Sharif Digital Repository

Conventional solid phase microextraction fibers posses relatively low recommended operating temperature, instability and swelling in organic solvents, breakage of the fiber, stripping of coatings, and bending of the needle. Some of these problems have been obviated by covalent bonding of the polymer phase to the fused-silica substrate by sol-gel technology, but the easy breakage of the fiber still is a remaining challenge In this work, after successful fabrication of unbreakable SPME fibers based on 3-(trimethoxysilyl)propyl methacrylate precursor deposited on the surface of copper wire, the same approach was carried out to synthesis new sol-gel based SPME fibers. Three different coated... 

Within the past few years, soil and groundwater resources contamination by petroleum-based products has become of great concern in the environmental engineering literature as a serious environmental problem throughout the world. Amongst petroleum hydrocarbons, groundwater contamination by Non-Aqueous Phase Liquids (NAPLs) is one of the most important environmental problems. In order to effectively remediate contaminated sites, knowledge of the distribution of the NAPLs is essential. The success of the remedial design will be dependent on the ability to predict the subsurface distribution of the NAPLs. Release of these compounds from spills and leaky underground storage tanks into subsurface... 

Natural gas contains small amount of benzene, toluene, ethyl benzene and meta-xylene (BTEX). These compounds are soluble in amine solutions and accumulate in aqueous amine solution during sour gas removal process. They produce problems such as foaming in amine adsorption columns. The aim of this work is to study BTEX removal from aqueous amine solution by means of activated carbon. Three different commercially available granular activated carbons were used in experiments. Experiments were divided in static and dynamic adsorption categories. In the static tests, equilibrium adsorption of all three activated carbons were performed and the most effective activated carbon sample determined by... 

In this study, a new resorcinol-formaldehyde xerogel was synthesized based on sol-gel technology and employed as a sorbent for micro solid phase extraction (µ-SPE) of BTEX and some selected pesticides from aqueous samples.
In the first part, a µ-SPE method in combined with headspace solvent microextraction (HS-SME) along with gas chromatography- mass spectrometry detection (GC–MS) was developed for the analysis of BTEX in aqueous samples. In our knowledge, this is for the first time that these two different extraction methods has been coupled to maximize the advantage of each extraction method. Influential parameters such as the peristaltic pump flow rate, extraction volume, extraction... 

In this project, melamine formaldehyde was chosen as initial substrate for its high porosity. Then for having superhydrophobic surface, surface functional groups were silanized and deactivated as a result. It was assumed that high porosity of prepared sorbent and its nonpolar nature, can increase extraction efficiency. To study extraction efficiency of the prepared sorbent, it was filled inside a needle and used for needle-trap head-space extraction of BTEX (abbreviation for Benzene, Toluene, Ethylbenzene and Xylenes). Needle packed with sorbent was held on headspace of sample containing BTEX and head- space was pumped with a peristaltic pump. Pumping introduces fresh sample to sorbent... 

This study aims to estimate the emission rate of Volatile Organic Components (VOCs) and hazardous air pollutants from the surface of evaporation ponds in oil and gas upstream industries. With respect to the irrecoverable consequences of such emissions, the emission of air pollutants in the oil and gas upstream industries are alarming. Hence, estimation of the pollutants’ emission and surface pollution monitoring are needed for controlling and decreasing of air pollutants in oil and gas upstream industries and also presenting and performing suitable and efficient solutions. The studied ponds in this research include 4 ponds in the oil and gas upstream industries which have been used for... 

In this study, gelatin/polyvinylpyrrolidone semi interpenetrating polymer network scaffold was synthesized in presence of glutaraldehyde as a cross linker and a porous structure was obtained by freeze drying method. The biocompatible network with properties like huge porosity, good thermal stability and establishing different interactions, was employed as an extractive phase in needle trap device and used for evaluation of benzene, toluene, ethylbenzene and xylene (BTEX) in conjugation with gas chromatography-flame ionization detector. For investigating semi interpenetrating polymer network efficiency, Different ratios of gelatin and polyvinylpyrrolidone (gelatin/polyvinylpyrrolidone: 1:0,... 

The aim of this thesis was to find the optimum retention time for treatment of synthetic petroleum wastewater by a wastewater treatment system made with a bucket, mineral material and earthworms residing in a vermibed. In order to make the desired flow happen, height difference was utilized. The polluting substance used for making wastewater was BTEX. As the wastewater was synthetic, the concentration was also a variable. The ultimate soluble concentration was 3200 mg/l and more concentrations were not tested. Parameters such as number of worms, worm’s growth rate and their distribution pattern, humidity amount and distribution and worm’s acclimatization time during organic loading shock...