HIGHLIGHTS


K. Takeuchi, T. Hayashi, M. Terrones, M. Endo; Nature Nanotechnology, doi:10.1038/nnano.2017.160). The hybrid membrane are obtained using a simple spray-on technology to coat a mixture of graphene oxide and few-layered graphene in solution onto a backbone support membrane of polysulfone modified with polyvinyl alcohol. The support membrane increases the robustness of the hybrid membrane, and is able to stand up to intense cross-flow, high pressure and chlorine exposure. Even in early stages of


development, the membrane rejected 85% of salt, adequate for agricultural purposes though not for drinking, and 96% of highly polluting dye molecules. Experimental results and molecular dynamic simulations have shown that the presence of deoxycholate enhances NaCl rejection in these graphene-based membranes. In addition, these novel hybrid-layered membranes exhibit better chlorine resistance than pure graphene oxide membranes. The desalination performance


and aggressive shear and chlorine resistance of these scalable graphene-based membranes are promising for use in practical water separation applications.


Sweeter way to make green products A more efficient process for extracting the sugars from wood chips, corn cobs and other organic waste from forests and farms has been developed (S. Sadula, A. Athaley, W. Zheng, M. Ierapetritou, B. Saha; ChemSusChem, 2017, 10, 2566). Current chemical and enzymatic


processes for producing cellulosic sugars are multistep, and energy- and water-intensive. This makes the resulting sugars expensive and the end products, though renewable, less competitive than those produced with petroleum. The new one-pot depolymerisation and saccharification process of woody biomass, energy crops, and agricultural residues produces soluble sugars with high yields (ca95%). The key to the technology is the


use of a concentrated solution of an inorganic salt in the presence of a small amount of mineral acid. The concentrated salt solution requires a minimal amount of water.


Scheme 4


0.4 A/mg of enzyme at 25°C


1 A/mg of enzyme at 50°C


New approach for changing CO2 into CO Open circuit voltage >1V


Enzymatic fuel cell A new enzymatic fuel cell (EFC) that is as effective as a platinum fuel cell, has been constructed by replacing the chemical catalyst (platinum) with bacterial enzymes: at the anode, hydrogenase, key for converting hydrogen into many microorganisms; and at the cathode, bilirubin oxidase (I. Mazurenko, K. Monsalve, P. Infossi, M-T. Giudici-Orticoni, F. Topin, N. Mano, E. Lojou; Energy Environ. Sci., 2017, 10, 1966) (Scheme 3). A carbon felt with suitably


adapted porosity is the host structure for the enzymes, which also serves as protection against chemical species


Scheme 3 Biocell using H2


/O2 fuel based on a


heat-stable hydroge- nase that resists oxygen and carbon monoxide at the anode and a heat-stable bilirubin oxidase at the cathode that provide currents of the order of amps per milligram of enzymes


Chemists at Yale and Oregon State University have developed a new process for converting carbon dioxide into carbon monoxide, potentially establishing a framework for creating fuels and chemical products from carbon emissions (Yueshen Wu, et al; ACS Cent. Sci., 2017, 3, 847) (Scheme 4). The heterogenised zinc–


porphyrin complex (zinc(II) 5,10,15,20-tetramesitylporphyrin) electrocatalyst delivers a turnover frequency as high as 14.4 site-1


s-1


and a Faradaic efficiency as high as 95% for CO2


electroreduction to CO


at −1.7V vs the standard hydrogen electrode in an organic/water mixed electrolyte. The researchers have discovered


a zinc-porphyrin complex that acts as a catalyst in an unexpected way: the zinc ion binds the reactant but does not change its oxidation state, while the porphyrin ion (or ligand) is reduced and delivers electrons to complete the reaction.


generated when oxygen is reduced, which changes enzyme activity. High total


turnover numbers, approaching 107 for BOD


The solution swells the particles of wood or other biomass, allowing the solution to interact with the fibres, much like a newspaper swells when water spills on it, making the process efficient. Lignin is separated as a solid for selective upgrading. Further integration of the upstream process with a reactive extraction step makes energy-efficient separation of sugars in the form of furans. TEA reveals that the process efficiency and integration enable, for the first time, economic production of feed streams that could profoundly improve process economics for downstream cellulosic bioproducts.


Scheme 2 A polyaromatic macrocycle capable of switching between open and closed forms in response to external stimuli has been developed (K. Kurihara, K. Yazaki, M. Akita, M. Yoshizawa; Angew. Chem. Int. Ed. Engl., 2017, 56, 11360)


and 108 for hydrogenase, were found, as was an impressive massic activity of 1Amg-1


with respect to the


mass of the electroactive enzyme molecules. The heat-stable enzymes can withstand temperatures between 25°C and 80°C. This device displays very high


power and stability, producing 15.8mWh of energy after 17h of continuous operation. Biomass can be used to provide both the fuel (hydrogen) and the catalyst (the enzymes), which are, by nature, renewable.


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