Electrochemical Desalination of a 50% w/w Sodium Hydroxide Solution, a Pharmaceutical Sterilization Agent

Abstract

Sodium hydroxide solutions are often employed as sterilization agents in the pharmaceutical industry. Here, the chloride content is considered as a critical impurity. In this study, an electrochemical method was developed to remove chloride ions (Cl¯) through the oxidative deposition of AgCl on a Ag anode. The Cl¯ content in the commercially available 50% w/w NaOH solution employed was approximately 100 mg Cl¯/kg NaOH. As the OH¯ content is approximately 18,000 times higher than the Cl¯ content, the formation of AgCl may be expected to be thermodynamically less favorable than the formation of Ag 2 O. However, activation energies for AgCl and Ag 2 O formation have been reported to be approximately 3.8 and 31.2 kJ/mol, respectively, and indicate that AgCl formation is favored. AgCl can be selectively produced by controlling the anode potential. Here, the Cl¯ concentration was reduced to less than 50 mg Cl¯/kg NaOH when an anode potential of 0.18 or 0.19 V vs. Hg/HgO (reference electrode) was applied for one hour at 50°C. XRD analysis and visual monitoring of the Ag anode confirmed the oxidative deposition of AgCl on the anode surface as well as the electrochemical desalination of the concentrated NaOH solution.

Highly Thermally Conductive Aramid Nanofiber Composite Films with Synchronous Visible/Infrared Camouflages and Information Encryption

“…However, their thermal conductivity coefficients ( λ ) are relatively low (~0.2 W/(m ⋅ K)). Although researchers commonly incorporate thermally conductive and electrically insulating fillers, such as boron nitride (BN), aluminum nitride (AlN), and silicon carbide (SiC), etc ., into polymers to fabricate thermally conductive and electrically insulating composites, [17–19] the value of λ of the reported thermally conductive and electrically insulating polymer composites are not particularly outstanding (with λ difficult to exceed 10 W/(m ⋅ K)) [20] . Silver nanowires (AgNWs), characterized by high λ (~420 W/(m ⋅ K)), large aspect ratios, and good chemical stability, [21,22] thus become ideal thermally conductive fillers for preparing high‐performance thermally conductive polymer composites [23,24] .…”

Recent Advances in Wide Bandgap Perovskite Solar Cells: Focus on Lead‐Free Materials for Tandem Structures

“…[ 3 ] Perovskite is used as a photovoltaic material, which has the chemical structure of ABX 3 (A = monovalent cation, such as Cs + , CH 3 NH 3 + (MA + ), and CH(NH 2 ) 2 + (FA + ); B = divalent cation, such as Pb 2+ , Sn 2+ , Ge 2+ , Bi 3+ , and Sb 3+ ; X = halide anion, such as I ‐ , Br ‐ , and Cl ‐ ) and excellent optoelectronic properties, such as long carrier lifetime, long diffusion length, and high absorption coefficient, as well as the advantages of tunable bandgap, low cost, and ease of manufacturing. [ 4–12 ] In particular, the properties of perovskite absorbents can be easily controlled by changing the elemental composition of the precursor used. In other words, it is possible to control the bandgap of perovskites by simply changing the halide composition from I ‐ to Br ‐ .…”

“…According to the thermodynamically determined maximum efficiency limit, known as the Shockley‐Queissier (S‐Q) limit, it can be observed that the perovskite absorbers currently being studied with a bandgap of 1.5 to 1.6 eV have a low theoretical power conversion efficiency (PCE) limit of approximately 30–31%. [ 9 ] Moreover, the S‐Q limit of ideal perovskite single‐junction solar cells with a bandgap of 1.3 to 1.4 eV is limited to approximately 33%. Single‐junction solar cells also suffer from thermalization loss and the limited absorption of photons with energy below the bandgap ( E g ) due to the mismatch between the solar spectrum and mono‐energetic absorption, combined with the interaction between excited carriers and lattice phonons, leading to the cooling of carriers towards the bandgap edge.…”