Search results for "Aqueous solution"
showing 10 items of 1610 documents
Novel modified poly vinyl chloride blend membranes for removal of heavy metals from mixed ion feed sample
2017
Herein, an attempt has been made to prepare a novel membrane with good efficiency for removal of heavy metal ions namely lead (Pb), cadmium (Cd) and chromium (Cr). 4-amino benzoic acid (ABA) was covalently grafted onto the poly vinyl chloride (PVC) backbone by CN bond to enhance the hydrophilicity. 1H NMR and ATR-IR spectroscopy analysis confirmed the chemical modification of PVC. Further the modified polymer was blended in different compositions with polysulfone (PSf) for optimization. Morphological changes that occurred in blend membranes, due to the incorporation of modified PVC was studied by AFM and SEM techniques. The effect on hydrophilicity and performance of blends owing to incorpo…
A model for the formation and degradation of bound residues of the herbicide 14C-isoproturon in soil
1999
Abstract The humic monomer catechol was reacted with 14 C-isoproturon and some of its metabolites, including 14 C-4-isopropylaniline, in aqueous solution under a stream of oxygen. Only in the case of 14 C-4-isopropylaniline, incorporation in oligomers, in fulvic acid-like polymers, and in humic acid-like polymers was observed. The main oligomer was identified by mass spectrometry as 4,5-bis-(4-isopropylphenylamino)-3,5-cyclohexadiene-1,2-dione. Oligomers and polymers containing bound 14 C-4-isopropylaniline were subjected to biodegradation studies in a loamy agricultural soil during 55 days by quantifying 14 CO 2 evolved. In all cases, significant mineralization rates could be determined, w…
Electrochemical treatment of aqueous solutions of organic pollutants by electro-Fenton with natural heterogeneous catalysts under pressure using Ti/I…
2018
The treatment of toxic organic pollutants by electro-Fenton (EF) presents some drawbacks such as the necessity to work at low pH and the low solubility of oxygen in water contacted with air or oxygen at room pressure that results often in slow and relatively low abatements. Here, the coupled adoption of natural heterogeneous catalysts and of relatively high pressure was proposed in order to improve the performances of EF for the treatment of organic pollutants. Caffeic acid (CA) and 3-chlorophenol were used as model resistant organic pollutants. EF process was performed using both conventional homogeneous FeSO4 and natural heterogeneous catalysts (pyrite, chalcopyrite, Fe2O3 and Fe3O4) as i…
Theoretical and practical aspects of chemical functionalization of carbon nanofibers (CNFs): DFT calculations and adsorption study
2011
The nitric acid-functionalized commercial carbon nanofibers (CNFs) were comprehensively studied by instrumental (XRD, BET, SEM, TGA) and theoretical (DFT calculations) methods. The detailed surface study revealed the variation in the characteristics of functionalized CNFs, such as a decreased (up to 34%) surface area and impacted structural, electronic and chemical properties. The effects of functional groups were studied by comparison with pristine nanofibers. The results showed that the C-C bond lengths of the modified CNFs varied significantly. Chemical functionalization altered the frontier orbitals of the pristine material, and therefore altered the nature of their interactions with ot…
Metal ion adsorption by phomopsis sp. Biomaterial in laboratory experiments and real Wastewater Treatments
2005
An insoluble material of polysaccharidic nature has been obtained by thermal alkali treatment of the filamentous fungus Phomopsis sp. FT-IR spectrum of the resulting material as well as its nitrogen content suggest that chitosan and glucans are the main components of the biomaterial. Information on Lewis base sites has also been obtained and used as a guideline in the evaluation of the complexing ability against a number of metal ions in aqueous media at pH in the range 4--6. Results indicate that after 24h contact time, up to 870 micromol/g of lead, 390 micromol/g of copper, 230 micromol/g of cadmium, 150 micromol/g of zinc and 110 micromol/g of nickel ions are adsorbed into the material. …
Azo-Dyes Photocatalytic Degradation in Aqueous Suspension of TiO2 Under Solar Irradiation
2002
Abstract The photodegradation of two common and very stable azo-dyes, i.e. methyl-orange (C14H14N3SO3Na) and orange II (C16H11N2SO4Na), is reported. The photocatalytic oxidation was carried out in aqueous suspensions of polycrystalline TiO2 irradiated by sunlight. Compound parabolic collectors, installed at the “Plataforma Solar de Almeria” (PSA, Spain) were used as the photoreactors and two identical reacting systems allowed to perform photoreactivity runs for the two dyes at the same time and under the same irradiation conditions. The disappearance of colour and substrates together with the abatement of total organic carbon content was monitored. The main sulfonate-containing intermediate…
Continuous monitoring of photocatalytic treatment by flow injection. Degradation of dicamba in aqueous TiO2 dispersions
2001
The possible use of flow injection (FI) to monitor the photocatalytic mineralization of dicamba (3,6-dichloro-2-methoxybenzoic acid) present at the trace level in aqueous solutions containing TiO2 suspensions has been evaluated. Experiments were performed in a stirred photochemical reactor equipped with a simple FI manifold, integrating an online filtration unit able to perform the monitoring of the UV absorbance of the irradiated solution every 4 min. The light source used was a medium pressure mercury lamp (125 W). During the initial steps of the reaction the formation of UV absorbing intermediates, which completely disappear in less than 80 min, was evidenced. Additional HPLC, DOC and ch…
Optical properties and quantum yield determination in photocatalytic suspensions
2006
Knowledge of the optical properties of photocatalytic suspensions is vital for a correct comparison of their energetic efficiency. In this work, the determination of both absorption and scattering coefficients of aqueous suspensions of commercial TiO2 powders irradiated by monochromatic light was carried out by measuring only one quantity—the transmitted photon flow—as a function of the catalyst mass and by applying an asymptotic form of the Kubelka–Munk solution of the radiative transfer equation. Applying a nonlinear fitting procedure the evaluation of the actual values of absorption and scattering coefficients was carried out. The limit for optically thick media of the Kubelka–Munk equat…
The preparation and evaluation of core-shell magnetic dummy-template molecularly imprinted polymers for preliminary recognition of the low-mass polyb…
2020
Abstract The design, preparation process, binding abilities, morphological characteristic and prospective field of application of dummy-template magnetic molecularly imprinted polymer (DMMIP) for preliminary recognition of the selected low-mass polybrominated diphenyl ethers (PBDE-47 and PBDE-99) from aquatic environment were investigated. The surface of iron oxide (Fe3O4) nanopowder (50–100 nm particles size) was modified with tetraethoxysilane and next prepared Fe3O4@SiO2 particles were dispersed in anhydrous toluene functionalized by (3-aminopropyl)triethoxysilane. Finally, MIPs' thin film layer on the surface of Fe3O4@SiO2@NH2 was formed in acetonitrile as a solvent solution, using ethy…
Comparative electrochemical treatments of two chlorinated aliphatic hydrocarbons. Time course of the main reaction by-products.
2011
The chlorinated aliphatic hydrocarbons conjugate toxicity with high chemical stability, bioaccumulation and long-range diffusivity. Chloroethanes are particularly ubiquitous in the industry and in household products, and their entry to the environment may entail potential risks for the living beings. At present, the US Environmental Protection Agency is carrying out the Endocrine Disruptor Screening Program (EDSP), where 1,2-dichloroethane (DCA) and 1,1,2,2-tetrachloroethane (TCA) are considered as priorities for their potential effects on the endocrine system. DCA is also found in the list of priority substances drawn up by the European Commission. To avoid the release of chloroethanes int…