Volume 7 Issue 1

Nonfood lignocellulosic biomass is an ideal substrate for biohydrogen production. By avoiding pretreatment steps (acid, alkali, or enzymatic), there is potential to make the process economical. Utilization of regional untreated lignocellulosic biomass by cellulolytic and fermentative thermophiles in a consolidated mode using a single reactor is one of the ways to achieve economical and sustainable biohydrogen production. Employing these potential microorganisms along with decentralized biohydrogen energy production will lead us towards regional and national independence having a positive influence on the bioenergy sector.

Based on its rich chemistry and broadly available raw material sources, hydroxymethylfurfural (HMF) has become one of the most promising platform compounds for chemicals and biofuels from renewable biomass, and its production has drawn much attention in recent years. However, it is currently still facing significant technical challenges to make it economically feasible in an industrial scale. Use of ionic liquids has provided a potential alternative to address such challenges. Some studies have shown that the use of ionic liquids and suitable catalysts can inhibit side reactions and decrease the formation of by-products, thus improving selectivity and yield during conversion of renewable biomass to HMF. Moreover, the use of ionic liquids also simplifies the HMF production procedures from crude biomass in a one-pot process.

Reducing basis weight could lead to huge savings of forest resources as well as energy consumption and waste treatment in the papermaking process. However, low basis weight paper generally lacks normal strength and stiffness. The lower the basis weight of the paper, the more important is surface sizing. Highly cross-linked cured epoxy resin, due to its epoxy group and phenyl group, has gained such outstanding mechanical properties and dimensional stability that it could be utilized to enhance paper strength and stiffness through surface sizing when incorporated with oxidized starch. In this study, the impacts of sizing volume, fluid temperature, curing agent, and curing system dosage on sizing were investigated. Our results indicated that a rigid resin layer and interpenetrating polymer network formed on the surface and in the inner layer of the paper, respectively. The formed resin layers strongly support the paper and thus resulted in the improvement of strength and stiffness.

The beta-O-4 bond cleavage of a non-phenolic β–O-4 type dimeric lignin model compound, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)-ethanol (III), was examined in systems using potassium tert-butoxide as a base (0.5 mol/l) and tert-butanol (tBuOH), dimethylsulfoxide, 1,4-dioxane, or tetrahydrofuran as a solvent. The β–O-4 bond of compound III was cleaved in any system at 30°C, and 2-methoxyphenol (II) was liberated. The amount of compound II liberated was close to the quantitative yield on the basis of the amount of compound III that disappeared, except for the treatment in the t-BuOH system. The reaction rate was dependent on what solvent was used. Half-life periods for these systems were roughly about 6.0, 3.0, 0.7, and 0.2h, respectively. It seemed that the rates were very high when the polarity of the solvents was low. Two reaction products generated from the aromatic ring with two methoxyl groups of compound III, 4-acetyl-1,2-dimethoxybenzene and 3,4-dimethoxybenzoic acid, were detected in all the systems. A peculiar reaction product, 1,2-dimethoxybenzene, was detected in a fairly large quantity, only when the latter two solvents with low polarities were applied.

Poplar (Populus alba L.) lumber with a nominal thickness of 7 cm from the Taleghan region in Iran was dried through convective kiln drying and under three different programs of T5–D2 (Forest Product Laboratory proposed program for poplar), T5–D4, and T5–D6 in order to obtain the optimum kiln schedule so as to protect the wood quality at an appropriate level up to final moisture content of 12±2%. Subsequently, the intensities of warps, superficial and internal cracks occurrence, residual stresses, drying rate, and final moisture gradient were measured. Results revealed that due to low warping values, more homogeneous final moisture profile, fewer internal cracks, and absence of superficial cracks in the program T5–D2 compared to the other two (T5–D4 and T5–D6), this program can be recommended as an optimum program for poplar lumber drying at commercial scale from the Taleghan region. On the other hand and from an energy efficiency point of view, in comparison with the mild schedule (T5-D2), the severe schedule (T5-D6) by saving 456 h of drying time, reduced electricity consumption by 6156 KWh and was therefore found to be $ 240.08 more profitable in this trial.

The aim of this work was to examine the influence the lignin component of wood on the photodegradation of high-density polyethylene (HDPE) in wood/HDPE (WPE) composites. The neat HDPE and wood/HDPE composites were prepared using a twin screw extruder followed by an injection moulder. The lignin content was varied from 0 to 29 %wt. of wood by the addition of delignified wood pulp into wood flour. The results suggested that the photodegradation of HDPE in WPE composites was accelerated by the presence of lignin; the chromophoric groups in the lignin enhanced UV adsorption onto the WPE composite surface. The carbonyl and vinyl indices, color, percentage crystallinity, and the melting temperature increased when the lignin contents were increased. The color fading in WPE composites resulted from photobleaching of lignin. In addition, the presence of lignin led to the development ofl cracks in WPE composites, especially at high lignin contents. For the effect of UV weathering time, the carbonyl and vinyl indices, discoloration, and percentage crystallinity increased as a function of UV weathering times, whereas the melting temperature of HDPE in both neat HDPE and WPE composites and water absorption of specimens decreased; the wood index in WPE composites increased during the initial UV weathering times and then decreased at 720 h weathering time.

Encapsulation of methane-producing bacteria was carried out with the objective of enhancing the rate of biogas production. Encapsulation with a one-step liquid-droplet-forming technique was employed for the natural membrane, resulting in spherical capsules with an average diameter and a membrane thickness of 4.3 and 0.2 mm, respectively. The capsules were made from alginate, using chitosan or Ca2+ as counter-ions, together with the addition of carboxymethylcellulose (CMC). A Durapore® membrane (hydrophilic PVDF) with a pore size of 0.1 µm was used for synthetic encapsulating sachets having width and length dimensions 3×3 and 3×6 cm2 for holding the bacteria. During the digesting process, the dissolved substrates penetrated through the capsule membrane, and biogas inside the capsules was able to escape by diffusion. The results indicate encapsulation to be a promising method of digestion, with a high density of anaerobic bacteria. The method holds considerable potential for further development of membranes and their applications.

Reversible thermochromic paper able to resist counterfeiting was prepared by adding reversible thermochromic microcapsules (RTM) to a slurry of cellulosic fibers, a process that is difficult to imitate. However, the loss of RTM is one of the biggest problems that inhibits industrial use of this approach. So, the retention of RTM in pulp was investigated. The RTM was synthesized by in-situ polymerization, and its properties were characterized. It exhibited strong color contrast between cool and heated conditions, and such behavior could be used to achieve distinctive anticounterfeiting characteristics in the paper. The surface of each microcapsule was smooth, and there was no coherence between particles. The diameters of the microcapsules were mainly in the range 3.0 μm to 5.0 μm. Retention of RTM was closely related to beating degree and pulp composition; the higher the beating degree and hardwood pulp content, the higher the retention of RTM. On the other hand, the retention of RTM was influenced by filler and retention aid. Retention aid promoted retention of RTM to some degree; however, filler was not conductive to retention of RTM. Different addition sequences between RTM and filler or retention aid also influenced the retention of RTM.

Cellulose fibers obtained from the textile industry (lyocell) were investigated as a potential reinforcement for thermoset phenolic matrices, to improve their mechanical properties. Textile cotton fibers were also considered. The fibers were characterized in terms of their chemical composition and analyzed using TGA, SEM, and X-ray. The thermoset (non-reinforced) and composites (phenolic matrices reinforced with randomly dispersed fibers) were characterized using TG, DSC, SEM, DMTA, the Izod impact strength test, and water absorption capacity analysis. The composites that were reinforced with lyocell fibers exhibited impact strengths of nearly 240 Jm-1, whereas those reinforced with cotton fibers exhibited impact strengths of up to 773 Jm-1. In addition to the aspect ratio, the higher crystallinity of cotton fibers compared to lyocell likely plays a role in the impact strength of the composite reinforced by the fibers. The SEM images showed that the porosity of the textile fibers allowed good bulk diffusion of the phenolic resin, which, in turn, led to both good adhesion of fiber to matrix and fewer microvoids at the interface.

As part of a program to reduce electrical energy consumption in the refining process, the effects of the ozone and alkaline peroxide treatments on fibre and handsheet properties, prior and subsequent to low consistency (LC) refining, were assessed and compared by applying different levels of ozone and a range of peroxide and alkali charges to a primary stage hemlock thermomechanical pulp (TMP). Both highly alkaline peroxide treatments and ozone treatments decreased the specific energy required for strong mechanical pulp. The improvement in pulp strength through alkaline peroxide treatment mainly resulted from pulp surface changes caused by generation of acid groups. The highly alkaline peroxide treatments significantly increased pulp brightness but did not promote the further fibrillation during the subsequent LC refining. On the other hand, ozone treatments provided tensile strength increases, along with small brightness enhancements for the dark hemlock TMP, and increased the tensile gains obtained through LC refining. The effects of ozone treatments on tensile strength before and after LC refining were the result of pulp surface modifications, fibre swelling, and loss of fibre wall integrity due to non-selective chemical attack. High levels of ozone treatment caused tear strength to decrease during subsequent LC refining.