Showing papers on "Sawdust published in 2011"

Production of green aromatics and olefins by catalytic fast pyrolysis of wood sawdust

Abstract: Catalytic fast pyrolysis of pine wood sawdust and furan (a model biomass compound) with ZSM-5 based catalysts was studied with three different reactors: a bench scale bubbling fluidized bed reactor, a fixed bed reactor and a semi-batch pyroprobe reactor The highest aromatic yield from sawdust of 14% carbon in the fluidized bed reactor was obtained at low biomass weight hourly space velocities (less than 05 h−1) and high temperature (600 °C) Olefins (primarily ethylene and propylene) were also produced with a carbon yield of 54% carbon The biomass weight hourly space velocity and the reactor temperature can be used to control both aromatic yield and selectivity At low biomass WHSV the more valuable monocyclic aromatics are produced and the formation of less valuable polycyclic aromatics is inhibited Lowering the reaction temperature also results in more valuable monocyclic aromatics The olefins produced during the reaction can be recycled to the reactor to produce additional aromatics Propylene is more reactive than ethylene Co-feeding propylene to the reactor results in a higher aromatic yield in both continuous reactors and higher conversion of the intermediate furan in the fixed bed reactor When olefins are recycled aromatic yields from wood of 20% carbon can be obtained After ten reaction–regeneration cycles there were metal impurities deposited on the catalyst, however, the acid sites on the zeolite are not affected Of the three reactors tested the batch pyroprobe reactor yielded the most aromatics, however, the aromatic product is largely naphthalene The continuous reactors produce less naphthalene and the sum of aromatics plus olefin products is higher than the pyroprobe reactor

Hydrogen production from biomass gasification with Ni/MCM-41 catalysts: Influence of Ni content

Abstract: The steam pyrolysis-gasification of biomass, wood sawdust, was carried out with a Ni/MCM-41 catalyst for hydrogen production in a two-stage fixed bed reaction system. The wood sawdust was pyrolysed in the first reactor and the derived products were gasified in the second reactor. The synthesised MCM-41 mesoporous catalyst supports were impregnated with different Ni loadings (5, 10, 20 and 40 wt.%), which were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature programmed reduction (TPR), transmission electron microscopy (TEM) and temperature-programmed oxidation (TPO). NiO particles were homogeneously dispersed inside the pores of 5, 10, and 20 wt.% Ni/MCM-41 catalysts; however, more bulkly NiO particles (up to 200 nm particle size) were detected outside the pores with an increase of the Ni loading up to 40 wt.%. Gas production was increased from 40.7 to 62.8 wt.%, hydrogen production was increased from 30.1 to 50.6 vol.% of total gas composition when the Ni loading was increased from 5 to 40 wt.% during the pyrolysis-gasification of wood sawdust. This work showed low coke deposition (from 0.5 to 4.0 wt.%) with valuable bio-oil by-products using the Ni/MCM-41 catalyst. The highly efficient conversion of renewable biomass resource to hydrogen and bio-oil with very low coke deposition indicates that biomass gasification on Ni/MCM-41 catalysts via two-stage reaction is a promising method for the development of the biorefinery concept.

Physical and combustion properties of briquettes produced from sawdust of three hardwood species and different organic binders

Abstract: The study was undertaken to assess the calorific value of briquettes produced from mixed sawdust of three tropical hardwood species (Afzelia africana, Terminalia superba, Melicia elcelsa) bonded with different binding agents (starch, cow dung and wood ash). Sawdust from each of the species was mixed with the binder in ratio of 70:30 for cow dung and wood ash and 70:15 of starch. The sawdust where mixed in a ratio 50:50 for each briquette combination produced. Combustion related properties namely percentage volatile matter, percentage ash content, percentage fixed carbon and calorific value of the briquettes where determined. All processing variables assessed in this study were not significantly different except for percentage fixed carbon at five percent level of probability. The result shows that briquette produced from sample of Afzelia africana and Terminalia superba combination bonded with starch had the highest calorific value of 33116kcal/kg while briquette produced from sample of Afzelia Africana and Terminalia superba bonded with ash had the least calorific value of 23991kcal/kg. Since the aim of briquetting is to produce briquette that will serve as good source of fuel and support combustion, the best briquette was produced when sawdust was mixed with starch. Also the use of mixed wood residue from the selected species and other hardwood species for briquette production should be encouraged as this will provide an alternative to firewood for household cheap energy source.

Comparative studies of physical characteristics of raw and modified sawdust for their use as adsorbents for removal of acid dye

Abstract: The present paper aims to investigate the physical characteristics of sawdust relative to its use as an adsorbent for removal of an acid dye (Orange G) from aqueous solutions. The raw sawdust was sieved to have a uniform size and was activated by sulphuric acid by refluxing the content at 60 oC for 4 h. Surface morphology and surface functional groups of both raw and modified sawdust samples were investigated by Scanning Electron Microscope (SEM), Energy Dispersive X-ray Analysis (EDX), Fourier Transformation Infrared (FTIR), and elemental analysis. All these analyses displayed significant change in the structure of the sawdust. The data obtained from batch adsorption experiments for the removal of the selected dye confirmed that adsorption characteristics of the modified sawdust were better than those of raw sawdust.

Bio-oil from Sawdust: Effect of Operating Parameters on the Yield and Quality of Pyrolysis Products

Abstract: This study investigated the effects of the pyrolysis temperature, feedstock particle size, and vapor residence time on the distribution and quality of liquid and char products from pyrolysis of sawdust in a fluidized-bed reactor. Sawdust and char samples were characterized with elemental and thermogravimetric analyses. Liquid bio-oil sample characterization was performed by Karl Fischer titration, elemental analysis, and gas chromatography–mass spectrometry (GC–MS). The bio-oil yield appeared to be maximized (≈62 wt %) at 500 °C, and the highest concentration of phenols was also produced at this temperature. Both the pyrolysis temperature and sawdust particle size had significant effects on the water content of the bio-oil with the water content being minimized at 500 °C. The yield of bio-oil showed a decreasing trend as the sawdust particle size was increased mainly because of the lower heating rate of larger sawdust particles. The effect of the residence time on the pyrolysis product distributions and t...

Application of polyaniline as an efficient and novel adsorbent for azo dyes removal from textile wastewaters

Abstract: In this work, application of polyaniline coated onto wood sawdust (PAni/SD) for the removal of methyl orange (MO) as a typical azo dye from aqueous solutions is introduced. The effects of some important parameters such as pH, initial concentration, sorbent dosage, and contact time on the uptake of MO solution were also investigated. In order to get a better comparison, adsorption experiments were also carried out using commercial grade of granulated activated carbon (GAC) and sawdust without coating (SD) at the same time. It was found that PAni/SD can be used to remove azo dyes such as MO from aqueous solutions very efficiently. Experimental data were analyzed by the Langmuir and Freundlich models of adsorption. Kinetic parameters for the adsorption of MO dyes for the selected adsorbents are also reported. In order to study the possibility of desorption for frequent application, chemical regeneration of the used adsorbents was also investigated. Desorption or recovery of dye and regeneration of adsorbent (PAni/SD) was found to be quite possible and of high performance. Application of modified sawdust with polyaniline for the removal of azo dye is very promising for textile wastewater treatment.

Energy Efficient Pilot-Scale Production of Wood Fuel Pellets made from a Raw Material Mix Including Sawdust and Rapeseed Cake

Abstract: Presently, most fuel pellets are made from sawdust or shavings. In Sweden, these materials are used to the maximum extent. As the demand for pellets increases, the supply of sawdust will be insufficient and other raw materials or mixes of raw materials will be used. This work investigates sawdust mixed with rapeseed cake. The latter is a residual product from the production of chemically unmodified oil refined from cold-pressed rape oil. At the Department of Energy, Environmental and Building Technology at Karlstad University, Sweden, a complete pilot-scale pellet production unit is located. The pellets are produced and tested for mechanical durability, length, bulk density and moisture content according to the Swedish Standard for pellets. During production, the load current, the die pressure and the die temperature were measured along with other parameters. The main purpose was to examine how the mixture of rapeseed cake and pine sawdust affected the energy consumption of the pelletising machine and mechanical durability of mixed fuel pellets. The results show that the energy consumption decreased and the amount of fines increased with increasing rapeseed cake in the wood fuel pellets. These results indicate that we must compromise between a decrease in the use of energy and a decrease in durability.

Biomass granular screw feeding: An experimental investigation

Abstract: Successful feeding is critical to biomass utilization processes, but difficult due to the heterogeneity, physical properties and moisture content of the particles. The objectives of the present study were to find the mechanisms of blockage in screw feeding and to determine the effects of particle mean size (0.5–15 mm), size distribution, shape, moisture content (10–60%), density and compressibility on biomass particle feeding at room temperature. Wood pellets, sawdust, hog fuel and wood shavings were tested in a screw feeder/lock hopper system previously employed to feed sawdust into a pilot-scale circulating fluidized-bed gasifier. Experimental results showed that large particles, wide size distributions, large bulk densities and high moisture contents generally led to larger torque requirements for screw feeding. The “choke section” and seal plug play important roles in determining the torque requirements.

Treated Tropical Wood Sawdust-Polypropylene Polymer Composite: Mechanical and Morphological Study

Abstract: In this research, composites based on treated tropical sawdust and polypropylene (PP) were prepared using hot press molding machine Raw sawdust was chemically treated with monomer, 2 - ethylhexyl methacrylate in order to improve the mechanical properties of the composites The influence of the chemically treated sawdust on the physical and mechanical properties of sawdust-PP composites were investigated at various loading level from 10 wt% up to 30 wt% Results indicate that the mechanical properties of the chemically treated sawdust–PP composites were found to be higher than those of the raw ones respectively The surface morphology obtained from scanning electron microscopy (SEM) showed that raw sawdust–PP composites possess surface roughness and weak interfacial adhesion between the matrix and the filler while the chemically treated one showed improved filler–matrix interaction This indicates that better dispersion of the filler with the PP matrix has occurred upon chemical treatment of the filler Water absorption tests showed that composites prepared from the chemically treated sawdust absorb lower amount of water compared to the ones prepared from raw sawdust, suggesting that hydrophilic nature of the cellulose in the sawdust has significantly decreased upon chemical treatment

The Removal of Hexavalent Chromium from Aqueous Solutions Using Modified Holly Sawdust: Equilibrium and Kinetics Studies

Abstract: The removal of hexavalent chromium from aqueous solutions onto modified holly sawdust was studied at varying initial hexavalent chromium concentrations, adsorbent doses, pHs and contact times. The removal of hexavalent chromium from aqueous solutions increased with increasing adsorbent dosage and contact time. The percentage of hexavalent chromium removed from the aqueous solutions decreased with increasing hexavalent chromium concentration and pH of the solution. The kinetics of the adsorption of hexavalent chromium onto modified holly sawdust was analyzed using pseudo first-order and pseudo second-order models. The pseudo second-order model described the kinetics of adsorption of hexavalent chromium. The Langmuir and Freundlich isotherm models were used for modeling of the adsorption equilibrium data. The Langmuir isotherm model well described the equilibrium data for the removal of hexavalent chromium by modified holly sawdust. The obtained maximum adsorption capacity was 18.86 mg/g at pH 7. The results showed that modified holly sawdust can be used as a low cost adsorbent for the treatment of aqueous solutions containing chromium.

Additives in wood pellet production – a pilot-scale study of binding agent usage

Abstract: Finland currently has tremendous enthusiasm to increase decentralised pellet production alongside of large-scale factories. The aim of research is to promote the development of eco-/cost-efficient Nordic wood-based pellet production by means of multidisciplinary research. Using Finnish conifer stem wood (bark-free Scotch pine sawdust and shavings) as a model raw material, the total functionality of a pilot-scale pellet facility combined with an extensive chemical toolbox was tested in this study to promote future development of eco- and cost-efficient wood-based pellet production in both quantitative and qualitative senses. Lignosulphonate, residual potato flour, and potato peel residue were used as adhesive binding agents. A pilot-scale pellet facility was equipped with a data logger for temperature and power measurements. The chemical toolbox included also novel specific staining and optical microscope methods and respirometric BOD Oxitop measurements. The results showed that adhesive binding agents increased the quality of pellets and changed inorganic characteristics, but did not have a significant effect on their calorimetric heat values. Lignosulphonate even increased the rate of production. Valuable information about both the pelletizing process and pellets is necessary in the future when developing good-quality pellets, a prime biofuel, from low-value and/or moist biomass that has undergone a cost-efficient drying process.

An effective adsorbent based on sawdust for removal of direct dye from aqueous solutions

Abstract: Sawdust, SD, was reacted with Sandene 850 (polyamine) in alkaline medium to yield cationized sawdust. The latter was characterized through its Fourier Transform Infrared (FT-IR) spectra and nitrogen content. Thus, obtained cationized sawdust was harnessed for removal of Direct Red 23 from aqueous solutions. Adsorption studies were performed under different agitation time, adsorbent and adsorbate concentrations and the onset of this on the adsorption capacity of Direct Red 23 onto cationized sawdust. Langmuir and Freundlich models were applied in the adsorption studies. The study showed that the cationized sawdust is effectively used in adsorption of Direct Red 23 from aqueous solutions.

Effects of Lignocellulosic in Wood Used as Substrate on the Quality and Yield of Mushrooms

Abstract: The objective of this study was to find out if the sawdust generated from some of the Ghanaian wood species can be used in the cultivation of pleurotus ostreatus (oyster mushroom) and their subsequent effect on the quality and yield of the mushrooms produced. Sawdust from three Ghanaian wood species (Triplochiton scleraxylon, Ceiba pentandra and Terminalia superba) were collected and their cellulose, hemicelluloses, lignin and nitrogen contents determined using standard methods. Triplochiton scleraxylon gave 46.76%, 15.69%, 27.55%, 0.01% w/w, Ceiba pentandra gave 44.79%, 15.32%, 34.08%, 0.02% w/w and Terminalia superba gave 46.64%, 16.29%, 31.17%, 0.02% w/w of the cellulose, hemicelluloses, lignin and nitrogen content respectively. Compost was then made from each of the wood and used as substrate for the cultivation of pleurotus ostreatus. The highest yield of mushroom was obtained from T. scleraxylon 334g followed by T. superba 277 g and C. pentandra gave the lowest yield of 193 g fresh weight after 3 flushes. The proximate composition of the mushrooms produced gave crude protein ranging 16.33 - 18.20, fat 1.67 - 2.07, carbohydrate 40.86 - 50.53, fibre 4.14 - 6.73 and ash content of 4.40% - 5.80%. The report has shown that the yield and nutritional content of the oyster mushroom on sawdust depends on the chemical constituents such as the cellulose content, the hemicellulose content, the lignin content, the nitrogen content of the particular substrate used. Triplochiton scleraxylon gave the best yield and nutritional content, considering that these substrates are freely available and regarded as “waste”, it can be used to cultivate edible mushrooms to supplement nutritional requirement and source of income to make life better for many people.

Biosorption Characteristics of Sawdust for the Removal of Cd(II) Ions: Mechanism and Thermodynamic Studies

Abstract: Surface reaction methodology was employed for the optimization of cadmium removal onto sawdust with respect to various physico-chemical parameters. FT-IR was principally employed for the assessment of the chemical structure of sawdust. The biosorption equilibrium data were best represented by Khan and Langmuir isotherms. The monolayer sorption capacity obtained from Langmuir model was found to be 41.21 mg/g. Biosorption showed pseudo second order rate kinetics at different initial concentration of Cd(II). The intraparticle diffusion study indicated that film diffusion may be involved in the current study. Thermodynamic parameters showed that the sorption process is exothermic and non-spontaneous.