Quest for high performance carbon capture membranes: Fabrication of SAPO-34 and CNTs-doped polyethersulfone-based mixed-matrix membranes

Gas separation process is an effective method for capturing and removing CO₂ from post-combustion flue gases. Due to their various essential properties such as ability to improve process efficiency, polymeric membranes are known to dominate the market. Trade-off between gas permeability and selectivity through membranes limits their separation performance. In this study, solution casting cum phase separation method was utilized to create polyethersulfone-based composite membranes doped with carbon nanotubes (CNTs) and silico aluminophosphate (SAPO-34) as nanofiller materials. Membrane properties were then examined by performing gas permeation test, chemical structural analysis and optical microscopy. While enhancing membranes CO₂ permeance, SAPO-34 and CNTs mixture improved their CO₂/N₂ selectivity. By carefully adjusting membrane casting factors such as filler loadings. Using Taguchi statistical analysis, their carbon capture efficiency was improved. The improved mixed-matrix membrane with loading of 5 wt% CNTs and 10 wt% SAPO-34 in PES showed highly promising separation performance with a CO₂ permeability of 319 Barrer and an ideal CO₂/N₂ selectivity of 12, both of which are within the 2008 Robeson upper bound. A better mixed-matrix membrane with outstanding CO₂/N₂ selectivity and CO₂ permeability was produced as a result of the synergistic effect of adding two types of fillers in optimized loading.     

Electrochemical oxidation of graphite in an intermediate temperature direct carbon fuel cell based on two-phases electrolyte

As a promising intermediate temperature fuel cell, Direct Carbon Fuel Cell (DCFC) with composite electrolyte composed of Samarium-Doped Ceria (SDC) and a binary carbonate phase (67 mol% Li₂CO₃/33 mol% Na₂CO₃) has a much higher efficiency compared with conventional power suppliers. In the present work, SDC powder has been synthesized by an oxalate co-precipitation process and used as solid support matrix for the composite electrolyte. Single cell with composite electrolyte layer is fabricated by a dry-pressing technique using LiNiO₂/Li₂Na₂CO₃/SDC as cathode and 1:9 (weight ratio) graphite mixture with 67 mol% Li₂CO₃/33 mol% Na₂CO₃ molten carbonate as anode. The cell is tested at 600–750 °C using electrolytical graphite mixture as fuel and O₂/CO₂ mixture as oxidant. A relatively good performance with high power density of 58 mW cm⁻² at 700 °C is achieved for a DCFC using 0.8 mm thick composite electrolyte layer. The sensibility of the 1 cm² DCFC single cell performance to the anode gas nature is also investigated. At temperatures higher than 700 °C, both carbon (C) and carbon monoxide (CO) can be considered as reacting fuel for the DCFC system.     

CuS@β-SnS nanocomposite electrocatalysts for efficient electrochemical water oxidation

Oxygen evolution reaction (OER) is an important key factor in favor of spotless energy production and storage. High cost and toxic elements can threaten the energy production. Only way to tackle the problem is that by utilizing the cost effective, earth-abundant and non toxic elements. In the present study, CuS, β-SnS and CuS@β-SnS nanocomposite were synthesized via co-precipitation process. X-Ray diffraction (XRD) spectra identify crystalline phases of synthesized samples. Raman spectra confirm nanocomposite formation and determine vibrational modes of molecules. Photoluminescence (PL) spectra revealed optical and electronic properties of synthesized materials. Flower-like morphology of CuS@β-SnS nanocomposite was analyzed by scanning electron microscopy (SEM) images. In addition, CuS@β-SnS nanocomposite exhibits 1111 F/g specific capacitance and 224 mV low overpotential. Further study revealed that CuS@β-SnS nanocomposite electrocatalyst displays good stability and excellent OER activity even over a prolong time. Remarkably, CuS@β-SnS nanocomposite revealed a low price water oxidation electrocatalyst and it builds a new pathway for practical water splitting applications.     

Wireless charging for cardiac pacemakers based on class-D power amplifier and a series–parallel spider-web coil

Biomedical implants (BMIs) and biomedical sensors (BMSs) help to improve quality of life, detect diseases, provide monitoring of vital signs, and take over the role of malfunctioning organs. These implants and sensors require continuous battery power to work effectively, but the batteries used are restricted by their limited capacity and lifetime. This research reported here involved the design and implementation of a wireless charging system based on a series–parallel spider-web coil (WPT-SP-SWC), specifically for cardiac pacemakers. The experimental design investigated several important parameters, including air gap, applied source voltage, coil size, and operating frequency. Performance metrics were evaluated in terms of output DC voltage, delivered output power, and power transfer efficiency. The target voltage was 5 V, which is adequate to charge a BMI such as a pacemaker, and three source voltages (5, 15, and 25 V) were tested. The design was examined at six operating frequencies, ranging from 1.78 MHz to 6.78 MHz. The most favorable results were achieved at 1.78 MHz. Power transfer efficiencies at a 10 mm air gap were 95.75% and 92.08% for applied voltages of 5 V and 15 V, respectively. The effectiveness of the proposed system was also validated by comparing the findings with previous articles.     

Synthesis and characterization of synthetic lubricants based on dibasic acid

Synthetic esters have long been used in a variety of applications due to their excellent thermal stability, excellent cleanliness, natural lubricity, and polarity. In the present work, we aimed to prepare some synthetic base oils through preparation of different dibasic esters by esterification of dicarboxylic acids (adipic acid and azelaic acid) with different linear alcohols (hexanol, octanol, and decanol) and branched alcohol (2-ethyl hexanol) at 120°C. The reaction yield ranges between 85% and 94%. Fourier-transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (¹H-NMR) spectroscopy were used to analyze the structures of the produced compounds. Using thermo gravimetric analysis (TGA), the heat stability of the produced esters was determined, and it was found that the prepared esters have high thermal stability. The degradation of the prepared esters takes place in the range between 300 and 600°C. The rheological behaviour of prepared esters shows Newtonian behaviours, which means that Newtonian fluids obey viscosity Newton's law. The viscosity is independent of the shear rate. The results showed that the lubricity properties, based on their pour point, flash point, and oxidation stability of the esters, were significantly affected by the linear and branched alcohols used. There is a slight increase in kinematic viscosity and viscosity index values with decreasing the internal chain length of the dibasic acid. The esters which were based on adipic acid such as C₁ exhibited maximum values of VI: 187 compared to those which were based on azelaic acid such as F₁ with VI: 182. Viscosity and viscosity index increases with increasing the number of carbon atoms of the used mono-ol alcohols. Using branched alcohols gave almost the same viscosity results compared to using linear alcohol with the same number of carbons. Almost all prepared esters give pour point results ≤ −30°C.     

Magnetite nanoparticles/polyvinyl pyrrolidone stabilized system for corrosion inhibition of carbon steel

The corrosion inhibitive effects of new polyvinylpyrrolidone stabilized crystalline super-paramagnetic nanoparticles (5–20?nm) were investigated. Several characterization techniques confirmed the high stability of the prepared stabilized nanoparticles in solution. The polarization and EIS measurements showed that the inhibition efficiency increased with increasing concentration of the magnetite nanoparticles. The results obtained from EIS and electrochemical polarization curves are in reasonably good agreement. The obtained results suggest that the prepared stabilized system is an excellent inhibitor for carbon steel corrosion in 1?M HCl solution.