Microalgae provide various potential advantages for biofuel production when compared with ‘traditional’ crops. Specifically, large-scale microalgal culture need not compete for arable land, while in theory their productivity is greater. In consequence, there has been resurgence in interest and a proliferation of algae fuel projects. However, while on a theoretical basis, microalgae may produce between 10- and 100-fold more oil per acre, such capacities have not been validated on a commercial scale. We critically review current designs of algal culture facilities, including photobioreactors and open ponds, with regards to photosynthetic productivity and associated biomass and oil production and include an analysis of alternative approaches using models, balancing space needs, productivity and biomass concentrations, together with nutrient requirements. In the light of the current interest in synthetic genomics and genetic modifications, we also evaluate the options for potential metabolic engineering of the lipid biosynthesis pathways of microalgae. We conclude that although significant literature exists on microalgal growth and biochemistry, significantly more work needs to be undertaken to understand and potentially manipulate algal lipid metabolism. Furthermore, with regards to chemical upgrading of algal lipids and biomass, we describe alternative fuel synthesis routes, and discuss and evaluate the application of catalysts traditionally used for plant oils. Simulations that incorporate financial elements, along with fluid dynamics and algae growth models, are likely to be increasingly useful for predicting reactor design efficiency and life cycle analysis to determine the viability of the various options for large-scale culture. The greatest potential for cost reduction and increased yields most probably lies within closed or hybrid closed–open production systems.

https://royalsocietypublishing.org/doi/pdf/10.1098/rsif.2009.0322

Placing microalgae on the biofuels priority list: a review of the technological challenges

Many algae have immense capability to sorb metals, and there is considerable potential for using them to treat wastewaters. Metal sorption involves binding on the cell surface and to intracellular ligands. The adsorbed metal is several times greater than intracellular metal. Carboxyl group is most important for metal binding. Concentration of metal and biomass in solution, pH, temperature, cations, anions and metabolic stage of the organism affect metal sorption. Algae can effectively remove metals from multi-metal solutions. Dead cells sorb more metal than live cells. Various pretreatments enhance metal sorption capacity of algae. CaCl2 pretreatment is the most suitable and economic method for activation of algal biomass. Algal periphyton has great potential for removing metals from wastewaters. An immobilized or granulated biomass-filled column can be used for several sorption/desorption cycles with unaltered or slightly decreased metal removal. Langmuir and Freundlich models, commonly used for fitting sorption data, cannot precisely describe metal sorption since they ignore the effect of pH, biomass concentration, etc. For commercial application of algal technology for metal removal from wastewaters, emphasis should be given to: (i) selection of strains with high metal sorption capacity, (ii) adequate understanding of sorption mechanisms, (iii) development of low-cost methods for cell immobilization, (iv) development of better models for predicting metal sorption, (v) genetic manipulation of algae for increased number of surface groups or over expression of metal binding proteins, and (vi) economic feasibility.

Use of Algae for Removing Heavy Metal Ions From Wastewater: Progress and Prospects

Two-dimensional transition-metal carbide materials (termed MXene) have attracted huge attention in the field of electrochemical energy storage due to their excellent electrical conductivity, high volumetric capacity, etc. Herein, with inspiration from the interesting structure of pillared interlayered clays, we attempt to fabricate pillared Ti3C2 MXene (CTAB–Sn(IV)@Ti3C2) via a facile liquid-phase cetyltrimethylammonium bromide (CTAB) prepillaring and Sn4+ pillaring method. The interlayer spacing of Ti3C2 MXene can be controlled according to the size of the intercalated prepillaring agent (cationic surfactant) and can reach 2.708 nm with 177% increase compared with the original spacing of 0.977 nm, which is currently the maximum value according to our knowledge. Because of the pillar effect, the assembled LIC exhibits a superior energy density of 239.50 Wh kg–1 based on the weight of CTAB–Sn(IV)@Ti3C2 even under higher power density of 10.8 kW kg–1. When CTAB–Sn(IV)@Ti3C2 anode couples with commercial AC ...

Pillared Structure Design of MXene with Ultralarge Interlayer Spacing for High-Performance Lithium-Ion Capacitors.

This review focuses on the use of layered and porous aluminosilicates and layered double hydroxides as catalysts for the Fenton reaction. In the general sections of this review we present the elementary equations leading to the generation of hydroxyl radicals from H2O2 and the subsequent reactivity of this highly aggressive species. After justifying the advantages of using insoluble solids as heterogeneous catalysts, replacing soluble iron salts, we discuss the desirable features that should have an ideal Fenton catalyst and which are the parameters to be considered when ranking the efficiency of the materials. The main part of this review is focused on presenting the results reported up to late 2009 obtained using layered and porous aluminosilicates as heterogeneous catalysts. The structure of these materials is briefly presented to highlight the benefits and advantages of each type of solid with respect to their use as catalysts. When presenting the catalytic data, special emphasis is made on the missing data that would be useful to clarify, the relative efficiency and performance of the materials. In the final concluding remarks we stress again that the present situation needs to be clarified to draw solid conclusions on the relative performance and efficiency of the tested catalysts.

Heterogeneous Fenton catalysts based on clays, silicas and zeolites

Raman spectroscopy for fluid inclusion analysis

We have explored the possibilities offered by environmental scanning electron microscopy (ESEM) to study minerals under a variety of conditions. Low-voltage SEM can be used to study minerals without coating with gold or carbon, thereby allowing the researcher to use other analytical techniques on the same sample. Changes in pressure and temperature can be used to study mineral reactions such as wetting and drying but also thermal behaviour such as dehydration, dehydroxation or decarbonation. The general principles shown are not limited to the study of minerals but can be applied to a range of materials.

Use of Environmental Scanning Electron Microscopy to Study Uncoated Minerals

This thesis is submitted in a format of published papers by the candidate. Advanced methods of electron microscopy and X-ray spectroscopy have been used to study the relationship between the pillars and the silicate structure ranging from Al13 and Ga13 complexes to the final products Al- and Ga-pillared clays. The Al13 and Ga13 pillared montmorillonites have been prepared by conventional and ultrasonic methods. The ultrasonic method has been proven to be effective and showed very good catalytically activity. Transmission electron microscopy combined with elemental mapping by EDS showed the distribution of the Ga and Al pillars in the clay structure. The use of gallium allowed the independent observation of the Ga pillar distribution from the Al distribution in the clay structure.
XPS spectra of the Ga13 pillared montmorillonites showed that the pillars has been changed from the original Keggin structure with a 7+ charge to something more stable with a lower charge upon intercalation. No direct evidence of the inverted silicon tetrahedron structure bonding to the pillar structure, as suggested by Plee in his original thesis, was observed. For comparative reasons the major aluminium hydroxide minerals in bauxite (gibbsite, bayerite and (pseudo-) boehmite) were studied. 
Detailed information about the Al13 structure was obtained by studying the basic sulphate and nitrate salts with XPS. The XPS results of a set of starting clays in comparison to the pillared clays indicated that small changes in the binding energy could explain the changes in the pillar structure and the formation of chemical bonds to the clay tetrahedral sheets during the calcination leading to the final products.

The morphology and structure of intercalated and pillared clays

Book Description "The new book on solid state chemistry presents studies of chemical, structural, thermodynamic, electronic, magnetic, and optical properties and processes in solids. Research areas include: bonding in solids, crystal chemistry, crystal growth mechanisms, diffusion epitaxy, high-pressure processes, magnetic properties of materials, optical characterization of materials, order-disorder, phase equilibria and transformation mechanisms, reactions at surfaces, statistical mechanics of defect interactions, structural studies and transport phenomena." -- Publisher's website.

Mid- and near-infrared spectroscopy of hydrothermally synthesized 2:1 phyllosilicates in the system Na2O-Al2O3-SiO2-H2O

BIOGRAPHY Theo Kloprogge got his PhD in geology/chemistry from Utrecht University and is currently employed at the Queensland University of Technology in the Inorganic materials Research Program. Theo Kloprogge is also adjunct professor at the Department of Geosciences, Texas Tech University, Lubbock, U.S and Secretary General of the International Association for the study of clays (AIPEA). ABSTRACT We have explored the possibilities offered by the Environmental SEM to study minerals under a variety of conditions. Low voltage SEM can be used to study minerals without coating with gold or carbon, thereby allowing the researcher to use other analytical techniques on the same sample. Changes in pr essure and temperature can be used to study mineral reactions such as wetting and drying but also the thermal behaviour such dehydration, dehydroxation or decarbonation. The general principles shown are not limited to the study of minerals but can be applied to a range of materials. KEY WORDS Environmental SEM, decomposition, heating stage SEM, low voltage SEM, minerals, wetting cycles ACKNOWLEDGMENTS We gratefully acknowledge support and infrastructure of the Queensland University of Technology and receipt of an ARC Linkage-Infrastructure grant for the environmental SEM. AUTHOR DETAILS J. Theo Kloprogge, Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Q 4001, Australia. E-mail t.kloprogge@qut.edu.au

Loc V. Duong

Papers

Use of Environmental Scanning Electron Microscopy to Study Uncoated Minerals

The morphology and structure of intercalated and pillared clays

Mid- and near-infrared spectroscopy of hydrothermally synthesized 2:1 phyllosilicates in the system Na2O-Al2O3-SiO2-H2O

Environmental sem: application of low voltage sem, heating stage sem and variable relative humidity sem to study uncoated minerals

FT-IR photoacoustic spectroscopy of kaolinite and gibbsite surfaces