The authors extend their appreciation to Dr. Thomas J. Emge and Wei Liu of Rutgers University for their analysis and expertise in small-angle X-ray diffraction and powder X-ray diffraction. Furthermore, the authors acknowledge Hao Wang for his support with the N2 adsorption experiments.

1. Al(OH)3 Nanoparticle Synthesis
<ol>
	<li>Dissolve 1.40 g of aluminum chloride hexahydrate in 5.822 g of deionized water.</li>
	<li>Add 2.778 g of L-arginine to the aqueous aluminum chloride solution while under magnetic stirring. Add the L-arginine slowly, so that the added arginine dissolves and does not form large clumps or chunks; furthermore, a slow addition reduces local concentrations of alkalinity and provides conditions for a more controllable hydrolysis.</li>
	<li>Once all the arginine dissolves ...

<ol>
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The authors have nothing to disclose.

The preparation of an aqueous aluminum chloride solution entailed the use of a crystalline hexahydrate salt of aluminum chloride. Although the anhydrous form can also be used, it is not preferred due to its significant hygroscopic properties, which make it difficult to work with and to control the concentration of aluminum. It is noteworthy that aluminum chloride solution should be used within several days of preparation because over time, the [Al(H2O)6]3+ aqua acid hydrolyzes to yield un...

Materials made of aluminum hydroxide are promising candidates for a variety of industrial applications, including catalysis, pharmaceuticals, water treatment, and cosmetics.1,2,3,4 At elevated temperatures, aluminum hydroxide absorbs a substantial amount of heat during decomposition to yield alumina (Al2O3), making it a useful flame-retarding agent.5 The four known polymorphs of aluminum hydroxide (i.e., gibbsite, bayerite, nordstrandite, and doyleite) have been investigated using computational and experimental techniques to improve our understanding of the formation and structures thereof6. The preparation of nanoscale particles is of particular interest due to their potential to exhibit quantum effects and properties differing from those of their bulk counterparts. Nanogibbsite particles with dimensions on the order of 100 nm are easily prepared under various conditions7,8,9,10,11,12,13,14.
Overcoming inherent challenges associated with reducing the particle sizes further is difficult; therefore, only a few cases exist where nanogibbsite particles have dimensions on the order of 50 nm.14,15,16,17 To the best of our knowledge, there have been no reports of nanogibbsite particles smaller than 50 nm. In part, this is attributed to the fact that nanoparticles tend to agglomerate due to electrostatic instability and the high probability for the formation of hydrogen bonds between the colloidal particles, especially in polar protic solvents. Our objective was to synthesize small Al(OH)3 nanoparticles by using exclusively safe ingredients and precursors. In the current work, aqueous particle aggregation was inhibited by incorporating an amino acid (i.e., L-arginine) as a buffer and stabilizer. Moreover, it is reported that the guanidinium-containing arginine prevented aluminum hydroxide particle growth and aggregation to yield an aqueous colloidal suspension with average particle sizes of 10-30 nm. It is proposed here that the amphoteric and zwitterionic properties of arginine mitigated the surface charge of aluminum hydroxide nanoparticles during the mild hydrolysis to disfavor particle growth beyond 30 nm. Although arginine was not capable of reducing the particle size below 10 nm, such particles were achieved by taking advantage of the &#34;cage&#34; confinement effect within the mesopores of MCM-41. Characterization of the Al-MCM-41 composite material revealed ultrafine aluminum hydroxide nanoparticles within the mesoporous silica, which has an average pore size of 2.7 nm.

<table border="0" cellpadding="0" cellspacing="0" width="650">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">aluminum chloride hexahydrate</td>
			<td style="width:103px;">Alfa Aesar</td>
			<td align="right" style="width:119px;">12297</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">L-arginine</td>
			<td style="width:103px;">BioKyowa</td>
			<td style="width:119px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">aluminum hydroxide</td>
			<td style="width:103px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">239186</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">Bio-Gel P-4 Gel</td>
			<td style="width:103px;">Bio-Rad</td>
			<td style="width:119px;">150-4128</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">Mesoporous siica (MCM-41 type)</td>
			<td style="width:103px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">643645</td>
			<td></td>
		</tr>
	</tbody>
</table>

facile preparation of ultrafine aluminum hydroxide particles with or without mesoporous mcm-41 in ambient environments

An aqueous suspension of nanogibbsite was synthesized via the titration of aluminum aqua acid [Al(H2O)6]3+ with L-arginine to pH 4.6. Since the hydrolysis of aqueous aluminum salts is known to produce a wide array of products with a wide range of size distributions, a variety of state-of-the-art instruments (i.e., 27Al/1H NMR, FTIR, ICP-OES, TEM-EDX, XPS, XRD, and BET) were used to characterize the synthesis products and identification of byproducts. The product, which was comprised of nanoparticles (10-30 nm), was isolated using gel permeation chromatography (GPC) column technique. Fourier transform infrared (FTIR) spectroscopy and powder X-ray diffraction (PXRD) identified the purified material as the gibbsite polymorph of aluminum hydroxide. The addition of inorganic salts (e.g., NaCl) induced electrostatic destabilization of the suspension, thereby agglomerating the nanoparticles to yield Al(OH)3 precipitate with large particle sizes. By utilizing the novel synthetic method described here, Al(OH)3 was partially loaded inside the highly ordered mesoporous framework of MCM-41, with average pore dimensions of 2.7 nm, producing an aluminosilicate material with both octahedral and tetrahedral Al (Oh/Td = 1.4). The total Al content, measured using energy-dispersive X-ray spectrometry (EDX), was 11% w/w with a Si/Al molar ratio of 2.9. A comparison of bulk EDX with surface X-ray photoelectron spectroscopy (XPS) elemental analysis provided insight into the distribution of Al within the aluminosilicate material. Furthermore, a higher ratio of Si/Al was observed on the external surface (3.6) as compared to the bulk (2.9). Approximations of O/Al ratios suggest a higher concentration of Al(O)3 and Al(O)4 groups near the core and external surface, respectively. The newly developed synthesis of Al-MCM-41 yields a relatively high Al content while maintaining the integrity of the ordered silica framework and can be used for applications where hydrated or anhydrous Al2O3 nanoparticles are advantageous.

Nanogibbsite Synthesis
Nanogibbsite was prepared by titrating AlCl3&#183;6H2O (14 wt%) with L-arginine to a final Arg/Al molar ratio of 2.75. The synthesis of nanogibbsite particles was monitored via SEC, which is a widely used analysis technique for partially hydrolyzed aluminum chloride solutions, capable of discerning five domains arbitrarily designated as peaks 1, 2, 3, 4, and 51...

Watch this Scientific Journal Video about Facile Preparation of Ultrafine Aluminum Hydroxide Particles with or without Mesoporous MCM-41 in Ambient Environments at JoVE.com

Facile Preparation of Ultrafine Aluminum Hydroxide Particles with or without Mesoporous MCM-41 in Ambient Environments

An ultrafine aluminum hydroxide nanoparticle suspension was prepared via the controlled titration of [Al(H2O)]3+ with L-arginine to pH 4.6 with and without cage-effect confinement within mesoporous channels of MCM-41.

An aqueous suspension of nanogibbsite was synthesized via the titration of aluminum aqua acid [Al(H2O)6]3+ with L-arginine to pH 4.6. Since the hydrolysis ...

The overall goal of this experiment is to develop a green methodology for the facile synthesis of stabilized ultra-fine aluminum hydroxide particles, which can be used to effectively introduce aluminum hydroxide or aluminum oxide onto a wide variety of materials. The newly developed synthesis produces a novel phase of ultra-fine aluminum hydroxide by implementing arginene as a mild base source. The main advantage of this technique is taking arginene, an edible basic amino acid, to neutralize aluminum chloride, to form ultra-fine aluminum hydroxide, and stabilize the particles.We solve agglomeration. The ability to prepare stabilized ultra-fine aluminum hydroxide paves the way for further structural and mechanistic studies, in attempts to better understand hydrolysis of aluminum monomers to bulk aluminum hydroxide. Demonstrating the procedure will be our intern, Viktor Dubovoy.To begin this procedure, dissolve 1.4 grams of aluminum chloride hexahydrate in 5.822 grams of deionized water. Slowly add 2.778 grams of L-arginine under magnetic stirring. Once the L-arginine is complete dissolved, heat the solution at 50 degrees celsius for 72 hours.Then, prepare gel permeation chromatography column by packing the gel in successive steps of adding gel, and then allowing water to flow through the column, to ensure proper packing. Pack the gel to approximately 80%of the column. Next, use an HPLC pump with a 10ml injector loop, to introduce 10ml of the synthesized ultra-fine aluminum hydroxide suspension into the column.Collect the majority of the peak-1 fraction over 100 minutes. Once a peak emerges on the LI detector, collect the LU end in 30 minute intervals. After this, add one weight percent solution of sodium chloride drop-wise to 10ml of the purified ultra-fine aluminum hydroxide, to induce precipitation.To begin, use a vacuum oven to activate one gram of MCM-41 at 120 degrees celsius under vacuum for three hours. Next, combine 9.6926 grams of aluminum chloride hexahydrate and 40.3074 grams of deionized water. Add 0.74 grams of activated MCM-41 to this aluminum chloride solution.Mix for one hour, to ensure homogeneity of the aluminum chloride diffused throughout the MCM-41 channels. Slowly add L-arginine under stirring, such that the final arginine-aluminum molar ratio is 2.75. Once the mixture is homogenous, heat it to 50 degrees celsius for 72 hours.After this, use a buchner funnel equipped with qualitative 90mm filter paper circles to filter the solution under vacuum. Wash the obtained aluminum MCM-41 material with excess deionized water. In this study, an ultra-fine aluminum hydroxide suspension is prepared, via the controlled titration of aluminum aqua acid with L-arginine.Magic angle spinning and MR analysis of the prepared aluminum MCM-41 material shows the presence of both octahedral and tetrahedral aluminum environments, which are commonly observed in mesoporus silica-modified aluminum species. Bulk and surface elemental composition data suggests that most of the aluminum penetrated into the pores, as opposed to building up on the surface. Small angle X-ray diffraction patterns are measured before and after aluminum loading, and are indexed based on hexagonal symmetry.Lattice reflections of 100, 110, 200 are observed in both samples, indicating that the insertion of aluminum had no significant impact on the highly-ordered porosity of MCM-41. Transmission electron microscopy of aluminum MCM-41 particles reveals that the silica framework remains intact after loading aluminum hydroxide particles. This technology can be feasibly scaled to synthesize commercial quantities of ultra-fine aluminum hydroxide, or aluminum functionized high-grade materials.This acid synthesis is not just extendable to aluminum hydroxide. It is also extendable to other metal oxides, which has far reaching applications in drug-delivery, catalysis, and personal care products. Why the synthesized repeat the amino acids but to generate the same purity and yield.

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10.7K Views.  Colgate-Palmolive Company. The overall goal of this experiment is to develop a green methodology for the facile synthesis of stabilized ultra-fine aluminum hydroxide particles, which can be used to effectively introduce aluminum hydroxide or aluminum oxide onto a wide variety of materials. The newly developed synthesis produces a novel phase of ultra-fine aluminum hydroxide by implementing arginene as a mild base source. The main advantage of this technique is taking arginene, an edible basic amino acid, to neutralize ...