Volume 7 Issue 3

Dihydrocumic acid was prepared from β-pinene through oxidation and dehydration. Then, ten oxime esters from dihydrocumic acid were synthesized. Reaction conditions of the oxime esters were adjusted and their structures were characterized by IR, 1H-NMR, MS, and elemental analysis. The antibacterial activity of these newly synthesized oxime esters against Gram-negative bacteria and Gram-positive bacteria was also investigated using the inhibition zone method. The preliminary results indicated that seven compounds displayed better antibacterial activity against Gram-negative bacteria compared with bromogeramine, a commercially available antibacterial agent.

Montmorillonite clay particles that had been prepared with an alklyl-ammonium surfactant were used to modify the moisture-sensitivity of bleached softwood kraft fibers through solvent exchange and adsorption methods. Moisture absorption and water uptake of the wood pulp fibers were significantly lower after the organo-nanoclay treatment. Thermal stability, surface energy, and surface morphology of the treated fibers were characterized using Thermogravimetric Analysis (TGA), Inverse Gas Chromatography (IGC), Scanning Electron Microscopy-Energy Dispersive X-ray Analysis (SEM-EDX), and Transmission Electron Microscopy (TEM) imaging. The Fourier Transform Infrared (FT-IR) spectral characteristics of the treated fibers were obtained to better understand the modified surface functional groups of the treated fibers. The treated bio-fibers had nano-scale surface roughness and a much reduced surface energy. The contact angle of water on the treated fiber mat was found to be higher than 160º. The thermal stability of the treated fibers was not affected by the modification.

The aim of this work was to study the potential application of four types of cereal straws: oats, maize, rapeseed, and barley, in order to obtain cellulose pulp through the Specel® process for use in the manufacture of 100% biodegradable and ecological packaging. Raw materials were chemically characterized to determine alcohol-extractives, ash, lignin, holocellulose, and α-cellulose. Cellulosic pulps obtained from raw materials were characterized to determine yield, Kappa number, and viscosity. Paper sheets made from cellulosic pulps were characterized to determine beating degree, tensile index, stretch, burst index, tear index, and brightness. Finally, the results were compared to the raw material used in the industrial manufacturing of packaging (wheat). The four studied raw materials (oats, maize, rapeseed, and barley) were judged to be suitable for use in the Specel® process to obtain cellulosic pulp suitable for production of ecological containers.

The effects of pretreatment agents on pectin removal and chemical compositions in cotton stalk bark were studied. The results showed that the reaction rates of the depectinization agents reacting with calcium pectinate were V_Na2C2O4 > V_Na5P3O10 > V_NaOH . The ratio of pectin removal reached 53.73% after pretreatment with 3% sodium oxalate. When the parameters of precondition were 3% sodium oxalate, 90 °C, and bleaching with 6.5% NaOH and 11% H2O2, the brightness of chemimechanical pulp from whole cotton stalk reached 76.18% ISO.

To assess the feasibility of implementing hemicellulose recovery stages in kraft mills, Eucalyptus globulus wood samples were subjected to aqueous treatments with hot, compressed water (autohydrolysis processing) to achieve partial dissolution of xylan. Autohydrolyzed solids were subjected to kraft pulping under selected conditions to yield a pulp of low kappanumber, and to an optimized TCF bleaching sequence made up of three stages (alkaline oxygen delignification, chelating, and pressurized hydrogen peroxide), with minimized additions of pulping and bleaching chemicals. The final product had a relatively low kappa number (1.4), 641 mL/g ISO intrinsic viscosity, and 86.4% brightness.

In the present work, a method for extracting cellulose from olive industry solid waste has been developed. The method involves subjecting solid olive waste to kraft pulping, followed by multistep bleaching processes. The totally free chlorine chemical bleaching sequence APEP was the most effective and gave an average cellulose yield of about 35%. The extracted cellulose was extensively characterized using FTIR, EMS, HPLC, and viscometry. Our key finding in this study is that the extracted cellulose was found to have physio-chemical properties that are similar to those of conventional microcrystalline cellulose (MCC). This is important, as our results show how lignocellulosic agricultural wastes can be utilized to produce high value cellulose powder.

Steam explosion pretreatment of wheat straw can solubilize a significant portion of the hemicellulosic component and enhance the enzymatic digestibility of the remaining cellulose for fermentation into ethanol. In this work, wheat straw was pretreated by steam explosion using different steam temperatures and retention times, and the chemical compositions of the raw and steam-exploded wheat straw were analyzed. Results showed that the content of hemicellulose decreased sharply at higher steam temperatures and longer retention times; however, the content of lignin changed inconspicuously. After pretreatment, the characteristics of the straw fiber were investigated by studying their proportion of microfibrils, SEM, and FTIR. To assess the differences among various pretreatment parameters, the concentration of the reducing sugar and glucose conversion were determined. The highest reducing sugar concentration and glucose conversion were achieved at the explosion conditions of a pretreatment temperature of 220 ºC and a residence time of 3 min.

Hot-water extraction of hemicelluloses, especially galactoglucomannans, from fractions of ground spruce wood with different particle sizes was studied at 170°C with extraction times up to 60 min. Extraction of spruce sapwood, heartwood, and thermomechanical pulp (TMP) was also compared at 160 to 180°C. Static batch extractions were carried out in an accelerated solvent extractor (ASE). The extracted hemicelluloses were characterized by sugar unit analysis and determination of acetyl groups and molar masses. The particle size significantly affected the extraction of ground wood. The total extraction yield, as well as the yields of hemicelluloses and monosaccharides, was the highest from the finest ground wood fraction (< 0.1 mm). The release of acetic acid, average molar mass of extracted hemicelluloses, and end-pH of the extracts were also dependent of the particle size, although to a lower extent. Irrespectively of the ground wood particle size, the yield of hemicelluloses reached a plateau after 40 min extraction at 170°C. The results indicate that extraction of hemicelluloses is limited mainly by the diffusion in the fiber wall, and for coarse wood shives also by the mass transfer in the wood matrix. There were only small differences in the hot-water extraction yields of hemicelluloses from spruce sapwood, heartwood, and TMP, considering both poly- and monosaccharides.

Antifungal effects of geothermal fluids obtained from the Ankara, Afyon, Denizli, and Eskişehir regions of Turkey on white-rot (Trametes versicolor, MAD-697) and brown-rot (Coniophora puteana, FPRL 11E) fungus (Basidiomycetes) were studied. Fungal experiments were performed on kraft paper and Scots pine wood (Pinus sylvestris L.). We used non-concentrated geothermal water and concentrated geothermal water (via evaporation) in ratios of 25%, 50%, and 75%. To evaluate the results, we measured the concentration of specific minerals in the geothermal fluids such as boron (B), arsenic (As), copper (Cu), sulfate (SO4), sodium (Na), chloride (Cl), fluoride (F), potassium (K), and ammonia (NH3). The highest antifungal effect was observed for a geothermal fluid from the Denizli region, followed by Ankara, Afyon, and Eskişehir, in decreasing order. Antifungal properties of GFs are thought to be associated with the type and amount of mineral substances. In addition, the antifungal effects increased with increasing concentrations of geothermal water.

Natural cotton fibers were pretreated with DMSO, NaOH, or ultrasonic waves and hydrolyzed by cellulase (Trichoderma vride G) to prepare nanocrystalline cellulose (NCC). The as-prepared samples were characterized by TEM, DLS, XRD, and FT-IR. The influences of the pretreatment on the yield and morphology of NCC were investigated. The alterations of the crystalline phase and chemical structure of NCC were also measured during the enzymolysis process. The experimental results proved that the pretreated cotton fibers could be hydrolyzed by the Trichoderma cellulase to prepare a nanosized strip (10 to 40 nm ´ 70 to 280 nm) and grainy (20 nm or 6 nm) crystalline cellulose, in which the different morphologies resulted from the different manners of pretreatment. The unaltered crystalline phase and chemical composition of NCC prepared by enzymolysis of pretreated cotton fibers were measured. The highest yield of NCC reached was 32.4%.