Research Articles

The aim of this study was to determine the optimum combination of wheat straw and white poplar (P. alba) chemimechanical pulps (CMPs) for producing newsprint paper. The CMP was prepared separately from the two raw materials. Cooking conditions included 10%, 12%, and 14% chemical charge based on w/w oven dry raw materials, maximum cooking temperatures of 120, 140, and 160 °C, and cooking time of 45 min. Hydrogen peroxide was used for bleaching the selected pulp. The results indicated that screened pulp yields were in the range of 54.3% to 61% and 80.9% to 85.9% for 18 cooking trials of wheat straw and white poplar, respectively. Handsheet brightness reached up to 52.9% and 61.9% for wheat straw and white poplar, respectively. The highest breaking length and burst index were related to CMP produced from 25% white poplar/75% wheat straw pulp blend. The best tear index was obtained using a mixture of 50% white poplar and 50% wheat straw pulp. Averages of breaking length, burst and tear indices ranged between 4.61 and 3.80 km, 2.31 and 2.55 kPa•m2/g, and 7.29 and 11.1 mN•m2/g, respectively. The strength properties of handsheets were higher than those reported for commercial newsprint except the breaking length of 50%/50% blend.

Enzymatic hydrolysate of poplar wood was used in this study to produce biobutanol by a mutant M-18. Plackett-Burman and Box-Behnken designs were adopted in order to screen crucial factors from various nutrient factors affecting butanol production. These factors included reducing sugar content of hydrolysate, MgSO4•7H2O, yeast extract, K2HPO4, FeSO4•7H2O, CaCO3, and ammonium sulfate. The results demonstrated that a reduction in sugar content, K2HPO4, and CaCO3 were the most critical factors. Yeast extract was also found to have a significant effect on biobutanol production by performing an analysis of variance (ANOVA). Optimal variables were 44.53 g/L of reducing sugar concentration, 1.36 g/L of K2HPO4, and 4.65 g/L of CaCO3 according to the Box-Behnken design. A model was established and used to predict a maximum biobutanol production of 7.59 g/L. Optimal conditions of fermentation were determined by orthogonal tests. Three distinct factors with important effects on biobutanol production were explored. The pH was identified as having the most significant effect on biobutanol biosynthesis. Optimized fermentation conditions for biobutanol production were determined at an initial pH of 6.5, temperature 36 °C, and inoculum quantity 9%. Under these conditions, a maximum biobutanol production of 8.41±0.20 g/L was achieved in verification experiments in a 3 L fermentation tank.

Effects of alkaline peroxide (AP) pre-treatment were investigated with respect to the extracted cellulose fibres from the vascular bundles of oil palm (Elaeis guineensis) fronds (OPF) rachis at different AP concentrations. The extracted fibres were prepared through the mechanical fibrillation resulting from the AP pre-treatment concentrations of the rachis. The cellulose fibres obtained were characterized using microscopic (SEM), spectroscopic (FTIR), thermal (TGA-DTG), and X-ray diffraction (XRD) techniques. The screen pulp yield was between 38.07% and 42.69%, which increased with the increase in the AP concentrations. The SEM showed a significant separation of the fibres after the AP pretreatment. FTIR spectroscopy and TGA showed significant dissolution of both lignin and hemicellulose molecules from the treated biomass at higher alkaline peroxide concentrations. The thermal stability of the extracted fibres ranged from 366 oC to 392 °C while the XRD results showed that the cellulose fibre extracted at H2O2/NaOH ratio of 2.5%: 2.0%,w/v AP concentrations gave the highest percentage crystallinity (35.7%). The handsheet made from the cellulose fibre showed that tensile, burst, and tear indexes increased with an increase in AP concentration. Duncan Multiple Range Test shows that mild alkaline peroxide pretreatment (medium concentrations) is best favoured for paper making pulp and bio-composite production.

Mechanical parameters of Scots pine wood (Pinus sylvestris L.) of low (about 8%) and high (higher than the fiber saturation point) moisture content (MC) subjected to tensile stress along the grains were studied. The measurements were performed for microtome samples sliced from either earlywood or latewood and for samples containing both earlywood and latewood. The effect of MC on the mechanical properties of earlywood and latewood of Scots pine was different. The MC was found to have greater influence on the tensile strength and modulus of elasticity in latewood than in earlywood, but its effect on strain at failure was greater in earlywood. As determined individually for earlywood and latewood, the tensile strength, modulus of elasticity, and the strain at failure that were calculated from the rule of mixtures (the weighted mean for earlywood and latewood) did not differ significantly from the values found in the samples containing both zones. This similarity was observed at low and high MC.

A new chelating material from mercerized cotton linter was prepared by a reaction with succinic anhydride in the presence of toluene/triethylamine and a 4-dimethylaminopyridine catalyst, followed by reacting with Fe(III) to obtain the final product. The materials were characterized by Fourier transform infrared spectrometry, scanning electron microscopy, and energy dispersive spectrometer; the adsorption of chromium(VI) from an aqueous solution was examined. The Langmuir isotherm accurately fit the experimental data, and the calculated adsorption ability of Fe(III)-loaded adsorbent for chromium(VI) was 11.1 mg/g. The adsorption process followed a pseudo-second-order kinetic model.

Wood material is a good reservoir for biogenic carbon storage. The use of wood material for outdoor products such as siding in the building construction sector presents limits. These limits are bound to the nature of wood material (hygroscopic property and anatomical structure). They are responsible for the dimensional variation associated with moisture content variations. Fungal attacks and coating layers adhesion on wood surface, are other problems. This research investigated the feasibility of impregnation with environmentally friendly chemicals, i.e., a citric acid-glycerol mixture (CA-G). The anti-swelling efficiency (ASE), hardness, biodegradation, and coating adhesion tests were performed on softwood specimens. ASE results were up to 53%. The equilibrium moisture content of the treated specimens was less than half of the untreated ones. FTIR spectroscopy showed bands at 1720 to 1750 cm-1, indicating the presence of ester bonds, and scanning electron microscopy images confirmed the polymerization and condensation of treatment solution inside the wood structure. Hardness and decay resistance were increased; however, treatment reduces coating adhesion. In conclusion, CA-G represents a promising eco-responsible solution for improving the technical performance of outdoor wood products.

This work discusses the preparation and characterization of hollow nanospheres based on kraft lignin (KL). Kraft lignin is a by-product of the papermaking industry and an abundant renewable resource. It was determined that adding water to a KL/THF solution induced KL to form hollow nanospheres via self-assembly. Scanning electron microscopy and transmission electron microscopy confirmed the hollow nanosphere morphology. The shell thickness of the hollow nanospheres was tunable by adjusting the initial KL concentration in THF, making the nanospheres a potential material for the encapsulation and controlled release of guest molecules. Ultraviolet (UV) and Fourier transform infrared (FTIR) spectroscopy confirmed the π-π stacking of aromatic rings as an important and distinctive mechanism for the formation of hollow KL nanospheres. The nanospheres were obtained simply and inexpensively, and they exhibited the characteristics of biocompatibility, biodegradability, and low toxicity. These advantages make hollow KL nanospheres attractive for applications in nanoscience and nanotechnology. This study developed an economically feasible and facile strategy for the effective use of biomass waste in sustainable chemistry.

Nano-cellulose was prepared via acid hydrolysis and cell crushing using microcrystalline cellulose as the raw material. Mesoporous TiO2 was then prepared via hydrothermal synthesis using butyl titanate as the titanium source and the previously prepared nano-cellulose as the template. It is confirmed by FT-IR and XRD that the commercial product P25 consisted of anatase and rutile mixed crystal structure, in which the content of anatase and rutile was 80.5% and 19.5%, respectively. The prepared TiO2 had an anatase single crystal structure. XPS analysis showed an elemental content of C, O, and Ti with two kinds of TiO2. TEM, HRTEM, and electron diffraction were used to characterize the particle size of the prepared mesoporous TiO2, mainly concentrated in the 10 to 20 nm range. Crystalline spacing was 0.35 nm (101). By comparison, the particle size of P25 was mainly distributed in the 15 to 25 nm range with a crystalline spacing of 0.35 (101) and 0.32 nm (110) respectively. XRD analysis was consistent with the results. Based on N2 adsorption-desorption isotherm curves it was evident that the surface area of prepared TiO2 and P25 was 38.92 m2/g and 53.54 m2/g, the cumulative pore volume of the two is 0.24 m2/g and 0.17 m2/g respectively. The experiments of photocatalytic degradation of rhodamine B showed that the catalytic ability of the prepared mesoporous TiO2 to degrade pollutants was better than commercial TiO2 under UV irradiation.

A novel sulfonated bamboo-derived carbon (SBC) was prepared through a one-pot simultaneous carbonization and sulfonation method using p-toluenesulfonic acid as the sulfonating agent. This method was used in place of the two-step method of high temperature carbonization followed by sulfonation, in order to reduce energy consumption and avoid the use of substantial amounts of strong liquid acid. The as-prepared catalyst bearing SO3H, COOH, and phenolic OH groups demonstrated efficient catalytic activity in the dehydration of fructose to 5-hydroxymethylfurfural (HMF), achieving 92.1% HMF yield in a mixture of tetrahydrofuran (THF) and dimethylsulfoxiden (DMSO) (volume ratio of THF/DMSO 3/7). The mixture had a fructose concentration of 0.08 g·mL-1 with a catalyst amount of 10% weight of fructose at 140 °C in 60 min. No distinct activity drop was observed after the initial deactivation during 5 recycling runs, confirming a good stability of the prepared catalyst. Moreover, kinetic data showed that SBC promoted fructose dehydration to HMF may follow pseudo-first order kinetics with the activation energy of 43.6 kJ·mol-1 under investigated conditions. The convenient catalyst preparation method and excellent catalytic performance of the catalyst provide an easy-handling and eco-friendly strategy for crude biomass utilization in catalyst production.

To investigate the effects on moisture sorption behavior of wood caused by the removal of chemical components, Populus euramericana flour (40 to 60 mesh) was divided into four groups: untreated, extractives removed, hemicellulose removed, and matrix removed. The samples at the fiber saturation point and under oven-dried conditions were separately exposed to relative humidities of 11%, 45%, and 75% at 25 °C for desorption and adsorption. Additionally, moisture changes were measured during the processes. The results showed that moisture changed rapidly for all four groups at the initial stage during sorption, after which the rate gradually decreased until a steady-state equilibrium was reached. Among the four groups, the samples from which extractives had been removed exhibited the highest moisture content and moisture sorption coefficient, followed by the untreated samples, hemicellulose removed, and matrix removed samples. With increasing relative humidity, the hysteresis ratio A/D of the samples increased, indicating a reduction in sorption hysteresis, which was further decreased by hemicellulose extraction.