Methane generation from Miocene lacustrine coals and organic-rich sedimentary rocks containing different types of organic matter

Ten selected samples with varying types and amounts of organic matter from two Miocene lacustrine basins in northwestern Turkey were analyzed by programmed-temperature open-system pyrolysis to determine methane generation potential and reaction kinetics. Open-system pyrolysis was performed at heating rates 0.1, 0.7 and 5.0 K/min, where generated gases were measured using an on-line gas chromatograph. Frequency factors and activation energy distributions of reaction kinetics for methane generation from the investigated lacustrine coals and sedimentary rocks indicated that type of kerogen controls the sequential order of methane generation. Methane from Type-III kerogen is generated at lower temperatures, which will be followed by methane from Type-II and Type-I kerogen. Methane generation potentials in the range 14-35 mg CH₄/g TOC correlates also with type of organic matter. For Type-III kerogen up to 28% of the total hydrocarbon generation potential belongs to methane. The respective value is only 2% for a Type-I kerogen.     

Durable antimicrobial treatment of cotton fabrics using N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride and polycarboxylic acids

N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride (HTCC), a water‐soluble chitosan quaternary ammonium derivative, was used as an antimicrobial agent for cotton fabrics. HTCC has a lower minimum inhibition concentration (MIC) against Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli compared to that of chitosan; however, the imparted antimicrobial activity is lost on laundering. Thus crosslinking agents were utilized to obtain a durable antimicrobial treatment by immobilizing HTCC. Several crosslinkers such as dimethyloldihydroxyethylene urea (DMDHEU), butanetetracarboxylic acid (BTCA), and citric acid (CA) were used with HTCC to improve the laundering durability of HTCC treatment by covalent bond formation between the crosslinker, HTCC and cellulose. The polycarboxylic acid treatment was superior to the DMDHEU treatment in terms of prolonged antimicrobial activity of the treated cotton after successive laundering. Also, the cotton treated with HTCC and BTCA showed improved durable press properties without excessive deterioration in mechanical strength or whiteness when compared to the citric acid treatment. With the addition of only 0.1% HTCC to BTCA solutions, the treated fabrics showed durable antimicrobial activity up to 20 laundering cycles. The wrinkle recovery angle and strength retention of the treated fabrics were not adversely affected with the addition of HTCC. Therefore, BTCA can be used with HTCC in one bath to impart durability of antimicrobial activity along with durable press properties to cotton fabric. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1567–1572, 2003     

Biodegradability of cellulose fabrics

Biodegradability of cellulose fabrics was evaluated by use of a soil burial test, an activated sewage sludge test, and an enzyme hydrolysis. Surface changes after biodegradation were observed by optical microscopy. From X‐ray diffraction analysis (XRD), changes in the crystallinities and the internal structures as a result of degradation were also investigated. It was shown that biodegradability decreased in the following order: rayon > cotton ? acetate. Rayon fibers, which have a low crystallinity and a low degree of orientation, showed the highest biodegradability in most cases. However, in spite of its low crystallinity, acetate fibers exhibited very low biodegradability, probably because of the presence of hydrophobic groups in its structure. On the other hand, linen showed an inconsistent behavior in that it had the highest biodegradability in the soil burial test, but a lower biodegradability than that of cotton in the activated sewage sludge test. XRD analysis revealed that there was a slight increase in the crystallinity of linen, cotton, and rayon fabrics at the initial stage, but a continuous decrease thereafter. From the correlation analysis, it was revealed that the biodegradability of cellulose fabrics was closely related to the moisture regain of the fibers, which reflects the hydrophilicity and internal structure of the fibers at the same time. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 248–253, 2004     

Continuous ethanol production from wood hydrolysate by chemostat and total cell retention culture

Chemostat and total cell retention cultures with internal filter system ofSaecharomyc.es cerevisiae H1-7 were carried out to produce ethanol from wood hydrolysate. Maximum ethanol productivity obtained in a chemostat with the aeration rate of 1 vvm was 3.79 g/(L·h). This was 20% higher than that in a chemostat without aeration. However, the substrate was not completely consumed at the dilution rate with the maximum productivity. The realistic productivity, which has higher than 99% conversion rate of substrate, was. 2.95 g/(L·h). The maximum productivity in the total cell retention culture was 6.65 g/(L·h) at the dilution rate of 0.19 h¹ and the residual glucose concentration was negligible.     

Modeling and economic analysis of CO<Subscript>2</Subscript> separation process with hollow fiber membrane modules

The main purpose of the study was to develop a model using ASPEN and Excel simulation method to establish optimum CO₂ separation process utilizing hollow fiber membrane modules to treat exhaust gas from LNG combustion. During the simulation, optimum conditions of each CO₂ separation scenario were determined while operating parameters of CO₂ separation process were varied. The characteristics of hollow fibers membrane were assigned as 60 GPU of permeability and 25 of selectivity for the simulation. The simulation results illustrated that 4 stage connection of membrane module is required in order to achieve over 99% of CO₂ purity and 90% of recovery rate. The resulted optimum design and operation parameters throughout the simulation were also correlated with the experimental data from the actual CO₂ separation facility which has a capacity of 1,000 Nm³/day located in the Korea Research Institute of Chemical Technology. Throughout the simulation, the operating parameters of minimum energy consumption were evaluated. Economic analysis of pilot scale of CO₂ separation plant was done with the comparison of energy cost of CO₂ recovery and equipment cost of the plant based on the simulation model. This work was presented at the 6 ^th Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006.     

Interfacial adhesion reaction of polyethylene and starch blends using maleated polyethylene reactive compatibilizer

The interfacial reaction of the polyethylene (PE)/starch blend system containing the reactive compatibilizer maleated polyethylene (m‐PE) was directly characterized by Fourier transform infrared (FTIR) spectroscopy. A significant amount of anhydride groups on m‐PE existed as hydrolyzed forms, resulting in a large amount of carboxyl groups. Using a vacuum‐heating‐cell designed in the laboratory, the carboxyl groups were successfully transformed into the dehydrolyzed state (i.e., anhydride group). This result enabled the direct spectroscopic observation of chemical reaction occurring at the interface. For the PE/starch blend system containing m‐PE, the chemical reaction at the interface was verified by the evolution of ester and carboxyl groups in the FTIR spectra. The effect of the reactive compatibilizer on the interfacial morphology was also examined by scanning electron micrography (SEM). Enhanced interfacial adhesion was clearly observed for the blend system containing reactive compatibilizer. Tensile strengths of blend systems containing m‐PE also increased noticeably compared with the corresponding system without compatibilizer. A similar observation was made for the breaking elongation data. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 767–776, 2002     

Effect of coke orientation on the electrochemical properties of lithium-ion battery anode

Journal of Applied Electrochemistry - In this study, Needle and Regular coke, which has different crystalline and orientation characteristics, were graphitized, and the effect of crystal changes on...     

Comparison of liquid-phase and methanol-swelling crosslinking processes of polyimide dense membrane for CO2/CH4 separation

To overcome the plasticization effect in polyimide membranes, many researchers have proposed crosslinking method. This can reduce an inter-segmental mobility by tightening and rigidifying the polymer chains. However, it is difficult to modify the whole polymer chains throughout the membrane because the reaction can be hindered by the diffusion rate of the crosslinker. In particular, it is hard for bulky crosslinker to penetrate a dense membrane with a small d-spacing. This study investigated the effect of crosslinking a dense Matrimid membrane with p-phenylenediamine (p-PDA) via two different crosslinking methods (i.e., methanol-swelling crosslinking process [M-SCP] and liquid-phase crosslinking process [L-PCP]). Most of the crosslinking reaction in M-SCP occurs on the membrane surface due to difficulty in penetration of the bulky p-PDA into the Matrimid dense membrane. In contrast, the L-PCP allows uniform crosslinking across the membrane. The membranes crosslinked using L-PCP showed excellent chemical resistance. Furthermore, the plasticization phenomenon was not observed in the membranes crosslinked using L-PCP with p-PDA more than 15%. Meanwhile, the membrane crosslinked using M-SCP exhibited poor plasticization and chemical resistance properties. These results showed that the L-PCP method can be more effective for the crosslinking of dense membrane to deliver both high plasticization and chemical resistance.     

Effects of anodizing voltage on the anodized and hydrothermally treated titanium surface

Anodic oxidation is the process of creating a titanium oxide layer with various defects more dense and stable. In this study, a dense, stable and porous oxide layer was formed using anodic spark oxidation on pure titanium surface and hydroxyapatite crystals were formed on its surface via a hydrothermal treatment. A mixture of 0.02M−GP (Glycerolphosphate disodium salt) and 0.2M-CA (Calcium acetate) was used as an electrolyte. By increasing the anodizing voltage to 220, 260, 300, and 360 V, the effects of the anodizing voltage were examined by evaluating the film properties after anodization and a hydrothermal treatment. Breakdown occurred around 230 V. As the voltage increased after breakdown, the pore size increased. After the hydrothermal treatment, the amount of HA crystal precipitation was also increased as the voltage increased. The mean surface roughness (Ra) of the anodizing surface was also increased as the voltage increased. The Ra value was larger in the hydrothermally treated group compared with the group treated with anodization as a result of the HA crystals present on the surface after the hydrothermal treatment. Corrosion resistance of the surface modified by anodization was significantly increased in a saline solution compared to that for the non-treated group; this increased further after the hydrothermal treatment. These increases were most likely due to a thick stable oxide layer formed through anodization. Thus, it is believed that titanium with its surface modified through anodic spark oxidation would be a suitable biomaterial due to its corrosion resistance and biocompatibility.     

The form error prediction in side wall machining considering tool deflection

In this research, an effective method for the form error prediction in side wall machining with a flat end mill is suggested. The form error is predicted directly from the tool deflection without surface generation by cutting edge locus with time simulation. The developed model can predict the surface form error accurately about 300 times faster than the previous method. Cutting forces and tool deflection are calculated considering tool geometry, tool setting error and machine tool stiffness. The characteristics and the difference of generated surface shape in up milling and down milling are discussed. The usefulness of the presented method is verified from a set of experiments under various cutting conditions generally used in die and mold manufacturing. This study contributes to real time surface shape estimation and cutting process planning for the improvement of form accuracy.