Volume 16 Issue 3

The disposal of automotive shredder residue (ASR) directly affects China’s goal of achieving a 95% recycling rate for end-of-life vehicles. Pyrolysis and gasification have gradually become the most commonly used thermochemical technologies for ASR recycling. To obtain more hydrogen-rich syngas, it is necessary to determine the optimal process parameters of the ASR pyrolysis and gasification process. The main process parameters of the two-stage ASR pyrolysis and gasification process were studied using the established Aspen Plus model. Through analyzing the effects of process parameters, such as the temperature, equivalence ratio, and mass ratio of steam to ASR feedstock, on the product distribution and product characteristics of ASR pyrolysis and gasification, the optimal process parameters were determined. A series of comparative experiments under different conditions were conducted. The experimental results verified the accuracy and reliability of the Aspen Plus simulation model for the ASR pyrolysis and gasification processes and verified the practical feasibility of the process parameters obtained from the simulation analysis.

The specific energy absorption of a thin-walled tube can be improved by filler. This study examined the potential use of a cheaper biomass filler, paper scraps, to enhance the energy absorption characteristics of the structure while reducing its cost, compared to that with a traditional filler such as foam material. Quasi-static crushing tests and finite element simulations were performed by using the explicit non-linear finite element software LS-DYNA to determine the improvements to the mean crushing force and specific energy absorption of the steel tube when filled with different densities of paper scraps. The mean crushing force and specific energy absorption of the empty tube, the paper scraps, and thin-walled tube filled with paper scraps were determined, and corresponding numerical simulations were performed. The simulation and test results showed that the impact performance of tube filled with paper scraps was greatly improved when paper scraps density was 0.35 g/cm3. By optimizing paper scraps filling structure, a new structure that could further enhance the specific energy absorption was obtained. The optimal scheme could increase the specific energy absorption of Q345 steel tube by 11.35%.

To investigate the effect of sodium alginate (SA) on the properties of wheat straw/polylactic acid (PLA) composites, four kinds of composites with different SA contents (0 wt%, 5 wt%, 10 wt%, and 15 wt%）were prepared via injection molding. The mechanical properties, moisture absorption, thermal stability, and infrared spectrum of the four kinds of composites were tested and analyzed, and the microstructure of the tensile section of the composites was observed via scanning electron microscopy. The degradability of the composites was also analyzed. The results showed that the wheat straw/PLA composites with 5% SA had better mechanical properties. Their tensile strength was 15.8%, 5.4%, and 19% higher than those of 0%, 10%, and 15% SA, respectively. The impact strength of the 5% SA composites changed to an acceptable degree relative to the non-SA composites, which had an impact strength of 28% lower than that of 0% SA but 51.9% higher than that of the 15% SA composite. The 5% SA composites had less hygroscopicity and better thermal stability, and adding SA enhanced the degradability of the composites. As the SA content increased, degradability increased greatly.

This study investigated the effects of adding ammonium dihydrogen phosphate (ADP) on the physical and chemical changes of a water-soluble extract of the inner part of oil palm trunk (OPT) to clarify the bonding mechanism of the binderless particleboard. The extract’s effect on ADP-added binderless particleboard was also investigated. OPT particles were treated by hot water at 60 °C for 6 h. Water-soluble extract and treated OPT particles were obtained. ADP was added to the water-soluble extract at 0, 10, and 40 wt%, and the mixtures were heated at 180 °C for 10 min. Furthermore, binderless particleboards using the treated particles were manufactured with similar condition. The 10 wt% ADP mixture changed the water-soluble extract to an insoluble substance, which was twice that of with 0 wt.% ADP addition. Infrared spectroscopy revealed peaks of furan and carbonyl in the insoluble substance. This indicated that the free sugar content in the water-soluble extract would change to furan compounds. Thermal analysis revealed that the resulting insoluble substance had good thermal stability, suggesting a high-molecular-weight substance. The insoluble substance would contribute to bonding of the binderless particleboards. In particular, a significant contribution to the water resistance was observed.

Agro-industrial waste is generated in large quantities, producing negative environmental impacts. For instance, in the distillation process of vinasses, up to 15 L are produced per alcohol produced. Therefore, it is necessary to search for ecological alternatives. Biological treatments are not recommended because vinasses contain compounds, such as melanoidins, which exert inhibitory activity against microorganisms. Thanks to this activity, melanoidins could be removed, recovered, and become a value-added product. In this study, Opuntia ficus-indica (OFI) mucilage, a natural biopolymer as coadjuvant, was used to improve the coagulation-flocculation process in the treatment of real samples of mezcal vinasses, after evaluating the individual effect of aluminum sulfate and ferric chloride. It was possible to eliminate 90% of color using ferric chloride, showing better removals than aluminum sulfate. However, the effect of ferric chloride plus OFI mucilage generated an adverse effect because the removal was under 17%. The individual effect of ferric chloride for chemical oxygen demand (COD) removal was 28%. This removal was improved by the addition of OFI mucilage, as it was able to increase removal to 84%. The natural coadjuvant was shown to be effective in the COD removal in the treatment of mezcal vinasse using the coagulation-flocculation process.

Partial replacement with coconut shell coarse aggregates was studied as a means to produce lightweight coconut shell concrete (CSC). Coconut shell concrete is a structural grade lightweight concrete that has a lower self-load compared to the normal weight concrete (NWC), which allowed the production of larger precast units. An experimental study and analysis were conducted using different volume percentages of 0%, 10%, 30%, 50%, and 70% of coconut shell as coarse aggregates, to produce M30 (30 MPa) grade concrete. The compressive strength of the NWC and CSC were obtained on the 7th and 28th day. The optimum results obtained for M30 grade concrete at 7th and 28th day of CSC were 34.2 and 38.6 MPa, respectively. In addition, the workability and weight-reduction were analyzed and compared with NWC. Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS/EDX) and Fourier transform infrared spectroscopy (FTIR) were also used to investigate the structural morphology, chemical composition, and infrared functional groups of the concrete.

In order to study the effects of a messmate heartwood extraction process on its cell wall pore structure and its drying ability, its nanopore structure was explored after via gas adsorption technology. Specifically, the messmate heartwood particles were extracted with methanol, and then the cell wall pore structure of the original and extracted samples were evaluated by N2 and CO2 sorption and pycnometer methods, respectively. Overall, compared with the original samples, the cell wall porosity, micropore volume, mesopore volume, BET specific surface area, and specific surface area of the micropores of the extracted messmate heartwoods increased by 2.55%, 0.007 cm3/g, 0.0014 cm3/g, 0.24 m2·g-1, and 21.9 m2·g-1, respectively. The cell wall pore volume measured via the gas adsorption method was smaller than the measurement from the pycnometer method. The results indicated that the presence of extractives made the messmate cell wall have a decreased pore volume and porosity, which may be one of the reasons messmate wood is difficult to dry. Messmate extractives primarily were present in the micropores of the cell wall in the range of 0.4 nm to 0.7 nm. However, gas sorption technology could not detect all the pores in the cell wall of the messmate heartwood sample.

Research indicates that users of thermally modified wood lack information regarding the improved performance and any variations that may exist for the “same” product when manufactured by different companies. The goal of this study was to evaluate the variability in mechanical properties of three thermally modified hardwoods and determine the variability between three different manufacturers. To determine the hardness, bending (modulus of elasticity and module of rupture) and shrinkage values, testing was conducted following ASTM standard D143. The samples were conditioned at 20 °C and a relative humidity of 65% until they reached an equilibrium moisture content before testing. Analysis of variance was used to determine the variability within and between the different processes used by each company. Seven out of 18 (39%) tests indicated that there were statistical differences regarding the mechanical performances of the wood samples. Yellow poplar had the least variation between companies (only difference in equilibrium moisture content, EMC) and red maple had the most (hardness, tangential shrinkage, and EMC). While the means for these properties were statistically different, the differences in application for hardness and EMC are slight. For example, the largest difference between processes in hardness was 83.6 kg, for tangential shrinkage, 0.45% and 1.37% for EMC. These differences are suggested to be inconsequential when compared to the values that exist between different species of untreated wood.

Armeniaca sibirica shell activated carbon (ASSAC) magnetized by nanoparticle Fe3O4 prepared from Armeniaca sibirica shell was investigated to determine its adsorption for Hg2+ from wastewater. Fe3O4/ASSAC was characterized using XRD (X-ray diffraction), FTIR (Fourier transform infrared spectroscopy), SEM (scanning electron microscopy), and BET (Brunauer–Emmett–Teller). Optimum adsorption parameters were determined based on the initial concentration of Hg2+, reaction time, reaction temperature, and pH value in adsorption studies. The experiment results demonstrated that the specific surface area of ASSAC decreased after magnetization; however the adsorption capacity and removal rate of Hg2+ increased 0.656 mg/g and 0.630%, respectively. When the initial concentration of Hg2+ solution was 250 mg/L and the pH value was 2, the adsorption time was 180 min and the temperature was 30 °C, and with the Fe3O4/ASSAC at 0.05 g, the adsorption reaching 97.1 mg/g, and the removal efficiency was 99.6%. The adsorption capacity of Fe3O4/ASSAC to Hg2+ was in accord with Freundlich isotherm models, and a pseudo-second-order kinetic equation was used to fit the adsorption best. The Gibbs free energy ΔGo < 0，enthalpy change ΔHo < 0, and entropy change ΔSo < 0 which manifested the adsorption was a spontaneous and exothermic process.

An approach of green in situ synthesis single-step method was applied to produce antibacterial paper. The objective was to investigate the effect of precursor addition on the formation of zinc oxide particles using an in situ single-step method. Zinc chloride concentrations of 0.1, 0.3, 0.5, and 0.7 M were prepared and added into a solution of algae extract and bamboo pulp. The prepared pulps were tested and made into handsheets using a papermaking machine based on TAPPI T205 (2006). Morphological observation of treated papers was conducted using a field emission scanning electron microscope (FESEM). An average of 400 to 570 nm zinc oxide spherical-shaped particle was observed on the fibers of paper. The percentage of element composition of the treated paper were 15.08% to 34.08% of zinc and 17.45% to 32.59% of oxygen captured via scanning electron microscopy with energy dispersive X-ray (SEM-EDX) analysis. The crystallinity test was performed using X-ray dispersion (XRD). A higher percentage of precursors exhibited a more amorphous structure. A measurement of more than 30% increment of inhibition zone was obtained from 10.00 to 25.00 mm against S. aureus, S. choleraesuis, and E. coli. Precursors addition of more than 0.3 M would have the most potential to enhance the growth of zinc oxide via in situ preparation, hence providing better antibacterial properties of the prepared papers.