Green Chemistry Blog

High purity silicon is essential for manufacturing solar panels. Unfortunately this prerequisite conversion of silica to elemental silicon requires a lot of energy, and the associated greenhouse gas emissions are significant. It has now been demonstrated that the ashes from burning biomass (rice hulls in this case) can provide a rich source of silica than can be reduced to give solar grade silicon.

For the preparation of the silica from rice hull ash only dilute acid and hot water are required. The energy requirement to then produce 99.9999% pure silicon is an order of magnitude less than the conventional process and is actually lower than the energy created by burning the rice hulls in the first place. As the carbon dioxide generated by burning biomass is originally fixed from the atmosphere by plants, the carbon footprint for the production of this sustainable silicon is very low.

Read the advanced article in Green Chemistry online now:

A low cost, low energy route to solar grade silicon from rice hull ash (RHA), a sustainable source

Julien C. Marchal, David J. Krug III, Patrick McDonnell, Kai Sun and Richard M. Laine

Green Chem., 2015, Advance Article. DOI: 10.1039/C5GC00622H

Chemists in Belgium have shown how an intriguing ionic liquid they developed 10 years ago can recover valuable rare earth metals from stockpiles of used fluorescent lamps and magnets.

Rare earth metals are important in high tech applications, but China controls most of the world’s dwindling supply, periodically setting export quotas and driving up prices. They occur naturally elsewhere, but new production is time consuming and costly to establish.

Read the full article in Chemistry World»

Read the  journal articles in Green Chemistry:

Rare-earth recycling using a functionalized ionic liquid for the selective dissolution and revalorization of Y2O3:Eu3+ from lamp phosphor waste
David Dupont and Koen Binnemans 
Journal Article
Green Chem., 2015,17, 856-868
DOI: 10.1039/C4GC02107J, Paper
Open Access

Recycling of rare earths from NdFeB magnets using a combined leaching/extraction system based on the acidity and thermomorphism of the ionic liquid [Hbet][Tf2N]
David Dupont and Koen Binnemans  
Green Chem., 2015, Advance Article
DOI: 10.1039/C5GC00155B, Paper
Free to access until 7 May 2015

The metal contamination introduced into the environment by mine tailings is a strikingly visual concern. As global demand for precious metals increases, many reserves are now regarded as critical. Pollution could be reduced and the effect of demand on resources lessened if effective reclamation of metals from mine tailings could be performed.

In work conducted jointly by scientists in the UK and in Spain, a bio-based mesoporous carbon material has been found to selectively absorb gold and platinum group metals from acidic solutions containing a mixture of metal salts representative of wastes typical of mining operations. The absorbed metals go on to create nanoparticles in the carbonaceous material. The spontaneous formation of nanoparticles on renewable carbon supports has potential applications in catalysis, or the metal could be isolated for other uses.

TEM image showing absorbed metal as nanoparticles and the Starbon® monolith (inset)

Read the advanced article in Green Chemistry online now:

Starch-derived carbonaceous mesoporous materials (Starbon®) for the selective adsorption and recovery of critical metals

Andrea Muñoz García, Andrew J. Hunt,* Vitaliy L. Budarin, Helen L. Parker, Peter S. Shuttleworth, Gary J. Ellis and James. H. Clark

Green Chem., 2015, Advance Article. DOI: 10.1039/C5GC00154D

The land use issues associated with biomass production points to marine biomass as a promising alternative. Seaweed is a rich resource, abundant in the world’s oceans. In addition to its potential for biofuel production, it is also important to obtain a stream of renewable chemicals from any seaweed bio-refinery to create an economically viable and sustainable process.

The present development, led by an Indian research team prominent in this field, creates a valuable side stream of chemical products to supplement the production of bio-ethanol from cellulose. Lipids, pigments and agar are all obtainable from the red algae feedstock by way of sequential extraction processes that improves the quality of the agar produced and significantly reduces the amount of auxiliary chemicals required compared to previous methods.

Read the advanced article in Green Chemistry online now:

This lipase is one of the most largely employed enzymes in industry © Valerio Ferrario

Taking an unconventional approach to biocatalysis has allowed scientists in Italy to improve enzyme recyclability with a solvent-free reaction mixture. And by emphasising a need to design processes, biocatalysts and reactors together, instead of separately, they hope to widen the industrial applications of nature’s catalysts.

Lucia Gardossi, from the University of Trieste in Italy, has been investigating solvent-free reaction mixtures, which appeal to industry because of their comparably small production volumes and lack of organic solvents to dispose of. Although their efficiency and selectivity are attractive, biocatalysed versions of industrial reactions are rarely economically viable. The typically viscous reaction mixtures require vigorous mixing, which damages the enzymes and limits their recyclability.

For the full story from Debbie, make sure to take a look at the page on Chemistry World!

This original research article is free to access unitl 11 March 2015. Download it here:

A Pellis et al, Green Chem., 2015, DOI: 10.1039/c4gc02289k

Open access communication: One-pot triangular chemoenzymatic cascades for the synthesis of chiral alkaloids from dopamine

Researchers at UCL, UK, have developed a novel use of one-pot, multi-step enzymatic catalysis for the synthesis of chiral alkaloids. Transaminase (TAm) and norcoclaurine synthase (NCS) were employed as catalysts. In the synthesis of the tetrahydroprotoberberine product two carbon-carbon bonds are created under mild conditions with good enantiomeric purity (ee >95%), all in a short duration (3.5 hours).

The successive Pictet-Spengler cyclisation reactions provide an atom economic approach and high enantioselectivity to the formation of this valuable class of products. The authors of this work recognise the “remarkable potential of in vitro biocatalysis for the formation of complex chiral compounds“, which is increasingly important to contemporary green chemistry.

This article is open access and available to everyone to read for free:

One-pot triangular chemoenzymatic cascades for the synthesis of chiral alkaloids from dopamine

B. R. Lichman, E. D. Lamming, T. Pesnot, J. M. Smith, H. C. Hailes and J. M. Ward

Green Chem., 2015, Advance Article. DOI: 10.1039/C4GC02325K

Efficient and selective conversion of lactic acid into acetaldehyde using a mesoporous aluminum phosphate catalyst

Acetaldehyde is needed by the chemical industry for many diverse applications, such as paint and cosmetic formulations, plastics and construction materials. As such there is a need for renewable acetaldehyde within the bio-based economy and bio-ethanol can be oxidised to give acetaldehyde for this purpose. Now an alternative process using lactic acid as a feedstock has been developed.

The catalyst for this transformation is a mesoporous aluminium phosphate, facilitating full conversion of the lactic acid and yields of acetaldehyde exceeding 90%. While the use of aluminium is very favourable compared to ethylene oxidation catalysts based on silver for example, the longevity of phosphorus reserves are a concern. However the catalyst is robust and can be used for over 200 hours. Also, the process is efficient at lower temperatures than are often needed for transformations of lactic acid.

Read the advanced article in Green Chemistry online now:

Efficient and selective conversion of lactic acid into acetaldehyde using a mesoporous aluminum phosphate catalyst

Congming Tang, Jiansheng Peng, Xinli Li, Zhanjie Zhai, Wei Bai, Ning Jiang, Hejun Gao and Yunwen Liao

Green Chem., 2015, Advance Article. DOI: 10.1039/C4GC01779J

Check out the following HOT articles, these have all been made free to access for a limited time:
Chemical conversion pathways for carbohydrates
Chandrani Chatterjee, Frances Pong and Ayusman Sen
Green Chem., 2015, Advance Article
DOI: 10.1039/C4GC01062K

Catalytic conversion of carbohydrate-derived oxygenates over HZSM-5 in a tandem micro-reactor system
Kaige Wang, Jing Zhang, Brent H. Shanks and Robert C. Brown
Green Chem., 2015, Advance Article
DOI: 10.1039/C4GC01784F

Upgrading biomass-derived furans via acid-catalysis/hydrogenation: the remarkable difference between water and methanol as the solvent
Xun Hu, Roel J. M. Westerhof, Liping Wu, Dehua Dong and Chun-Zhu Li
Green Chem., 2015, Advance Article
DOI: 10.1039/C4GC01826E

Recent progress on supported polyoxometalates for biodiesel synthesis via esterification and transesterification
Nilesh Narkhede, Sukriti Singh and Anjali Patel
Green Chem., 2015, Advance Article
DOI: 10.1039/C4GC01743A

A novel D-glucosamine-derived pyridyl-triazole@palladium catalyst for solvent-free Mizoroki–Heck reactions and its application in the synthesis of Axitinib
Chao Shen, Hongyun Shen, Ming Yang,Chengcai Xia and Pengfei Zhang
Green Chem., 2015, Advance Article
DOI: 10.1039/C4GC01606H  

Aqueous ionic liquid solutions as alternatives for sulphide-free leather processing
R. Vijayaraghavan, N. Vedaraman, C. Muralidharan, A. B. Mandal and D. R. MacFarlane
Green Chem., 2015, Advance Article
DOI: 10.1039/C4GC01476F

Si-mediated fabrication of reduced graphene oxide and its hybrids for electrode materials
Barun Kumar Barman and Karuna Kar Nanda
Green Chem., 2015, Advance Article
DOI: 10.1039/C4GC01485E

Conversion of biomass derived valerolactone into high octane number gasoline with an ionic liquid
Jiayu Xin, Dongxia Yan, Olubunmi Ayodele, Zhan Zhang, Xingmei Lu and Suojiang Zhang
Green Chem., 2015, Advance Article
DOI: 10.1039/C4GC01792G

Ionic liquids: not always innocent solvents for cellulose
Matthew T. Clough, Karolin Geyer, Patricia A. Hunt, Sunghee Son, Uwe Vagt and Tom Welton
Green Chem., 2015, Advance Article
DOI: 10.1039/C4GC01955E

Electrocatalytic upgrading of model lignin monomers with earth abundant metal electrodes
Chun Ho Lam, Christy B. Lowe, Zhenglong Li, Kelsey N. Longe, Jordan T. Rayburn, Michael A. Caldwell, Carly E. Houdek, Jack B. Maguire, Christopher M. Saffron, Dennis J. Miller and James E. Jackson
Green Chem., 2015, Advance Article
DOI: 10.1039/C4GC01632G