Preparation and application of catalytic polymeric membranes based on PVDF/cobalt nanoparticles supported on MWCNTs

Catalytic Thermal Decomposition of NO2 by Iron(III) Nitrate Nonahydrate-Doped Poly(Vinylidene Difluoride)

The products of thermal decomposition of iron nitrate nonahydrate doped into poly(vinylidene difluoride) are examined using Mössbauer spectroscopy. Very little of the expected nitrogen dioxide product is observed, which is attributed to Fe³⁺ catalysis of the decomposition of NO₂. The active site of the catalysis is shown to be Fe(OH)₃ in the polymer matrix, which is, unexpectedly, reduced to Fe(OH)₂. Thermodynamic calculations show that the reduction of Fe³⁺ is exergonic at sufficiently high temperatures. A reaction sequence, including a catalytic cycle for decomposition of NO₂, is proposed that accounts for the observed reaction products. The role of the polymer matrix is proposed to inhibit transport of gas-phase products, which allows them to interact with Fe(OH)₃ doped in the polymer.

Analysis of the chemical behavior at the molecular level of lined pipes with fluoropolymers in a sodium hypochlorite production line/bibliographic review

This case study is about finding the best fluoropolymer coating for pipes that resists the sodium hypochlorite continue production, which is one of the most aggressive chemical processes that can lead to molecular attack in reactors made by lined pipes. There are several types of coatings pipe such as fiberglass, polymers and elastomers, but the fluoropolymers which have unique properties that make them resistant to chemical attack. In this production process, the premature deterioration of coating pipes is common, due to the expansion of chlorine at the inlet of the reactor, caused by the reaction of chlorine–sodium hydroxide, this is the critical point of the process. Some problems that we find is the chemical attack in that some fluoropolymers coating suffer premature degradation caused by the chemical compatibility, in this case, we explain in detail the chemical and molecular composition of each of the fluoropolymers and how this change occurs at the molecular level. While the lined pipes are the best economical option for chemicals applications, however, it is important to know the correct coating to ensure a long lifetime and avoid piping changes due to premature degradation. Based on the findings of the chemical resistance of each fluoropolymer under study, it is determined which is the best fluoropolymer that resists continuous production of sodium hypochlorite. Results were obtained by a systematic review of the literature.