Papers by Keyword: Benzene

Abstract: The article is devoted to mathematical modeling and fuzzy logic in controlling the process of adsorption purification of isobutane and isobutylene from impurities. The article also conducted research on the production of high-purity isobutane and isobutylene from the isobutane-isobutylene fraction of pyrolysis gas. A method has been developed for increasing the purity of isobutane and isobutylene fractions isolated from pyrolysis gas using sulfuric acid. It is proposed to introduce adsorption units into the plant technological scheme for separating the hydrocarbons isobutane and isobutylene from the C4 fraction of pyrogas, with the help of which it has been proven to obtain isobutane and isobutylene hydrocarbons of high purity up to 99.9%. The processes of selecting adsorbents for the additional purification of the isobutane fraction from isobutylene impurities were also studied and activated carbon of the AP-3 grade was selected, and for the additional purification of the isobutylene fraction from impurities of normal butylene’s, CaA zeolite was selected. The main reactions have been studied and a mathematical model of the processes for producing pure isobutylene and isobutane has been developed, taking into account recycling; also, artificial intelligence (AI) has been used when selecting adsorbents to optimize the processes of purifying the pyrolysis gas fraction of isobutane and isobutylene from impurities.

Abstract: The structure of graphene has been described in this research work by introducing some innovative elementary theoretical concepts such as: - interpretation of the free electron pair not as a concentration of the electron cloud on one side of the nucleus (lone pair), but as a symmetrical distribution of the electron cloud on both sides, - hypothesis that in polar bonds and the vast majority of multiple bonds, one electron is shared, not an electron pair and distinction of intermolecular bonds in bi-electronic and mono-electronic, - interpretation of the transformation of the geometry of molecules in relation to the number of bonds as a result of changes in the spatial relationships between atoms, and not as a result of the hybridization of orbitals and prediction and calculation of the spatial parameters of molecules (topology, bond lengths and angles) by applying trigonometric equations and other geometric rules, - consideration that the formation of multiple bonds occurs thanks to the transformation of bi electronic bonds (sigma) into mono-electronic bonds. This transformation serves to increase the quantity of electrons available to form pi bonds which intensifies the cohesion between the atoms. According to the proposed model, it is a dense cross-linking of π bonds inside each graphene ring that allows exceptional cohesion, strength and stability to a thin "spiderweb" formed by a single layer of atoms.

Abstract: This work has studied the performance of benzene treatment from cigarette smoke using the prepared CNT/TiO₂/PVA loaded on the paper filter in the air purifier reactor. CNT/TiO₂ nanomaterial was prepared from a mixture of carbon nanotubes modified with sulfuric acid and titanium dioxide by a simple mixing method in the ambient temperature. CNT/TiO₂ nanomaterial was then loaded on the paper filter by a filtrating technique using 12%w/v polyvinyl alcohol (PVA) as a co-polymer. The weight of CNT/TiO₂ loaded on the paper filter was fixed at 3 g. The ratios of CNT: TiO₂ was varied at 1:5, 1:10, and 1:15 w/w, respectively. The performance of air purifier using CNT/TiO₂/PVA loaded on the paper filter with various ratios was investigated on the photocatalytic activity of benzene treatment from cigarette smoke under visible light. The decreased benzene concentrations were analyzed by GC-FID. As the results, the ratio of CNT/TiO₂ loaded on the paper filter at 1:10 showed the highest performance by up to 45%, while the ratio of CNT/TiO₂ at 1:15 showed 30% and CNT/TiO₂ at 1:5 was the lowest of 22%, respectively. This is because adding the optimum CNT to TiO₂ can be improved the adsorption efficiency and the ability to degrade benzene from cigarette smoke. Additionally, CNT also assists in reducing the recombination of TiO₂ particles that effect to the high performance on the photocatalytic activity. Therefore, the prepared CNT/TiO₂/PVA loaded on the paper filter could be used for the air treatment.

Abstract: Mesoporous silica (MPS) is a porous silica material with various pore structures. In this study, mesocellular foam silica (MCF) was synthesized and functionalized by hexamethyldisilazane (HMDS) to study effects of surface chemistry on benzene adsorption capability. Physical and chemical properties of pristine and functionalized MCFs were characterized and compared. Scanning and transmission electron microscopy showed that the complex pore structures of the MCFs were retained after the functionalization at relatively high temperature (573K). TGA and FTIR results showed that the functionalization led to a reduction of water adsorbed on the surfaces of the MCF. The functionalization improved adsorption of benzene compared to the pristine MCF and the optimum HMDS:SiO₂ molar ratio was 1.5. The amount of benzene adsorbed has a linear relationship with the concentration of benzene in the environment. This relationship enables quantitative benzene detection by using the functionalized MCF as sensing materials in resistive-type or gravimetric-type benzene gas sensors.

Abstract: In order to explore an efficient and rapid method for treating typical volatile organic compounds (VOCs), benzene, as a HYPERLINK "javascript:void (0)" representative of VOCs, was catalytically oxidized by hopcalite under microwave irradiation. The decontamination performance under different conditions was studied, and the influences of some factors on the benzene conversion ratio were tested, such as microwave irradiation power, initial benzene concentration, catalyst amount and gas humidity. Results showed that benzene conversion ratio could reach 99.2% under the condition that microwave power, initial benzene concentration, gas flow and catalyst bed height were 70W, 1917mg/m³,1.0L/min, and 3.86cm separately. It is concluded that microwave irradiation can promote the catalytic oxidation of benzene and it has higher energy efficiency than traditional heating.

Abstract: Gas sensitive metal/metal-oxide field effect transistors based on silicon carbide were used to study the sensor response to benzene (C₆H₆) at the low parts per billion (ppb) concentration range. A combination of iridium and tungsten trioxide was used to develop the sensing layer. High sensitivity to 10 ppb C₆H₆ was demonstrated during several repeated measurements at a constant temperature from 180 to 300 °C. The sensor performance were studied also as a function of the electrical operating point of the device, i.e., linear, onset of saturation, and saturation mode. Measurements performed in saturation mode gave a sensor response up to 52 % higher than those performed in linear mode.

Abstract: Effect of acid and heat treatments of multi-walled carbon nanotubes (MWCNTs) on benzene detection was investigated. For acid treatment, MWCNTs were treated by hydrochloric acid (HCl) for 1 h meanwhile other batches of MWCNTs were treated by heating under air ambient at 500^°C for 1 h. Pristine, HCl-treated and heat-treated MWCNTs were separately coated with ethyl cellulose (EC) by spin-coating prior to fabrication of three different sensors named as EC/pristine MWCNTs, EC/HCl-MWCNTs and EC/heat-MWCNTs sensors, respectively. Each fabricated sensor was exposed to benzene vapor at room temperature for testing its sensing performance based on an increase in its electrical resistance which was sensitive to benzene vapor. Response of the sensors fabricated from EC/HCl-MWCNTs and EC/heat-MWCNTs were 3.66 and 1.92 times higher than that of EC/pristine MWCNTs, respectively. Sensitivity of all sensors would be attributed to swelling of EC, resulting in loosening of MWCNT network after benzene vapor exposure. In addition, the difference of sensing response of the EC/pristine MWCNTs when compared with those of EC/HCl-MWCNTs and EC/heat-MWCNTs would be ascribed to different crystallinity and functionalization of MWCNTs sidewalls, suggesting that acid and heat treatments of MWCNTs would be promising techniques for improvement of benzene detection.

Abstract: An aerobic benzene-degrading heterotrophic nitrifying strain Pseudomonas sp.BN5 was isolated from the well domesticated microbes. Growth and nitrification characteristics were investigated with the benzene as the sole carbon and energy source and the NH+4-N as nitrogen source under aerobic condition. It was demonstrated that the favorite C/N ratio, temperature and speed of Pseudomonas sp.BN5 was 10, 30°C and 180rpm, respectively. About 70.86% of ammonium and 100% of benzene was removed after 72 h of incubation at initial benzene and ammonium concentration of 52.37mg/L and 16.13mg/L, respectively. Only trace accumulation of nitrate was observed during the process.

Abstract: The new method for synthesis of Benzene-d₆ was discovered. In this process, [Cp*PMe₃IrH₃][OTf] was used as the catalyst at H/D exchange reaction between benzene and deuterium oxide. The prepared method was in an overall yield of 20% and chemical purity of 99.7%. The product contained stable isotopes at 98% enrichment. The MS spectra, ¹³C NMR, IR between benzene and benzene-d₆ were discussed.

Abstract: The world is currently facing the problem brought by plastic waste, as well as energy crisis. It is known that catalytic cracking of low density polyethylene (LDPE) waste can produce liquid fuels with similar properties to fossil fuels, hence serve as a solution to the problems mentioned. However, the problem of pipelines clogging by molten plastic feed during the cracking process has to be solved before the process can be up-scaled to continuous process. It was proposed that LDPE waste can be dissolved in suitable solvent before being catalytically cracked under suitable conditions. This study was done to investigate the behavior of virgin LDPE (in powder form) dissolved in several chosen solvents, namely benzene, toluene, chlorobenzene, isooctane, xylene and trichloroethylene, and compare the result with previous work. From the study, it was observed that LDPE samples could dissolve in benzene and toluene to a high extent. On the other hand, isooctane acted as a weak solvent towards LDPE powder. The difference of LDPE solubility in solvents was attributed to the surface area per unit mass of LDPE samples. Despite the superior property of benzene as solvent for LDPE, the safety factor study showed that toluene, xylene and trichloroethylene were more suitable to be used in LDPE dissolution. However, care should be taken to minimize possible effects of the solvents towards the body while using the solvents mentioned.