Papers by Keyword: Purification

Abstract: The synthesis of CaO/zeolite nanocomposite as a highly active and effective adsorbent for patchouli oil purification has been developed. This research aims to improve the quality of patchouli oil by synthesizing CaO/zeolite nanocomposites using a solid-state mixing method. The used mass ratios of zeolite:CaO were 0:100, 20:80, 40:60, 60:40, 80:20 and 100:0 (w/w), then nanocomposites with various zeolite-to-CaO ratios were then calcined at various temperature of 300°C, 400°C and 500°C. The zeolite, CaO and nanocomposites were characterized by using the Fourier-transform infrared (FTIR), X-ray fluorescence spectrometer (XRF) and surface area analyzer (SAA). The nanocomposites were then applied to patchouli oil and the assessment results of physical and chemical properties of patchouli oil were determined according to Indonesian National Standard (SNI) 06-2385-2006. After patchouli oil purification using ZECA nanocomposite, the acid number decreased from 5.42 to 0.39 mg KOH/g oil, the patchouli alcohol (PA) content increased from 33.08 to 34.27% and the Fe level decreased from 1.39 to 0.31 ppm.

Abstract: The research of the influence of technological modes has been carried out and the negative influence of contaminating impurities on the lead iodide crystallization process has been grounded. The new technological approach to PbI₂ single crystals growth has been proposed, which, unlike traditional methods, is based on increasing of the purity of the source components at the initial stage of technological process. The comparative analysis of the proposed growth technique with other known methods has been made, the efficiency of the purification operation of the Pb and I₂ source components for the obtention and properties of PbI₂ single crystals has been determined. The main types of defects during PbI₂ crystallization from the melt have been analyzed and technological approaches for elimination of the structural violations have been proposed.

Abstract: This study investigated the purification and refining method for producing a nanometer size zinc oxide (ZnO) from the low-grade ZnO commercial powder using low cost ammonium carbonate solution as a leaching agent. The atomic absorption spectroscopy results show that the concentration of iron, lead and cadmium can be dramatically reduced by ammonium carbonate leaching and washing. X-ray diffraction (XRD) and scanning electron microscope (SEM) results show that structural properties can improve the degree of the preferential c-axis orientation, grain size, and surface morphology of ZnO by solvent evaporation. All physical and chemical results are of particular significance for the preparation of purified ZnO for device fabrication in photovoltaic industry, functional ZnO coatings, and polymer nanocomposite applications.

Abstract: An efficient, economic and easy method for removing 99% of catalyst particle from high pressure carbon monoxide (HiPCO) single walled carbon nanotubes (SWCNT) is reported. The experiment is carried out at low temperature followed by acid treatment. The process exploited here is oxidation of the carbon impurities to gaseous phase as CO₂ and removal of oxidized catalyst debris using acid treatment. Stability of SWCNT at these temperatures does not allow any damage to the nanotubes, however, some damage is observed which can be attributed to the oxidation of catalyst particles and their removal. The purified sample showed very less/no amount of amorphous carbon and catalyst impurities. Characterization of the material was carried out using Raman spectroscopy, Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM), Transmission electron microscope (TEM) and Energy Dispersive Spectroscopy (EDAX). The resultant SWCNT were found to be highly pure. EDAX spectroscopy showed that the purified sample had only 0.5wt% of catalyst impurities whereas the as prepared once have 9.09wt%, also, TGA curve of the treated sample showed a very significant increase in the oxidation temperature indicating less defect and less catalyst content in the sample. The non- carbonaceous residue after purification is about 0.3%. highly efficient purification of SWCNT using the proposed method. This work provides a basis on removing the catalyst particles completely.

Abstract: A novel method to remove impurity silicon from aluminum melt by the addition of K₂TiF₆ was studied. The mechanism for silicon removal is the formation and sedimentation of Ti(Al_1-x,Si_x)₃ phase and the removal efficiency is mostly decided by the solubility of silicon in TiAl₃ phase, which increases with the increasing of the initial silicon concentration in aluminum melt. The effect of holding temperature on the impurity Si purification efficiency was investigated and the result indicated that the effect of holding temperature is very finite.

Abstract: In order to make the natural quartz up to the standard of high purity quartz sands, quartz ores are processed to obtain high purity quartz sands by the purifying technologies which include grinding, high-intensity magnetic concentration, flotation and acid leaching, washed by deionized water. The phase, morphology and composition of the prepared quzrtz sands were determined by X-ray diffraction, scanning electron microscope and inductively coupled plasma spectrometers.The results show that impurity minerals adsorb onto the quartz mineral surfaces. Magnetic minerals were removed by magnetic concentration experiment, while other impurities were removed by flotation and acid leaching experiments and they show excellent cleaning effect. Finally a high purity quartz product which contains higher than 99.95% SiO₂, less than 0.003% Fe₂O₃, and less than 0.01% Al₂O₃ was obtained.

Abstract: The addition of base NaOH and KOH solutions and the application of an air stone and a stirrer to develop turbulence in water scrubbing method were carried out to study the purification process of raw biogas. Various concentrations of the base solutions and constant stirrer speed was applied. The work results showed that the best performance in increasing CH₄ content, about 70% improvement, was reached with the addition of NaOH on 2% concentration. On the other hand, about 96% and 100% improvement for CO₂ and H₂S respectively were obtained under 2% NaOH addition coupled with a stirrer. The addition of base solutions was very effective to increase absorbent pH level, thus maintaining absorption process in longer duration and prevented saturation of absorbent. Moreover, the application of a stirrer in packed bed column further improved the biogas quality. The improvement was resulted from the generated biogas bubble and turbulence which led to prolong contact time between absorbent and biogas.

Abstract: The direct removal of metal impurity from Si wafer by continuous-wave (CW) laser irradiation has been studied. The wafer was irradiated by linear (Nd:YAG) CW laser with a wavelength of 1064nm. The irradiated region of the wafer experienced melting and subsequent recrystallization process during the laser heating and cooling processes. This leads to the redistribution of the metal impurity along the depth direction. The depth profile of metal atoms in Si was measured by secondary ion mass spectrometry (SIMS). The concentration of the metal ions in the CW laser irradiated sample was dramatically decreased at the measurement range of SIMS. Thermal fields of Si wafer irradiated by CW-laser were numerically simulated to explain the SIMS results. A finite element method with a two-dimensional model was selected in the simulation process. The depth of the maximum temperature for the laser irradiated wafer in the irradiation process was related to many parameters, such as, the energy density of the laser and the velocity of the sample moving. The simulation results agree well with our experiment results.

Abstract: Water pollution comprises all of those compounds that change the quality of groundwater and surface water, therefore reducing the suitability of natural water for human use and other vital processes. These compounds result from human activities, especially those that are industrial, agricultural and domestic.The polyamide thin film composite reverse osmosis membranes become important in desalination of sea water and brackish water or waste water. However the polyamide reverse osmosis membranes tend to fouling due to their hydrophobic and rough surfaces. In this study flux and rejection of waste water from aluminum production industry were obtained during filtration process by using modified commercial composite membranes. Amount of fouling was evaluated with unmodified and modified membranes. Rejection of iron particles and PH of feed and permeate solutions were determined after filtration process. Results shows that modified membranes were performed higher metal ion rejection and antifouling performance than unmodified membranes.

Abstract: The biopolymer material, lignin, was recovered from the black liquor by acidification of the black liquor using sulfuric acid. Several purification techniques were carried out to produce the high purity of lignin such as gradual precipitation of lignin from black liquor (first stage: precipitation at pH 7, second stage: precipitation at pH 2) and the diluting of crude lignin by sodium hydroxide then followed by re-precipitation at different temperature. Subsequently, the impurities of lignin product resulted from each purification techniques was determined as ash content that analyzed using temperature program furnace; and the content of lignin was investigated using spectrophotometer UV-Vis. The result showed that the content of lignin of material produced from gradual precipitation was approximately 77.6%. It was higher than the content of lignin about 3.4% of material produced from direct precipitation to pH 2. In addition, the elevating of temperature from 40 to 60°C was no considerably affect to the content of lignin in precipitate produced from re-precipitation of crude lignin solution in sodium hydroxide. Nonetheless, the content of lignin of precipitate improved 15% when the temperature of re-precipitation of crude lignin solution in sodium hydroxide was raised from room temperature to 40-60°C.