Volume 15 Issue 1

Allelochemicals are generally harmful to plant species during one or more of the regeneration phases. This study investigated the influence of biochar in mitigating allelopathic effects of Eucalyptus camaldulensis in plants (Acacia gerrardii and Acacia ampliceps). The seed germination was relatively delayed by dried leaf extract (DLE) on the first day. Both DLE and date palm biochar (DPB) relatively decreased radicle hypocotyl development of both the target species (when compared with the control). In the seedling growth trial, most of the parameters were suppressed by either DLE or DPB. The results revealed that the inhibitory effects of DLE was less pronounced in the case of seed germination when compared with seedling growth. Moreover, any DLE treatments that were mixed with DPB allowed the suppressed plants to develop well. This effect was indicated by the positive value of relative allelopathic effect (RAE). The relative growth rates of seedling height (RGRH) varied for the different treatment combinations. Most of the treatment combinations resulted in a higher RGRH in test cases than in the control. This study provides meaningful results that support the hypothesis that biochar can be used as an absorptive substance in the immobilization of allelopathic chemicals.

The article describes the granulometric analysis of airborne wood dust of African padauk (Pterocarpus soyauxii). Sandpaper was used under industrial relevant conditions to generate wood dust with a relatively wide particle size distribution (<63, 63, 71, 100, 200, 315, or 500 µm). This article aimed to perform a sieve analysis of the wood dust of African Padauk, characterize its morphological structure, determine certain physical properties (density, bulk density, and moisture content), and assess the effect of airborne dust particle size on minimum ignition temperatures. The 100-μm fraction was the most frequent dust particle size and represented 42.14 ± 1.049%. The ignition temperature of airborne dust was 390 °C for the 500-μm fraction and 370 °C for the 71-μm fraction.

A water and organic soluble N-benzyl-N,N-diethyl quaternized chitosan (NSQC) material was synthesized using chitosan, benzaldehyde, and bromoethane. Amino groups on chitosan reacted with benzaldehyde to form a Schiff base intermediate. Quaternized chitosan was obtained by reacting the Schiff base with bromoethane. The quaternized chitosan was dissolved in an organic solution with dissolved cellulose and cast to prepare quaternized chitosan/cellulose (QCC) film. The molecular structure, morphology, tensile strength, thermal stability, and antibacterial activity effects of NSQC-treated cellulose film were studied in detail. The results showed that the NSQC product exhibited superior solubility in deionized water and dimethylacetamide. The addition of NSQC as a reinforcing agent in QCC film enhanced the interlinking of fibers and slowed down the rate of cellulose pyrolysis, which improved the tensile properties and thermal stability of the cellulose film. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of NSQC showed that it had good antibacterial activity against Staphylococcus aureus and Escherichia coli. The QCC film also showed contact sterilization ability with regards to two kinds of bacteria, which suggested that QCC film has the potential for applications in food packaging and bacterial barriers.

Solid-state fermentation was carried out for production of gibberellin via the addition of enzymatic hydrolysate from steam-exploded corn stalks during the culture period. The enzymatic hydrolysate from the steam-exploded corn stalks was added to the culture medium during the solid-state fermentation period, which improved gibberellin production. When the enzymatic hydrolysate was added into the 400 mL/kg dry basis substrate in the solid-state fermentation after 60 h, the temperature was 30 °C, the pH was 7.00, the mass ratio of solid to liquid was 1:1.1, and the fermentation period was 168 h. This led to the largest gibberellin yield (9.48 g/kg dry basis), and when compared with pre-optimization, the gibberellin yield increased by 135%. The optimum conditions to maximize the biomass for the fermentation process were obtained; the temperature was 32 °C for a gibberellin yield of 9.20 g/kg dry basis, the pH was 6.00 and the mass ratio of solid to liquid was 1:1.1 for a gibberellin yield of 9.48 g/kg dry basis, and the fermentation period was 96 h for a gibberellin yield of 6.94 g/kg dry basis. Therefore, a new alternative way for gibberellin production via solid-state fermentation has been demonstrated.

Clogging is a critical problem that restricts the delamination of fibers in a high-pressure homogenizer (HPH). In this work, bleached bamboo pulp fibers were pretreated in TEMPO/NaBr/NaClO system prior to high-pressure homogenization to study the clogging condition in a high-pressure homogenizer. Effects of the additional amount of NaClO on the functional groups and morphologies of the bamboo pulp fiber were evaluated by conductometric titration, Fourier transform infrared spectroscopy (FTIR), fiber morphology analysis, and scanning electron microscopy (SEM). The fiber morphology analyzer revealed that the addition of NaClO facilitated to reduce the length of the fiber. The SEM images showed that TEMPO-mediated oxidation had a destructive effect on the fiber surface. The carboxylate contents of bamboo pulp fibers increased with the addition of NaClO, which were beneficial for increasing the critical concentrations of suspensions in the HPH. Nanocelluloses were successfully isolated from the TEMPO-oxidized bamboo pulp with different clogging critical concentrations, as were revealed by atomic force microscopy (AFM).

With an increasing interest in a wider scope of biomass feedstocks for biocomposite production, the potential influence of a possibly higher proportion of fines material needs to be addressed. In the pulp and paper industry, at least two major classes of fines material are identified; blocky fines and fibrillar fines. These differ in their aspect ratio, with the later having substantially higher aspect ratio. In this study, the physical impact of blocky fines (from CTMP refining) and fibrillar fines (produced via Super® Masscolloider refining) on a wet formed compression molded polypropylene (PP) matrix biocomposites were compared. The results indicated that in wet formed compression molded polymer matrix composites, both blocky (CTMP) and fibrillar (SMC) fines have a significant negative impact on modulus of rupture (MoR). Additionally, blocky CTMP fines also have a significant negative impact on modulus of elasticity (MoE). It is postulated that this is due to fibril agglomeration, in the case of fibrillar fines, and low aspect ratio in combination with some agglomeration, in the case of blocky CTMP fines. The indication is that fines material that has not been treated to minimize agglomeration has limited benefits as a reinforcing agent, and only a negative impact on most properties in wet formed compression molded polymer matrix composites.

The recycling and utilization of the Castanea mollissima Blume shell can ensure the sustainable development of its processing industry. Composting the C. mollissima shell yields a safe compost product with a high maturity level. In this study, the changes in the temperature, carbon to nitrogen ratio, ammonium-nitrogen levels, nitrate-nitrogen levels, and the seed germination index of composting C. mollissima shells were monitored during its co-composting process with sheep and chicken manure, and a compost maturity index system was established. The results suggested that livestock and poultry manure could accelerate the composting process of C. mollissima shells and prolong the thermophilic phase during the composting. Both the carbon to nitrogen ratio and the ammonium-nitrogen levels in the compost decreased with the prolongation of the composting time, while the nitrate-nitrogen levels and the seed germination index increased during the compositing process. A Pearson correlation analysis indicated that carbon-nitrogen ratio, nitrate-nitrogen levels, and the seed germination index could be used to evaluate the compost maturity of C. mollissima shells.

Wood can be regarded as the single most important natural resource of the future, as it is a magnificent gift of nature. However, wood is a highly variable and complex material. Branch wood is a part of a tree that requires careful attention due to several disadvantages, making it less favorable for industrial use. This study was conducted to identify the basic properties of branch wood of Acacia gerrardii, Tamarix aphylla, and Eucalyptus camaldulensis, and to highlight its potential utilizations. Branch wood of all the examined species had several drawbacks that markedly limit its potential for commercial uses. It might not be favorable for particleboard, flakeboard, or fiberboard because of its high shrinkage. Even though all of the fibers showed suitability as a raw material for pulp and paper, the quality is low due to the high density of vessels or parenchyma proportions. However, branch wood of all examined species might be used as a blending material (papermaking and glued plates) or for light construction purposes. In considering the chemical composition of branch wood, classes of green products, such as biofuel, bioenergy, and biochar might maximize the value of branch wood. These offer numerous benefits to support human needs in the future.

The authors explored the possibility of using persimmon byproducts as raw materials for obtaining kraft pulps. Various unbleached and bleached kraft pulps via pulping and bleaching processes were prepared. Then, their characteristics were determined and compared with those of commercial kraft pulps. For the highest screened yield of persimmon byproduct unbleached kraft pulps, the optimal pulping conditions were a liquid ratio of 5:1, an active alkali concentration of 25%, a sulfidity of 30%, and a cooking time of 3 h. Furthermore, the authors obtained persimmon byproduct bleached kraft pulps (PB-BKPs) with an ISO brightness of 73% via three-stage bleaching using 3% ClO2, 1.5% NaOH, and 3.5% ClO2. Moreover, PB-BKP prepared under optimal pulping and bleaching conditions had physical characteristics similar to those of commercial mixed-hardwood bleached kraft pulp, but with relatively low ISO brightness. Therefore, as raw materials, persimmon byproducts can be used for manufacturing a bleached kraft pulp.

The study was undertaken to establish the thermal treatment parameters of spruce (Picea abies L.) wood that would ensure the highest possible value of the specific modulus of elasticity (E/ρ) and, thus, the best acoustic performance. The basic acoustic parameters of spruce wood were determined prior to and after its thermal treatment. As a result of thermal treatment, the samples density slightly decreased by about 1%, irrespective of temperature applied. The average value of Young modulus of the samples after modification at 120 to 160 °C increased from 10.1 to 10.7 GPa (6%). The specific modulus of elasticity increased on average by 6.5%. Increase of the modification temperature to 180 °C resulted in decreasing of the values of mechanical parameters by over 4%.