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aquatic-media
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The Study of Currents Caused by the Sunlight in Coastal Areas with Submerged and Emergent Vegetation
, M.Sc. Thesis Sharif University of Technology ; Jamali, Mirmosadegh (Supervisor)
Abstract
Aqueous environment with vegetation in coastal areas plays important role in ecologic systems. The plants in aqueous environment caused to vertical and lateral changes of flow velocity profile. When sunlight penetrates the water, it will turns into heat energy. The plants caused to blocking the light path, to make a difference in temperature and thus the density differences on the horizon. This density gradient will lead to the gravity flow. Due to the observations, in coastal wetlands, beside the plants the emerged from the water, there are some completely submerged plants that their root in the soil and shallow layer of fluid covered on them. This study to approaching the conditions, is...
A Superhydrophobic Melamine Formaldehyde Sorbent for Micro Extraction of Pollutants from Aquatic Media
,
M.Sc. Thesis
Sharif University of Technology
;
Bagheri, Habib
(Supervisor)
Abstract
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...
Effect of Harsh Environments on the Mechanical Properties and Durability of Fly Ash-Based Geopolymer Concretes
, M.Sc. Thesis Sharif University of Technology ; Ghaemian, Mohsen (Supervisor) ; Toufigh, Vahab (Supervisor)
Abstract
In the present study, the performance of fly ash-based geopolymer concrete blended with cement as an additional calcium source under exposure to marine, acidic and alkaline environments was evaluated. Three mixtures of fly ash-based geopolymer concrete with different cement ratios (0, 10 & 20%) were prepared and immersed in tap water, seawater, sulfuric acid, and sodium hydroxide solutions for up to one year. Change in the appearance, weight, compressive strength, splitting tensile strength, energy absorption and microstructure of the specimens were evaluated at 1, 3, 6, 9 and 12 months of exposure. Ultrasonic pulse velocity test was also used to determine its relationship with the...
Synthesis and Characterization of Chitosan-Modified Metal-Organic Framework to Remove Contaminants from Aquatic Environment
, M.Sc. Thesis Sharif University of Technology ; Hamzehluyan, Tayebeh (Supervisor) ; Shojaei Segherloo, Akbar (Supervisor) ; Molavi, Hossein (Co-Supervisor)
Abstract
In the present work, a series of nanohybrids based on ZIF-8 as a physicochemical stable metal-organic framework (MOF) and different amounts of Chitosan (CS) (0.5–15 wt%) were synthesized and used as adsorbents for anionic (Congo Red, CR) and cationic (malachite green, MG) dyes from contaminated water in single and binary dye solutions. The single adsorbents and their nanohybrids were characterized by FESEM, FTIR, XRD, TGA, BET, and zeta potential measurements. The experimental adsorption results displayed that the synthesized nanohybrids presented higher adsorption capacity for anionic dyes compared to cationic dyes in both single and binary dye solutions. It was deduced that the...
Headspace solvent microextraction as a simple and highly sensitive sample pretreatment technique for ultra trace determination of geosmin in aquatic media
, Article Journal of Separation Science ; Volume 29, Issue 1 , 2006 , Pages 57-65 ; 16159306 (ISSN) ; Salemi, A ; Sharif University of Technology
2006
Abstract
A headspace solvent microextraction method was developed for the trace determination of geosmin, an odorant compound, in water samples. After performing the extraction by a microdrop of an organic solvent, the microdrop was introduced directly into a GC-MS injection port. One-at-the-time optimization strategy was applied to investigate and optimize some important extraction parameters such as type of solvent, drop volume, temperature, stirring rate, ionic strength, sample volume, and extraction time. The analytical data exhibited an RSD of less than 5% (n = 5), a linear calibration range of 5-900 ng/L (r2 > 0.998), and a detection limit of 0.8 and 3.3 ng/L using two different sets of...
Polyaniline-nylon-6 electrospun nanofibers for headspace adsorptive microextraction
, Article Analytica Chimica Acta ; Volume 713 , 2012 , Pages 63-69 ; 00032670 (ISSN) ; Aghakhani, A ; Sharif University of Technology
2012
Abstract
A headspace adsorptive microextraction technique was developed using a novel polyaniline-nylon-6 (PANI-N6) nanofiber sheet, fabricated by electrospinning. The homogeneity and the porosity of the prepared PANI-N6 sheet were studied using the scanning electron microscopy (SEM) and nanofibers diameters were found to be around 200nm. The novel nanofiber sheet was examined as an extracting medium to isolate some selected chlorobenzenes (CBs), as model compounds, from aquatic media. The extracted analytes were desorbed using μL-amounts of solvent and eventually an aliquot of extractant was injected into gas chromatography-mass spectrometry (GC-MS). Various parameters affecting the extraction and...
Membrane protected conductive polymer as micro-SPE device for the determination of triazine herbicides in aquatic media
, Article Journal of Separation Science ; Volume 33, Issue 8 , 2010 , Pages 1132-1138 ; 16159306 (ISSN) ; Khalilian, F ; Naderi, M ; Babanezhad, E ; Sharif University of Technology
Abstract
A micro-SPE technique was developed by fabricating a rather small package including a polypropylene membrane shield containing the appropriate sorbent. The package was used for the extraction of some triazine herbicides from aqueous samples. Solvent desorption was subsequently performed in a microvial and an aliquot of extractant was injected into GC-MS. Various sorbents including aniline-ortho-phenylene diamine copolymer, newly synthesized, polypyrrole, multiwall carbon nanotube, C18 and charcoal were examined as extracting media. Among them, conductive polymers exhibited better performance. Influential parameters including extraction and desorption time, desorption solvent and the ionic...
Novel unbreakable solid-phase microextraction fiber by electrodeposition of silica sol-gel on gold
, Article Journal of Separation Science ; Volume 34, Issue 22 , 2011 , Pages 3246-3252 ; 16159306 (ISSN) ; Sistani, H ; Ayazi, Z ; Sharif University of Technology
Abstract
A new technique for preparation of an unbreakable solid-phase microextraction (SPME) fiber, using sol-gel technology is developed. Primarily, an ultrathin two-dimensional intermediate film was prepared by hydrolysis of 3-(trimethoxysilyl)-1-propanthiol self-assembled monolayer grafted onto gold, then a stationary phase by electrodeposition of 3-(trimethoxysilyl) propylmethacrylate as a precursor, tetramethyl orthosilicate and polyethylene glycol as a coating polymer was produced. The scanning electron microscopy images revealed that the new fiber exhibits a rather porous and homogenous surface. The thermal stability of the fabricated fiber was investigated by thermogravimetric analysis. The...
A novel needle trap sorbent based on carbon nanotube-sol-gel for microextraction of polycyclic aromatic hydrocarbons from aquatic media
, Article Analytica Chimica Acta ; Volume 683, Issue 2 , January , 2011 , Pages 212-220 ; 00032670 (ISSN) ; Ayazi, Z ; Aghakhani, A ; Sharif University of Technology
2011
Abstract
A new type of composite material based on carbon nanotubes (CNTs) and sol-gel chemistry was prepared and used as sorbent for needle trap device (NTD). The synthesized composite was prepared in a way to disperse CNTs molecules in a sol-gel polymeric network. CNT/silica composites with different CNT doping levels were successfully prepared, and the extraction capability of each composite was evaluated. Effects of surfactant and the oxidation duration of CNTs on the extraction efficiency of synthesized composites were also investigated. The applicability of the synthesized sorbent was examined by developing a method based on needle trap extraction (NTE) and gas chromatography mass spectrometry...
Optimization of some experimental parameters in the electro membrane extraction of chlorophenols from seawater
, Article Journal of Chromatography A ; Volume 1216, Issue 45 , 2009 , Pages 7687-7693 ; 00219673 (ISSN) ; Khalilian, F ; Bagheri, H ; Lee, H. K ; Sharif University of Technology
2009
Abstract
An electro membrane extraction (EME) methodology was utilized to study the isolation of some environmentally important pollutants, such as chlorophenols, from aquatic media based upon the electrokinetic migration process. The analytes were transported by application of an electrical potential difference over a supported liquid membrane (SLM). A driving force of 10 V was applied to extract the analytes through 1-octanol, used as the SLM, into a strongly alkaline solution. The alkaline acceptor solution was subsequently analyzed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. The parameters influencing electromigration, including volumes and pH of the donor and...