Volume 16 Issue 3

The secondary treated effluents of pulp and paper mills contain high chemical oxygen demand (COD) that is associated with organic matter. Therefore, this study explores the adsorption of substances contributing to COD using CoFe2O4 and quartz sand-coated CoFe2O4 in batch and fixed-bed column experiments. X-ray diffraction, scanning electron microscopy, Brunauer–Emmett–Teller analysis, and X-ray photoelectron spectroscopy were used to characterize the adsorbents. The quartz sand-loaded CoFe2O4 exhibited a larger pore volume and average pore size. Batch experiments revealed that adsorption on CoFe2O4 closely fit the pseudo-second-order model. To explore the effects of bed depth, feed flow rate, and initial solution pH on the breakthrough characteristics of CoFe2O4-coated sand, fixed-bed column experiments were conducted, and the breakthrough curves were drawn from the ratio of influent COD concentration to effluent COD concentration. The breakthrough time decreased with an increase in the feed flow rate and initial pH but increased with the bed depth. According to the X-ray photoelectron spectroscopy analysis, CoFe2O4-coated sand showed excellent stability due to negligible leaching of metallic elements. These findings have important implications for the advanced treatment of industrial wastewater.

Castanopsis fargesii is among the most prevalent hardwood species in South China. To improve the poor dimensional stability of C. fargesii wood, heat treatments were performed using vacuum or sand as the medium at four temperatures from 170 °C to 215 °C for 4 h. As a medium, vacuum or sand can create a low oxygen environment. The results showed that, as the temperature increased, the oven-dry density decreased, whereas the dimensional stability and the total color change (∆E*) increased with both media, two different changing patterns of a* and b* were observed, the lignin content increased, and the holocellulose content decreased. The oven-dry density decreased 9.4% and 25.5%, volume shrinkage ratio decreased 27.8% and 37.7%, and the ∆E* was 19.63 and 45.52, the lignin contents increased from 17.62% to 28.62% and 42.87%, and the holocellulose contents decreased from 80.49% to 69.43% and 51.04% when C. fargesii wood was heated under vacuum and with sand at 215 °C, respectively. Overall, sand heat treatment affected wood physical and chemical properties more than vacuum heat treatment. The analysis of functional groups and crystallinity also showed that there were severe changes in C. fargesii wood under sand heat treatment.

Non-destructive evaluation methods for timber stiffness are gaining increased interest as an alternative to static testing since they can be fast, cost-effective, and transportable, as well as non-destructive. The objective of this study was to evaluate the accuracy and limitations of a newly developed smartphone application (SMART THUMPER™) for the non-destructive evaluation of timber stiffness properties. The study determined the effect of the length, density (species), and cross-section sizes of the timber samples on the stiffness results. The results were compared to beam identification by non-destructive grading (BING©), an existing commercial non-destructive testing technology for evaluating the mechanical quality of wood and other materials. It was found that the application can be used to reliably estimate the stiffness of various timber products with a resonance frequency value below 2000 Hz. Frequencies greater than 2000 Hz were found to induce errors due to the smartphone microphone, which is engineered to acquire a lower frequency range. A reliability matrix providing an indication of the accuracy of SMART THUMPER™ estimation was presented, which may also prove useful in selecting appropriate sample lengths prior to testing. The sample length or dimensions can be manipulated to lower the frequency, and hence, to improve the results.

Climate-dependent changes in wood anatomical characteristics were studied for Rosa sp. and Nerium oleander sp. grown in phytosociological areas. For this purpose, wood samples were taken from the individual wood species grown in Antalya, Eskisehir, and Kastamonu provenances, where Terrestrial, Black Sea, and Mediterranean climate types prevail, and 11 anatomical characters were identified or calculated. As a result of the study, it has been determined that the climate has large effects on the characteristics that are the subject of the study and that each characteristic is at a higher level in individuals grown in areas where different climate types prevail. The highest values in Rosa species were obtained in the individuals grown under Terrestrial climate type in all characteristics except for LW (lumen widths), EC (elasticity coefficients), and FF (F-Factors.) Whereas in Nerium oleander, the highest values were obtained in individuals grown in the Mediterranean climate type in FL (fibre lengths), LW (lumen widths), FR (felting ratios), and EC (elasticity coefficients). For the same species type, in the Terrestrial climate, RIJID (rigidity coefficients), MUHT (Muhlstep ratios), and RUNK (Runkel ratios), and in the Black Sea climate DWT (double wall thicknesses) and WT (wall thicknesses) characteristics had high values.

Sweet sorghum bagasse (SSB) is potential feedstock for bioethanol production due to its natural abundance and high cellulose content (> 40%). This work compared the impact of three variables relative to the enzymatic hydrolysis of SSB kraft pulp. The three variables were the biosurfactant from lignin derivative known as amphiphilic lignin derivatives (A-LD), the enzyme loading level, and the hydrolysis time. These variables were optimized by response surface methodology (RSM) with a Box-Behnken design (BBD). The concentration of polyethylene glycol (PEG) 4000 was also optimized to compare it with the A-LD performance in the enzymatic hydrolysis process. After optimization, the A-LD produced a higher reducing sugar yield (RSY) (99.45%) than the PEG 4000. The difference in the predicted versus experimental values of the RSY was less than 4%, which means that the model was highly predictive. The adequacy of the model was confirmed by a regression value close to 1 for the A-LD assisted test. The result implies that the A-LD significantly improved the enzymatic hydrolysis performance to enhance the RSY. Moreover, the BBD is adequate and useful to identify the optimum concentration of surfactant.

Bamboo is mainly grown in hilly areas, and the harvesting of bamboo basically relies on labor. Moreover, the bamboo is prone to splitting problems during harvesting. To liberate labor and improve work efficiency, the crack propagation principle of bamboo was studied. Based on this study, a new cutting scheme using spiral feed was proposed. Additionally, a new bamboo cutting mechanism was designed. The new cutting mechanism, when installed on a harvesting vehicle, can automatically complete the cutting operation. The cutting mechanism is different from the traditional ones, and it uses four sets of saw blades for spiral feed cutting around the bamboo, which can reduce the splitting probability during the cutting process. Finally, a solid model of the cutting mechanism was built, and the basic movement process was simulated to verify the feasibility of the bamboo cutting mechanism.

This study focuses on volatile aromatic constituents extracted using solid-phase microextraction (SPME) from underground and aboveground Bambusa oldhamii shoots. Analysis was conducted using the extracts after heating at various temperatures and for various durations. Results of gas chromatography-mass spectrometry (GC-MS) revealed six SPME-extracted volatile aromatic compounds in underground B. oldhamii shoots and eleven in aboveground B. oldhamii shoots. Methyl salicylate with a characteristic mint aroma and methoxy-phenyl oxime that gives a smell of fresh shrimp and crabs are the main volatile compounds found in underground and aboveground shoots of B. oldhamii, respectively. Moreover, the two types of shoots tested also contain volatile compounds including fatty acids: n-hexadecanoic acid (27.94%) and aliphatic aldehyde: trans-2-nonenal (16.31%), respectively. The GC-MS analysis of underground and aboveground B. oldhamii shoots steamed at 100 C for 60 min revealed n-hexadecanoic acid as the main fatty acid compound.

Characterized by its light weight, high strength, and good flexibility, round bamboo is a natural functional biomaterial with a multi-level structure. Cracking is a key factor hindering its wider application. Moisture changes cause cracking when the round bamboo is dried. Therefore, studying moisture variations in the drying process of round bamboo can effectively reduce or solve the cracking problem. In this study, microwave drying with computer tomography (CT) imaging technology was used to understand the distribution and migration of moisture in round bamboo in the course of drying. The results indicated that water content has a significant correlation with the CT value, which can be used to achieve rapid determination of water content. The radial water content of samples gradually decreased from bamboo green (outer) to bamboo yellow (inner). The axial water content was high in the middle and low on both ends. As the water content decreased, the axial moisture distribution was consistent. The internode moisture mainly moved from the junction of bamboo yellow and bamboo partition, entered the adjacent cavity, and then gradually moved outward. Thus, the microwave drying method can effectively achieve industrial drying of round bamboo and prevent cracking.

Large amounts of solid residues are generated after extraction of active ingredients from herbs for the production of natural medicine, but the residues have not been well utilized. In this work, cationic nanofibrillated cellulose (CCNF) was prepared from the solid residues of Astragali Radix by etherification and homogenization. The CCNF was mixed with sodium alginate (SA) to create a hydrogel dressing by physical interactions between CCNF and SA without any addition of cross-linker. The CCNF-SA dressing exhibited moderate viscosity, good moisture-maintaining property, great antibacterial activities, good cytocompatibility, and clear acceleration of wound healing on rats. Furthermore, this CCNF-SA dressing with nanofibrous structure had moderate air permeability. Therefore, the CCNF-SA hydrogel could be used potentially as a skin wound dressing. Development of cost-effective and bioactive wound dressing materials is of crucial importance to reduce the burden on patients and healthcare systems. Also, this work provides a new strategy for valorization of the solid residues of herbs.

Salix psammophila has been extensively used as a sand barrier material for various desertification control applications. Elucidating the long-term decomposition characteristics and nutrient cycling process of this sand barrier in desert environments is of great importance. In this study, which was conducted for 1 to 9 years, changes in the mass loss percentage and the residual percentage in the decomposition process were explored of S. psammophila sand barriers in arid Northwestern China. In addition, the S. psammophila analysis nutrient elements release rule and its influence on soil properties were evaluated. The results showed that the decomposition process of S. psammophila sand barriers exhibited a “slow-fast” trend. After decomposition time for 9 years, mass decreased remarkably, and the residual percentage was 33.6%. Further, the nutrient release characteristics differed. C, P, and K were in the release state, whereas N was in the enrichment state. The decomposition percentage of the sand barriers was significantly correlated with N, P, K, C/N, C/P, and N/P (p < 0.05). The soil nutrient contents of C, P, and K contents increased 3.43, 2.23, and 2.08 g/kg compared to the initial values, respectively. The soil nutrient contents of N contents decreased 0.19 g/kg.