RESUMO
Large pore (4.6-7.6 nm) and well-dispersed benzene bridged mesoporous organosilica nanoparticles with uniform particle size of ≈50 nm are prepared via a biphasic approach. They can be directly used as nanocarriers without surface modification for the intracellular delivery of therapeutic proteins.
Assuntos
Benzeno/química , Nanocápsulas/química , Nanoconjugados/química , Nanoporos/ultraestrutura , Compostos de Organossilício/química , Ribonuclease Pancreático/química , Reagentes de Ligações Cruzadas/química , Preparações de Ação Retardada/síntese química , Difusão , Composição de Medicamentos/métodos , Humanos , Células MCF-7 , Nanocápsulas/administração & dosagem , Nanocápsulas/ultraestrutura , Nanoconjugados/ultraestrutura , Tamanho da Partícula , Transição de Fase , Porosidade , Ribonuclease Pancreático/administração & dosagemRESUMO
Nanoporous organosilica membranes are successfully coated on porous alumina tubes and tested for desalination via membrane distillation. The membranes produced pure water (up to 13 kg m(-2) h(-1)) across an extreme range of salt concentrations (10-150 g L(-1) NaCl) at moderate temperatures (≤60 °C) without exhibiting the characteristic flux decay of competing materials.
Assuntos
Nanoestruturas/química , Compostos de Organossilício/química , Salinidade , Purificação da Água , Água/química , Tamanho da Partícula , Porosidade , Cloreto de Sódio/química , Propriedades de Superfície , TemperaturaRESUMO
In this work, liquid biofuel (bio-oil) was produced by pyrolizing cassava peel. The experiments were conducted isothermally in a fixed-bed tubular reactor at temperatures ranging from 400 to 600°C with a heating rate of 20°C/min. The chemical compositions of bio-oil were analyzed by a gas chromatography mass spectrometry (GC-MS) technique. For the optimization of liquid product, temperature was plotted to be the most decisive factor. The maximum yield of bio-oil ca. 51.2% was obtained at 525°C and the biofuel has a gross calorific value of 27.43 MJ/kg. The kinetic-based mechanistic model fitted well with experimental yield of pyrolysis products with the mean squared error (MSE) of 13.37 (R(2)=0.96) for solid (char), 16.24 (R(2)=0.95) for liquid (bio-oil), and 0.49 (R(2)=0.99) for gas.
Assuntos
Biocombustíveis/análise , Frutas/química , Temperatura Alta , Manihot/química , Anaerobiose , Cromatografia Gasosa-Espectrometria de Massas , Cinética , Modelos Químicos , TermogravimetriaRESUMO
This work shows for the first time the potential of cobalt oxide silica (CoO(x)Si) membranes for desalination of brackish (1 wt.% NaCl), seawater (3.5 wt.% NaCl) and brine (7.5-15 wt.% NaCl) concentrations at feed temperatures between 25 and 75 °C. CoO(x)Si xerogels were synthesised via a sol-gel method including TEOS, cobalt nitrate hydrate and peroxide. Initial hydrothermal exposure (<2 days) of xerogels prepared with various pH (3-6) resulted in densification of the xerogel via condensation reactions within the silica matrix, with the xerogel synthesised at pH 5 the most resistant. Subsequent exposure was not found to significantly alter the pore structure of the xerogels, suggesting they were hydrostable and that the pore sizes remained at molecular sieving dimensions. Membranes were then synthesised using identical sol-gel conditions to the xerogel samples and testing showed that elevated feed temperatures resulted in increased water fluxes, whilst increasing the saline feed concentration resulted in decreased water fluxes. The maximum flux observed was 1.8 kg m(-2) h(-1) at 75 °C for a 1 wt.% NaCl feed concentration. The salt rejection was consistently in excess of 99%, independent of either the testing temperature or salt feed concentration.
RESUMO
Lignocellulosic biomass is the most abundant and bio-renewable resource with great potential for sustainable production of chemicals and fuels. This critical review provides insights into the state-of the-art accomplishments in the chemocatalytic technologies to generate fuels and value-added chemicals from lignocellulosic biomass, with an emphasis on its major component, cellulose. Catalytic hydrolysis, solvolysis, liquefaction, pyrolysis, gasification, hydrogenolysis and hydrogenation are the major processes presently studied. Regarding catalytic hydrolysis, the acid catalysts cover inorganic or organic acids and various solid acids such as sulfonated carbon, zeolites, heteropolyacids and oxides. Liquefaction and fast pyrolysis of cellulose are primarily conducted over catalysts with proper acidity/basicity. Gasification is typically conducted over supported noble metal catalysts. Reaction conditions, solvents and catalysts are the prime factors that affect the yield and composition of the target products. Most of processes yield a complex mixture, leading to problematic upgrading and separation. An emerging technique is to integrate hydrolysis, liquefaction or pyrolysis with hydrogenation over multifunctional solid catalysts to convert lignocellulosic biomass to value-added fine chemicals and bio-hydrocarbon fuels. And the promising catalysts might be supported transition metal catalysts and zeolite-related materials. There still exist technological barriers that need to be overcome (229 references).
Assuntos
Biocombustíveis , Biomassa , Celulose/química , Catálise , Hidrogenação , Hidrólise , Solventes/químicaRESUMO
In this work we investigate the potential of a polyethylene glycol-polypropylene glycol-polyethylene glycol, tri-block copolymer as a template for a hybrid carbon/silica membrane for use in the non-osmotic desalination of seawater. Silica samples were loaded with varying amounts of tri-block copolymer and calcined in a vacuum to carbonize the template and trap it within the silica matrix. The resultant xerogels were analyzed with FTIR, Thermogravimetric analysis (TGA) and N2 sorption techniques, wherein it was determined that template loadings of 10 and 20% produced silica networks with enhanced pore volumes and appropriately sized pores for desalination. Membranes were created via two different routes and tested with feed concentrations of 3, 10 and 35 ppk of NaCl at room temperature employing a transmembrane pressure drop of 85% (in most cases >95%) and fluxes higher than 1.6 kg m-2 h-1. Furthermore, the carbonized templated membranes displayed equal or improved performance compared to similarly prepared non-templated silica membranes, with the best results of a flux of 3.7 kg m-2 h-1 with 98.5% salt rejection capacity, exceeding previous literature reports. In addition, the templated silica membranes exhibited superior hydrostability demonstrating their potential for long-term operation.
RESUMO
Ionic liquid (IL)-reconstituted acrylic acid (AA)-functionalized cellulose microparticles were successfully prepared by a water-in-oil suspension technique preliminary modification with AA in homogeneous condition. Cellulose was fully dissolved in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) IL, and subsequently was grafted homogeneously with AA and N,N'-methylenebisacrylamide (N,N'-MBA) initiated with ammonium persulfate. The grafted cellulose was spheroidized using white silicone oil as the dispersion medium and Span 80 as a dispersant and then reconstituted from [Bmim]Cl. Reaction conditions were optimized to obtain microparticles with both the highest possible grafting efficiency and most uniform bead sizes. Fourier transform infrared spectroscopy, scanning electron microscopy, and an optical microscope were employed to provide structural information for the functionalized IL-reconstituted cellulose microparticles. These microparticles were shown to behave as good sorbents for Cu(II), Ni(II), Fe(III) ions.