Volume 9 Issue 4

The objective of this study was to investigate the influence of acid dye on color change, modulus of rupture, modulus of elasticity, shear strength (parallel loading), thickness swelling rate, and water absorption rate of bamboo-based fiber composites from Phyllostachys pubescens. Bamboo fiber veneers were treated with acid black via three procedures: dyed in water at 20 °C, dyed in water at 90 °C, and dyed in ethanol at 75 °C. The samples dyed in ethanol at 75 °C and those dyed in water at 90 °C had a higher exhaustion rate than those dyed in water at 20 °C. The color change of bamboo fiber veneers exhibited similar variation trends by the three methods. The dyeing procedure slightly reduced the modulus of rupture and modulus of elasticity of bamboo-based fiber composites. Compared with the samples dyed in water, the samples dyed in ethanol had reduced shear strength (parallel loading) and modulus of elasticity. The thickness swelling rate and water absorption rate of bamboo-based fiber composite samples were reduced by the dye treatment.

Enzymatic treatment was used to induce liberation of antioxidant phenolics from under-utilized sweet lime peel (CLP). Small rotatable central composite design (SRCCD) was selected to optimize the conditions of enzymatic processing, i.e., enzyme concentration (2 to 5%), pH (5 to 8), temperature (30 to 75 °C), and incubation time (30 to 120 min). The morphological characterization of enzymatically hydrolyzed CLP was performed using field emission scanning electron microscopy (FESEM). Extracts obtained under suitable conditions were characterized for their phenolic profile by use of reverse-phase high-performance liquid chromatography coupled with a diode array detector (RP-HPLC-DAD) and evaluated for in vitro antioxidant activities. The observed results revealed that optimum enzymatic pre-treatment doubled the recovery of phenolic antioxidants with maximum Trolox equivalent antioxidant capacity (TEAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging potential (IC50). The observed results indicate that enzyme-assisted extraction might be a green choice to revalorize agro-processing residues.

Microcrystalline cellulose was prepared from wastes of Tithonia diversifolia, inflorescence stems of Musa sapientum, and Musa paradisiaca by soda-anthraquinone–ethanol pulping method. They were bleached by sodium chlorite and then alpha-cellulose was isolated, followed by preparation of microcrystalline cellulose. The study revealed the effect of various processing stages on the properties of the cellulose obtained. Yields of more than 80% of microcrystalline cellulose were obtained. Fourier transform infrared (FTIR) and solid state 13C Nuclear magnetic resonance (13C NMR) confirmed the presence of the major expected peaks in microcrystalline cellulose. Scanning electron microscopy (SEM) revealed that Musa species had short fiber length and mixtures of non-aggregated spherical, rod-shaped and thread like microcrystalline cellulose, but Tithonia diversifolia had aggregate crystal packed formation. The results compared well with those of other authors and were able to meet most of the requirements specified in British Pharmacopoeia. The study revealed that a drug excipient like microcrystalline cellulose that could protect thermo-labile active ingredients could be successfully obtained from abundant non-woody agricultural wastes.

In this study, mixed southern hardwood was pretreated via a hydrothermal process at 160 °C for 1 h. Alkaline pulping was then conducted on both the pretreated and original chips to prepare pulp with Kappa 17 and 30. For the Kappa 30 pulps, oxygen delignification was further carried out to render Kappa 17. After pulping, the different pulps with similar Kappa 17 were bleached by the D0(EP)D1 sequence. Pulping results show that the pretreated chips are easier to cook and necessitate less alkaline charge to achieve a similar Kappa without decreasing the pulp viscosity. Under similar bleaching conditions, hydrothermal pretreatment leads to pulps with a higher brightness, viscosity, and paper sheet opacity and scattering coefficient, while also lowering the burst and tensile strength. Furthermore, the pulp fiber length, fiber width, and percentage of fines decreases, yet the coarseness, curl index, and kink index increase. However, the paper properties of bleached pulps are not improved significantly when subjected to modified continuous cooking (MCC) pulping or oxygen delignification.

The main chemical indicators for healthy wood and rotted wood at different decay levels in two species, namely Juglans mandshurica Maxim. and Pinus koraiensis, were preliminary analyzed. The cellulose content, lignin content, and relative crystallinity were measured using the nitric acid-ethanol method, acid-insoluble lignin, and X-ray diffraction to further explore the process of wood decay. Results indicated that the cellulose content and relative crystallinity decreased and the acid-insoluble lignin content increased as wood decay increased. X-ray diffraction results showed that there were no significant changes in the lattice structure between healthy wood and rotted wood. Approximately 98.3% and 99.9% of the variations in wood decay for Juglans mandshurica Maxim. and Pinus koraiensis, respectively, can be explained by the comprehensive effect of the above chemical indicators.

Indigenous species in coastal barren communities are subject to anthropogenic and environmental pressures; some species are in decline, and there is uncertainty about their long-term survival. The authors added supplemental soil carbon in the form of red oak biochar to calcined clay (1:9) to determine the effect of this treatment on survival of legume (Lupinus perennis and Baptisia tinctoria) and non-legume (Vaccinium angustifolium and Quercus ilicifolia) species during a period spanning two and a half seasons of unirrigated pot tests. Red oak biochar used in the experiment was produced from pyrolysis, the thermochemical devolitization and carbonization of the starting biomass. Biochar significantly affected the survival rates of all species (P=<.03). Biochar-treated non-legumes had higher survival rates (P=<.10) than similarly treated legumes. Future investigations of biochars, particularly those evolved from recycled lignocellulosic wastes, associated with survival, should focus on reversal of habitat loss.

Recyclable cellulose loose-fill insulation has been commonly used in heavy timber construction for treating attic areas, under floors, and wall cavities. Through the kraft process, the unbleached cellulose adopts a texture characterized by small crumbs, forming a porous medium. In this work, different samples of a single layer of loose-fill cellulose insulation with different thicknesses were tested to measure their sound absorption properties, the airflow resistivity, and porosity for both dry and moist samples. The regression coefficients for an empirical model were calculated using a numerical optimization method. It is concluded that the model predicts the acoustical performance of this material well and that the sound absorption properties of the material are similar to those of mineral fiber-based materials.

A torrefaction testing method using TG-FTIR is presented, ensuring accuracy of torrefaction temperature and time. Torrefaction experiments of rice husk were performed at different temperatures (200, 230, 260, and 290 °C) for 30 min. The effect of torrefaction on the fuel characteristics was studied. Yields of carbon and oxygen, as well as solid and energy, were also considered. TG-FTIR analysis showed that in the depolymerization stage of the torrefaction process, CO2 characteristic peaks appeared, while those of carbonyl compounds and aromatic hydrocarbons were weaker. In the devolatilization stage, the characteristic peaks of CO2 and H2O were significant. Meanwhile, carbonyl compounds, aromatic hydrocarbons, and phenols were gradually produced. After that, each absorption peak gradually became weaker. After torrefaction at 290 °C, more than 76.6% of energy was retained in torrefied rice husk, while the solid yield was only 65.6%. 1.8%~52.2% of oxygen in rice husk was released in the torrefaction temperature range of 200 °C to 290 °C. Torrefaction increased the heating value, reduced the oxygen content, and improved the storability, which indicates that torrefaction is an effective way to improve the properties of rice husk.

In-situ CaCO3 loading of old newspaper (ONP) fiber furnish was studied as a method to improve the properties of recycled newsprint paper. The effects of in-situ loading on the morphological and physical properties of ONP furnish were examined comparatively with conventional loading methods (addition of ground or precipitated CaCO3, without and with pre-flocculation treatment). The effective residual ink content (ERIC) and macro sticky content began to decrease as soon as the in-situ CaCO3 formation started by the injection of carbon dioxide to the reaction tank, where the ONP furnish and calcium oxide mixture was agitated in high shear. When the reaction finished at pH 7, there were no more decreases of ERIC value and sticky content. Improvement of first pass retention and brightness was significant for the in-situ CaCO3 loading method. The decrease in breaking length with the addition of CaCO3 in the in-situ formation method was equivalent to or slightly lower than that of the CaCO3 pre-flocculation method, which is a method well known to give higher strength properties. Optical images from the FlowCAM® dynamic imaging particle analyzer showed strongly attached organic (fines) and inorganic (CaCO3) materials in the in-situ CaCO3 loading method.

Furfural, as an organic compound derived from biomass materials, was used to partially substitute for formaldehyde in the synthesis of UF resin. Urea-formaldehyde-furfural co-condensed (UFFR) resins with different substitute ratios of furfural to formaldehyde (FR/F) were prepared. The effects of the FR/F substitute ratio on the performances of UFFR resins were investigated. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) and Fourier transform infrared spectroscopy (FT-IR) were applied to characterize the chemical structures of UFFR resins. Plywood bonded by these resins was manufactured, and its bond strength and formaldehyde emission were measured. The results showed that the substitution of furfural in place of formaldehyde could reduce the free formaldehyde content effectively at the expense of prolongation of the curing time. The spectra of MALDI-TOF and FTIR confirmed the co-condensation of urea-formaldehyde-furfural both in uncured and cured resins. Plywood prepared under optimized parameters could yield high bond strength and low formaldehyde emission, which were 0.84 MPa and 0.23 ppm, respectively. The optimized parameters were as follows: a FR/F substitute ratio of 1/3; 1% (NH4)2S2O8 as the curing agent; and a hot pressing temperature of 130 °C. Hence, it is feasible to substitute partially formaldehyde by furfural to prepare UFFR resins as wood adhesives for plywood.