Volume 12 Issue 2

The stalks that are left on the field after harvesting rapeseed crops could be used to make packaging grade paper. This work evaluates the suitability of mechanical and thermomechanical pulps from rapeseed stalks for papermaking, with a view to alleviating the limitations of recycled fluting. Their performance was compared to that of commercial fluting (recycled fluting) of the same basis weight, 100 g/m2, and to that of virgin pulps from pine wood. The thermomechanical pulp was refined to improve key mechanical properties. Its drainability was found to be very low, even before refining, and its breaking length after beating to 1200 PFI revolutions, 4 km, surpassed that of sheets of recycled fluting that were obtained under similar conditions. These findings support the hypothesis that high-yield pulps from rapeseed stalks are a strong choice of virgin fibres to produce fluting and, generally speaking, packaging paper.

After a long absence, tropical wood species are beginning to be applied in the production of interior elements and construction once again. Due to their positive reaction to thermal treatment, they are increasingly subjected to such processes. Tropical hard wood, in spite of some deficiencies of mechanical properties, are still better than softwoods. Another advantage of this wood is its higher durability in comparison with softwoods. However, there is a lack of knowledge about the properties of treated tropical wood species. Specifically, little is known about their reaction to fire, which is necessary in the application of this wood. This study investigated the effects of thermal treatment of Teak (Tectona grandis Linn) wood on selected burning characteristics. Results obtained from raw (untreated) wood test specimens were compared with results obtained from test specimens subjected to thermal treatment at 160 °C, 180 °C, and 210 °C. The monitored characteristics were weight loss and the burn rate. The thermal treatment of teak wood significantly increased its flammability and accelerated its combustion. In addition, its burn rate was higher than in untreated wood, reflecting that it is necessary to add fire retardants to thermally-treated teak wood.

Recently, biomass-based deinking agents have attracted considerable interest in the pulp and paper industry due to their clean, renewable, and good deinking properties. In this study, the xylanase loaded biomass-based deinking agent (XBD) was prepared with coconut oleic acid, palmitic acid, rosin, and xylanase. The preparation technology of XBD was optimized by an orthogonal test and range analysis. The effects of the moisture content, free alkali, and chelating agent on the enzyme activity of XBD were determined via a single factor experiments. Based on the analysis of the optical and physical properties, the optimum xylanase addition into the biomass-based deinking agent was 15 wt.%, the brightness of the secondary fiber after flotation was 60.2% ISO, and the effective residual ink concentration was 223 ppm.

Valorization of lignocellulosic waste residues in the development of potential biodegradable composites has been of recent research interest. Recent research has shown that wheat straw can be used as a reinforcement material for the synthesis of novel polyvinyl alcohol (PVOH)-based composites. However, certain pretreatment methodology needs to be used for the selective removal of the lignin component. The de-lignification of native wheat straw was performed using an in-house isolated ligninolytic consortium. The bio-composites were developed using the de-lignified wheat straw along with PVOH as the matrix phase and glycerol as a plasticizer via a compression molding technique. In this study, a structural analysis by Fourier transform infrared spectroscopy (FT-IR) showed that the enzymatic treatment led to noticeable changes in the chemical structure of the materials used. A dynamic mechanical analysis (DMA) of the composites revealed an increase in the tensile strength of the sample from 46.1 MPa ± 0.1 MPa to 53.0 MPa ± 0.9 MPa, upon the addition of the plasticizer. Also, there was a noticeable increase in the tensile modulus of composites from 2,130 MPa to 4,520 MPa, respectively. Topographical features of the newly synthesized PVOH-based bio-composites were observed using scanning electron microscopy.

Activated carbon (RSAC) was prepared using the two steps of hydrothermal carbonization (HTC) and chemical activation from the sawdust of Calamus gracilis, commonly known as Rattan (RS). The HTC process was carried out using a Teflon-lined autoclave to produce hydrochar, followed by chemical activation using phosphoric acid (H3PO4). The highest removal percentage obtained for lead, Pb(II), and zinc, Zn(II), cations were 86.71% and 64.26%, respectively, using the initial adsorbate concentration of 350 mg/L at 30 °C. These values strongly indicated the promising adsorption potential of the newly prepared hydrochar-based activated carbon (RSAC) for the better management of industrial wastewater and effluents. The analysis of the equilibrium sorption data revealed that these adsorptions followed the Langmuir isotherm model and the pseudo-second order kinetic model. The adsorption process was endothermic and spontaneous. The prepared carbon (RSCAC) showed enhanced surface area with porous texture, which could effectively aid for elimination of Pb(II) and Zn(II) cations from waste water.

To obtain a functional composite paper with antibacterial activity, 2-hydroxypropyl trimethylammonium chloride chitosan (HACC) was prepared and sprayed onto the surface of paper made of bamboo fiber. HACC was synthesized from chitosan with 2,3-epoxypropyl trimethylammonium chloride (GTAMC), and the optimal preparation conditions were selected by single-factor tests. The highest degree of substitution (DS) of HACC reached 0.868, when the ratio of chitosan to GTAMC was 1:4, and the water solubility was noticeably improved. The structural characterization demonstrated the successful modification on the original chitosan with a decrease in heat stability and the peak correlated with hydroxypropyl trimethylammonium chloride groups in FTIR. The addition of HACC in the bamboo fiber paper greatly increased the antibacterial activity, and water absorption was higher as well. These results may serve as a basis for the modification and the preparation of chitosan antibacterial agents.

Nanocellulose (NC) is an attractive reinforcement agent that can be incorporated into protective coatings because it is a renewable, biodegradable, and biocompatible polymer resource. In this study, a series of epoxy resin-based nanocomposites were prepared in the form of coatings with various amounts of NC loadings, and the coatings were applied onto mild steel at room temperature. The characterizations of the NC and nanocomposites were performed via X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and Fourier transform infrared spectroscopy (FTIR). The thermophysical properties of the nanocomposites were evaluated using differential scanning calorimetry (DSC) and thermogravimetry (TGA) analyses. The transparency of the nanocomposite specimens was examined by ultraviolet visible (UV-Vis) spectroscopy in the range of 300 to 800 nm. The corrosion protection properties of the coated mild steel substrates immersed in a 3.5% NaCl solution were studied comparatively by electrochemical impedance spectroscopy (EIS). The results showed that all of the nanocomposite coatings with NC noticeably influenced the epoxy-diamine liquid pre-polymer, both physically and chemically. Furthermore, the 1 wt.% NC nanocomposite coating system was found to have the most pronounced anti-corrosion properties, as confirmed by a 30-day EIS study.

The objective of this study was to understand the effect of different concentrations of xylose and glucose on butyric acid production by Clostridium tyrobutyricum. C. tyrobutyricum was cultured in a medium containing xylose, glucose, or mixtures of xylose and glucose as the main carbon source. The butyric acid concentration increased from 3.5 to 16.3 g/L in the xylose media, and from 2.6 to 27.0 g/L in the glucose media when the initial sugar concentration increased from 5 to 75 g/L. The yield from xylose to butyric acid started to decrease as the sugar concentration was above 35 g/L, while for glucose media higher glucose concentration resulted in higher yield. At low sugar concentrations (5 g/L or 15 g/L), xylose was more efficient than glucose for butyric acid generation, but at high concentrations (55 or 75 g/L), glucose was more efficient. In mixtures containing both sugars, glucose was the preferred sugar for bacteria growth and xylose was rapidly consumed only after the glucose was exhausted. The xylose to glucose ratio affected bacterial growth and butyric acid production. High xylose to glucose ratios (4:1 or 3:2) showed better butyric acid production than low ratios (1:1, 2:3, or 1:4) when the total initial sugar content in the media was kept at 30 g/L.