Easily Applicable Heterogeneous Catalyst from Sustainable Resources: Anchoring of Pd Nanoparticles onto Chemically Poly(2-amino thiophenol)-Modified Wool Fabrics

Abstract

For preparing the Pd nanoparticle (PdNP)-decorated heterogeneous catalyst material, wool fabric was utilized as a practical platform after enriching its chemical functionality with two straightforward chemical processes. First, wool keratin was transformed to a reduced structure (WSH) with NaHS by extracting −SH groups and then reconstructed to the S−S linkages by the covalent attachment of 2-amino thiophenol (2-ATP). The graft copolymerization of 2-ATP onto this 2-ATP/WSH surface was ensured to prepare a P2ATP-g-WSH copolymer fabric. As the second process, the polymerization of 2-ATP was also performed on the WSH fabrics to prepare a P2ATP/WSH composite. The PdNP anchoring was subsequently ensured onto these copolymer and composite samples through the in situ reduction of Pd 2+ to the PdNPs. The conditions yielding the highest PdNP content were investigated in detail, and the PdNP formation abilities of both fabrics prepared by different routes were compared. It was observed that the contribution of PdNPs through the P2ATP/WSH composite route was relatively high compared to that of the copolymer route. The structural and morphological alterations in the wool nature, the existence, the oxidation state, and the relative abundance (%) of PdNPs with respect to the Pd 2+ ions were evidenced by many techniques in detail. After examining the performance of the PdNP composites in the catalytic reduction of two nitroarenes to the aminoarenes, the Pd/ P2ATP/WSH demonstrated satisfactorily high performance in terms of reduction yield (%), reduction rate constant (min −1 ), and reusability, compared to that of Pd/P2ATP-g-WSH.

Sequential Deposition of Polyaminothiophenols and Gold Nanoparticle on Wool Fabrics: Fabric Composites as Efficient Catalysts in the Reduction of Nitroarenes

“…Unlike our previous study regarding PdNPs deposition onto P2ATP modified wool, [14] this finding suggests that the AuNPs deposition performances of the modified materials are almost similar, even the difference in PATP deposition routes, the position of the SH groups that are available for AuNP coordination, and PATP contents (%).…”

“…In the previous study, ATR-FTIR analysis demonstrated that the chemical reduction pretreatment of wool resulted in the alterations of secondary peptide structure from α-helix to βsheet through the shifts in the NH stretching vibrations of amide I band (at 1640 cm À 1 ). [14] After successive 3,4-ATP immobilization and polymerization steps, the characterization studies were continued, and the respective ATR-FTIR spectra of the samples are listed in Figure 2.…”

“…For this purpose, the polymerization reactions were conducted at two different APS concentrations, including 0.4 M and 0.6 M, where the monomer/oxidant mol ratios were taken more than 2, considering the polymerization of ATP molecules. [14] The direct coating of the WSH fabrics (composite formation) was also investigated to monitor the polymerization process, and the results are presented in Figure 1a. As can be seen from the figure, the P3ATP or P4ATP contents % of the samples increased with increasing APS concentration, and this increase was more remarkable in the P3ATP/WSH composite.…”

“…These conjugated monomers can be easily polymerized or deposited on the surfaces using a suitable oxidizing source, such as chemical oxidants (i. e., persulfates) in chemical polymerization and electrical potential in electrochemical polymerization in an aqueous acidic medium. [14][15] The presence of thiol groups also enables the permanent disulfide link construction with the thiol groups containing surfaces. Thus, chemically-durable support materials can be prepared by straightforward disulfide modification or reconstruction.…”

“…Only in our recent study, the grafting or coating of poly(2-amino thiophenol) (P2ATP) onto the wool keratin was studied for the decoration of PdNPs that can be used as a practical heterogeneous catalyst platform for 4-nitroaniline (4-NA) and 2-nitrophenol (2-NP) reduction. [14] Unlike these published works, we investigated the covalent assembly of 3-ATP and 4-ATP conjugated monomers onto the WSH in this study. Following this step, in-situ oxidative polymerization ensured P3ATP or P4ATP polymers grafted onto the modified WSH surface.…”