Volume 13 Issue 4

Forest pests are commonly transported along with wood packaging materials. Ports in the United States continue to intercept invasive pests in cross-section timbers that are packaged with steel or heavy consignments. The large cross-section timbers present a greater risk because the fumigation and kiln treatments that are currently used in treating wood packaging materials are not effective on large cross-section materials. The objective of this study is to determine the effectiveness of steam and vacuum for heat-treating large cross-section timbers in wood skids and crates, according to the heat-treating requirements of ISPM 15 (IPPC 2013) specifying 56 °C for a minimum of 30 minutes throughout the profile of the wood. Three wood species of large dimension timbers were tested. The timbers were partially air-dried to moisture contents for poplar at 39.1% MC, pine 38.3% MC, and oak 60.6% MC. Larvae of the pinewood sawyer beetles (Monochamus spp.) were used as a representative surrogate for invasive cerambycids. The initial vacuum pressure was 100 mm Hg and the test chamber temperature was set for 90 °C. The treatment cycle was continued until the core temperature of the large timber reached the required 56 °C for 30 min. To measure the temperature profiles within the timbers, thermocouples were placed at various locations. After each test, the larvae were recovered and assessed for mortality.

Uranium adsorption was evaluated on rice straw-based carbon (RSK carbon) that had been KOH-oxidized and impregnated with ionic-liquid. Experiments were performed in fixed bed mode using 100 mg/L uranium solution at 3 different bed depths (12, 6, and 3 cm). Uranium adsorption decreased with increasing bed depth. Agreement between column and batch values was judged to be acceptable in light of inherent differences in continuous versus batch operations. Batch mode reaches equilibrium without continuous solution feeding. However, the solution in fixed bed mode was fed constantly without equilibrium. The bed depth service time (BDST) model was used to investigate uranium adsorption. BDST plots were linear, with a high correlation coefficient (R > 0.97), representing its validity when used for fixed bed of RSK carbon. The failure of the 50% breakthrough BDST curve to pass through the origin point may be due to the complex mechanism of uranium removal by RSK carbon. The calculated BDST slopes were in good agreement with the experimental values, while the values of their intercept slightly varied within certain limit of experimental error. These results support the validity of BDST model for designing a fixed bed column for uranium adsorption onto RSK carbon.

Lignin is a complex natural polymer and by-product of the pulp and paper industry. Currently, the increasing interest in bio-based products has motivated the search for alternative renewable feedstocks that can sustainably replace synthetic polymers. Because of the phenolic functionalities of lignin, this natural polymer has attracted interest for application in biomaterials. Among various products, polymeric foams stand out as a potential product in which lignin incorporation has resulted in improved mechanical and thermal properties. This paper reviews the state of lignin foam development, with emphasis placed on phenol-lignin types.

After the kraft or soda pulping of lignocellulosic materials to produce pulp suitable for papermaking, the spent pulping liquor typically has been recovered by multi-effect evaporation, followed by incineration in a recovery boiler.  This review article considers one unit operation, eutectic freeze crystallization (EFC), that may have potential to save some of the energy that is presently consumed in the evaporation step during recovery of inorganic chemicals from spent pulping liquor.  Based on a review of the literature it appears that EFC can be employed to obtain relatively pure sodium sulfate and sodium carbonate, along with relatively pure water (in the form of ice) from the spent liquor, under the assumption that lignin previously has been removed by acidification and precipitation.  Issues of inorganic scale formation, during the operation of an EFC process applied to lignin-free black liquor, will require research attention.  The chemical reactions to regenerate the active pulping chemicals sodium hydroxide and sodium sulfide from sodium carbonate, sodium sulfate, and other compounds isolated by EFC can be carried out either in a separate operation or by returning the materials to the feed of an existing recovery boiler.

Wood products are usually treated with wood preservatives to protect them from deterioration. Pressure or non-pressure preservative treatments can be utilized to incorporate biocide into the wood, depending on the applications of the end-products. Thermal and chemical modifications of wood represent alternative treatments that enhance the dimensional properties of wood and provide biological resistance. However, there is also a current trend to apply nanotechnology for wood preservation. Nanomaterials with unique properties can enhance the performance of wood preservatives, thereby increasing the service lifetime of the wood products. Nanotechnology can be applied for this purpose through impregnation of wood with a suspension of metallic nanoparticles, or through encapsulation of biocide with nanocarriers. Additionally, various nanomaterials also can be used in wood modification, especially coating treatment to provide superior service ability. Nevertheless, more studies are required to provide guidelines regarding the safety upon application of nanomaterials. This review will give an overview of current wood preservation techniques. Additionally, this paper examines current research on how nanotechnology is being applied for wood preservation.