Abstract: Biological conversion of biomass to methane has
received increasing attention in recent years. Grasses have been
explored for their potential anaerobic digestion to methane. In this
review, extensive literature data have been tabulated and classified.
The influences of several parameters on the potential of these
feedstocks to produce methane are presented. Lignocellulosic
biomass represents a mostly unused source for biogas and ethanol
production. Many factors, including lignin content, crystallinity of
cellulose, and particle size, limit the digestibility of the hemicellulose
and cellulose present in the lignocellulosic biomass. Pretreatments
have used to improve the digestibility of the lignocellulosic biomass.
Each pretreatment has its own effects on cellulose, hemicellulose and
lignin, the three main components of lignocellulosic biomass. Solidstate
anaerobic digestion (SS-AD) generally occurs at solid
concentrations higher than 15%. In contrast, liquid anaerobic
digestion (AD) handles feedstocks with solid concentrations between
0.5% and 15%. Animal manure, sewage sludge, and food waste are
generally treated by liquid AD, while organic fractions of municipal
solid waste (OFMSW) and lignocellulosic biomass such as crop
residues and energy crops can be processed through SS-AD. An
increase in operating temperature can improve both the biogas yield
and the production efficiency, other practices such as using AD
digestate or leachate as an inoculant or decreasing the solid content
may increase biogas yield but have negative impact on production
efficiency. Focus is placed on substrate pretreatment in anaerobic
digestion (AD) as a means of increasing biogas yields using today’s
diversified substrate sources.
Abstract: In this research, it is aimed not only microwave synthesis of magnesium borates but also evaluation of magnesium wastes. Synthesis process can be described with the reaction of Mg wastes and boric acid using microwave energy. X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) were applied to synthesized minerals. According to XRD results, magnesium borate hydrate mixtures were obtained as mcallisterite (pdf# = 01-070-1902, Mg2(B6O7(OH)6)2.9(H2O)) at higher crystallinity properties was achieved at the mole ratio raw material 1:1. Also, other kinds of magnesium borate hydrates were obtained at lower crystallinity such as admontite (pdf # = 01-076-0540, MgO(B2O3)3.7(H2O)), inderite (pdf # = 01-072-2308, 2MgO.3B2O3.15(H2O)) and magnesium borate hydrates (pdf # = 01-076-0539, MgO(B2O3)3.6(H2O)). FT-IR spectrums indicated that minor changes were seen at the band values of characteristic stretching in each experiment. At the end of experiments it is seen that using microwave energy may contribute positive effects to design of synthesis process such as reducing reaction time and products at higher crystallinity.
Abstract: In this research, n-dodecylthiol was added to P3HT/ PC70BM polymer solar cells to improve the crystallinity of P3HT and enhance the phase separation of P3HT/PC70BM. The improved crystallinity of P3HT:PC70BM doped with 0-5% by volume of n-dodecylthiol resulted in improving the power conversion efficiency of polymer solar cells by 33%. In addition, thermal annealing of the P3HT/PC70MB/n-dodecylthiolcompound showed further improvement in crystallinity with n-dodecylthiol concentration up to 2%. The highest power conversion efficiency of 3.21% was achieved with polymer crystallites size L of 11.2nm, after annealing at 150°C for 30 minutes under a vacuum atmosphere. The smaller crystallite size suggests a shorter path of the charge carriers between P3HT backbones, which could be beneficial to getting a higher short circuit current in the devices made with the additive.
Abstract: Polybag and mulch film in agricultural field are used plastics which caused environmental problems after transplantation and planting processes due to the discarded wastes. Thus a degradable polybag was designed in this study to replace non degradable polybag with natural biodegradable resin that is widely available, namely sago starch (SS) and polyvinyl alcohol (PVA). Hybrid blend consists of SS, PVA and linear low density polyethylene (LLDPE) was compounded at different ratios. The thermal and mechanical properties of the blends were investigated. Hybrid films underwent landfill degradation tests for up to 2 months. The films showed gelation and melting transition existed for all three systems with significant melting peaks by LLDPE and PVA. All hybrid blends loses its LLDPE semi crystalline characteristics as PVA and SS systems had disrupted crystallinity and enhanced the amorphosity of the hybrid system. Generally, blending SS with PVA improves the mechanical properties of the SS based materials. Tensile strength of each film was also decreased with the increase of SS contents while its modulus had increased with SS content.
Abstract: We constructed an atomic structure model for a PAN-based carbon fiber containing amorphous structures using molecular dynamics methods. It was found that basic physical properties such as crystallinity, Young’s modulus, and thermal conductivity of our model were nearly identical to those of real carbon fibers. We then obtained the tensile strength of a carbon fiber, which has no macro defects. We finally determined that the limitation of the tensile strength was 19 GPa.
Abstract: Enzymatic hydrolysis is one of the major steps involved in the conversion from sugarcane bagasse to yield ethanol. This process offers potential for yields and selectivity higher, lower energy costs and milder operating conditions than chemical processes. However, the presence of some factors such as lignin content, crystallinity degree of the cellulose, and particle sizes, limits the digestibility of the cellulose present in the lignocellulosic biomasses. Pretreatment aims to improve the access of the enzyme to the substrate. In this study sugarcane bagasse was submitted chemical pretreatment that consisted of two consecutive steps, the first with dilute sulfuric acid (1 % (v/v) H2SO4), and the second with alkaline solutions with different concentrations of NaOH (1, 2, 3 and 4 % (w/v)). Thermal Analysis (TG/ DTG and DTA) was used to evaluate hemicellulose, cellulose and lignin contents in the samples. Scanning Electron Microscopy (SEM) was used to evaluate the morphological structures of the in natura and chemically treated samples. Results showed that pretreatments were effective in chemical degradation of lignocellulosic materials of the samples, and also was possible to observe the morphological changes occurring in the biomasses after pretreatments.
Abstract: In this study, static batch fermentation was used for bacterial cellulose production in date syrup solution (Bx. 10%) at 28°C using Gluconacetobacter. xylinus (PTCC 1734). The physicochemical properties of standard Sigma CMC and the produced carboxymethyl bacterial cellulose (CMBC) were studied using FT-IR spectroscopy, X-ray diffractometry (XRD) and Scanning Electron Microscopy (SEM). According to the FT-IR spectra the bands at 1664 and 1431 cm-1 indicate that carboxylic acid groups and carboxylate groups exist on the surface. The SEM imaging of CMBC and CMC carried out in magnification of 1K. Comparing the SEM imaging obviously showed that the ribbon shape in CMC remained but the length of ribbons became shorter while that shape changed to flake shape for CMBC. Determination of the area under XRD patterns demonstrated that the crystallinity amount of CMC was more than that for CMBC (51.08% and 81.84% for CMBC and CMC, respectively).
Abstract: The production of biodiesel from crude palm oil with
a homogeneous base catalyst is unlikely owing to considerable
formation of soap. Free fatty acids (FFA) in crude palm oil need to
be reduced, e.g. by esterification. This study investigated the activity
of sulfated zirconia calcined at various temperatures for esterification
of FFA in crude palm oil to biodiesel. It was found that under a
proper reaction condition, sulfated zirconia well catalyzes
esterification. FFA content can be reduced to an acceptable value for
typical biodiesel production with a homogeneous base catalyst.
Crystallinity and sulfate attachment of sulfated zirconia depend on
calcination temperature during the catalyst preparation. Too low
temperature of calcination gives amorphous sulfated zirconia which
has low activity for esterification of FFA. In contrast, very high
temperature of calcination removes sulfate group, consequently,
conversion of FFA is reduced. The appropriate temperature range of
calcination is 550-650 oC.
Abstract: Nylon 6-clay hybrid/neat nylon 6, sheath/core
bicomponent nanocomposite fibers containing 4 wt% of clay in
sheath section were melt spun at different take-up speeds. Their
orientation and crystalline structure were compared to those of neat
nylon 6 fibers. Birefringence measurements showed that the
orientation development in sheath and core parts of bicomponent
fibers was different. Crystallinity results showed that clay did not act
as a nucleating agent for bicomponent fibers. The neat nylon 6 fiber
had a smooth surface while striped pattern was appeared on the
surface of bicomponent fiber containing clay due to thermal
shrinkage of the core part.
Abstract: We investigated a modified thermal evaporation
method in the growth process of ZnO nanowires. ZnO nanowires
were fabricated on p-type silicon substrates without using a metal
catalyst. A simple horizontal double-tube system along with
chemical vapor diffusion of the precursor was used to grow the ZnO
nanowires. The substrates were placed in different temperature
zones, and ZnO nanowires with different diameters were obtained for
the different substrate temperatures. In addition to the nanowires,
ZnO microdiscs with different diameters were obtained on another
substrate, which was placed at a lower temperature than the other
substrates. The optical properties and crystalline quality of the ZnO
nanowires and microdiscs were characterized by room temperature
photoluminescence (PL) and Raman spectrometers. The PL and
Raman studies demonstrated that the ZnO nanowires and microdiscs
grown using such set-up had good crystallinity with excellent optical
properties. Rectifying behavior of ZnO/Si heterostructures was
characterized by a simple DC circuit.
Abstract: Photo-crosslinked rice starch-based biodegradable
films were prepared by casting film-solution on leveled trays and
ultra violet (UV) irradiation was applied for 10 minute. The effect of
the content (3%, 6% and 9 wt. %)of photosensitiser (sodium
benzoate) on mechanical properties, water vapor permeability (WVP)
and structural properties of rice starch films were investigated. The
tensile strength increased while elongation at break and water
resistance properties of rice starch films decreased with addition and
increasing content of photosensitiser. The % crystallinity of rice
starch films were decreased when the content of photosensitiser
increased and UV were applied. The results showed that the
carboxylate group band of sodium benzoate was found in the FTIR
spectrum of rice starch films and found that incorporation of 6% of
photosensitiser into the films showed a higher absorption band of
resulted films. This result pointed out the highest interaction between
starch molecules was occurred.
Abstract: In this study, we sought to investigate the mercury
removal efficiency of manganese oxides from natural gas. The
fundamental studies on mercury removal with manganese oxides
sorbents were carried out in a laboratory scale fixed bed reactor at 30
°C with a mixture of methane (20%) and nitrogen gas laden with 4.8
ppb of elemental mercury. Manganese oxides with varying surface
area and crystalline phase were prepared by conventional precipitation
method in this study. The effects of surface area, crystallinity and
other metal oxides on mercury removal efficiency were investigated.
Effect of Ag impregnation on mercury removal efficiency was also
investigated. Ag supported on metal oxide such titania and zirconia as
reference materials were also used in this study for comparison. The
characteristics of mercury removal reaction with manganese oxide
was investigated using a temperature programmed desorption (TPD)
technique.
Manganese oxides showed very high Hg removal activity (about
73-93% Hg removal) for first time use. Surface area of the manganese
oxide samples decreased after heat-treatment and resulted in complete
loss of Hg removal ability for repeated use after Hg desorption in the
case of amorphous MnO2, and 75% loss of the initial Hg removal
activity for the crystalline MnO2. Mercury desorption efficiency of
crystalline MnO2 was very low (37%) for first time use and high (98%)
after second time use. Residual potassium content in MnO2 may have
some effect on the thermal stability of the adsorbed Hg species.
Desorption of Hg from manganese oxides occurs at much higher
temperatures (with a peak at 400 °C) than Ag/TiO2 or Ag/ZrO2.
Mercury may be captured on manganese oxides in the form of mercury
manganese oxide.
Abstract: Coal fly ash (CFA) generated by coal-based thermal
power plants is mainly composed of some oxides having high
crystallinity, like quartz and mullite. In this study, the effect of CFA
crystallinity toward lead adsorption capacity was investigated. To get
solid with various crystallinity, the solution of sodium hydroxide
(NaOH) of 1-7 M was used to treat CFA at various temperature and
reflux time. Furthermore, to evaluate the effect of NaOH-treated CFA
with respect to adsorption capacity, the treated CFA were examine as
adsorbent for removing lead in the solution. The result shows that
using NaOH to treat CFA causes crystallinity of quartz and mullite
decrease. At higher NaOH concentration (>3M), in addition the
damage of quartz and mullite crystallinity is followed by crystal
formation called hydroxysodalite. The lower crystalllinity, the higher
adsorption capacity.
Abstract: Bacterial cellulose, a biopolysaccharide, is produced by the bacterium, Gluconacetobacter xylinus. Static batch fermentation for bacterial cellulose production was studied in sucrose and date syrup solutions (Bx. 10%) at 28 °C using G. xylinus (PTCC, 1734). Results showed that the maximum yields of bacterial cellulose (BC) were 4.35 and 1.69 g/l00 ml for date syrup and sucrose medium after 336 hours fermentation period, respectively. Comparison of FTIR spectrum of cellulose with BC indicated appropriate coincidence which proved that the component produced by G. xylinus was cellulose. Determination of the area under X-ray diffractometry patterns demonstrated that the crystallinity amount of cellulose (83.61%) was more than that for the BC (60.73%). The scanning electron microscopy imaging of BC and cellulose were carried out in two magnifications of 1 and 6K. Results showed that the diameter ratio of BC to cellulose was approximately 1/30 which indicated more delicacy of BC fibers relative to cellulose.
Abstract: The complexity of lignocellulosic biomass requires
a pretreatment step to improve the yield of fermentable sugars. The
efficient pretreatment of corn cobs using microwave and potassium
hydroxide and enzymatic hydrolysis was investigated. The
objective of this work was to characterize the optimal condition of
pretreatment of corn cobs using microwave and potassium
hydroxide enhance enzymatic hydrolysis. Corn cobs were
submerged in different potassium hydroxide concentration at varies
temperature and resident time. The pretreated corn cobs were
hydrolyzed to produce the reducing sugar for analysis. The
morphology and microstructure of samples were investigated by
Thermal gravimetric analysis (TGA, scanning electron microscope
(SEM), X-ray diffraction (XRD). The results showed that lignin
and hemicellulose were removed by microwave/potassium
hydroxide pretreatment. The crystallinity of the pretreated corn
cobs was higher than the untreated. This method was compared
with autoclave and conventional heating method. The results
indicated that microwave-alkali treatment was an efficient way to
improve the enzymatic hydrolysis rate by increasing its
accessibility hydrolysis enzymes.
Abstract: The complex structure of lignocellulose leads to great
difficulties in converting it to fermentable sugars for the ethanol
production. The major hydrolysis impediments are the crystallinity of
cellulose and the lignin content. To improve the efficiency of
enzymatic hydrolysis, microbial pretreatment of corncob was
investigated using two bacterial strains of Bacillus subtilis A 002 and
Cellulomonas sp. TISTR 784 (expected to break open the crystalline
part of cellulose) and lignin-degrading fungus, Phanerochaete
sordida SK7 (expected to remove lignin from lignocellulose). The
microbial pretreatment was carried out with each strain under its
optimum conditions. The pretreated corncob samples were further
hydrolyzed to produce reducing glucose with low amounts of
commercial cellulase (25 U·g-1 corncob) from Aspergillus niger. The
corncob samples were determined for composition change by X-ray
diffraction (XRD), Fourier transform infrared spectroscopy (FTIR),
and scanning electron microscope (SEM). According to the results,
the microbial pretreatment with fungus, P. sordida SK7 was the most
effective for enhancing enzymatic hydrolysis, approximately, 40%
improvement.
Abstract: The characterisation of agro-wastes fibres for composite applications from Nigeria using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) has been done. Fibres extracted from groundnut shell, coconut husk, rice husk, palm fruit bunch and palm fruit stalk are processed using two novel cellulose fibre production methods developed by the authors. Cellulose apparent crystallinity calculated using the deconvolution of the diffractometer trace shows that the amorphous portion of cellulose was permeable to hydrolysis yielding high crystallinity after treatment. All diffratograms show typical cellulose structure with well-defined 110, 200 and 040 peaks. Palm fruit fibres had the highest 200 crystalline cellulose peaks compared to others and it is an indication of rich cellulose content. Surface examination of the resulting fibres using SEM indicates the presence of regular cellulose network structure with some agglomerated laminated layer of thin leaves of cellulose microfibrils. The surfaces were relatively smooth indicating the removal of hemicellulose, lignin and pectin.
Abstract: Zeolite A and MCM-41 have extensive applications in basic science, petrochemical science, energy conservation/storage, medicine, chemical sensor, air purification, environmentally benign composite structure and waste remediation. However, the use of zeolite A and MCM-41 in these areas, especially environmental remediation, are restricted due to prohibitive production cost. Efficient recycling of and resource recovery from coal fly ash has been a major topic of current international research interest, aimed at achieving sustainable development of human society from the viewpoints of energy, economy, and environmental strategy. This project reported an original, novel, green and fast methods to produce nano-porous zeolite A and MCM-41 materials from coal fly ash. For zeolite A, this novel production method allows a reduction by half of the total production time while maintaining a high degree of crystallinity of zeolite A which exists in a narrower particle size distribution. For MCM-41, this remarkably green approach, being an environmentally friendly process and reducing generation of toxic waste, can produce pure and long-range ordered MCM-41 materials from coal fly ash. This approach took 24 h at 25 oC to produce 9 g of MCM-41 materials from 30 g of the coal fly ash, which is the shortest time and lowest reaction temperature required to produce pure and ordered MCM-41 materials (having the largest internal surface area) compared to the values reported in the literature. Performance evaluation of the produced zeolite A and MCM-41 materials in wastewater treatment and air pollution control were reported. The residual fly ash was also converted to zeolite Na-P1 which showed good performance in removal of multi-metal ions in wastewater. In wastewater treatment, compared to commercial-grade zeolite A, adsorbents produced from coal fly ash were effective in removing multi heavy metal ions in water and could be an alternative material for treatment of wastewater. In methane emission abatement, the zeolite A (produced from coal fly ash) achieved similar methane removal efficiency compared to the zeolite A prepared from pure chemicals. This report provides the guidance for production of zeolite A and MCM-41 from coal fly ash by a cost-effective approach which opens potential applications of these materials in environmental industry. Finally, environmental and economic aspects of production of zeolite A and MCM-41 from coal fly ash were discussed.
Abstract: Biofuels, like biobutanol, have been recognized for
being renewable and sustainable fuels which can be produced from
lignocellulosic biomass. To convert lignocellulosic biomass to
biofuel, pretreatment process is an important step to remove
hemicelluloses and lignin to improve enzymatic hydrolysis. Dilute
acid pretreatment has been successful developed for pretreatment of
corncobs and the optimum conditions of dilute sulfuric and
phosphoric acid pretreatment were obtained at 120 °C for 5 min with
15:1 liquid to solid ratio and 140 °C for 10 min with 10:1 liquid to
solid ratio, respectively. The result shows that both of acid
pretreatments gave the content of total sugar approximately 34–35
g/l. In case of inhibitor content (furfural), phosphoric acid
pretreatment gives higher than sulfuric acid pretreatment.
Characterizations of corncobs after pretreatment indicate that both of
acid pretreatments can improve enzymatic accessibility and the better
results present in corncobs pretreated with sulfuric acid in term of
surface area, crystallinity, and composition analysis.
Abstract: Composites based on a biodegradable polycaprolactone (PCL) containing 0.5, 1.0 and 2.0 wt % of titanium dioxide (TiO2) micro and nanoparticles were prepared by melt mixing and the effect of filler type and contents on the thermal properties, dynamic-mechanical behaviour and morphology were investigated. Measurements of storage modulus and loss modulus by dynamic mechanical analysis (DMA) showed better results for microfilled PCL/TiO2 composites than nanofilled composites, with the same filler content. DSC analysis showed that the Tg and Tc of micro and nanocomposites were slightly lower than those of neat PCL. The crystallinity of the PCL increased with the addition of TiO2 micro and nanoparticles; however, the cc for the PCL was unchanged with micro TiO2 content. The thermal stability of PCL/TiO2 composites were characterized using thermogravimetric analysis (TGA). The initial weight loss (5 wt %) occurs at slightly higher temperature with micro and nano TiO2 addition and with increasing TiO2 content.