Volume 8 Issue 4

A direct synthesis of methyl levulinate from the degradation of paper sludge in a methanol medium at moderate temperatures ≤ 230 °C) was performed using low-concentration sulfuric acid (≤ 0.05 mol/L) as the catalyst. Response surface methodology with a four-factor, five-level central composite rotatable design was employed to optimize the process conditions for . The yields of methyl levulinate and dimethyl ether as a function of the process variables were fitted to second-order polynomial models through application of multiple regression analyses. A good agreement between the experimental and modeled data was obtained. When the controlled yield of dimethyl ether was less than 20%, a maximum methyl levulinate yield of 54.8% was achieved, corresponding to 27.7% (w/w) overall yield for dry paper sludge. The findings indicated that paper sludge can act as a potential biomass material for upgrading and converting into high value-added chemicals.

The wood pellet industry has been in a growing trend worldwide. The Southern U.S. has been proposed as a good location to further develop wood pellet industries geared toward the supply of international markets. This research looks into the current status of the wood pellet industry of the region in terms of consumption of biomass, installed capacity, and production levels of wood pellets. It assesses the known future developments for the region (Virginia, North Carolina, South Carolina, Georgia, and Florida). The study also includes an analysis of major ports within the region. Currently, companies within the region have a total production capacity of over 4.7 million tons of pellets, while the current production levels are estimated at 3.1 million tons. Research indicates that at least 20 facilities within the region will be opening their operations, and the expected capacity of the wood pellet industry will then be over 5 million tons of pellets per year. The biomass requirement for the production of these pellets was determined, and the current production level requires over 11 million tons of green biomass (55% moisture content). Future developments may require over 13 million tons, making the industry total over 24 million tons in coming years.

TEMPO oxidation was performed on never-dried bleached softwood kraft pulp fibres to study the influence of reaction temperature and the dosage of sodium hypochlorite in the oxidation treatment. It was found that oxidation at a high temperature shortened oxidation time, but it also resulted in more extensive degradation of the pulp. Harsh reaction conditions (high temperature and high dosage of sodium hypochlorite) enabled the rapid disintegration of pulp fibres with a low energy demand. The freeze-dried disintegrated pulp fibres had a high absorption capacity of saline liquid, 40 to 80 g/g, and retained 9 to 14 g saline liquid/g material in a standard centrifuge retention test. Four different models were investigated to describe the kinetics of TEMPO oxidation of pulp fibres. However, none of the models could adequately describe all the mechanisms involved in this reaction system. The results showed that the diffusion of hypochlorite ions was sufficiently fast compared to the chemical reactions. In contrast, the concentration of the catalytic compounds, NaBr and TEMPO, both had a strong influence on the reaction rate. Results show that the reactions have different phases, possibly with different rate-determining steps. It remains to be determined which reaction steps correspond to the different phases.

The possibility of using cellulose from kenaf as reinforcing fibres in lithium-conducting composite polymer electrolytes based on 49% poly(methyl methacrylate)-grafted natural rubber and LiCF3SO3 has been explored. Cellulose was extracted from kenaf bast fibres by a two-step chemical treatment, specifically an alkali treatment and a bleaching process. High-performance composite polymer electrolytes were prepared by solution casting with various compositions of cellulose (0-10 wt%). Scanning electron microscopy was used for morphological studies of the kenaf fibres at each stage of treatment. The morphology of the electrolytes showed a good dispersion of the cellulose fibres. Infrared spectroscopy showed significant interactions between Li+ ions from the salt and the C=O and C-O-C groups of methyl methacrylate. X-ray diffraction analysis showed that the crystallinity of the polymer host increased upon addition of cellulose and decreased upon addition of salt. Composite electrolytes with 4 wt% cellulose exhibited the best mechanical performance with 10.9 MPa and 995 MPa for tensile strength and Young’s modulus, respectively. The electrolyte films were analyzed by electrochemical impedance spectroscopy and the optimum value of ionic conductivity of SPE with cellulose was 5.3×10-7 Scm^-1. The addition of cellulose involved a weak decrease of the conductivity, which might be due to interactions between cellulose, polymer, and LiCF3SO3. The incorporation of cellulose fibres in polymer electrolytes provides a high reinforcing effect at an acceptable level of ionic conductivity.

The effect of biochar amendment of a multi-element contaminated soil on the transfer and accumulation of Cd, Zn, Pb, and As in wheat was investigated in this study. Addition of biochars from rice residues (straw, husk, and bran) significantly decreased shoot Cd, Zn, and Pb concentrations by up to 71%, 37%, and 60%, respectively, but increased As by up to 199%. Biochar additions decreased the NH4NO3-extractable concentrations of Cd, Zn, and Pb in soil by 23 to 81%, 29 to 94%, and 31 to 92%, respectively, especially straw-char treatment, though biochar treatment increased the concentration of As by 64 to 2650%. A decrease in biochar particle size generally favored the immobilization of Cd, Zn, and Pb in soil and reductions in their accumulation in wheat shoot, but this was reversed for As. Increases of up to 21%, 70%, 59%, and 40% in shoot biomass, root length, and shoot P and K levels, respectively, of wheat seedlings were caused by biochar amendments. Biochar has the potential to reduce accumulations of Cd, Zn, and Pb in wheat shoot and improve its growth.

Microcrack behaviors in black and red heartwoods of Cryptomeria japonica were compared in this study. Black and red heartwoods have extremely different green moisture contents but similar wood structure. Small heartwood samples were prepared from these two types of green wood. Moisture contents of black and red heartwood were 201.5% and 51.3%, respectively. The samples were dried at 50 °C in a controlled-environment chamber with a relative humidity below 5%. The propagation of microcracks was continuously observed using a confocal laser scanning microscope while the samples dried. The electrical resistivity of the surface was also measured to assess surface moisture content. Results showed that the transformation of the microcracks was similar between black and red heartwoods. However, the appearance of microcracks in the black heartwood was delayed, whereas the microcracks appeared in red heartwood immediately after drying. These suggested that in-situ observation is essential for distinguishing when microcracks emerged. It was also suggested the green moisture content of heartwood has a major effect on the occurrence of microcracks. Drying conditions must be adjusted to account for the moisture content of green heartwood, even for specimens of the same species that have the same anatomical structure.

the combination of increased specific surface area, electrostatic forces, and hydrophobic interactions, thus compensating for the loss of optical properties resulting from LC refining. The mechanical hydraulic force generated by the high refining energy disturbed the FWA retention. Therefore, high refining energy could improve the adsorption of FWAs when they are added after refining, but for better performance, the refining energy should be controlled and lowered. In addition, small amounts of calcium salt added after refining can also ameliorate the adsorption of FWAs.

Transformation of the hemicellulose fraction in an environmentally benign manner to deliver high value-added chemicals is critical for the integrated utilization of biomass. Amongst all the chemicals derived from hemicellulose, furfural (produced by hydrolysis of xylan into xylose and successive dehydration of the latter) is a promising option. In this manuscript, a catalytic approach for converting xylan and xylose into furfural co-catalyzed by choline chloride-citric acid·H2O, a deep eutectic solvent (DES) synthesized from biorenewable building blocks, and trivalent metal chloride was developed. Choline chloride-citric acid·H2O acted as both reaction medium and Brønsted acid catalyst. Both monophasic route and biphasic route (with methyl isobutyl ketoneas extractant for in situ extraction of furfural) were proposed. The highest furfural yields obtained from xylose and xylan in monophasic approach were 59.3% and 54.2%, respectively, at 140 °C, and these values increased to 73.1% and 68.6% when biphasic system was applied for the reaction. Moreover, in biphasic system, choline chloride-citric acid and metal chloride could be recycled and reused for 5 runs with stable catalytic ability.

Magnetic chitosan composite microparticles (MCCPs) were successfully prepared using a simple one-step co-precipitation method and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM). The experimental results showed that the particles possessed a honeycomb-like porous structure and had super-paramagnetic properties, with a saturation magnetization of about 33.3 emu/g. Congo red (CR), an anionic azo dye, was used to investigate the adsorption properties of the MCCPs. The adsorption kinetics data and isotherms produced from these experiments indicated that CR adsorption onto the MCCPs was best fitted with a pseudo-second-order kinetic equation and was well described by the Langmuir model. Thermodynamic parameters such as the changes in Gibbs free energy (ΔG0), enthalpy (ΔH0), and entropy (ΔS0) were also estimated; the results revealed that the adsorption process was spontaneous and endothermic. The regeneration studies demonstrated that the MCCPs can be used as a reusable adsorbent for CR adsorption from aqueous solution. The molecular similarity between chitosan and cellulose suggests that the present results might serve as a model of what might be achieved with a cationic derivative of cellulose.

The wood industry continues to strive to reduce production costs and increase productivity to remain competitive. Knowledge of the effect of wood cutting parameters on power consumption could increase energy efficiency, reducing operating costs and increasing profitability. Measuring power consumption also provides information about other variables, such as tool edge wear, occurrence of catastrophic failures, and other parameters that affect the quality of the sawn boards and the momentary efficiency of the breakdown process. In this work, power consumption during sawing of Pinus sylvestris L. using a double arbor circular saw was investigated. Both climb-sawing and counter-sawing were considered. The experiments were carried out under normal production circumstances in two Swedish sawmills. The relationship between cutting parameters and theoretical power consumption was investigated. The experimental power consumption increased by 11 to 35% during an 8-h shift, mainly due to an increase in the tooth radius. Additionally, this study showed that climb-sawing consumed more power than counter-sawing.