Tag Archives: green chemistry

Synthesizing titanium dioxide nanoparticles with herbal extracts

Leave a reply

It was somewhat unexpected to see a science collaboration between an Iranian researcher and an Iraqi researcher given the two countries engaged in a hard-fought war for almost eight years (1980 – 88). However, since almost 30 years have passed, it seems at least two people feel it’s time to approach things differently. A Jan. 28, 2016 news item on Nanotechnology Now announces the research,

Environmental preservation is today one of the greatest concerns of scientists in all scientific aspects.

Given the direct effect of chemical industry on environment, chemists try to present new methods for the synthesis of materials with less chemical pollution but more biocompatibility.

Iranian and Iraqi researchers studied the possibility of the application of herbal extracts to synthesize titanium dioxide nanoparticles. Results prove that the herbal extract enables production of nanoparticles at a higher rate and efficiency but less environmental pollution.

A Jan. 28, 2016 Fars Agency news release, which originated the news item, expands on the theme,

The aim of the research was to synthesize titanium dioxide nanoparticles in a simple, fast and cost effective manner with high efficiency in the presence of Euphorbia heteradena Jaub extract. This plant is found commonly in the western and central parts of Iran.

The nanoparticles also have application in the degradation of organic materials and water and wastewater purification due to their appropriate stability, non-toxicity and photocatalytic activity.

The method presented in this research is in agreement with global standards of green chemistry unlike other chemical methods. In fact, no toxic solvent or reactant (such as chemical reducers and stabilizers) has been used in this method. Elimination of by-products during the synthesis of nanoparticles and ease of production scaling up from laboratorial scale to industrial one are among the other advantages of the new method.

According to the researchers, instability of the synthetic nanoparticles is one of the challenges in previous studies. However, experiments suggest that no structural change is observed in the synthetized nanoparticles even after two months.

Here’s a link to and a citation for the researchers’ 2015 paper,

Synthesis and characterization of titanium dioxide nanoparticles using Euphorbia heteradena Jaub root extract and evaluation of their stability by Mahmoud Nasrollahzadeh, S. Mohammad Sajad. Ceramics International Volume 41, Issue 10, Part B, December 2015, Pages 14435–14439 doi:10.1016/j.ceramint.2015.07.079 Available online 21 July 2015

This paper is behind a paywall.

Using stevia to synthesize gold nanoparticles?

Leave a reply

The research into using stevia as a greener alternative to synthesize gold nanoparticles is from Iran (from a June 2, 2015 news item on Nanotechology Now),

Iranian researchers suggested the extract of stevia plant as a replacement for chemical solvents and reducers in the synthesis of gold nanoparticles.

A May 31, 2015 Iran Nanotechnology Initiative Council news release, which originated the news item, provides a little more detail,

Various chemical methods have been proposed for the synthesis of gold nanoparticles as the application of these particles has increased. These methods cause some problems, including environmental pollution and difficulty in synthesis. This research studied the possibility of using stevia leaf extract to reduce gold ions into atomic nanoparticles.

According to the researchers, the extract of stevia plant is biocompatible and it acts as a reducing and stabilizing agent. In addition, the simplicity of the method easily makes possible the quick biosynthesis of gold nanoparticles in different sizes.

Since the antibacterial effect of gold nanoparticles has been proved, these materials can be used in the production of detergents, packaging industry and production of medical drugs.

Gold nanoparticles stabilized with stevia extract in this research are absorbed by cells more than nanoparticles coated with chemical stabilizers (polymers). The reason is that nanoparticles stabilized with herbal extract contain various proteins and fibers on their surface. Therefore, the nanoparticles are more probable to diffuse into the cells through the multiple receivers of protein in comparison with the dual receiver of protein and chemical polymer. Therefore, it is expected that the transfer of protein and drugs into the cells can be adjusted by changing the size and shape of the nanoparticles.

Here’s a link to and a citation for the paper,

GC–MS analysis of bioactive components and synthesis of gold nanoparticle using Chloroxylon swietenia DC leaf extract and its larvicidal activity by Govindasamy Balasubramani, Rajendiran Ramkumar, Narayanaswamy Krishnaveni, Rajamani Sowmiya, Paramasivam Deepak, Dhayalan Arul, & Pachiappan Perumal. Journal of Photochemistry and Photobiology B: Biology Volume 148, July 2015, Pages 1–8  doi:10.1016/j.jphotobiol.2015.03.016

This paper is behind a paywall.

Transmetalation, substituting one set of metal atoms for another set

Leave a reply

Transmetalation bears a resemblance of sorts to transmutation. While the chemists from the University of Oregon aren’t turning lead to gold through an alchemical process they are switching out individual metal atoms, aluminum for indium. From a July 21, 2014 news item on ScienceDaily,

The yield so far is small, but chemists at the University of Oregon have developed a low-energy, solution-based mineral substitution process to make a precursor to transparent thin films that could find use in electronics and alternative energy devices.

A paper describing the approach is highlighted on the cover of the July 21 [2014] issue of the journal Inorganic Chemistry, which draws the most citations of research in the inorganic and nuclear chemistry fields. [emphasis mine] The paper was chosen by the American Chemical Society journal as an ACS Editor’s Choice for its potential scientific and broad public interest when it initially published online.

One observation unrelated to the research, the competition amongst universities seems to be heating up. While journals often tout their impact factor, it’s usually more discreetly than in what amounts to a citation in the second paragraph of the university news release, which originated the news item.

The July 21, 2014 University of Oregon news release (also on EurekAlert), describes the work in more detail,

The process described in the paper represents a new approach to transmetalation, in which individual atoms of one metal complex — a cluster in this case — are individually substituted in water. For this study, Maisha K. Kamunde-Devonish and Milton N. Jackson Jr., doctoral students in the Department of Chemistry and Biochemistry, replaced aluminum atoms with indium atoms.

The goal is to develop inorganic clusters as precursors that result in dense thin films with negligible defects, resulting in new functional materials and thin-film metal oxides. The latter would have wide application in a variety of electronic devices.

“Since the numbers of compounds that fit this bill is small, we are looking at transmetelation as a method for creating new precursors with new combinations of metals that would circumvent barriers to performance,” Kamunde-Devonish said.

Components in these devices now use deposition techniques that require a lot of energy in the form of pressure or temperature. Doing so in a more green way — reducing chemical waste during preparation — could reduce manufacturing costs and allow for larger-scale materials, she said.

“In essence,” said co-author Darren W. Johnson, a professor of chemistry, “we can prepare one type of nanoscale cluster compound, and then step-by-step substitute out the individual metal atoms to make new clusters that cannot be made by direct methods. The cluster we report in this paper serves as an excellent solution precursor to make very smooth thin films of amorphous aluminum indium oxide, a semiconductor material that can be used in transparent thin-film transistors.”

Transmetalation normally involves a reaction done in organic chemistry in which the substitution of metal ions generates new metal-carbon bonds for use in catalytic systems and to synthesize new metal complexes.

“This is a new way to use the process,” Kamunde-Devonish said, “Usually you take smaller building blocks and put them together to form a mix of your basic two or three metals. Instead of building a house from the ground up, we’re doing some remodeling. In everyday life that happens regularly, but in chemistry it doesn’t happen very often. We’ve been trying to make materials, compounds, anything that can be useful to improve the processes to make thin films that find application in a variety of electronic devices.”

The process, she added, could be turned into a toolbox that allows for precise substitutions to generate specifically desired properties. “Currently, we can only make small amounts,” she said, “but the fact that we can do this will allow us to get a fundamental understanding of how this process happens. The technology is possible already. It’s just a matter of determining if this type of material we’ve produced is the best for the process.”

Here’s a citation for and a link to the paper,

Transmetalation of Aqueous Inorganic Clusters: A Useful Route to the Synthesis of Heterometallic Aluminum and Indium Hydroxo—Aquo Clusters by Maisha K. Kamunde-Devonish, Milton N. Jackson, Jr., Zachary L. Mensinger, Lev N. Zakharov, and Darren W. Johnson. Inorg. Chem., 2014, 53 (14), pp 7101–7105 DOI: 10.1021/ic403121r Publication Date (Web): April 18, 2014

Copyright © 2014 American Chemical Society

This paper appears to be open access (I was able to view the HTML version when I clicked).

Green chemistry and zinc oxide nanoparticles from Iran (plus some unhappy scoop about Elsevier and access)

Leave a reply

It’s been a while since I’ve featured any research from Iran partly due to the fact that I find the information disappointingly scant. While the Dec. 22, 2013 news item on Nanowerk doesn’t provide quite as much detail as I’d like it does shine a light on an aspect of Iranian nanotechnology research that I haven’t previously encountered, green chemistry (Note: A link has been removed),

Researchers used a simple and eco-friendly method to produce homogenous zinc oxide (ZnO) nanoparticles with various applications in medical industries due to their photocatalytic and antibacterial properties (“Sol–gel synthesis, characterization, and neurotoxicity effect of zinc oxide nanoparticles using gum tragacanth”).

Zinc oxide nanoparticles have numerous applications, among which mention can be made of photocatalytic issues, piezoelectric devices, synthesis of pigments, chemical sensors, drug carriers in targeted drug delivery, and the production of cosmetics such as sunscreen lotions.

The Dec. 22, 2013 Iran Nanotechnology Initiative Council (INIC) news release, which originated the news item, provides a bit more detail (Note: Links have been removed),

By using natural materials found in the geography of Iran and through sol-gel technique, the researchers synthesized zinc oxide nanoparticles in various sizes. To this end, they used zinc nitrate hexahydrate and gum tragacanth obtained from the Northern parts of Khorassan Razavi Province as the zinc-providing source and the agent to control the size of particles in aqueous solution, respectively.

Among the most important characteristics of the synthesis method, mention can be made of its simplicity, the use of cost-effective materials, conservation of green chemistry principals to prevent the use of hazardous materials to human safety and environment, production of nanoparticles in homogeneous size and with high efficiency, and most important of all, the use of native materials that are only found in Iran and its introduction to the world.

Here’s a link to and a citation for the paper,

Sol–gel synthesis, characterization, and neurotoxicity effect of zinc oxide nanoparticles using gum tragacanth by Majid Darroudi, Zahra Sabouri, Reza Kazemi Oskuee, Ali Khorsand Zak, Hadi Kargar, and Mohamad Hasnul Naim Abd Hamidf. Ceramics International, Volume 39, Issue 8, December 2013, Pages 9195–9199

There’s a bit more technical information in the paper’s abstract,

The use of plant extract in the synthesis of nanomaterials can be a cost effective and eco-friendly approach. In this work we report the “green” and biosynthesis of zinc oxide nanoparticles (ZnO-NPs) using gum tragacanth. Spherical ZnO-NPs were synthesized at different calcination temperatures. Transmission electron microscopy (TEM) imaging showed the formation most of nanoparticles in the size range of below 50 nm. The powder X-ray diffraction (PXRD) analysis revealed wurtzite hexagonal ZnO with preferential orientation in (101) reflection plane. In vitro cytotoxicity studies on neuro2A cells showed a dose dependent toxicity with non-toxic effect of concentration below 2 µg/mL. The synthesized ZnO-NPs using gum tragacanth were found to be comparable to those obtained from conventional reduction methods using hazardous polymers or surfactants and this method can be an excellent alternative for the synthesis of ZnO-NPs using biomaterials.

I was not able to find the DOI (digital object identifier) and this paper is behind a paywall.

Elsevier and access

On a final note, Elsevier, the company that publishes Ceramics International and many other journals, is arousing some ire with what appears to be its latest policies concerning access according to a Dec. 20, 2013 posting by Mike Masnick for Techdirt Note: Links have been removed),

We just recently wrote about the terrible anti-science/anti-knowledge/anti-learning decision by publishing giant Elsevier to demand that Academia.edu take down copies of journal articles that were submitted directly by the authors, as Elsevier wished to lock all that knowledge (much of it taxpayer funded) in its ridiculously expensive journals. Mike Taylor now alerts us that Elsevier is actually going even further in its war on access to knowledge. Some might argue that Elsevier was okay in going after a “central repository” like Academia.edu, but at least it wasn’t going directly after academics who were posting pdfs of their own research on their own websites. While some more enlightened publishers explicitly allow this, many (including Elsevier) technically do not allow it, but have always looked the other way when authors post their own papers.

That’s now changed. As Taylor highlights, the University of Calgary sent a letter to its staff saying that a company “representing” Elsevier, was demanding that they take down all such articles on the University’s network.

While I do feature the topic of open access and other issues with intellectual property from time to time, you’ll find Masnick’s insights and those of his colleagues are those of people who are more intimately familiar (albeit firmly committed to open access) with the issues should you choose to read his Dec. 20, 2013 posting in its entirely.

Put some iron in your perfume and in your drugs

Leave a reply

A Nov. 28, 2013 University of Toronto (Ontario, Canada) news release (also on EurekAlert) by Sean Bettan describes a new ‘green’ process, featuring iron, for use in the drug and perfume industries,

University of Toronto researchers have developed a series of techniques to create a variety of very active iron-based catalysts necessary to produce certain compounds used in the drug and perfume industry. The new synthetic methods promise to be safer, more economical and more environmentally friendly than traditional industrial processes.

There’s not much detail in the news release about this interesting work,

“There is a research effort world-wide to make chemical processes more sustainable and green, by replacing the rare, expensive and potentially toxic elements used in hydrogenation, catalytic converters in cars, fuel cells for the efficient conversion of chemical energy into electricity, and silicone coatings, with abundant ions such as iron,” says U of T chemistry professor Robert Morris, principal investigator of a study reported in the November 29 issue of Science. “Iron is about 10,000 times cheaper to obtain than ruthenium. Less than 200 metric tons of platinum-type metals are mined in the world every year and not all of it can be recycled after use. They are not essential to life and can be toxic.”

“We found a way to make the ferrous form of iron behave in a catalytic process much more efficiently than a precious metal.  We did this by finding molecules containing nitrogen, phosphorus, carbon and hydrogen, that bond to, and enhance, the reactivity of iron,” says Morris.

The scientists inexpensively produced varieties of alcohol with different biological properties — which can be used in flavour and drug synthesis — and different smells, a property important to the perfume industry. In one example from the study, the precursor alcohol to a cancer treatment can be made using the hydrogenation process catalyzed by iron. Using iron, the resulting complex is often a better catalyst than the industrial one based on ruthenium.

Here’s a link to and a citation for the paper,

Amine(imine)diphosphine Iron Catalysts for Asymmetric Transfer Hydrogenation of Ketones and Imines by Weiwei Zuo, Alan J. Lough, Young Feng Li, & Robert H. Morris. Science 29 November 2013: Vol. 342 no. 6162 pp. 1080-1083 DOI: 10.1126/science.1244466

This paper is behind a paywall.

Occasionally, I write about green chemistry as I did in a Jan. 10, 2011 posting about a McGill University (Montreal, Quebec, Canada) green chemistry breakthrough and about cinnamon-based green chemistry.

GreenCentre Canada births Precision Molecular Design Corporation

Leave a reply

An Aug. 9, 2013 news item on Azonano features Ontario Network of Excellence (ONE) member, Centre of Excellence for Commercialization and Research (CECR) member, and business incubator, GreenCentre Canada,

GreenCentre Canada has recently incorporated its third spinoff company, Precision Molecular Design Corporation. Based on a technology invented at Carleton University, Precision Molecular Design’s proprietary ALD precursors enable “greener” production of smaller and faster microchips for the semiconductor industry.

The Aug. 8, 2013 GreenCentre Canada news release, which originated the news item, describes the innovation and the new company,

Precision Molecular Design’s breakthrough metal deposition technology allows manufacturers to generate circuit interconnects in successive layers one atom at a time. This will allow the semiconductor industry to develop the next generation of smaller microchips, ushering in new miracles of miniaturization. The technology will also enable the production of microchips with less waste and lower power consumption. For the consumer, this means longer battery life, more convenient sizing, less heat generation and a reduced carbon footprint.
Invented by Professor Sean Barry of Carleton, GreenCentre originally supported this breakthrough ALD technology with proof-of-principle funding of $16,000 and, in 2011, in-licensed the technology for continued commercial development. In 2012, GreenCentre licensed the technology to Digital Specialty Chemicals, a fine chemical manufacturer, to develop an industrial process to manufacture the precursors.

Precision Molecular is now looking for investors and partners for their precursors and offer development and contract services for the development of materials and processes for the ALD market.

Launched in July 2013, the Precision Molecular Design website is here.

As for its progenitor, GreenCentre Canada, here’s a little more about the organization from its About Us page (Note: Links have been removed),

Formed in 2009 and funded by the governments of Ontario and Canada, and industry, GreenCentre is a member of the Ontario Network of Excellence (ONE) and the Centres of Excellence for Commercialization and Research (CECR).  GreenCentre’s product and application development activities are housed in a 10,000 square foot facility dominated by state-of-the-art web labs with solvent-handling systems, inert atmosphere glove boxes and standard analytical equipment. GreenCentre is located at Innovation Park at Queen’s University in Kingston, Ontario, Canada.

The organization’s main focus is on developing green chemistry solutions and, presumably, new businesses.

Canadian and Japanese researchers create new technique for using iron nanoparticles in greener hydrogenation process

Leave a reply

McGill University’s Audrey Moores and her team’s latest green chemistry work with researchers at RIKEN (The Institute of Physical and Chemical Research, Wako, Japan) and the Institute for Molecular Science (Okazaki, Japan) is featured in a June 27, 2013 news item on Nanowerk,

Researchers from McGill University, RIKEN (The Institute of Physical and Chemical Research, Wako, Japan) and the Institute for Molecular Science (Okazaki, Japan) have discovered a way to make the widely used chemical process of hydrogenation more environmentally friendly – and less expensive.

Hydrogenation is a chemical process used in a wide range of industrial applications, from food products, such as margarine, to petrochemicals and pharmaceuticals. The process typically involves the use of heavy metals, such as palladium or platinum, to catalyze the chemical reaction. While these metals are very efficient catalysts, they are also non-renewable, costly, and subject to sharp price fluctuations on international markets.

Because these metals are also toxic, even in small quantities, they also raise environmental and safety concerns. Pharmaceutical companies, for example, must use expensive purification methods to limit residual levels of these elements in pharmaceutical products. Iron, by contrast, is both naturally abundant and far less toxic than heavy metals.

Previous work by other researchers has shown that iron nanoparticles — tiny pieces of metallic iron — can be used to activate the hydrogenation reaction. Iron, however, has a well-known drawback: it rusts in the presence of oxygen or water. When rusted, iron nanoparticles stop acting as hydrogenation catalysts. This problem, which occurs with so much as trace quantities of water, has prevented iron nanoparticles from being used in industry.

The June 27, 2013 McGill University news release on EurekAlert, which originated the news item, provides details about the new technique,

The key to this new method is to produce the particles directly inside a polymer matrix, composed of amphiphilic polymers based on polystyrene and polyethylene glycol. The polymer acts as a wrapping film that protects the iron surface from rusting in the presence of water, while allowing the reactants to reach the water and react.

This innovation enabled the researchers to use iron nanoparticles as catalyst in a flow system, raising the possibility that iron could be used to replace platinum-series metals for hydrogenation under industrial conditions.

“Our research is now focused on achieving a better understanding of how the polymers are protecting the surface of the iron from water, while at the same time allowing the iron to interact with the substrate,” says Audrey Moores, an assistant professor of chemistry at McGill and co-corresponding author of the paper.

…

“The approach we have developed through this collaboration could lead to more sustainable industrial processes,” says Prof. Uozumi [Prof. Yasuhiro Uozumi of Riken]. “This technique provides a system in which the reaction can happen over and over with the same small amount of a catalytic material, and it enables it to take place in almost pure water — the green solvent par excellence.”

I last wrote about greener chemistry and iron nanoparticles in a March 28, 2012 posting concerning some work at the University of Toronto while the last time McGill, green chemistry, and Audrey Moores were mentioned here was in a Jan. 10, 2011 posting concerning ‘nanomagnetics.

For those who are interested in this latest work from McGill, here’s a link to and a citation for the published paper,

Highly efficient iron(0) nanoparticle-catalyzed hydrogenation in water in flow by Reuben Hudson, Go Hamasaka, Takao Osako, Yoichi M. A. Yamada, Chao-Jun Li, Yasuhiro Uozumi, and Audrey Moores.
Green Chem., 2013, Advance Article DOI: 10.1039/C3GC40789F

First published online 27 Jun 2013

This paper is behind a paywall.

When mining for gold nanoparticles use substitute cornstarch for cyanide

Leave a reply

A May 14, 2013 news release from Northwestern University (US) on EurekAlert notes that researchers have found cornstarch can be used in the place of cyanide to extract gold,

Northwestern University scientists have struck gold in the laboratory. They have discovered an inexpensive and environmentally benign method that uses simple cornstarch — instead of cyanide — to isolate gold from raw materials in a selective manner.

This green method extracts gold from crude sources and leaves behind other metals that are often found mixed together with the crude gold. The new process also can be used to extract gold from consumer electronic waste.

Commonly used techniques, according to the news release, are problematic,

Current methods for gold recovery involve the use of highly poisonous cyanides, often leading to contamination of the environment. Nearly all gold-mining companies use this toxic gold leaching process to sequester the precious metal.

“The elimination of cyanide from the gold industry is of the utmost importance environmentally,” said Sir Fraser Stoddart, the Board of Trustees Professor of Chemistry in the Weinberg College of Arts and Sciences. “We have replaced nasty reagents with a cheap, biologically friendly material derived from starch.”

Here’s how the researchers made their accidental discovery (from the news release),

Zhichang Liu, a postdoctoral fellow in Stoddart’s lab and first author of the paper, took two test tubes containing aqueous solutions — one of the starch-derived alpha-cyclodextrin, the other of a dissolved gold (Au) salt (called aurate) — and mixed them together in a beaker at room temperature.

Liu was trying to make an extended, three-dimensional cubic structure, which could be used to store gases and small molecules. Unexpectedly, he obtained needles, which formed rapidly upon mixing the two solutions.

“Initially, I was disappointed when my experiment didn’t produce cubes, but when I saw the needles, I got excited,” Liu said. “I wanted to learn more about the composition of these needles.”

…  said Stoddart, a senior author of the paper[,] “The needles, composed of straw-like bundles of supramolecular wires, emerged from the mixed solutions in less than a minute.”

After discovering the needles, Liu screened six different complexes — cyclodextrins composed of rings of six (alpha), seven (beta) and eight (gamma) glucose units, each combined with aqueous solutions of potassium tetrabromoaurate (KAuBr4) or potassium tetrachloroaurate (KAuCl4).

He found that it was alpha-cyclodextrin, a cyclic starch fragment composed of six glucose units, that isolates gold best of all.

“Alpha-cyclodextrin is the gold medal winner,” Stoddart said. “Zhichang stumbled on a piece of magic for isolating gold from anything in a green way.”

Alkali metal salt waste from this new method is relatively environmentally benign, Stoddart said, while waste from conventional methods includes toxic cyanide salts and gases. The Northwestern procedure is also more efficient than current commercial processes.

The supramolecular nanowires, each 1.3 nanometers in diameter, assemble spontaneously in a straw-like manner. In each wire, the gold ion is held together in the middle of four bromine atoms, while the potassium ion is surrounded by six water molecules; these ions are sandwiched in an alternating fashion by alpha-cyclodextrin rings. Around 4,000 wires are bundled parallel to each other and form individual needles that are visible under an electron microscope.

“There is a lot of chemistry packed into these nanowires,” Stoddart said. “The elegance of the composition of single nanowires was revealed by atomic force microscopy, which throws light on the stacking of the individual donut-shaped alpha-cyclodextrin rings.”

The atomic detail of the single supramolecular wires and their relative disposition within the needles was uncovered by single crystal X-ray crystallography.

As I’ve noted before, the perennial science story is a ‘mistake’ leading to an exciting discovery and this is one more example. I think it’s one of the things that scientists don’t get enough credit for, their ability to reshape a disappointing result into a new discovery or, in the vernacular, ‘make lemonade out of lemons’.

Here’s a link to and a citation for the research paper,

Selective isolation of gold facilitated by second-sphere coordination with α-cyclodextrin by Zhichang Liu, Marco Frasconi, Juying Lei, Zachary J. Brown, Zhixue Zhu, Dennis Cao, Julien Iehl, Guoliang Liu, Albert C. Fahrenbach, Youssry Y. Botros, Omar K. Farha, Joseph T. Hupp,  Chad A. Mirkin & J. Fraser Stoddart. Nature Communications 4, Article number: 1855  doi:10.1038/ncomms2891 Published 14 May 2013

This article is open access.

Phyto-mining; using plants to extract minerals

2 Replies

Plants do it anyway, so, why not harness their ability to absorb nutrients and transform them into various materials for the mining industry? In the scientists at the University of York (UK) mentioned in a Sept. 20, 2012 news item on Nanowerk are doing precisely that,

Scientists at the University of York are to lead an international team that will explore the use of plants to recover precious metals from mine tailings around the world.

Researchers in the University’s Green Chemistry Centre of Excellence and the Centre for Novel Agricultural Products (CNAP) aim to develop ways to extract platinum group metals (PGM) discarded during mine processing which might then be used in catalysis. The research will investigate “phyto-mining,” which involves growing plants on mine waste materials to sponge up PGM into their cellular structure.

Initial studies show that plant cells used to phyto-mine PGM can be turned into materials for a variety of industrial applications – the one in most demand being catalytic converters for vehicle emissions control.

The Sept. 20, 2012 University of York news release (which originated the news item) notes,

The $1.4 million PHYTOCAT project is supported by the G8 Research Councils Initiative on Multilateral Research Funding. The team is led by the University of York in the UK with support from Yale University, the University of British Columbia and Massey University in New Zealand. [emphasis mine]

Professor James Clark, the Director of the Green Chemistry Centre of Excellence at York, says: “We are looking at ways of turning these residual metals into their catalytically active form using the plants to extract them from the mine waste. The plant is heated in a controlled way with the result that the metal is embedded in a nano-form in the carbonised plant.

“The trick is to control the decomposition of the plant in a way which keeps the metal in its nano-particulate or catalytically active form. Catalysis is being used more and more in industrial processes and particularly for emission control because of the demand for cleaners cars, so ‘phyto-mining’ could provide a sustainable supply of catalytically active metals.”

For PGM phyto-mining, the researchers will investigate plants known as hyperaccumulators which include about 400 species from more than 40 plant families. Plants such as willow, corn and mustard have evolved a resistance to specific metals and can accumulate relatively large amounts of these metals, which once absorbed into the plants’ cellular structure form nano-scale clusters than can then be used directly as a catalyst.

Professor Neil Bruce, of CNAP, added: “The ability of plants to extract PGMs from soil and redeposit the metal as nanoparticles in cells is remarkable. This project will allow us to investigate the mechanisms behind this process and provide a green method for extracting metals from mine tailings that are currently uneconomical to recover.”

(It makes sense that the University of British Columbia from my home province is participating, given the province’s heavy involvement in the mining industry.)

This proposed phyto-mining process has much in common with phytoremediation where plants are grown in polluted areas so they can absorb the pollutants from the soil as per my March 30, 2012 posting, which featured a guest writer, Joe Martin on the topic of phytoremediation.

I wonder what they will be doing to the plants for make them more suitable for the phyto-mining process.

Greenish chemistry and silver nanoparticles in Iran

Leave a reply

Iranian scientists are using lecithin to synthesize and bind silver nanoparticles more tightly to wool according to this April 25, 2012 news item on Nanowerk,

“Bearing the basic concepts of the green chemistry in the mind, we have managed to synthesize the nanoparticles both in the aqueous phase and over a woolen medium. We employed Lecithin to serve as the stabilizer and carrier of the silver nanoparticles through the woolen medium,” says Hossein Barani, a member of the research group [at Amirkabir University of Technology, Iran].

The goals targeted by this research project apparently include the synthesis of silver nanoparticles with the help of Lecithin as a biodegradable surface active agent, to apply environmentally friendly chemicals in the synthesis of nanoparticles, simultaneous synthesis and loading of the nanoparticles into the fiber structures which effectively improves the quality and durability of the washing.

“Lecithin acts as a stabilizer for the silver nanoparticles during their synthesis step and also is the vehicle by which the nanoparticles are transferred into the woolen fiber structures. The prepared silver nanoparticles possess approximate dimensions of 7 nm and are entrapped inside a liposomic vesicle,” Barani added.

Here are some of the advantages (from the news item),

“Simultaneous synthesis and loading of the silver nanoparticles is in favor of the loading efficiency and durability of washing. In addition, the presence of Lecithin boosts the loading quality, avoids excessive concentration of the nanoparticles upon the fibers’ surfaces, reduces the undesired yellowing of the fabric, and increases the antibacterial performance through a gradual release with lowest toxicity for fibroblast cells,” he reiterated.

Apparently, it would be fairly easy to transfer this process to industry (from the news item),

Barani also evaluated the commercialization of the method as promising, and said, “In case of industrial investment, the proposed approach can be implemented to the production line of textile companies with practical ease.”