A.B. Dayang Radiah

Effect of physical pretreatment on dilute acid hydrolysis of water hyacinth (Eichhornia crassipes)

Effects of different physical pretreatments on water hyacinth for dilute acid hydrolysis process (121 ± 3 °C, 5% H(2)SO(4), 60 min) were comparatively investigated. Untreated sample had produced 24.69 mg sugar/g dry matter. Steaming (121 ± 3 °C) and boiling (100 ± 3 °C) for 30 min had provided 35.9% and 52.4% higher sugar yield than untreated sample, respectively. The highest sugar yield (132.96 mg sugar/g dry matter) in ultrasonication was obtained at 20 min irradiation using 100% power. The highest sugar production (155.13 mg sugar/g dry matter) was obtained from pulverized samples. Hydrolysis time was reduced when using samples pretreated by drying, mechanical comminution and ultrasonication. In most methods, prolonging the pretreatment period was ineffective and led to sugar degradations. Morphology inspection and thermal analysis had provided evidences of structure disruption that led to higher sugar recovery in hydrolysis process.

Biological treatment of produced water in a sequencing batch reactor by a consortium of isolated halophilic microorganisms

Produced water or oilfield wastewater is the largest volume of a waste stream associated with oil and gas production. The aim of this study was to investigate the biological pretreatment of synthetic and real produced water in a sequencing batch reactor (SBR) to remove hydrocarbon compounds. The SBR was inoculated with isolated tropical halophilic microorganisms capable of degrading crude oil. A total sequence of 24 h (60 min filling phase; 21 h aeration; 60 min settling and 60 min decant phase) was employed and studied. Synthetic produced water was treated with various organic loading rates (OLR) (0.9 kg COD m−3 d−1, 1.8 kg COD m−3 d−1 and 3.6 kg COD m−3 d−1) and different total dissolved solids (TDS) concentration (35,000 mg L−1, 100,000 mg L−1, 150,000 mg L−1, 200,000 mg L−1 and 250,000 mg L−1). It was found that with an OLR of 0.9 kg COD m−3 d−1 and 1.8 kg COD m−3 d−1, average oil and grease (O&G) concentrations in the effluent were 7 mg L−1 and 12 mg L−1, respectively. At TDS concentration of 35,000 mg L−1 and at an OLR of 1.8 kg COD m−3d−1, COD and O&G removal efficiencies were more than 90%. However, with increase in salt content to 250,000 mg L−1, COD and O&G removal efficiencies decreased to 74% and 63%, respectively. The results of biological treatment of real produced water showed that the removal rates of the main pollutants of wastewater, such as COD, TOC and O&G, were above 81%, 83 %, and 85%, respectively.

An innovative procedure for large-scale synthesis of carbon nanotubes by fluidized bed catalytic vapor deposition technique

After the efforts of the first decade, scientists and technicians are facing the big challenge of going from laboratory studies to the large scale production of carbon nanotubes (CNTs) and their ultimate commercial applications. Therefore, innovations in the CNT manufacturing process and its engineering are strongly required. To this contribution, a new technique for the mass production of CNTs by fluidized bed catalytic chemical vapor deposition (FBCVD) has been developed. The CNTs synthesis reactions were carried out in the presence of iron‐cobalt supported on alumina as a catalyst and ethanol as the source of carbon at 600°C. The product was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and X‐ray diffractometry (XRD). The results revealed that this technique offers the fabrication of large quantities of CNTs which has the important quality of being free from large amorphous carbon, open‐ended with narrow diameter distribution, and having good morphology with few defects. The proposed design has other remarkable advantages, such as simplicity, low cost, energy savings, completely controllable and easy to scale‐up, which make it suitable for industrial scale production.

Fluidized Bed Chemical Vapor Deposition Synthesis of Carbon Nanotubes Using Different Fe–Co/Alumina Catalytic Powders

Catalytic particles, Iron-Cobalt supported on Alumina, with different metal compositions were investigated in fluidized bed chemical vapor deposition of Ethanol at 600°C to produce carbon nanotubes (CNTs). The characteristics of catalytic particles as well as product were studied using different analytical techniques. Results indicated that the dispersion of metallic nanoparticles was higher when small amounts of two kinds of metal were used. However, lowering of metal content was not always favored with respect to process efficiency. This study proved atomic ratio of the active metals in bimetallic catalyst is not an accurate specification, and mass ratio of the metals should be considered. Also, it was demonstrated that the characteristics of catalytic particles, such as pore structure and their size as well as distribution of the metallic nanoparticles, need to be suitably modified to get the desired quality and quantity of CNTs.

Low-Temperature Synthesis of Carbon Nanotubes via Floating Catalyst Chemical Vapor Deposition Method

Carbon nanotubes (CNTs) are widely synthesized at high temperatures via floating catalyst chemical vapor deposition (FC-CVD) method. It is important to reduce the synthesis temperature of CNTs to allow better control of the reactors conditions and to eliminate the formation of carbon by-products. The main objective of this work was to synthesize carbon nanotubes at low temperatures. Temperature in-situ monitoring unit was used to monitor the temperature profile in the reactor. Benzene and ferrocene were used as the carbon source and catalyst precursor, respectively. The minimum pyrolysis temperature of benzene was successfully estimated, and the investigation of temperature profile in the reactor was achieved. In this work, multi-walled CNTs were successfully synthesized for synthesis temperatures between 540°C and 600°C. Based on the analyses, the qualities of CNTs produced were profoundly improved with the increase of synthesis temperatures.