Fluorinated copolyimide membranes for sour mixed-gas upgrading

Three random and two block 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)-based copolyimides with different 6FpDA:Durene molar ratio varying from 25 to 80% were prepared and characterized. The pure-gas permeation data of their membranes were investigated at 100 psi and 22 °C. The CO₂/CH₄ ideal selectivity coefficient increased to around 47 with the increase of the 6FpDA content to 80% in the copolymer backbone while the CO₂ permeability coefficient found to be the highest (378 barrer) with highest Durene content copolymer. Based on its attractive pure-gas permeation properties(CO₂/CH₄ = 47), 6FDA-6FpDA/6FDA-Durene (4:1) block copolyimide was selected for further analyses, where the effect of pressure and temperature on its gas transport properties was evaluated. Furthermore, the mixed-gas permeation properties were investigated using multicomponent sweet and sour gas mixtures prepared from N₂ (30% or 10%), CH₄ (59%), C₂H₆ (1%), CO₂ (10%), and H₂S (0% or 20%)accordingly. The sweet mixed-gas CO₂/CH₄ selectivity and CO₂ permeability coefficients of 6FDA-6FpDA/6FDA-Durene (4:1) are around 39 and 45 barrer, respectively, at elevated pressure (800 psi). The polymer, however, showed nonideal behavior when subjected to high H₂S-content gas mixture (20 vol. % H₂S), where the CO₂/CH₄ selectivity value dropped to around 21 and the H₂S/CH₄ selectivity coefficient is 13. The CO₂ and H₂S permeability coefficients are 42 and 26 barrer, respectively, at an upstream pressure up to 500 psi. When plotted on the combined acid gas permeability-selectivity curve, the polymer separation efficiency was nearby the high-performing polymers reported in the literature, and way superior to the industrial standard glassy polymer, cellulose acetate, used currently in gas separation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48336.     

Biosorption of copper (II) onto immobilized cells of Pycnoporus sanguineus from aqueous solution: equilibrium and kinetic studies

The ability of white-rot fungus, Pycnoporus sanguineus to adsorb copper (II) ions from aqueous solution is investigated in a batch system. The live fungus cells were immobilized into Ca-alginate gel to study the influence of pH, initial metal ions concentration, biomass loading and temperature on the biosorption capacity. The optimum uptake of Cu (II) ions was observed at pH 5 with a value of 2.76mg/g. Biosorption equilibrium data were best described by Langmuir isotherm model followed by Redlich-Peterson and Freundlich models, respectively. The biosorption kinetics followed the pseudo-second order and intraparticle diffusion equations. The thermodynamic parameters enthalpy change (10.16kJ/mol) and entropy change (33.78J/molK) were determined from the biosorption equilibrium data. The FTIR analysis showed that OH, NH, CH, CO, COOH and CN groups were involved in the biosorption of Cu (II) ions onto immobilized cells of P. sanguineus. The immobilized cells of P. sanguineus were capable of removing Cu (II) ions from aqueous solution.     

Evaluation of ballistic performance of hybrid Kevlar®/Cocos nucifera sheath reinforced epoxy composites

The aim of this research is replacement of petroleum resource-based costlier Kevlar^® 29 fabric (K) with a naturally woven novel Cocos nucifera sheath (CS) for ballistic applications. Cocos nucifera sheath is a bio waste, and it is termed as ‘Natural Textile’. Nine and twelve layered hybrid and nonhybrid laminates were fabricated with different layering sequence by hand lay-up method followed by hot pressing. Energy absorption and ballistic limit of the laminated composites were evaluated using a single stage gas gun ballistic setup with 8?mm hemispherical stainless steel projectile. The obtained results revealed that hybrid composites and CS/epoxy composite panels exhibited higher energy absorption (30%) and ballistic limit (13%) compared to Kevlar^® fabric/epoxy composites. It is due to CS’s chemical composition, architecture, and unique shock wave dissipation mechanism. Hence, this new eco-friendly material will efficiently replace Kevlar^® fabric in the ballistic composites.     

Evaluation of Failure and Repair of the Jebba and the Shiroro Hydroelectric Power Stations

Journal of Failure Analysis and Prevention - Nigeria power generation hovers around 7000 MW as at January 2019; this is far less than the national required electricity per capita value....     

The Effect of Single, Binary and Ternary Anions of Chloride, Carbonate and Phosphate on the Release of 2,4-Dichlorophenoxyacetate Intercalated into the Zn–Al-layered Double Hydroxide Nanohybrid

Intercalation of beneficial anion into inorganic host has lead to an opportunity to synthesize various combinations of new organic–inorganic nanohybrids with various potential applications; especially, for the controlled release formulation and storage purposes. Investigation on the release behavior of 2,4-dichlorophenoxyacetate (2,4-D) intercalated into the interlayer of Zn–Al-layered double hydroxide (ZAN) have been carried out using single, binary and ternary aqueous systems of chloride, carbonate and phosphate. The release behavior of the active agent 2,4-D from its double-layered hydroxide nanohybrid ZANDI was found to be of controlled manner governed by pseudo-second order kinetics. It was found that carbonate medium yielded the highest accumulated release of 2,4-D, while phosphate in combination with carbonate and/or nitrate speeds up the release rate of 2,4-D. These results indicate that it is possible to design and develop new delivery system of latex stimulant compound with controlled release property based on 2,4-D that is known as a substance to increase latex production of rubber tree, Hevea brasiliensis.     

Enhanced Dickson voltage multiplier rectenna by developing analytical model for radio frequency harvesting applications

Radio frequency (RF) energy harvesting has experienced a rapid development recently because of the increasing number of RF transmitter sources. This article illustrates a novel analytical model for the voltage multiplier rectifier at 900 MHz. The model proposes a method of deriving the output characteristics of the rectifying circuits in terms of two main parameters; voltage and current. The design consists of seven stages of Dickson voltage multiplier rectifier. A Schottky diode HSMS 285C was used in the design. Equations for the model were developed. These equations were used to extract the values of output voltage and current. A simulation was optimized using advanced design systems. The system was correspondingly fabricated and tested for input power range of 1 × 10^?5‐1 × 10^?1 W. Experimental results show that an output voltage of 5.45 V and current of 1.26 × 10^?5 A are achieved at 10 dBm using a 10 kΩ load, achieving an efficiency of 37.82%.