Physical chemistry
Atume Emmanuel Terhemen
Abstract
This study was conducted to apply the Atume’s series in the absolute prediction of melting and freezing points of a wide range of saturated liquid and solid hydrocarbons. The calculated results that were obtained, shows that a range of 92% to 99% accuracy was theoretically achieved when compared ...
Read More
This study was conducted to apply the Atume’s series in the absolute prediction of melting and freezing points of a wide range of saturated liquid and solid hydrocarbons. The calculated results that were obtained, shows that a range of 92% to 99% accuracy was theoretically achieved when compared to experimental results. Basically, precise interpolations were deployed by equating the energies released by frozen liquid molecules to the energies absorbed by their corresponding boiling molecules; which represents their lower and upper energy fixed points respectively. These two fixed points were also found to vary infinitesimally and inversely to each other. The energies absorbed or released, molar masses, and trigonometric properties formed the basis for this method. In branched chain hydrocarbons, the melting points of their corresponding linear molecules were also used as reference points to determine their melting and freezing points; indicating the mathematical relationships between their fixed points and trigonometric properties.
Physical chemistry
Fawad Ahmad
Abstract
Research in the area of electrocatalytic reduction of CO2 to value-added products has grown briskly in the past few decades. This is due to the increasing amount of CO2 in the atmosphere and a steady rise in global fuel demand. Serious efforts are urgently needed to minimize to CO2 emission and enhance ...
Read More
Research in the area of electrocatalytic reduction of CO2 to value-added products has grown briskly in the past few decades. This is due to the increasing amount of CO2 in the atmosphere and a steady rise in global fuel demand. Serious efforts are urgently needed to minimize to CO2 emission and enhance sources of global energy demand. Electrochemical reduction (ECR) of CO2 is considered to be the best solution which not only reduces the increasing CO2 accumulation but also produces valuable fuels and chemicals. Sluggish kinetics, high over potential, low selectivity, low durability and competitive side reactions are the focal issues, to overcome these problems an efficient electrocatalyst is needed. Here in this mini review we had tried to discuss the fundamental factors that greatly influences catalytic activity of the catalyst in the light of updated experimental and computational data, which include size, crystal plane, grain boundary, metal metal-oxide interface and finally a brief note on metal free catalyst and future perspective of ECR of CO2.
Physical chemistry
Mahmoud Ahmed Taher; Adel mohamed Amine; Bassam Khalaf Damarany
Abstract
For many years of production of phosphate fertilizer very large amounts of phosphogypsum (PG) occupied large area, causing chemical and radiological environmental. Using of PG in building materials represents a good method for lowering the cost of cement production and dispose of phosphogypsum as chemical ...
Read More
For many years of production of phosphate fertilizer very large amounts of phosphogypsum (PG) occupied large area, causing chemical and radiological environmental. Using of PG in building materials represents a good method for lowering the cost of cement production and dispose of phosphogypsum as chemical and radioactive waste. Fresh wet hemihydrate phosphogypsum, cement and pozzolana additive were mechanically activated together and from mixing Portland pozzolanic cement (PPC) with PG, these mixes were prepared at different replacements (by weight) of raw gypsum (RG)with purified PG ranging from 1–5% . The purified PG was obtained by calcining PG at temperatures of 200, 400, 600, 800 and 1000 ᵒC. The compressive strength, bulk density, total porosity, combined water and free lime of different hardened mortars were obtained following 3, 7, 28 and 90 days of curing. In addition, the setting time of cement pastes. The highest percentage increase in strength was found to be for PG calcined at temperatures of 800 and 1000 ᵒC. The incorporation of PG in the cement paste has dramatically increased its initial and final setting times. FTIR spectroscopic analysis and scanning electron microscopy (SEM) were used for investigate the change in structure of mortars after curing and change in morphology and microstructure of some hardened pastes.
Physical chemistry
Kingsley Ogemdi Iwuozor
Abstract
Wastewaters from chemical industries are characterized by the presence of heavy metallic ions, chemical contaminant and turbidity. Exposure to lead (Pb), for example, is recognized as a major risk factor for several human diseases, and the structure of industrial ecological systems have made exposure ...
Read More
Wastewaters from chemical industries are characterized by the presence of heavy metallic ions, chemical contaminant and turbidity. Exposure to lead (Pb), for example, is recognized as a major risk factor for several human diseases, and the structure of industrial ecological systems have made exposure to Pb unavoidable for most people alive today. The removal of these toxic metals and contaminants from industrial wastewater is a matter of great interest in the field of water pollution, which is a serious cause of water degradation. Coagulation-flocculation is a widely used method for wastewater treatment especially if the wastewater is discharged into surface water. Coagulation/flocculation is a commonly used process in water and wastewater treatment in which compounds such as ferric chloride and/or polymer are added to wastewater in order to destabilize the colloidal materials and cause the small particles to agglomerate into larger settle able flocs. Therefore, the futuristic use as well as the present demerits of this process is necessary for the treatment of effluents.
Physical chemistry
Esam Arafa Gomaa; Mahmud Nabil Abdel Hady; Mahmoud Hanfy Mahmoud; Doaa Ahmed El Kot
Abstract
Cyclic Voltammetry of Cobalt chloride with different concentrations was measured experimentally using DY2000 potentiostat. We used 0.1 M KCl as supporting electrolyte. Glassy carbon working electrode was used, purified and polished before use. The other two electrodes are platinum wire and Ag/AgCl electrode ...
Read More
Cyclic Voltammetry of Cobalt chloride with different concentrations was measured experimentally using DY2000 potentiostat. We used 0.1 M KCl as supporting electrolyte. Glassy carbon working electrode was used, purified and polished before use. The other two electrodes are platinum wire and Ag/AgCl electrode put in saturated KCl solution were used. The complex characters for the interaction of CoCl2 with Ceftriaxone disodium salt (Cefs) were studied with the use of different Ceftriaxone disodium salt (Cefs) concentrations at 298.65 K. The oxidation, reduction mechanisms and the stability constants of the complexes formed are discussed. Scan rate and different kinetic parameters resulted from the interaction of CoCl2 with Ceftriaxone disodium salt (Cefs) were also evaluated and their values were discussed.
Physical chemistry
Oyebanji M. Opeyemi; Hitler Louis; Chinanso I. Oparab; Oyebanji O. Funmilayo; Thomas O. Magu
Abstract
A remarkable source of renewable energy is the Dye-sensitized solar cells (DSCs). However, the major limitation of power conversion efficiency (PCE) of devices is their inability to produce electricity using photons from the nearinfrared (NIR) spectral region. Some Metal-free organic sensitizers ...
Read More
A remarkable source of renewable energy is the Dye-sensitized solar cells (DSCs). However, the major limitation of power conversion efficiency (PCE) of devices is their inability to produce electricity using photons from the nearinfrared (NIR) spectral region. Some Metal-free organic sensitizers make use of strong electron donating or withdrawing moieties to tune the optical band gap to allow the absorption of lower energy wavelengths in charge transfer systems while porphyrins and phthalocyanines compounds are used to shift the Soret and Q bands toward lower energy absorption. Various molecules are been synthesized to improve and increase the power conversion efficiency of the compounds. This study discusses the structure of these compounds, working principles and their derivatives as recent advances been carried out to improve the power efficiencies of the compounds.
Inorganic chemistry
Zahra Javanshir; Saeed Jameh-Bozorghi; Parasto Peyki
Abstract
In this research DFT calculations were used to investigate the neighboring effects on cheletropic reaction of 2,5-Dihydrothiophene sulfone(1). Structural properties and stereoelectronic behavior in the activation energy and enthalpy of cheletropic reaction was performed for 2,5-Dihydrothiophene sulfone ...
Read More
In this research DFT calculations were used to investigate the neighboring effects on cheletropic reaction of 2,5-Dihydrothiophene sulfone(1). Structural properties and stereoelectronic behavior in the activation energy and enthalpy of cheletropic reaction was performed for 2,5-Dihydrothiophene sulfone where substitutions of CF3; CCl3 and CBr3 that were placed on Sulfolen were investigated by using DFT-B3LYP/6-311+G** level of theory. The Results of calculations using B3LYP, HF and MP2 [basic 6-311+G**] showed that the trend of electronic effects on the cis and trans state is different. Reaction rate and activation energy in cis compounds showed that increasing electronegativity and decreasing the band length reduced the reaction speed. Trend of reaction rate and activation energy in Trans compounds showed that in cheletropic reaction rate and activation energy not only electronic effects but also the Steric effects play a main role. DFT/B3LYP/6-311+G** calculation results also confirm these results. In cis compounds, 2,5- three Floro metyl Sulfolen(2) has the highest activation energy about (12.25 kcal/mol) and the lowest rate of reaction. In trans compounds, Trans-2,5- three chloro metyl Sulfolen(7) has the highest activation energy about (12.99 kcal/mol) and the lowest rate of reaction.
Physical chemistry
Hussayn Bakhshy; Seyyed Mohammad Ali Rohani; Payam Heydari; Reza Asadi
Abstract
In the current study, a new model for micro-scale cooling systems is presented. The small-scale refrigerator is modeled by engraving channels and a micro nozzle on the sides of a rectangular glass. The system has the capability to reduce the temperature from 300K to 80 in 5 seconds using nitrogen as ...
Read More
In the current study, a new model for micro-scale cooling systems is presented. The small-scale refrigerator is modeled by engraving channels and a micro nozzle on the sides of a rectangular glass. The system has the capability to reduce the temperature from 300K to 80 in 5 seconds using nitrogen as the working fluid. The model consists of three elements, heat exchanger, nozzle and expansion tank and all the parts of the cooling system is stationary. For this novel model, pressure drop through the channels and nozzle sections is presented and by using these information, temperature drop through the nozzle is obtained regarding the high Mach number at the throat of the convergence-divergence micro-nozzle. Due to the characteristics of this in-plane micro-nozzle, the heat exchange is modeled through the time in the glass, and temperature of the cooling system is reported.
