Name: extraction of ramie fiber in alkali hydrogen peroxide system supported by controlled-release alkali source
Uploaded: 2018-02-06T13:30:00
Description: Watch this Scientific Journal Video about Extraction of Ramie Fiber in Alkali Hydrogen Peroxide System Supported by Controlled-release Alkali Source at JoVE.com

This work was supported by the earmarked fund for China Agriculture Research System for Bast and Leaf Fiber Crops (grant number CARS-19), The China Academy of Agricultural Science and Technology Innovation Project (grant number ASTIP-IBFC07), The innovation fund for graduate students in Donghua University (grant number 16D310107), The &#39;Xiaoping science and technology innovation team&#39; (industrialization integrated R &#38; D group of bast fiber biological degumming), China Scholarship Council.

1. Oxidation Degumming of Ramie
<ol>
	<li>Preparing the oxidation degumming solution
	<ol>
		<li>Dissolve 2 g H2O2, 1 g alkali (a mixture of Mg(OH)2 and NaOH), 0.4 g Na5P3O10, 0.1 g anthraquinone, and 0.2 g HEDP in 100 mL distilled water to make the degumming solution.</li>
	</ol>
	</li>
	<li>Oxidation degumming of ramie
	<ol>
		<li>Immerse 10 g raw ramie in the degumming solution and scour it under 85 &#176;C for 60 min...

<ol>
	<li>Yuan, J. G., Yu, Y. Y., Wang, Q., Fan, X. R., Chen, S. Y., Wang, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modification+of+ramie+with+1-butyl-3-methylimidazolium+chloride+ionic+liquid.">Modification of ramie with 1-butyl-3-methylimidazolium chloride ionic liquid.</a> Fiber Polym. 14, 1254-1260 (2013).</li><li>Kipriotis, E., Heping, X., Vafeiadakis, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ramie+and+kenaf+as+feed+crops.">Ramie and kenaf as feed crops.</a> Ind Crop Prod. 68, 126-130 (2015).</li><li>Rebenfeld, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fiber:+the+old+and+the+new.">Fiber: the old and the new.</a> J Text Inst. 92, 1-9 (2001).</li><li>Ramamoorthy, S. K., Skrifvars, M., Persson, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+of+natural+fiber+used+in+biocomposites:+plant,+animal+and+regenerated+cellulose+fiber.">A review of natural fiber used in biocomposites: plant, animal and regenerated cellulose fiber.</a> Polym Rev. 55, 107-162 (2015).</li><li>Yu, H. Q., Yu, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+various+retting+methods+on+properties+of+kenaf+fiber.">Influence of various retting methods on properties of kenaf fiber.</a> J Text Inst. 101 (5), 452-456 (2010).</li><li>Fan, X. S., Liu, Z. W., Liu, Z. T., Lu, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+chemical+degumming+process+for+ramie+bast+fiber.">A novel chemical degumming process for ramie bast fiber.</a> Text Res J. 80, 2046-2051 (2010).</li><li>Liu, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Research on the application of sodium percarbonate the degumming of ramie. , (2013).</li><li>Meng, C. R., Yu, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Study+on+oxidation+degumming+of+ramie+fiber.">Study on oxidation degumming of ramie fiber.</a> Adv Mater Res. , 881-883 (2014).</li><li>Liu, Z. C., Duan, S. W., Sun, Q. X., Zhang, Y. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rapid+process+of+ramie+biodegumming+by+Pectobacterium+sp.+CXJZU-120.">A rapid process of ramie biodegumming by Pectobacterium sp. CXJZU-120.</a> Text Res J. 82 (15), 1553-1559 (2012).</li><li>Guo, F. F., Zou, M. Y., Li, X. Z., Zhao, J., Qu, Y. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+effective+degumming+enzyme+from+Bacillus+sp.+Y1+and+synergistic+action+of+hydrogen+peroxide+and+protease+on+enzymatic+degumming+of+ramie+fiber.">An effective degumming enzyme from Bacillus sp. Y1 and synergistic action of hydrogen peroxide and protease on enzymatic degumming of ramie fiber.</a> BioMed Res Int. , (2013).</li><li>Li, Z. L., Yu, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+peroxide+and+softness+modification+on+properties+of+ramie+fiber.">Effect of peroxide and softness modification on properties of ramie fiber.</a> Fiber Polym. 15, 2105-2111 (2014).</li><li>Li, Z. L., Meng, C. R., Yu, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+oxidized+cellulose+introduced+into+ramie+fiber+by+oxidation+degumming.">Analysis of oxidized cellulose introduced into ramie fiber by oxidation degumming.</a> Text Res J. 85 (20), 2125-2135 (2015).</li><li>Xueren, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Green bleaching technologies of pulp. , (2008).</li><li>Erkselius, S., Karlssom, O. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Free+radical+degradation+of+hydroxyethy+cellulose.">Free radical degradation of hydroxyethy cellulose.</a> Carbohydr Polym. 62, 344-356 (2005).</li><li>Meng, C. R., Liu, F. M., Li, Z. L., Yu, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+cellulose+protection+agent+used+in+the+oxidation+degumming+of+ramie.">The cellulose protection agent used in the oxidation degumming of ramie.</a> Textile Research Journal. 86 (10), 1109-1118 (2016).</li><li>Long, X., Xu, C., Du, J., Fu, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+TAED/H2O2/NaHCO3+system+as+an+approach+to+low-temperature+and+near-neutral+pH+bleaching+of+cotton.">The TAED/H2O2/NaHCO3 system as an approach to low-temperature and near-neutral pH bleaching of cotton.</a> Carbohydr Polym. 95, 107-113 (2013).</li><li>Yun, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Studies on magnesium-based hydrogen peroxide bleaching and mechanisms of deinked pulp. , (2014).</li><li>Zhang, W., Kong, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Replacement+of+sodium+peroxide+bleaching+by+magnesium-based+peroxide+bleaching+for+pulp.">Replacement of sodium peroxide bleaching by magnesium-based peroxide bleaching for pulp.</a> Paper Sci Technol. 29, 25-28 (2010).</li><li>Meng, C. R., Li, Z. L., Wang, C. Y., Yu, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alkali+Source+Used+in+the+Oxidation+Degumming+of+Ramie.">Alkali Source Used in the Oxidation Degumming of Ramie.</a> Text Res J. 87 (10), 1155-1164 (2017).</li><li>Gorski, D., Engstrand, P., Hill, J., Axelsson, P., Johansson, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mg(OH)2-based+hydrogen+peroxide+refiner+bleaching:+influence+of+extractives+content+in+dilution+water+on+pulp+properties+and+energy+efficiency.">Mg(OH)2-based hydrogen peroxide refiner bleaching: influence of extractives content in dilution water on pulp properties and energy efficiency.</a> Appita Journal. 63 (3), 218-225 (2010).</li><li>Leduc, C., Martel, J., Danea, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficiency+and+effluent+characteristic+from+Mg(OH)2-based+hydrogen+peroxide+bleaching+of+high-yield+pulps+and+deinked+pulp.">Efficiency and effluent characteristic from Mg(OH)2-based hydrogen peroxide bleaching of high-yield pulps and deinked pulp.</a> Cellulose Chemistry &amp; Technology. 44 (7-8), 271-276 (2010).</li></ol>

The setting of Mg(OH)2 substitution rate and reaction temperature was the key point of this protocol. Mg(OH)2 substitution rate can influence the pH value and thus oxidation ability of degumming solution. The best Mg(OH)2 substitution rate for ramie degumming was 20%, because cellulose cannot receive enough protection under a substitution rate below 20%, and an excessive amount of residual gums (low DP value and crystallinity) would be retained in fiber under a substitution rate above 20%...

Ramie, commonly known as &#39;China grass&#39; is a perennial herb whose fiber can be used as an excellent material for the textile industry1,2. It is one of the main economic crops native to China; the production of ramie in China has accounted for more than 90% of the total yield in the world1,2. Ramie fiber is one of the strongest and longest plant fibers, lustrous with an almost silky appearance3,4. The long length of ramie fiber make it suitable for single fiber spinning, which is seldom seen in bast fiber. The textile made from ramie fiber possesses many excellent properties, such as coolness, antibacterial, excellent thermal conductivity, ventilation, etc.3,4
Cellulose is the main component of ramie fibers, and the other components in ramie, such as pectin, lignin, water soluble materials, are defined as gums5,6. Ramie fiber can be extracted by dissolving the gums in solution containing chemical reagents, in a process defined as degumming5,6. Mainly two approaches of ramie fiber extraction exist: chemical degumming and bio-degumming. The energy consumption, time consumption, and COD value of degumming wastewater in traditional chemical degumming is rather high, as cellulose fiber is extracted by scouring raw ramie in concentrated NaOH under high pressure for 6 to 8 h7,8. Alternatively, bio-degumming is an eco-friendly option for ramie fiber extraction. Nevertheless, the harsh reaction condition and sophisticated equipment inhibit its further industrial application9,10. Therefore, oxidation degumming with alkali hydrogen peroxide presents a valuable and alternative application to focus on, for it requires shorter degumming time and lower degumming temperature11,12. However, due to the strong oxidation ability of the peroxides, substantial cellulose degradation may occur during the degumming process, which can cause great damage to fiber properties13,14. This is the biggest drawback of alkali peroxide oxidation degumming of ramie.
In previous studies, ramie fiber was extracted in an alkali hydrogen peroxide system supported only by sodium hydroxide15. However, due to the strong alkalinity of sodium hydroxide, the oxidation reaction speed of hydrogen peroxide was difficult to control and thus resulted in great damage to the treated fiber7. To improve the properties of ramie fiber, a controlled-release alkali source, which is composed of sodium hydroxide and magnesium hydroxide, is used in this study to offer an alkali condition and buffer the pH value of alkali hydrogen peroxide system16,17.
The rationale behind this technology can be described as follows. Magnesium hydroxide is slightly soluble in distilled water, and it can dissolve gradually into the degumming solution with the consumption of OH- and keep the pH value and thus oxidation ability of degumming solution in an appropriate range18. The substitution rate (SR) of magnesium hydroxide is defined as the mole proportion of NaOH replaced by magnesium hydroxide under the total alkali dosage of 10%, and the substitution rate can be calculated by the following equation. Moreover, Mg2+ can prevent cellulose degradation caused by over oxidation19,20.
<img alt="Equation 1" src="/files/ftp_upload/56461/56461eq1.jpg" />
Here, M2 (g) is the weight of Mg(OH)2, M1 (g) is the weight of NaOH, 40 is the molecular weight of NaOH, 58 is the molecular weight of Mg(OH)2, 2 is the number of OHs in Mg(OH)2, and SR is the substitution rate.
The technology of this protocol can be extended to the extracting, bleaching, and modifying of plant materials in an alkali hydrogen peroxide system. However, it must be noted that the selection of pH value and reaction temperature of the alkali hydrogen peroxide system is key for this technology21. The pH value of the alkali hydrogen peroxide system can be adjusted by changing the substitution rate17. The pH value and thus oxidation ability of the alkali hydrogen peroxide system decrease with the increasing of substitution rate. When the reaction temperature is set at 85 &#176;C, the free radical reaction plays the main role in the system and the strong oxidation of the system is suitable for dissolving materials; when the reaction temperature is set at 125 &#176;C, the free radical reaction is inhibited and a large amount of HOO exists in the system, which makes the system suitable for bleaching19.

<table>
	<tbody>
		<tr>
			<td>Hydrogen peroxide, 30%</td>
			<td>Fisher Scientific</td>
			<td>H325-100</td>
			<td>Chemical for degumming</td>
		</tr>
		<tr>
			<td>Magnesium hydroxide, 99%</td>
			<td>Fisher Scientific</td>
			<td>AA1236722</td>
			<td>Chemical for degumming</td>
		</tr>
		<tr>
			<td>Sodium hydroxide</td>
			<td>Fisher Scientific</td>
			<td>S318-1</td>
			<td>Chemical for degumming</td>
		</tr>
		<tr>
			<td>Sodium bisulfite</td>
			<td>Fisher Scientific</td>
			<td>S654-500</td>
			<td>Chemical for degumming</td>
		</tr>
		<tr>
			<td>Sodium tripolyphosphate</td>
			<td>Fisher Scientific</td>
			<td>AC218675000</td>
			<td>Chemical for degumming</td>
		</tr>
		<tr>
			<td>Anthraquinone, &#62;98%</td>
			<td>Fisher Scientific</td>
			<td>AC104930500</td>
			<td>Chemical for degumming</td>
		</tr>
		<tr>
			<td>1-Hydroxy Ethylidene-1,1-Diphosphonic Acid</td>
			<td>Fisher Scientific</td>
			<td>50-901-10243</td>
			<td>Chemical for degumming</td>
		</tr>
		<tr>
			<td>Degumming oil</td>
			<td>Minglong auxiliaries limited liability company, Yiyang, Hunan,China</td>
			<td>&#8212;&#8212;</td>
			<td>Chemical for degumming</td>
		</tr>
		<tr>
			<td>Ethyl alcohol</td>
			<td>Fisher Scientific</td>
			<td>A962-4</td>
			<td>Chemical for testing</td>
		</tr>
		<tr>
			<td>Benzene</td>
			<td>Fisher Scientific</td>
			<td>AA43817AE</td>
			<td>Chemical for testing</td>
		</tr>
		<tr>
			<td>Copper wire,0.5mm (0.02in) dia</td>
			<td>Fisher Scientific</td>
			<td>AA10783H4</td>
			<td>Chemical for testing</td>
		</tr>
		<tr>
			<td>Cupriethylenediamine solution 1mol/L</td>
			<td>Fisher Scientific</td>
			<td>24991</td>
			<td>Chemical for testing, caution toxic</td>
		</tr>
		<tr>
			<td>Nitric acid (65% ~68% )</td>
			<td>Fisher Scientific</td>
			<td>A200-612GAL</td>
			<td>Chemical for testing, caution</td>
		</tr>
		<tr>
			<td>Ethylenediamine</td>
			<td>Fisher Scientific</td>
			<td>AC118420100</td>
			<td>Chemical for testing</td>
		</tr>
		<tr>
			<td>Potassium permanganate</td>
			<td>Fisher Scientific</td>
			<td>P279-500</td>
			<td>Chemical for testing</td>
		</tr>
		<tr>
			<td>Sulphuric acid</td>
			<td>Fisher Scientific</td>
			<td>A300C-212</td>
			<td>Chemical for testing</td>
		</tr>
		<tr>
			<td>Silver sulfate</td>
			<td>Fisher Scientific</td>
			<td>S190-25</td>
			<td>Chemical for testing</td>
		</tr>
		<tr>
			<td>Raw ramie</td>
			<td>Guangyuan limited liability company, Changde, Hunan,China</td>
			<td>&#8212;&#8212;</td>
			<td>Raw materials</td>
		</tr>
		<tr>
			<td>Electric-heated&#160;thermostatic&#160;water&#160;bath</td>
			<td>Senxin Experiment equipment limited liability company,Shanghai,China</td>
			<td>DK-S28</td>
			<td>Equipments for degumming</td>
		</tr>
		<tr>
			<td>High temperature lbaorator dyeing machine</td>
			<td>Shanghai Longda chemcials Crop.</td>
			<td>RY-1261</td>
			<td>Equipments for degumming</td>
		</tr>
		<tr>
			<td>Thermometer</td>
			<td>Sichuan Shubo (group)Co.,Ltd</td>
			<td>100 &#176;C</td>
			<td>Equipments for degumming</td>
		</tr>
		<tr>
			<td>Vacuum suction machine</td>
			<td>Yukang KNET ,Shanghai,China</td>
			<td>SHB-IIIA</td>
			<td>Equipments for testing Mg(OH)2 solublity</td>
		</tr>
		<tr>
			<td>Suction flask</td>
			<td>Sichuan Shubo (group)Co.,Ltd</td>
			<td>1000mL</td>
			<td>Equipments for testing Mg(OH)2 solublity</td>
		</tr>
		<tr>
			<td>Sand-core funnels</td>
			<td>Sichuan Shubo (group)Co.,Ltd</td>
			<td>35mL</td>
			<td>Equipments for testing Mg(OH)2 solublity</td>
		</tr>
		<tr>
			<td>Oxidation reduction potential meter</td>
			<td>Dapu instrument, Shanghai, China</td>
			<td>MODEL 421</td>
			<td>Equipments for testing ORP value</td>
		</tr>
		<tr>
			<td>pH meter</td>
			<td>Hanna instruments,Beijing,China</td>
			<td>HI 98129</td>
			<td>Equipments for testing pH value</td>
		</tr>
		<tr>
			<td>Acid burette</td>
			<td>Sichuan Shubo (group)Co.,Ltd</td>
			<td>50mL</td>
			<td>Equipments for testing H2O2 content</td>
		</tr>
		<tr>
			<td>Flask</td>
			<td>Sichuan Shubo (group)Co.,Ltd</td>
			<td>250mL/500mL</td>
			<td>Equipments for testing H2O2 content;&#160; residual gums content</td>
		</tr>
		<tr>
			<td>Electric furnace</td>
			<td>Jiangyi Experiment instruments limited liability company,Shanghai,China</td>
			<td>800-2000W</td>
			<td>Equipments for testing residual gums content</td>
		</tr>
		<tr>
			<td>Reflux condensing tube</td>
			<td>Sichuan Shubo (group)Co.,Ltd</td>
			<td>250mL</td>
			<td>Equipments for testing residual gums content; COD value</td>
		</tr>
		<tr>
			<td>Fiber cutter (40mm)</td>
			<td>Changzhou No.2 Textile Machine Co.,Ltd</td>
			<td>Y171A</td>
			<td>Equipments for testing fiber density</td>
		</tr>
		<tr>
			<td>Ostwald viscometer</td>
			<td>Taizhou, jiaojiang, glass instruments company</td>
			<td>0.6mm</td>
			<td>Equipments for testing fiber PD value</td>
		</tr>
		<tr>
			<td>Spherical fat extractor</td>
			<td>Sichuan Shubo (group)Co.,Ltd</td>
			<td>250mL</td>
			<td>Equipments for testing fiber PD value</td>
		</tr>
		<tr>
			<td>Soxhlet extractor</td>
			<td>Sichuan Shubo (group)Co.,Ltd</td>
			<td>250mL</td>
			<td>Equipments for testing fiber PD value</td>
		</tr>
		<tr>
			<td>Torsion&#160;balance</td>
			<td>Liangping instrucments Co.,Ltd,Shanghai, China</td>
			<td>JN-B</td>
			<td>Equipments for testing fiber density</td>
		</tr>
		<tr>
			<td>Fiber strength instrument</td>
			<td>Xinxian instruments, shanghai,China</td>
			<td>XQ-2</td>
			<td>Equipments for testing fiber tensile property</td>
		</tr>
		<tr>
			<td>Tension clamp</td>
			<td>Depu textile technology Co.,Ltd, Changzhou, jiangsu, China</td>
			<td>0.3cN/dtex</td>
			<td>Equipments for testing fiber tensile property</td>
		</tr>
		<tr>
			<td>COD&#160;thermostatic&#160;heater</td>
			<td>Qiangdao Xuyu environment protection technology Lit company</td>
			<td>DL-801A</td>
			<td>Equipments for testing COD value</td>
		</tr>
		<tr>
			<td>FTIR</td>
			<td>Thermo Fisher, America</td>
			<td>Nicolet</td>
			<td>FTIR analysis</td>
		</tr>
		<tr>
			<td>XRD</td>
			<td>Rigaku, Japan</td>
			<td>D/max-2550 PC</td>
			<td>XRD analysis</td>
		</tr>
		<tr>
			<td>Electronic balance</td>
			<td>Shanghai jingtian Electronic instrument Co.,Ltd</td>
			<td>FA2004A</td>
			<td>Generral equipments</td>
		</tr>
		<tr>
			<td>Drying oven</td>
			<td>Tonglixinda&#160; instruments, Tianjin,China</td>
			<td>101-2AS</td>
			<td>Generral equipments</td>
		</tr>
		<tr>
			<td>Weighing bottle</td>
			<td>Sichuan Shubo (group)Co.,Ltd</td>
			<td>50x30</td>
			<td>Generral equipments</td>
		</tr>
		<tr>
			<td>Beaker</td>
			<td>Sichuan Shubo (group)Co.,Ltd</td>
			<td>500mL</td>
			<td>Generral equipments</td>
		</tr>
		<tr>
			<td>Sample sieve</td>
			<td>Xiaojin hardware instruments Co.,Ltd, Shangyu, Zhejiang</td>
			<td>120 mesh</td>
			<td>Generral equipments</td>
		</tr>
		<tr>
			<td>Glass rod</td>
			<td>Sichuan Shubo (group)Co.,Ltd</td>
			<td>&#8212;&#8212;</td>
			<td>Generral equipments</td>
		</tr>
		<tr>
			<td>Cylinder</td>
			<td>Sichuan Shubo (group)Co.,Ltd</td>
			<td>250mL, 50mL</td>
			<td>Generral equipments</td>
		</tr>
		<tr>
			<td>Pipette</td>
			<td>Sichuan Shubo (group)Co.,Ltd</td>
			<td>5mL, 10mL</td>
			<td>Generral equipments</td>
		</tr>
		<tr>
			<td>Rubber&#160;suction&#160;bulb</td>
			<td>Sichuan Shubo (group)Co.,Ltd</td>
			<td>&#8212;&#8212;</td>
			<td>Generral equipments</td>
		</tr>
		<tr>
			<td>Orign</td>
			<td>OriginLab</td>
			<td>8.0</td>
			<td>Software for figure drawing</td>
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extraction of ramie fiber in alkali hydrogen peroxide system supported by controlled-release alkali source

This protocol demonstrates a method for ramie fiber extraction by scouring raw ramie in an alkali hydrogen peroxide system supported by a controlled-release alkali source. The fiber extracted from ramie is a type of textile material of great importance. In previous studies, ramie fiber was extracted in an alkali hydrogen peroxide system supported only by sodium hydroxide.However, due to the strong alkalinity of sodium hydroxide, the oxidation reaction speed of hydrogen peroxide was difficult to control and thus resulted in great damage to the treated fiber. In this protocol, a controlled-release alkali source, which is composed of sodium hydroxide and magnesium hydroxide, is used to provide an alkali condition and buffer the pH value of the alkali hydrogen peroxidesystem. The substitution rate of magnesium hydroxide can adjust the pH value of the hydrogen peroxide system and has great influence on the fiber properties. The pH value and oxidation-reduction potential (ORP) value, which represents the oxidation ability of alkali hydrogen peroxide system, were monitored using a pH meter and ORP meter, respectively. The residual hydrogen peroxide content in the alkali hydrogen peroxide system during the extraction process and the chemical oxygen demand (COD) value of wastewater after fiber extraction are tested by KMnO4 titration method. The yield of fiber is measured using a precision electronic balance, and residual gums of fiber are tested by a chemical analysis method. The polymerization degree (PD value) of fiber is tested by an intrinsic viscosity method using the Ubbelohde viscometer. The tensile property of fiber, including tenacity, elongation, and rupture, is measured using a fiber strength instrument. Fourier transform infrared spectroscopy and X-ray diffraction are used to characterize the functional groups and crystal property of fiber. This protocol proves that the controlled-release alkali source can improve the properties of the fiber extracted in an alkali hydrogen peroxide system.

The solubility of Mg(OH)2 in distilled water and degumming solution was studied (Figure 1). The effect of Mg(OH)2 substitution rate on pH value and ORP value (Figure 2) of the degumming solution was tested. The degumming yield and residual gums of fiber degummed under various Mg(OH)2 substitution rate were calculated (Figure 3). DP value, crystallinity, tensile proper...

Watch this Scientific Journal Video about Extraction of Ramie Fiber in Alkali Hydrogen Peroxide System Supported by Controlled-release Alkali Source at JoVE.com

Extraction of Ramie Fiber in Alkali Hydrogen Peroxide System Supported by Controlled-release Alkali Source

Presented here is a protocol for extraction of ramie fiber in alkali hydrogen peroxide system supported by controlled-release alkali source.

This protocol demonstrates a method for ramie fiber extraction by scouring raw ramie in an alkali hydrogen peroxide system supported by a ...

The overall goal of this procedure is to improve the tensile properties of ramie fiber, prepared in a hydrogen peroxide oxidation degumming system by using a controlled release alkali source made by partially replacing sodium hydroxide with magnesium hydroxide. This method can help answer key questions in the field of oxidative extraction of natural fibers, such as extraction of ramie and flax fiber prepared in hydrogen peroxide oxidation degumming system. The main advantage of this technique is that pH and thus oxidation ability of the degumming solution can be controlled by adjusting the substitute rate of the magnesium hydroxide.We first had the idea for this method when we found that if sodium hydroxide was used as a alkaline source, the pH value of the degumming solution dropped quickly, making it difficult to control the hydrogen peroxide reaction speed. First, dissolve hydrogen peroxide, alkali, sodium triphosphate, anthraquinone, and HEDP in 100 milliliters of distilled water to make the degumming solution. Immerse 10 grams of raw ramie in the degumming solution and scour it at 85 degrees Celsius for 60 minutes.Following this, increase the temperature to 125 degrees Celsius and scour for another 60 minutes. Now, dissolve 0.4 grams of sodium bisulfite in 100 milliliters of distilled water to prepare the reducing solution. After scouring, treat the degummed ramie fiber in the reducing solution at 90 degrees Celsius for 60 minutes.After reducing the degummed ramie fiber, wash it thoroughly with deionized water. Immerse the fiber in degumming oil at 90 degrees Celsius for 15 minutes, then dry the fiber in an oven at 125 degrees Celsius for four hours. Prepare degumming solutions with magnesium hydroxide substitution rates of zero, 20, 40, 60, 80, and 100%as previously described.Immerse the raw ramie in the degumming solutions, then scour at 85 degrees Celsius for 60 minutes. Wash the combined ORP electrode with distilled water. After air drying, immerse the combined ORP electrode in the degumming solutions to record the ORP value every 10 minutes.Immerse the pH electrode in the degumming solutions to record the pH value every 10 minutes. Next, test the hydrogen peroxide content of the degumming solutions every 10 minutes by the potassium permanganate titration method according to the Chinese standard. Degrease the ramie fiber by submerging it in a two to one mixture of benzene and ethyl alcohol.After allowing the solvent to evaporate, cut the fiber into short pieces using scissors. Place the samples in a weighing container, and keep them in a controlled humidity atmosphere until it reaches equilibrium water content before removing for test purposes. Now, immerse a copper wire in concentrated nitric acid, followed by 98%anhydrous ethylenediamine.Then, wash the copper wire thoroughly with distilled water. Place the fiber sample and copper wire in a flask. Add 10 milliliters of distilled water and 10 milliliters of one mol per liter cupriethylenediamine solution to the glass bottle.Add a magnetic stir bar to the flask and stir the mixture for one hour to prepare the ramie fiber cupriethylenediamine solution. Following this, transfer 6.5 milliliters of the ramie fiber solution to an Ubbelohde viscometer to measure its intrinsic viscosity. Finally, set the clamping distance at 20 millimeters, and the descending speed of the bottom clamp at 20 millimeters per minute.After equilibrating the fiber samples under standard atmospheric conditions, test the tenacity, breaking elongation, and work of rupture of the fiber using the fiber strength instrument under the appropriate conditions. Although the solubility of magnesium hydroxide in degumming solution was higher than distilled water, due to the slight effect of degumming auxiliaries, it was still insufficiently soluble. When a controlled release alkali source was applied, the pH was stable, and decreased with increasing substitution rate.Decrease of the ORP value was slower under higher substitution rate. Residual gum analysis revealed that the yield of degumming and residual gums of fiber increased with the substitution rate. The DP value, crystallinity, and tensile properties increased with the substitution rate, but decreased with substitution rate higher than 20%The COD value decreased by 20%under the substitution rate of magnesium hydroxide.In FTIR patterns of the fiber, signals due to the stretching vibration of CH and OH and cellulose were observed. The carbinol peak was attributed to the CO stretching of COH bending and hemicellulose, and this signal was stronger when the substitution rate was lower, which indicates that hemicellulose can be removed more effectively under a lower substitution rate. Although the residual hydrogen peroxide contents increased when using the controlled release alkali source, the substitution rate did not influence the residual hydrogen peroxide content.Once mastered, this technique can be done in about 200 minutes if it is performed appropriately. While attempting this procedure, it's important to remember to control the substitution rate of the magnesium hydroxide. After its development, this technique paved the way for researchers in the field of oxidation natural fiber extraction, or bleaching.After watching this video, you should have a good understanding of how to adjust the pH value of working solution, with a controlled release alkali source, and the method of natural fiber extraction. Don't forget that working with cupriethylenediamine can be extremely hazardous, and appropriate precautions should always be taken while performing this procedure.

extraction-ramie-fiber-alkali-hydrogen-peroxide-system-supported

Research

JoVE Journal

Chemistry

Exfoliation of Egyptian Blue and Han Blue, Two Alkali Earth Copper Silicate-based Pigments

In a visualized example of the ancient past connecting with modern times, we describe the preparation and exfoliation of CaCuSi4O10 and BaCuSi4O10, the colored components of the historic Egyptian blue and Han blue pigments. The bulk forms of these materials are synthesized by both melt flux and solid-state routes, which provide some control over the crystallite size of the product. The melt flux process is time intensive, but it produces relatively large crystals at lower reaction temperatures. In comparison, the solid-state method is quicker yet requires higher reaction temperatures and yields smaller crystallites. Upon stirring in hot water, CaCuSi4O10 spontaneously exfoliates into monolayer nanosheets, which are characterized by TEM and PXRD. BaCuSi4O10 on the other hand requires ultrasonication in organic solvents to achieve exfoliation. Near infrared imaging illustrates that both the bulk and nanosheet forms of CaCuSi4O10 and BaCuSi4O10 are strong near infrared emitters. Aqueous CaCuSi4O10 and BaCuSi4O10 nanosheet dispersions are useful because they provide a new way to handle, characterize, and process these materials in colloidal form.

The preparation and exfoliation of CaCuSi4O10&#160;and BaCuSi4O10 are described. Upon stirring in hot water, CaCuSi4O10 spontaneously exfoliates into monolayers, whereas BaCuSi4O10&#160;requires ultrasonication in organic solvents. Near infrared (NIR) imaging illustrates the NIR emission properties of these materials, and aqueous dispersions of these nanomaterials are useful for solution processing.

In a visualized example of the ancient past connecting with modern times, we describe the preparation and exfoliation of CaCuSi4O10 and BaCuSi4O10, the ...

Preparing Adherent Cells for X-ray Fluorescence Imaging by Chemical Fixation

X-ray fluorescence imaging allows us to non-destructively measure the spatial distribution and concentration of multiple elements simultaneously over large or small sample areas. It has been applied in many areas of science, including materials science, geoscience, studying works of cultural heritage, and in chemical biology. In the case of chemical biology, for example, visualizing the metal distributions within cells allows us to study both naturally-occurring metal ions in the cells, as well as exogenously-introduced metals such as drugs and nanoparticles. Due to the fully hydrated nature of nearly all biological samples, cryo-fixation followed by imaging under cryogenic temperature represents the ideal imaging modality currently available. However, under the circumstances that such a combination is not easily accessible or practical, aldehyde based chemical fixation remains useful and sometimes inevitable. This article describes in as much detail as possible in the preparation of adherent mammalian cells by chemical fixation for X-ray fluorescent imaging.

Here, we present a protocol on how to determine the quantity and distribution of metals in a sample using synchrotron X-ray fluorescence. We focus on adherent cells, and describe the chemical fixation method to prepare this sample. We then describe how to mount and image the sample using synchrotron X-rays.

X-ray fluorescence imaging allows us to non-destructively measure the spatial distribution and concentration of multiple elements simultaneously over ...

Supercritical Nitrogen Processing for the Purification of Reactive Porous Materials

Supercritical fluid extraction and drying methods are well established in numerous applications for the synthesis and processing of porous materials. Herein, nitrogen is presented as a novel supercritical drying fluid for specialized applications such as in the processing of reactive porous materials, where carbon dioxide and other fluids are not appropriate due to their higher chemical reactivity. Nitrogen exhibits similar physical properties in the near-critical region of its phase diagram as compared to carbon dioxide: a widely tunable density up to ~1 g ml-1, modest critical pressure (3.4 MPa), and small molecular diameter of ~3.6 &#197;. The key to achieving a high solvation power of nitrogen is to apply a processing temperature in the range of 80-150 K, where the density of nitrogen is an order of magnitude higher than at similar pressures near ambient temperature. The detailed solvation properties of nitrogen, and especially its selectivity, across a wide range of common target species of extraction still require further investigation. Herein we describe a protocol for the supercritical nitrogen processing of porous magnesium borohydride.

Nitrogen is an effective supercritical fluid for extraction or drying processes due to its small molecular size, high density in the near-liquid supercritical regime, and chemical inertness. We present a supercritical nitrogen drying protocol for the purification treatment of reactive, porous materials.

Supercritical fluid extraction and drying methods are well established in numerous applications for the synthesis and processing of porous materials. ...

A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions

There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) hydrogen fuel cells. Researchers seeking to develop such systems require a method of measuring the generated hydrogen. Herein, we describe a simple, low-cost, and robust method to measure the hydrogen generated from the reaction of solids with aqueous solutions. The reactions are conducted in a conventional one-necked round-bottomed flask placed in a temperature controlled water bath. The hydrogen generated from the reaction in the flask is channeled through tubing into a water-filled inverted measuring cylinder. The water displaced from the measuring cylinder by the incoming gas is diverted into a beaker on a balance. The balance is connected to a computer, and the change in the mass reading of the balance over time is recorded using data collection and spreadsheet software programs. The data can then be approximately corrected for water vapor using the method described herein, and parameters such as the total hydrogen yield, the hydrogen generation rate, and the induction period can also be deduced. The size of the measuring cylinder and the resolution of the balance can be changed to adapt the setup to different hydrogen volumes and flow rates.

The study of methods to generate on-demand hydrogen for fuel cells continues to grow in importance. However, systems to measure hydrogen evolution from the reaction of chemicals with water can be complicated and expensive. This article details a simple, low-cost, and robust method to measure the evolution of hydrogen gas.

There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) ...

Real-time Breath Analysis by Using Secondary Nanoelectrospray Ionization Coupled to High Resolution Mass Spectrometry

Exhaled volatile organic compounds (VOCs) have aroused considerable interest, since they can serve as biomarkers for disease diagnosis and environmental exposure in a non-invasive manner. In this work, we present a protocol to characterize the exhaled VOCs in real time by using secondary nanoelectrospray ionization coupled to high resolution mass spectrometry (Sec-nanoESI-HRMS). The homemade Sec-nanoESI source was readily set up based on a commercial nanoESI source. Hundreds of peaks were observed in the background-subtracted mass spectra of exhaled breath, and the mass accuracy values are -4.0-13.5 ppm and -20.3-1.3 ppm in the positive and negative ion detection modes, respectively. The peaks were assigned with accurate elemental composition according to the accurate mass and isotopic pattern. Less than 30 s is used for one exhalation measurement, and it takes approximately 7 min for six replicated measurements.

A protocol for characterizing chemical composition of exhaled breath in real time by using secondary nanoelectrospray ionization coupled to high resolution mass spectrometry is demonstrated.

Exhaled volatile organic compounds (VOCs) have aroused considerable interest, since they can serve as biomarkers for disease diagnosis and environmental ...

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F&#8722;

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound electrons with neutral molecules/atoms. State-of-the-art in vacuo anion generation techniques allow application to a broad range of atomic, molecular, and cluster anion systems. These are separated and selected using time-of-flight mass spectrometry. Electrons are removed by linearly polarized photons (photo detachment) using table-top laser sources which provide ready access to excitation energies from the infra-red to the near ultraviolet. Detecting the photoelectrons with a velocity mapped imaging lens and position sensitive detector means that, in principle, every photoelectron reaches the detector and the detection efficiency is uniform for all kinetic energies. Photoelectron spectra extracted from the images via mathematical reconstruction using an inverse Abel transformation reveal details of the anion internal energy state distribution and the resultant neutral energy states. At low electron kinetic energy, typical resolution is sufficient to reveal energy level differences on the order of a few millielectron-volts, i.e., different vibrational levels for molecular species or spin-orbit splitting in atoms. Photoelectron angular distributions extracted from the inverse Abel transformation represent the signatures of the bound electron orbital, allowing more detailed probing of electronic structure. The spectra and angular distributions also encode details of the interactions between the outgoing electron and the residual neutral species subsequent to excitation. The technique is illustrated by the application to an atomic anion (F&#8722;), but it can also be applied to the measurement of molecular anion spectroscopy, the study of low lying anion resonances (as an alternative to scattering experiments) and femtosecond (fs) time resolved studies of the dynamic evolution of anions.

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F&lt;sup&gt;&amp;#8722;&lt;/sup&gt;

Here, we present a protocol for photoelectron imaging of anionic species. Anions generated in vacuo and separated by mass spectrometry are probed using velocity mapped photoelectron imaging, providing details of anion and neutral energy levels, anion and neutral structure and the nature of the anion electronic state.

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound ...

Extraction of Lignin with High &#946;-O-4 Content by Mild Ethanol Extraction and Its Effect on the Depolymerization Yield

Lignin valorization strategies are a key factor for achieving more economically competitive biorefineries based on lignocellulosic biomass. Most of the emerging elegant procedures to obtain specific aromatic products rely on the lignin substrate having a high content of the readily cleavable &#946;-O-4 linkage as present in the native lignin structure. This provides a miss-match with typical technical lignins that are highly degraded and therefore are low in &#946;-O-4 linkages. Therefore, the extraction yields, and the quality of the obtained lignin are of utmost importance to access new lignin valorization pathways. In this manuscript, a simple protocol is presented to obtain lignins with high &#946;-O-4 content by relatively mild ethanol extraction that can be applied to different lignocellulose sources. Furthermore, analysis procedures to determine the quality of the lignins are presented together with a depolymerization protocol that yields specific phenolic 2-arylmethyl-1,3-dioxolanes, which can be used to evaluate the obtained lignins. The presented results demonstrate the link between lignin quality and potential for the lignins to be depolymerized into specific monomeric aromatic chemicals. Overall, the extraction and depolymerization demonstrates a trade-off between the lignin extraction yield and the retention of the native aryl-ether structure and thus the potential of the lignin to be used as the substrate for the production of chemicals for higher-value applications.

Extraction of Lignin with High &amp;#946;-O-4 Content by Mild Ethanol Extraction and Its Effect on the Depolymerization Yield

Here, we present a protocol to perform ethanol extraction of lignin from several biomass sources. The effect of the extraction conditions on the lignin yield and &#946;-O-4 content are presented. Selective depolymerization is performed on the obtained lignins to obtain high aromatic monomer products.

Lignin valorization strategies are a key factor for achieving more economically competitive biorefineries based on lignocellulosic biomass. Most of the ...

U2O5 Film Preparation via UO2 Deposition by Direct Current Sputtering and Successive Oxidation and Reduction with Atomic Oxygen and Atomic Hydrogen

We describe a method to produce U2O5 films in situ using the Labstation, a modular machine developed at JRC Karlsruhe. The Labstation, an essential part of the Properties of Actinides under Extreme Conditions laboratory (PAMEC), allows the preparation of films and studies of sample surfaces using surface analytical techniques such as X-ray and ultra-violet photoemission spectroscopy (XPS and UPS, respectively). All studies are made in situ, and the films, transferred under ultra-high vacuum from their preparation to an analyses chamber, are never in contact with the atmosphere. Initially, a film of UO2 is prepared by direct current (DC) sputter deposition on a gold (Au) foil then oxidized by atomic oxygen to produce a UO3 film. This latter is then reduced with atomic hydrogen to U2O5. Analyses are performed after each step involving oxidation and reduction, using high-resolution photoelectron spectroscopy to examine the oxidation state of uranium. Indeed, the oxidation and reduction times and corresponding temperature of the substrate during this process have severe effects on the resulting oxidation state of the uranium. Stopping the reduction of UO3 to U2O5 with single U(V) is quite challenging; first, uranium-oxygen systems exist in numerous intermediate phases. Second, differentiation of the oxidation states of uranium is mainly based on satellite peaks, whose intensity peaks are weak. Also, experimenters should be aware that X-ray spectroscopy (XPS) is a technique with an atomic sensitivity of 1% to 5%. Thus, it is important to obtain a complete picture of the uranium oxidation state with the entire spectra obtained on U4f, O1s, and the valence band (VB). Programs used in the Labstation include a linear transfer program developed by an outside company (see Table of Materials) as well as data acquisition and sputter source programs, both developed in-house.

U2O5 Film Preparation via UO2 Deposition by Direct Current Sputtering and Successive Oxidation and Reduction with Atomic Oxygen and Atomic Hydrogen

This protocol presents the preparation of U2O5 thin films obtained in situ under ultra-high vacuum. The process involves oxidation and reduction of UO2 films with atomic oxygen and atomic hydrogen, respectively.

We describe a method to produce U2O5 films in situ using the Labstation, a modular machine developed at JRC Karlsruhe. The Labstation, an essential part ...

Experimental Methods for Efficient Solar Hydrogen Production in Microgravity Environment

Long-term space flights and cis-lunar research platforms require a sustainable and light life-support hardware which can be reliably employed outside the Earth's atmosphere. So-called 'solar fuel' devices, currently developed for terrestrial applications in the quest for realizing a sustainable energy economy on Earth, provide promising alternative systems to existing air-revitalization units employed on the International Space Station (ISS) through photoelectrochemical water-splitting and hydrogen production. One obstacle for water (photo-) electrolysis in reduced gravity environments is the absence of buoyancy and the consequential, hindered gas bubble release from the electrode surface. This causes the formation of gas bubble froth layers in proximity to the electrode surface, leading to an increase in ohmic resistance and cell-efficiency loss due to reduced mass transfer of substrates and products to and from the electrode. Recently, we have demonstrated efficient solar hydrogen production in microgravity environment, using an integrated semiconductor-electrocatalyst system with p-type indium phosphide as the light-absorber and a rhodium electrocatalyst. By nanostructuring the electrocatalyst using shadow nanosphere lithography and thereby creating catalytic 'hot spots' on the photoelectrode surface, we could overcome gas bubble coalescence and mass transfer limitations and demonstrated efficient hydrogen production at high current densities in reduced gravitation. Here, the experimental details are described for the preparations of these nanostructured devices and further on, the procedure for their testing in microgravity environment, realized at the Bremen Drop Tower during 9.3 s of free fall.

Efficient solar-hydrogen production has recently been realized on functionalized semiconductor-electrocatalyst systems in a photoelectrochemical half-cell in microgravity environment at the Bremen Drop Tower. Here, we report the experimental procedures for manufacturing the semiconductor-electrocatalyst device, details of the experimental set-up in the drop capsule and the experimental sequence during free fall.

Long-term space flights and cis-lunar research platforms require a sustainable and light life-support hardware which can be reliably employed outside the ...

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry

With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is designed and prepared according to the methodology developed by surface organometallic chemistry (SOMC). In this framework, catalytic cycles can be determined by isolating crucial intermediates. All air-sensitive materials are handled under inert atmosphere (using gloveboxes or a Schlenk line) or high vacuum lines (HVLs, &#60;10-5 mbar). The preparation of SiO2-700 (silica dehydroxylated at 700 &#176;C) and subsequent applications (the grafting of complexes and catalytic runs) requires the use of HVLs and double-Schlenk techniques. Several well-known characterization methods are used, such as Fourier-transform infrared spectroscopy (FTIR), elemental microanalysis, solid-state nuclear magnetic resonance spectroscopy (SSNMR), and state-of-the-art dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP-SENS). FTIR and elemental microanalysis permit scientists to establish the grafting and its stoichiometry. 1H and 13C SSNMR allows the structural determination of the hydrocarbon ligands coordination sphere. DNP SENS is an emerging powerful technique in solid characterization for the detection of poorly sensitive nuclei (15N, in our case). SiO2-700 is treated with about one equivalent of the metal precursor compared to the amount of surface silanol (0.30 mmol&#183;g-1) in pentane at room temperature. Then, volatiles are removed, and the powder samples are dried under dynamic high vacuum to afford the desired materials [(&#8801;Si-O-)Hf(&#951;2&#960;-MeNCH2)(&#951;1-NMe2)(&#951;1-HNMe2)]. After a thermal treatment under high vacuum, the grafted complex is converted into metal imido silica complex [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)]. [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] effectively promotes the metathesis of imines, using the combination of two imine substrates, N-(4-phenylbenzylidene)benzylamine, or N-(4-fluorobenzylidene)-4-fluoroaniline, with N-benzylidenetert-butylamine as substrates. A significantly lower conversion is observed with the blank runs; thus, the presence of the imido group in [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is correlated to the catalytic performance.

A new group IV metal catalyst for imine metathesis is prepared by grafting amine metal complex onto dehydroxylated silica. Surface metal fragments are characterized using FT-IR, elemental microanalysis, and solid-state NMR spectroscopy. Further dynamic nuclear polarization surface enhanced NMR spectroscopy experiments complement the determination of the coordination sphere.

With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is designed and prepared ...