Fourier transform infrared study of polypyrrole–poly(vinyl alcohol) conducting polymer composite films: Evidence of film formation and characterization

The electrochemical preparation of polypyrrole (PPY)–poly(vinyl alcohol) (PVA) conducting polymer composite films on an indium–tin oxide glass electrode from an aqueous solution containing a pyrrole monomer, a p‐toluene sulfonate electrolyte, and a PVA insulating polymer is reported. The prepared PPY–PVA composite films were characterized by Fourier Transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and conductivity measurements. The FTIR study showed that the composite of PPY and PVA formed through bond formation between PVA and the p‐toluene sulfonate dopant anion. The conductivity data of PPY–PVA showed that with increasing PVA concentration in the pyrrole solution, the conductivity of the prepared PPY–PVA film increased up to a certain level due to an increase in conjugation length, and later, it decreased with further increases in the PVA concentration in the solution due to a decrease in conjugation length. This was supported by the FTIR band intensity I₁₅₆₀/I₁₄₈₀. The TGA results show that the PPY–PVA polymer composite film was thermally more stable than the PPY film. A shielding effectiveness of 45.6 dB was exhibited by the PPY–PVA composite film in the microwave frequency range. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4107–4113, 2006     

Optimized reuse and bioconversion from retentate of pre‐filtered palm oil mill effluent (POME) into microbial protease by Aspergillus terreus using response surface methodology

BACKGROUND: The membrane filtration process enables the treatment of wastewater, producing permeate which is less polluted. However, disposal is usually required for the retentate, which is produced as a concentrated constituent along with the permeate. In this study, the authors explored the possibility of reusing, rather than disposing of, the retentate of pre‐filtered palm oil mill effluent (POME) as a fermentation substrate in protease production by a wild type strain of Aspergillus terreus IMI 282743. In addition, the quantitative and interactive effects of the concentration factor for retentate, temperature, inoculum concentration, and fermentation time on the optimization of protease production were investigated using response surface methodology (RSM). RESULTS: Using RSM, the optimum conditions were found to be a concentration factor of 7.27, temperature of 37.95 °C, inoculum concentration of 1.30% (v/v) and fermentation time of 3.83 days. The protease production was increased 4.37‐fold in comparison with the results obtained under non‐optimized conditions. CONCLUSION: To a certain extent, protease production could be enhanced with an increase in concentration factor and temperature, and a decrease of inoculum concentration and fermentation time. Also, POME retentate was found to be a good substrate for protease production with high product activity and without nutrient supplementation. Copyright © 2009 Society of Chemical Industry     

Palm‐based bio‐composites hybridized with kaolinite

This study described the mechanical and thermal properties of hybrid bio‐composites from oil palm empty fruit bunch (EFB) fibers and kaolinite. The polyurethane (PU) used as matrix is formed by reacting palm kernel oil (PKO)‐based polyester with crude isocyanate. The blending ratio of PU to EFB fibers was fixed at 35 : 65 and kaolinite was added at 0, 5, 10, 15, and 20% (by weight). The occurrence of chemical interactions between the hydroxyl terminals in both fillers and the PU system was determined via FTIR spectroscopy. Hybrid bio‐composites showed improved stiffness, strength, and better water resistance with the addition of kaolinite to an extent. At 15% of kaolinite loading, maximum flexural and impact strengths were observed. The interaction between kaolinite with PU matrix and EFB fibers enhanced the mechanical properties of the bio‐composites, which was justified from the FTIR spectrum. However, over‐packing of kaolinite was observed at 20% kaolinite loading, which ruptured the cellular walls and degraded strength of the bio‐composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

MHD convective flow adjacent to a vertical surface with prescribed wall heat flux

The steady magnetohydrodynamic (MHD) mixed convection flow adjacent to a vertical surface with prescribed heat flux is investigated. The governing partial differential equations are transformed into a system of ordinary differential equations, which is then solved numerically by a finite-difference method. The features of the flow and heat transfer characteristics for different values of the governing parameters are analyzed and discussed. Both assisting and opposing flows are considered. It is found that dual solutions exist for the assisting flow, besides that usually reported in the literature for the opposing flow.     

Highly reflective nc-Si:H/a-CNx:H multilayer films prepared by r.f. PECVD technique

Multilayer thin films consisting of a-CN_x:H/nc-Si:H layers prepared by radio-frequency plasma enhanced chemical vapour (r.f. PECVD) deposition technique were studied. High optical reflectivity at a specific wavelength is one of major concern for its application. By using this technique, a-CN_x:H/nc-Si:H multilayered thin films (3-11 periods) were deposited on substrates of p-type (111) crystal silicon and quartz. These films were characterized using ultra-violet-visible-near infrared (UV-Vis-NIR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field effect scanning electron microscopy (FESEM) and AUGER electron spectroscopy (AES). The multilayered films show high reflectivity and wide stop band width at a wavelength of approximately 650 ± 60 nm. The FTIR spectrum of this multilayered structure showed the formation of Si-H and Si-H₂ bonds in the nc-Si:H layer and CC and N-H bonds in a-CN_x:H layer. SEM image and AES reveal distinct formation of a-CN_x:H and nc-Si:H layers in the cross section image with a decrease in interlayer cross contamination with increasing number of periods.     

Effects of Dilute Acid Pretreatment on Chemical and Physical Properties of Kenaf Biomass

In the current research, kenaf represents an agricultural biomass that possesses enormous potential for industrial applications. Because of its complex structure, which is composed of cellulose, hemicellulose, and lignin, pretreatment process was conducted. Here, dilute acid pretreatment process was conducted, statistically using the response surface method, which included three parameters: mass of biomass (g), temperature (°C), and time (min). About 2 g of kenaf biomass was treated with 2% dilute sulphuric acid, and it was found to have higher glucose conversion (25.3%) when the process was conducted for 60 min at the temperature of 180°C. The main aim of the current research is to investigate the chemical and physical changes of kenaf biomass before and after the pretreatment. The changes could be clearly seen in the cellulose, hemicellulose, and lignin composition before and after the pretreatment, which were evaluated via TAPPI standard test methods. Morphological observation under scanning electron microscope confirmed the changes that took place on the kenaf biomass from complex to simple surface structure. Fourier transform infrared analysis confirmed the presence of cellulose, hemicellulose, and lignin contents of the kenaf biomass before and after pretreatment. Crystallinity of the treated kenaf biomass also increased from 46.6% to 70.0%, as evidenced from X-ray diffractometer analysis.     

Syngas Production via Bi-Reforming of Methane Over Fibrous KCC-1 Stabilized Ni Catalyst

Topics in Catalysis - Bi-reforming of methane (BRM) technology has the potential to serve as an alternative energy source while also mitigating greenhouse gas emissions. However, the main hurdle in...