideas on soil, water and or bacteria for further studies.