Research Articles

Long chain omega-3 fatty acids such as eicosapentaenoic acid (EPA) are essential for the regulation of critical biological functions in humans and other mammals. EPA production via solid state fermentation of sunflower press cake was investigated using eight fungal strains representing the genus Mortierella. During this study the effect of supplementing the sunflower press cake substrate with 10% (w/w) linseed oil was studied with regard to the supplement’s impact on EPA production and the polyunsaturated fatty acid profile of the fermented substrate. The addition of the linseed oil improved the EPA yield of most strains, leading to a reduction in the average arachidonic acid:EPA ratio from 50.68 to 3.66. The ratio of polyunsaturated to saturated fatty acids was increased significantly (t=5.75, p=0.05) by the addition of linseed oil, with higher desaturation levels among the 20-carbon fatty acids. The strains that produced the highest levels of EPA on sunflower press cake supplemented with linseed oil were Mortierella alpina Mo 46 and Mortierella basiparvispora Mo 88, which produced 6.4 mg and 5.8 mg EPA per g of sunflower press cake, respectively.

Heavy metal’s release without treatment poses a significant threat to the environment. Heavy metals are non-biodegradable and persistent. In the present study the ash of water hyacinth (Eichhornia crassipes), was used to remove six metals from aqueous solutions through biosorption. Results of batch and column experiments showed excellent adsorption capacity. Removal of lead, chromium, zinc, cadmium, copper, and nickel was 29.83, 1.263, 1.575, 3.323, 2.984 and 1.978 µgg-1, respectively. The biosorptive capacity was maximum with pH >8.00. Desorption in µgg-1 of ash for lead, chromium, zinc, cadmium, copper, and nickel was 18.10, 9.99, 11.99, 27.54, 21.09, and 3.71 respectively. Adsorption/desorption of these metals from ash showed the potential of this technology for recovery of metals for further usages. Hydrogen adsorption was also studied with a Sievert-type apparatus. Hydrogen adsorption experiments showed significant storage capacity of water hyacinth ash.

Acacia hybrid (Acacia mangium x auriculiformis), a wood species of low dimensional stability which is used almost exclusively for pulp, paper, or as firewood, was heat treated in nitrogen at 210-230 ºC for 2 to 6 hours. The changes in color and anti-swelling efficiency (ASE) of wood after heat treatment were determined for the different heat treatment conditions. The results show that heat treatment mainly resulted in the darkening of wood tissues, and heat-treated wood had better dimensional stability than those of the control samples. Chemical modifications of wood components were determined by FT-IR analysis. Spectra indicated that the hydroxyl group content was reduced by increased treatment intensity. This result coincides with the increase in dimensional stability of heat-treated wood. Heat treatment of acacia hybrid wood shows an interesting potential to improve the quality and value for solid wood products from plantation-grown wood species.

This study investigates effects of six kenaf cultivars named Cubano, Niger, Cubano 2032, 9277, 7551, and 7566 and three harvesting time stages on the properties of pulp and handsheet paper made from kenaf. Six cultivars of an Iranian kenaf (Hibiscus cannabinus L.), were planted on 19 May 2007, and harvested after 85, 105, and 135 days. It was understood that with the increase of plant age, fiber yield increased. Maximum yield at each of three harvesting time stages was related to Niger. Consequently, if a high fiber yield is sought, Niger can be recommended, but for a paper with high strength properties, Cubano 2032 is strongly suggested. This cultivar produces a paper with significant burst, tear, breaking length and fold endurance even though its yield was somewhat lower than that of Niger at short harvesting times. Moreover, at second harvesting time stage, maximum strength properties of handsheets such as burst, tear, and breaking length, were seen in Cubano, though the fiber yield of this cultivar was a bit lower than Niger, but still more than Cubano 2032. We showed that a minor positive change in the handsheet properties could be achieved through harvesting kenaf at the third stage as compared to the first and second stages.

In order to study the thermal decomposition characteristics of hemicellulose, a highly efficient procedure was carried out to extract hemicellulose from corn stalk. Several different sugar units were observed by 13C NMR spectra to show the presence and species of hemicellulose. Following isolation of the hemicellulose, experimental research on its thermal behavior were carried out with a thermogravimetric analyzer under inert atmosphere at heating rates ranging from 10 to 50°C/min, and the kinetic parameters were calculated by the Kissinger and Ozawa methods, respectively. It was found that the thermal degradation of hemicellulose mainly occurred in the temperature range 180-340°C with a final residue yield of 24% at 700°C. An increase of the heating rate could slightly increase both the temperatures at which the peak weight loss rate was observed and the maximum value of weight loss rate. The activation energy (E) and the pre-exponential factor (lnA) obtained by the Kissinger and Ozawa methods were 213.3kJ mol-1, 211.6kJ mol-1 and 46.2min-1, 45.9min-1, respectively. Even though the data showed little difference, the fitting degree of the Ozawa method was better than that of the Kissinger method. The experimental results and kinetic parameters may provide useful data for effective design and improvement of thermochemical conversion units.

In order to prepare nanoparticles, corn cobs were treated with sodium hydroxide in the range 0-6 mole/litre (0-24% of sodium hydroxide on oven dry basis) at 165 oC for 1.5 h at a liquor to solid ratio of 4.5:1. The sample obtained at the optimised condition (4.5 mole/litre) was washed with deionised water, disintegrated, and filtered through 80 mesh screens. Powder thus obtained was delignified by acidified sodium chlorite and dried in a vacuum oven to constant weight. Dried powder was further separated by 270 mesh screens. An average particle size approximately equal to 22 nm was observed by Transmission Electron Microscopy (TEM). Its crystallinity was determined by XRD analysis. The aggregated particle size was observed in the micron range by Scanning Electron Microscopy (SEM).

The fast growing aquatic weed water hyacinth, which is available almost year-round in the tropics and subtropics, was utilized as the chief source of cellulose for production of fuel ethanol via enzymatic hydrolysis and fermentation. Fungal cellulases produced on-site by utilizing acid-alkali pretreated water hyacinth as the substrate were used as the crude enzyme source for hydrolysis of identically pretreated biomass. Four different modes of enzymatic hydrolysis and fermentation were trialed in the present study for optimization of the yield of ethanol. Two common yeasts viz., Saccharomyces cerevisiae and Pachysolen tannophilus, were used for fermentation of hexose and pentose sugars in the hydrolysate. Significant enhancement of concentration (8.3 g/L) and yield (0.21 g/g) of ethanol was obtained through a prefermentation hydrolysis-simultaneous saccharification and fermentation (PH-SSF) process, over the other three processes viz., separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), and single batch bioconversion (SBB) by utilizing fungal culture broth with and without filtration as crude enzyme source.

The aim of this research is to examine the market potential for wood plastic composite (WPC) products in the highway construction sector in place of non-renewable materials (e.g. virgin plastic and steel) and preservative-based products (treated wood). State-level transportation officials indicate that the majority of highway construction purchases are conducted by highway construction contractors. Results from a mail survey of highway contractors in eight western U.S. states indicate that a substantial volume of highway construction material may be suitable for substitution with WPCs. Overall, respondents were not familiar with WPC as a material, but compared it favorably with other materials commonly used in the sector. When making purchase decisions, respondents were most concerned with products meeting regulatory specifications, cost, availability, and trust in quality. Attributes related to sustainability, location of manufacture, and content of recycled material were viewed as less important.

Effects of ultrasonic pretreatment on the bleaching of chemimechanical pulp (CMP) fiber of triploid Chinese white Poplar were investigated. Before single-stage hydrogen peroxide bleaching, CMP was sonicated at 1.5% pulp consistency and 50oC for 20min with 90% amplitude and 20s pulse; these conditions showed the most favorable effect of a 3.5% ISO increase of brightness, reaching a final value of 80.2% ISO. The benefit may be because the ultrasound can accelerate heterogeneous reactions, which arise from the impingement of microjets and shockwaves on the solid surface, which are then capable of inducing striking changes in surface morphology, composition, and reactivity. To prove the theory, the surface structure and surface morphology were investigated by SEM and AFM, and the crystalline structure and characteristics of the cellulose in terms of XRD and FT-IR were also evaluated.

A new simple and safe method for quantifying lignin content in lignocellulosic biomass is described. The approach consists of measuring the absorbance of a solution of whole biomass dissolved in the ionic liquid 1-n-butyl-3-methyl imidazolium chloride, [Bmim][Cl], at 440 nm via ultraviolet- (UV-) visible spectrophotometry. An extinction coefficient for a lignin standard, highly pure lignin isolated from biomass through an organosolv process, is used in conjunction with the Beer-Lambert Law to calculate the lignin concentration. Principal component analysis (PCA) of Fourier Transform-Infrared (FTIR) spectra collected for several different lignin standards was performed to understand the differences in their chemical structure and composition (e.g., the relative amounts of syringyl and guaiacyl units). A rapid FTIR analysis of the whole biomass sample with unknown lignin content is required to assist in the proper selection of the lignin standard for the subsequent spectrophotometric analysis. The proposed method was tested and validated on two biomass types: Yellow poplar and Southern pine. The spectrophotometric approach yielded lignin contents for Yellow poplar and Southern pine of 25.7 ± 1.1% and 26.7 ± 0.7%, respectively, which are comparable to the values obtained by a standard wet chemical protocol, 25.1% ± 0.7 and 26.6 ± 0.4%, respectively.