4,4′-Isopropylidenebis(2,6-dibromophenol) Photocatalytic Debromination on Nano- and Micro-Particles Fe3O4 Surface

Background: Tetrabromobisphenol A (4,4’-isopropylidenebis(2,6-dibromophenol), TBBPA) is one of the most widely used brominated flame retardants. Due to its widespread use, high lipophilicity, and persistence, it has been detected in various environmental samples. Therefore, it is of great significance to develop methods to efficiently remove TBBPA from the contaminated environment. Objective: The aim of our study was to examine photocatalytic dehalogenation of TBBPA on microand nano-sized Fe3O4 exposed to the visible light. The Fe3O4 catalyst was chosen due to its indisputable low impact on the environment. Methods: A solution of TBBPA (1.84 × 10-4 mol dm-3) with a pH = 8 with suspended catalyst was illuminated (light intensity about 1.1x1017 photons per second, spectrum range 200-600 nm) for 1 hour. Analysis of the reaction progress was carried out by HPLC measurements of TBBPA decay and potentiometric measurements of an increase in bromide concentration. Results: The degradation process seems to be the most effective for TBBPA in the reaction mixture containing the n-Fe3O4 (t0.5 ≈ 2 min). Slightly lower degradation efficacy is observed for TBBPA degradation in the presence of the μ-Fe3O4 (decay within the first 5 min). TBBPA decomposition of both n-Fe3O4 and μ-Fe3O4 is accompanied by different bromide concentrations time-profile. Conclusion: The photogenerated electron-induced degradation by dissociative-attachment to the aromatic ring was followed by bromine ion expulsion. The micro-magnetite showed a strong tendency for adsorption of bromide anions during the process, which could be adventurous for the overall waste-decontamination process.

On the upper dual Zariski topology

Let R be a ring with identity and M be a left R-module. The set of all second submodules of M is called the second spectrum of M and denoted by Specs(M). For each prime ideal p of R we define Specsp(M) := {S? Specs(M) : annR(S) = p}. A second submodule Q of M is called an upper second submodule if there exists a prime ideal p of R such that Specs p(M)? 0 and Q = ? S2Specsp(M)S. The set of all upper second submodules of M is called upper second spectrum of M and denoted by u.Specs(M). In this paper, we discuss the relationships between various algebraic properties of M and the topological conditions on u.Specs(M) with the dual Zarsiki topology. Also, we topologize u.Specs(M) with the patch topology and the finer patch topology. We show that for every left R-module M, u.Specs(M) with the finer patch topology is a Hausdorff, totally disconnected space and if M is Artinian then u.Specs(M) is a compact space with the patch and finer patch topology. Finally, by applying Hochster?s characterization of a spectral space, we show that if M is an Artinian left R-module, then u.Specs(M) with the dual Zariski topology is a spectral space.

Determination of differential pencils with impulse from interior spectral data

In this paper, we are concerned with the inverse spectral problems for differential pencils defined on $[0,\pi ]$ [ 0 , π ] with an interior discontinuity. We prove that two potential functions are determined uniquely by one spectrum and a set of values of eigenfunctions at some interior point $b\in (0,\pi )$ b ∈ ( 0 , π ) in the situation of $b=\pi /2$ b = π / 2 and $b\neq \pi /2$ b ≠ π / 2 . For the latter, we need the knowledge of a part of the second spectrum.