Ascorbic Acid-Assisted Polyol Synthesis of Iron and Fe/GO, Fe/h-BN Composites for Pb2+ Removal from Wastewaters

Abstract

Iron powders and Fe/graphene oxide and Fe/boron nitride composites were synthesized by means of a polyol synthesis method. The effect of NaOH/Fe and ascorbic acid/Fe ratios on the characteristics of synthesized products were evaluated. The samples were characterized by X-ray diffraction, scanning and transmission electron microscopy, low-temperature nitrogen adsorption and Raman-spectroscopy. Ascorbic acid-assisted polyol synthesis resulted in the 10-fold decrease of the iron particles' size and almost 2-fold increase of lead removal efficiency. The deposition of iron on the surface of graphene oxide lead to the formation of small 20-30 nm sized particles as well as bigger 200-300 nm sized particles, while the reduction in presence of boron nitride resulted in the 100-200 nm sized particles. The difference is attributed to the surface state of graphene oxide and boron nitride. Adsorption properties of the obtained materials were studied in the process of Pb 2+ ion removal from wastewater. Nanomaterials 2020, 10, 37 2 of 17 followed precisely. It was reported by H. Chiriac et al. [7] that refluxing of iron sulphate solution in the presence of NaOH in ethylene glycol led to the formation of spherical particles with wide size distribution in a range from 60 to 400 nm.One of the important aspects of iron powders' synthesis by polyol method is the ability to control particles' sizes in various ways. R.J. Joseyphus et al. [8] reported that the choice of polyol affects the size of iron particles. They found that the size decreases in the sequence of ethylene glycol > propylene glycol > trimethylene glycol. However, as a side effect of the decrease of particles' size they observed substantial oxidation of iron particles during the process. Another approach to control the particles' size during polyol process is the utilization of microwave radiation which enhances kinetics of particles' formation. In the works of S. Komarneni et al. [9] and M.N. Nadagouda [10], authors used a microwave-assisted polyol synthesis approach to synthesize rod-shaped submicron iron particles. A successful approach to the synthesis of iron with particles' sizes below 100 nm was proposed by R.J. Joseyphus et al. [11]. They used hexachloroplatinic acid as a nucleating agent for the synthesis of iron under heterogeneous nucleation conditions. Although the concentration of Pt ions was as low as 2 × 10 −7 M, the scaling up of the technology will lead to appreciable cost effects. Thus, other routes to reduce particles' sizes of polyol-synthesized iron should be considered. One such approach constitutes the addition of more powerful reducing agents to the polyol-iron salt system.An ascorbic acid was widely used by different scientific groups for the synthesis of nanosized metal particles. Mostly, the attention was concentrated on the synthesis of noble metals and their alloys. Au [12,13], Ag [14,15], Pt [16,17], Pd [18] and different bimetallic [19,20] nanoparticles were successfully synthesized using ascorbic acid as the reducing agent. It was also ...

Ball-Milled Processed, Selective Fe/h-BN Nanocatalysts for CO2 Hydrogenation

“…The XPS Fe 2p spectra showed doublets at 713 and 726.2 eV corresponding to the Fe 2p 3/2 and Fe 2p 1/2 states, respectively . The Fe 2p 3/2 peak of the Fe/h-BN sample produced by H 2 reduction was deconvoluted into two components centered at 712.7 and 710.5 eV, corresponding to iron in +3 and +2 oxidation states, respectively . The iron oxides can be present either as separate phases or as the passivation layer on the surface of metallic iron.…”

“…46 The Fe 2p 3/2 peak of the Fe/h-BN sample produced by H 2 reduction was deconvoluted into two components centered at 712.7 and 710.5 eV, corresponding to iron in +3 and +2 oxidation states, respectively. 47 The iron oxides can be present either as separate phases or as the passivation layer on the surface of metallic iron. After ball milling of the Fe/h-BN sample at 300 rpm, the intensity of the peak corresponding to +3 iron state increased.…”

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Sonophotocatalytic Degradation of Malachite Green by Nanocrystalline Chitosan-Ascorbic Acid@NiFe2O4 Spinel Ferrite

“…The characteristic absorption peaks of chitosan (red line) belong to 3439 cm −1 (N-H stretching broadly with mix of -OH group), 2885 cm −1 (aliphatic -CH 2 stretching), 1659 cm −1 (CO-NH bending), 1575 cm −1 (-N-H bending), and 1159 cm −1 (C-O-C pyranoid ring) [28]. The FTIR spectra ascorbic acid (blue line) shows peaks at 3207-3790 cm −1 (-OH stretching of four different -OH groups), 2733, 3003 cm −1 (-CH in aliphatic and ring stretching), 1752 cm −1 (-C=O carbonyl stretching), 1659 cm −1 (C-O stretching), 1107 cm −1 , 1116 cm −1 (C-O-C stretching), and 675 and 751 cm −1 (-OH out of plane deformation) [35]. The FTIR spectra of CTAS@NIFE (magenta line) represent all of the characteristic peaks from individual constituents with reduced intensity and new peaks at 2164 cm −1 (R-N-C stretching due to bonding between chitosan and ascorbic acid) and 2288 cm −1 (-NH-O oxime stretching due to bonding between NIFE and chitosan-ascorbic acid biopolymer matrix) [31].…”