Borohydride‐functionalized polydopamine‐coated open cell polyurethane foam as a reusable soft structured material for reduction reactions: Application to the removal of a dye

Abstract

Open cell polyurethane foams coated with mussel‐inspired polydopamine can be used as support for borohydride anions through their complexation by the catechol groups of the polydopamine layer. This strong interaction prevents borohydride hydrolysis and oxidation, and based on the redox mediator properties of polydopamine, the so‐functionalized polydopamine‐coated open cell polyurethane foams can act as efficient and reusable soft structured materials for the reduction of methylene blue in aqueous solution without additional sodium borohydride (NaBH4). Very low amounts of released boron sub‐products and very small potential of hydrogen (pH) increase are observed in comparison to previous processes using dissolved NaBH4. This considerably reduces the environmental impact of the reducing structured material on the treated wastewater compared to the latter. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 329–335, 2019

An efficient bio‐inspired catalytic tool for hydrogen release at room temperature from a stable borohydride solution

“…37,38 As mentioned in the experimental section, iron doping with FeCl 3 was performed in order to increase the chemical stability of the PDA film under harsh alkaline medium. 39 As expected, 42 the PDA content on OCPUF was higher when NaIO 4 (10 to 16 wt%) was used than when O 2 (3 to 5 wt%) was used. Low magnification scanning electron microscopy (SEM) images of OCPUF@PDA/Fe revealed a rough coating of PDA on the whole surface of the polyurethane foam independently of the nature of the used oxidant ( Figure 3B,C).…”

“…In this work, we propose to improve the metal reduction by using a solution of NaBH 4 as a reduction agent. 42 The employed method took its inspiration from Delgado and collaborators' process that led to the synthesis of well-dispersed, thin and highly active Co NPs on an anatase support. This process was carried out at room temperature in the presence of polyvinylpyrrolidone as a NPs size' stabilizer.…”

“…According to the method published by Lefebvre et al, 36 it is possible to use the redox properties of polydopamine‐coated OCPUF in order to concomitantly synthesize and graft metal(0) nanoparticles on the foam surface (eg, Ag NPs). In this work, we propose to improve the metal reduction by using a solution of NaBH 4 as a reduction agent 42 . The employed method took its inspiration from Delgado and collaborators' process that led to the synthesis of well‐dispersed, thin and highly active Co NPs on an anatase support.…”

“…These results tend to show that polydopamine itself catalyses the hydrolysis of NaBH 4 . According to the open literature, a probable catalytic effect of PDA itself could indeed well result from a redox mediator role of PDA in the hydrolysis reaction, 41,48‐50 as well as from the formation of catecholborane groups on PDA that could also release H 2 42 . A minor role of PDA‐complexed Fe can, however, not be excluded.…”

Polydopamine – its Prolific Use as Catalyst and Support Material

“…Exposure to air at room temperature for six days proved to be somewhat more beneficial (90 % conversion in run 14 decreasing to 48 % in run 18). In a recent study they fabricated two oxidized PDA/PU samples and then loaded them with NaBH 4 . One made by the usual method (dopamine/Tris, rt, 12 h, in air; sample PDA O2 PU), whereas the other was made by treating PU in a mixture of dopamine, NaOAc, and NaIO 4 (pH 5, rt, 24 h).…”