Equilibrium, Kinetic and Thermodynamic studies of adsorption of cationic dyes from aqueous solution using ZIF-8

Zeolitic imidazolate framework-8 (ZIF-8) is one type of (MOFs) that has been synthesized and characterized and detailed analysis of Crystal violet (CV) and Malachite Green (MG) adsorption behaviour. Impact of different variables on batch method as a function of solution pH, concentration of CV and MG, dose of ZIF-8, Contact time and temperature were analyzed and optimal test conditions were determined. Scanning electron microscopy (SEM) was used to measure surface alterations of the ZIF-8. The surface area and volume of the pores were found to be 495.199 m2g–1 and 0.026 cm3g−1, respectively as determined by the Brunauer-Emmett-Teller (BET) test. ZIF-8 point of zero charging (pHPZC) was calculated and was found 7.9. Adsorption data were modeled on isotherms for adsorption of Langmuir, Freundlich, Dubinin–Radushkevich and Temkin. Equilibrium data from the adsorption processes showed that the Langmuir is fitted with CV and MG adsorption. Pseudo-first order, pseudo-second order, kinetic models Weber and Morris and Elovich were used to analyze the kinetic data obtained at different initial dye concentrations. The kinetics of adsorption showed that the action in adsorption adopted the processes of pseudo-second - order kinetic model and chemisorption. The thermodynamic parameter such as ∆G, ∆S and ∆H has been determined. Study of thermodynamics for adsorption indicated the reaction was endothermal and spontaneous

Hydrophobic Polymers Flooding

Crude oil and other petroleum products are crucial to the global economy today due to increasing energy demand approximately (~1.5%) per year and significant oil remaining after primary and secondary oil recovery (~45-55% of original oil in place, OOIP), which accelerates the development of enhanced oil recovery (EOR) technologies. Polymer flooding through hydrophobically associated polyacrylamides (HAPAM) is a widely implemented EOR-technique, so they attracted much attention on both academic and industrial scales. Hydrophobically associating polyacrylamide (HAPAM) prepared by free radical emulsion polymerization of acrylamide (AM) monomer, divinyl sulfone as hydrophobic crosslinked moiety and surfmers, to chemically anchor a surfmer and hydrophobic crosslinker moiety onto the back bone of acrylamide chain. After that, polymeric nanocomposite was prepared through copolymerization of prepared HAPAM with different molar ratios of silica nanoparticles through one shot synthesis. Rheological properties for the prepared composites were evaluated. Wettability evaluation carried through quantitative and qualitative techniques where the results indicate novel polymers ability to alter rock wettability from oil-wet to water- wet

Preliminary Investigation of the Corrosion Behavior of Proprietary Micro-alloyed Steels in Aerated and Deaerated Brine Solutions

The corrosion performance of fairly new generation of micro-alloyed steels was compared in different concentrations of aerated and deaerated brines. Electrochemical polarization, weight loss and surface analyses techniques were employed. The results showed a threshold of corrosion rate at 3.5 wt.% NaCl in both aerated and deaerated solutions. The average corrosion current density for steel B, for example, increased from 1.3 µA cm¯² in 1 wt.% NaCl to 1.5 µA cm¯² in 3.5 wt.% NaCl, but decreased to 1.4 µA cm¯² in 10 wt.% deaerated NaCl solutions. The aerated solutions exhibited an average of over 80% increase in corrosion current density in the respective concentrations when compared with the deaerated solution. These results can be attributed to the effects of dissolved oxygen (DO) which has a maximum solubility in 3.5 wt.% NaCl. DO as a depolarizer and electron acceptor in cathodic reactions accelerates anodic metal dissolution. The difference in carbon content and microstructures occasioned by thermo-mechanical treatment contributed to the witnessed variation in corrosion performance of the steels. Specifically, the results of the various corrosion techniques corroborated each other and showed that the corrosion rate of the micro-alloyed steels can be ranked as CR[Steel A] < CRₓ₆₅ < CR[Steel B] < CR[Steel C]

Absorption and infrared spectra of gamma irradiated ternary silicate glasses containing cobalt

711-721 Optical and infrared absorption spectra of undoped ternary silicate and CoO doped glasses were measured before and after successive gamma ray irradiation. The results obtained revealed the existence of cobalt ions mainly in tetrahedral coordination in such host glasses. The radiation-induced defects created by gamma irradiation are related to intrinsic effect of the glass constituents and extrinsic effect due to the cobalt ions. The response of the glass to irradiation and the growth rate of colour center formation are related to the equilibrium between the formation and annihilation processes of induced colour centers and the saturation or equilibrium state reached by successive irradiation

Stenolaemate bryozoans from the Carboniferous of Egypt

This is the first detailed taxonomic study of Carboniferous bryozoans from the autochthonous southern margin of the Palaeotethys between western Libya and southernmost Turkey. Eleven bryozoan species, all first documented in this vast region, are described from the vicinity of the Gulf of Suez. Four species have been derived from the Mississippian (middle Visean) Um Bogma Formation, southwestern Sinai, eastern side of the gulf. In total seven species were identified from the Pennsylvanian. They are from the lower Moscovian Abu Durba Formation, southwestern Sinai, eastern side of the Gulf, and from the upper Moscovian Rod El Hamal Formation, Eastern Desert/Wadi Araba, on its western side. Three species of Fistulipora are described in open nomenclature, two from the Mississippian and one from the Pennsylvanian. One species from the Mississippian is new - Parastenodiscus sinaiensis sp. nov. (Trepostomata). Bryozoans from the Um Bogma Formation show relations to the Mississippian (Visean) of Ukraine, whereas some of the Pennsylvanian bryozoans are also known from the Russian platform and northwestern Spain, thus indicating a general Palaeotethys affinity

Investigation of Optimum Polymerization Conditions for Synthesis of Cross-Linked Polyacrylamide-Amphoteric Surfmer Nanocomposites for Polymer Flooding in Sandstone Reservoirs

Currently enhanced oil recovery (EOR) technology is getting more attention by many countries since energy crises are getting worse and frightening. Polymer flooding by hydrophobically associated polyacrylamides (HAPAM) and its modified silica nanocomposite are a widely implemented technique through enhanced oil recovery (EOR) technology. This polymers class can be synthesized by copolymerization of acrylamide (AM), reactive surfmer, functionalized silica nanoparticles, and a hydrophobic cross-linker moiety in the presence of water soluble initiator via heterogeneous emulsion polymerization technique, to form latexes that can be applied during polymer flooding. Chemical structure of the prepared copolymers was proven through different techniques such as Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic spectroscopy (1H&13C-NMR), and molecular weight was measured by gel permeation chromatography. Study of the effects of monomer, surfmer, cross-linker, silica, and initiator concentrations as well as reaction temperature was investigated to determine optimum polymerization conditions through single factor and orthogonal experiments. Evaluation of the prepared copolymers for enhancing recovered oil amount was evaluated by carrying out flooding experiments on one-dimensional sandstone model to determine recovery factor