Volume 6 Issue 3

Cellulose-graft-poly(methylmethacrylate) (cellulose-g-PMMA) copolymers were prepared by homogeneous atom transfer radical polymerization (ATRP) under mild conditions, in an attempt to develop an efficient way to modify the surface of cellulose. A cellulose macro-initiator was successfully synthesized by direct homogeneous acylation of cellulose with 2-bromopropionyl bromide in a room temperature ionic liquid (RTIL), 1-allyl-3-methylimidazolium chloride ([AMIM]Cl). Copolymers were obtained via ATRP of methyl methacrylate (MMA) with CuBr/penta-methyldiethylenetriamine (PMDETA) as catalyst and N,N-dimethyl-formamide (DMF) as solvent without homopolymer byproduct. The grafting copolymers were characterized by 1H-NMR, 13C-NMR, and FTIR. The grafted PMMA chain was obtained by the hydrolysis of the cellulose backbone and analyzed by GPC and TGA measurements. In addition, the assemblies or aggregates formed by cellulose-g-PMMA copolymers were studied by means of TEM and AFM. The results indicated that the graft polymerization occurred from the cellulose backbone and the obtained copolymers had grafted polymer chains with well-controlled molecular weight and polydispersity; the cellulose graft copolymer in solution could aggregate and self-assemble into sphere-like structures.

Acacia is a fast-growing plant that has high potential in commercial plantations in tropical areas. It is already being grown as a plantation crop for building and industrial raw materials, as well as for reforestation of difficult sites. Extensive cultivation of this promising tree would enrich the natural resources besides being useful for industrial raw material, waste land management, and afforestation. In addition, Acacia exhibits extensive medicinal values. In view of the medicinal importance of Acacia nilotica and the therapeutic utility of flavonoids, an attempt has been made to isolate novel flavonoids from the wood of cultivated A. nilotica. The extraction of crude ethanol extract from the A. nilotica wood was followed by fractionation with chloroform, ethyl acetate, and methanol in increasing order of polarity of the solvent. The mixed ethyl acetate and methanol extract afforded three pure compounds through column chromtomatography and fractional crystallization. Among the isolated phenolic compounds, a new acylated flavonoidic glycoside, tricin-4′-O-β-(6′′-hydroxycinnamic)-glucoside (1) was isolated from the wood of A. nilotica together with two known compounds, gallic acid and apigenin. Their structures were established by chemical evidence, spectroscopic techniques (FT-IR, 1H-NMR, 13C-NMR, HSQC, HMBC, and ESI-MS), and by comparison with already existing spectroscopic data. The yield of novel tricin glucoside showed that it make up to 0.0786% of mixed ethyl acetate and acetone extract.

Supply chain and delivered cost models for seven feedstocks (loblolly pine, Eucalyptus, natural hardwood, switchgrass, Miscanthus, sweet sorghum, and corn stover) were built, simulating a supply of 453,597 dry tons per year to a biorefinery. Delivered cost of forest-based feedstocks ranged from $69 to $71 per dry ton. On the other hand, delivered cost of agricultural biomass ranged from $77.60 to $102.50 per dry ton. The total production area required for fast growing feedstocks was estimated as between 22,500 to 27,000 hectares, while the total production area for feedstocks with lower biomass productivity ranged from 101,200 to 202,300 hectares (corn stover and natural hardwood, respectively). Lower delivered cost per ton of carbohydrate and million BTU were found for loblolly pine, Eucalyptus, and natural hardwood. In addition, agricultural biomass had higher delivered costs for carbohydrate and energy value.

Large visible dirt specks and microscopic ink particles are released from the surface of recycled paper when pulping toner and pigment-based inkjet ink printed papers. The applicability of pulp fractionation during laboratory scale pulping was investigated without chemicals to prevent the redeposition of small ink particles to fibers, and furthermore to break down the large toner fragments. Reference pulping was performed without fractionation stages, and the two pulping procedures were compared in terms of bound ink and dirt speck content. The results show that while the microscopic ink particles redeposit to the fibers at the very beginning of conventional pulping, the redeposition can be minimized by removing the detached ink particles from the vicinity of the fibers as soon as they have been detached. Thus, it is recommended to remove the ink from the pulp before a substantial defiberization level is achieved. In addition, the dirt specks broke down more efficiently in fractional pulping than in reference pulping at the same pulping consistency.

To investigate the effects of biomass feedstock and pretreatment method on the enzyme requirement during hydrolysis, swichgrass and coastal Bermuda grass pretreated using H2SO4, NaOH, and Ca(OH)2 at the optimal conditions were subjected to enzymatic hydrolysis using two enzyme combinations: NS 50013 + NS 50010 and Cellic CTec + Cellic HTec. The enzyme loadings were optimized, and correlations between feedstock property, pretreatment strategy, and enzyme usage were evaluated. The results show that pretreatment methods resulting in greater lignin contents in the pretreated biomass were generally associated with higher enzyme requirements. More sugars could be recovered from alkaline-pretreated biomass during enzymatic hydrolysis due to the better carbohydrate preservation achieved at mild pretreatment temperatures. The cellulase enzyme, Cellic CTec, was more efficient in catalyzing the hydrolysis of coastal Bermuda grass, a feedstock more digestible than the pretreated swichgrass, following pretreatment with NaOH or Ca(OH)2.

The particleboards with different density from specially prepared particles from black locust and willow were prepared. The standard mechanical parameters of the panels were investigated, as well as the corner wall connections with eccentric connecting fitting element or confirmat strength. The screw withdrawal resistance and hinge bearing were also measured for investigated panels. The results, compared to the strength of commercial particleboards, show that excluding panels from black locust with low density, the rest of the panels can be successfully used for furniture production purposes.

The aim of this study was to observe the effects of alkaline activating agents on the characteristics, composition, and surface morphology of the designed activated carbons. Activated carbons were prepared by pyrolysis of Acacia mangium wood in the presence of two basic activating agents (calcium oxide and potassium hydroxide). The extent of impregnation ratio of precursor to activating agents was fixed at 2:1(w/w). Prior to pyrolysis, 24 hours soaking was conducted at 348 K. Activation was carried out in a stainless steel capped graphite crucible at 773 K for 2 hours in the absence of purge gas. The burn-off percentage was found to be 70.27±0.93% for CaO activated carbon (COAC) and 73.30±0.20% for KOH activated carbon (PHAC). The activating agents had a strong influence on the surface functional groups as well as elemental composition of these activated carbons. Characterization of the activated carbon obtained was performed with field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and nitrogen adsorption as Brunauer, Emmett and Teller (BET) and Dubinin-Radushkevich (DR) isotherms.

The solubility of lignin from bagasse in mixed solution was investigated and explained by the solubility parameter (). To explore the lignin solubility, enzymatic hydrolysis/mild acidolysis lignin (EMAL) isolated from bagasse was used as the starting material to prepare lignin solution by ultrasonic treatment. The lignin content in solution was determined by UV-vis spectroscopy at a wavelength of 280 nm. The results showed that 240 minutes of ultrasonic treatment was needed to achieve lignin dissolution equilibrium in the 1,4-butanediol/water mixture. Maximum lignin solubility (14.6 g/L) occurred at a concentration of 80% (v/v). The δ-value of lignin (14.0 (cal/cm3)1/2) was calculated based on the atomic and functional groups present in the phenylpropane unit. The δ-values of the 1,4-butanediol/water showed a decrease from 22.31 to 11.09 (cal/cm3)1/2 as the concentration of 1,4-butanediol increased. The maximum lignin solubility predicted by the δ-value should occur at a concentration of 80% (v/v), which agreed with the experimental result.

A pilot-scale membrane process for the concentration of effluent from an alkaline peroxide mechanical pulping (APMP) plant was investigated. Specifically, the cross-flow velocity and volume reduction were optimized again for a higher flux and a lower system energy consumption. A mathematical model was established to obtain the optimal parameters. Estimates were obtained of the expected savings in energy and water. The obtained optimal concentration conditions were: molecular weight cut-off at 10,000 Dalton, trans-membrane pressure at 3 bar, feed temperature at 50 oC, cross-flow velocity at 2 m/s, and volume reduction at 0.9. The average permeate flux under these conditions was 43.21 l/m2.h. The total solids content was increased from 25.47 g/L in the feed to 128.36 g/L in the concentrate. The permeate had low total solids content of 11.03 g/L, Chemical Oxygen Demand of 9180 mg/l, and Biochemical Oxygen Demand of 5870 mg/L. Such qualities would allow the permeate to be reused in the APMP process after a light biochemical treatment. With this new membrane concentration process, about 1402 kWh energy can be saved and 22 m3 effluent discharge can be reduced for each ton of pulp produced.

The effect of wood flour and coupling agent content on the hygroscopic thickness swelling rate of polypropylene composites was investigated in this study. To meet this objective, the wood flour was compounded with polypropylene and coupling agent in an internal mixer; then the samples were fabricated by injection molding. The concentration was varied from 40 to 60% for wood flour and from 0 to 4% for coupling agent. A swelling model developed by Shi and Gardner (2006) was used to study the thickness swelling process of polypropylene/wood flour composites, from which the parameter KSR can be used to quantify the swelling rate. The results indicated that the swelling model provided a good prediction of the hygroscopic thickness swelling process of polypropylene-wood flour composites immersed in water. The minimum thickness swelling values were observed in composites made of 40% wood flour and 4% of PP-g-MA. Thickness swelling of the composite increased with immersion time, reaching a certain value at saturation point, after which the composites water content remained constant. Also, a good linear relationship was fit between KSR and coupling agent contents. When the coupling agent content increased, KSR linearly decreased. The maximum tensile modulus was achieved with 60% wood flour and 4% of PP-g-MA. The SEM revealed a positive effect of coupling agent on interfacial bonding between sawdust flour and polymer matrix.