Carbon fiber is a well-established high value-added material. However, its price is considerably high. Lignin obtained from oil palm frond (OPF) is a compatible precursor for carbon fiber production. This study aims to determine the feasibility of OPF lignin obtained under subcritical phenol conditions by focusing on its fundamental properties (purity and particulate matter content) as a precursor for carbon fiber production. This study also focuses on the effect of temperature (260–300 °C), time (5–30 min), and solid loading (6 and 10 g) on these properties. From the results obtained, the highest lignin purity of 95.1% was obtained at 260 °C, 5 min, and 10 g solid loading. Meanwhile, the lowest particulate content of 15.6% was obtained at 300 °C, 30 min, and 6 g solid loading. It can be further concluded that at higher temperature and longer reaction time, the low molecular weight compounds are dissolved in the liquid product, resulting in a decrease in the lignin purity as well as the particulate matter content.
The use of exoelectrogenic bacteria to produce electricity has attracted much attention recently. One of the applications of this kind of bacteria is microbial fuel cell (MFC). This current study aims to investigate the effects of duration and wavelength of light radiation on agar salt-bridge MFC performance via bacteria in terms of electricity voltage and power density. Activated sludge was used as an inoculum of the MFC. The experiments were conducted under two radiation modes, i.e., normal solar radiation and full-time radiation by artificial lamps: fluorescent and LED lamps. The LED lamps include red (632 nm), yellow (594 nm), green (515 nm), and blue (463 nm). The results showed that the full-time radiation enhanced the electricity generation a little more than normal solar radiation. Among the colors, yellow LED gave the highest power density than others with less chronological fluctuations.
We propose a simple formulation to determine achieved improvements on investment level as a function of work in a commercial forestry operation. Two trial approaches are presented. The first attempts to formulate the relationship between unit costs and environmental loads such as CO2 emissions and energy consumption as a function of logging residue transportation distance. In general, transportation efficiency increases with scale: modal transfer from small to large scale transportation can be achieved through enabling infrastructure investment, such as the provision of intermediate landings. In our case study, four transport capacities were considered (i.e. trucks with 0.35, 2, 4 and 10 t capacities), with loading by a grapple loader sited at an intermediate landing. The optimum formulation was then applied to the second trial, which focused on infrastructure development for broad-leaved species harvesting, namely the construction of forest road networks. Three modes of extraction were considered, grappling, winching and a simple cable system, with two levels of infrastructure provision: 2.5 m wide spur road networks using mini-forwarders and 3.0 m wide forest road networks using 0.45 m3 bucket class excavator machines. Application of the derived formulation indicated thresholds for when each of the modes or systems was most appropriate.
In this study, in-situ catalytic upgrading of bio-oils derived from the fast pyrolysis of cellulose, hemicellulose, and lignin over various commercial zeolites was investigated. The liquid products were recovered with acetone in an ice-cold trap and analyzed by Gas chromatography-Mass spectrometry (GC–MS) and the gas products (CO, CO2, CH4 and H2) were analyzed by Gas Chromatography-Thermal Conductivity Detector (GC-TCD). It is found that H-ZSM-5 (HSZ-822), H-Beta (HSZ-931) and H-USY (HSZ-330) exhibited high performance for the conversion of oxygenated compounds in the bio-oils to aromatic hydrocarbons. Also, it is found that the biomass feedstock types showed great influence on the hydrocarbon compositions when using the same catalyst. High yield of BTXs was obtained by catalytic upgrading of the bio-oils derived from the cellulose and lignin over H-USY and H-Beta zeolites. In contrast, the remarkable production of xylene was observed in the catalytic upgrading of the bio-oils derived from the hemicellulose over all zeolite types. Moreover, the reusability of these three zeolites was in the order of H-Beta > H-USY > H-ZSM-5.
Today, power generation utilizing renewable energy such as biomass fuel has been attracting much attention as a solution to energy and environmental problems. In this research, we devised a new mechanism to achieve high power generation by using a Stirling engine, which is highly efficient, with steam as a working fluid We carried out a theoretical calculation of the case where steam was put into the high-temperature cylinder during the isochoric heating process of the Stirling engine. This calculation showed that the mechanism can greatly improve the output, compared with the one without steam. We also conducted the same calculation in a γ-Stirling engine, and confirmed the improvement of the output. Furthermore, when we used biomass fuel to operate the γ-Stirling engine with the mechanism using steam, we found that we need more than 50 kg of running water per 1 kg of wood chips in order to operate it efficiently. To obtain this amount of running water, therefore, the engine should be constructed in the areas along the coast and rivers, where its performance is expected to be developed to a practical level.
For future sustainable-energy development, H2 is a promising fuel. Cellulose suspensions can be decomposed by 27.12-MHz radio frequency in-liquid plasma to produce H2. In-liquid plasma decomposition uses an electrolyte solution of Na2SO4 to improve the efficiency of H2 production. H2 is the main product generated by plasma breakdown of cellulose; however, small quantities of carbon monoxide, carbon dioxide, and other low-grade flammable gases are also produced. Plasma generation requires the electron emission which increase with collision of Na+ and SO42− ions onto a copper electrode. Therefore, size of plasma increases with the concentration of Na2SO4 which leads to an increase in the decomposition amount of cellulose, so the energy efficiency improved. In addition, to estimate OH radical concentration, H2O2 concentration in solution was measured. Since OH radicals are consumed for cellulose decomposition, the concentration of H2O2 in the cellulose suspension was very small.
This paper experimentally and numerically investigates the growth rate of SiO2 film by thermal CVD from the oxidization of hexamethyldisiloxane in a horizontal tubular reactor. The control steps of the mass transfer were changed from the surface reaction to the diffusion of raw material. By using the differential reactor model, the surface reaction rate was dependent on not only the first order of the hexamethyldisiloxane concentration, but also the power 0.55 of the oxygen concentration. The activation energy of the reaction rate constant was 127 kJ/mol. In the diffusion control step, the apparent diffusion coefficient was obtained by Akiyama’s model and dependent on the power 1.75 of the temperature. Except for the diffusion control step, the growth rate distribution was partly reproduced by numerical simulation of heat and mass transfer using the chemical reaction.
In this study, active carbon produced from tires waste using pyrolysis was investigated. As tires were made predominantly from the petroleum product rubber, they have a high heating value, as well as high volatile content and medium sulfur content. Those properties make them excellent candidates for pyrolysis, which can be used to recover energy and by-products. Pyrolysis has been conducted until the temperature of 750 °C and holds in residence time variation of 5, 60, and 120 min after oil and gas completely produced. Char was produced via pyrolysis then activated by chemical activation using NaCl solution for 24 hours followed by drying at the temperature of 100 °C for 1 hour. Activated carbon as pyrolysis product then analyzed using Scanning Electron Microscope, BET analysis and N2 adsorption analysis. It was observed that the pore size of the resulting carbon generally increases as increasing of residence time. In addition, increasing residence time also resulted in enhanced higher porosity development after chemical activation using NaCl as high as 2.19 nm with BET surface area of 28.19 m2/g. The formation of pores with an average diameter of pore 8 µm was observed on the carbon surface.