Elsevier

Current Applied Physics

Volume 40, August 2022, Pages 110-118
Current Applied Physics

Probing the role of hydrolytically stable, 3-aminopropyl triethoxysilane crosslinked chitosan/graphene oxide membrane towards Congo red dye adsorption

https://doi.org/10.1016/j.cap.2021.07.006Get rights and content

Highlights

  • A green novel chitosan/graphene oxide (GO) nanocomposite membrane was synthesized.

  • Chitosan/GO membrane showed promising results for the removal of toxic dye, this membrane can be used for the potential applications as adsorbent (membrane separation technology).

  • Swelling and hydrolytic study exposed the other possible uses/application of membranes.

  • Results showed the possibility of exploring a new hybrid system for contaminants removal which can be incorporated in various flow systems and can be easily recovered.

Abstract

In this investigation, the practicability of utilizing 3-aminopropyl triethoxysilane (3-APTES) crosslinked chitosan (Ch)/graphene oxide (GO) membranes were explored for adsorptive removal of anionic dyes from aqueous medium. Membranes were successfully fabricated through solution casting technique. Strong interactions amongst matrix (chitosan), 3-APTES, polyvinylpyrrolidone (PVP) and GO were confirmed by Infrared spectroscopy. Thermal stability of the chitosan was improved by adding graphene oxide and results were verified via thermogravimetric (TGA) analysis. Swelling and hydrolytic results confirmed that 2 %-Ch/PVP was a stable membrane while increasing the amount of 3-APTES in the chitosan nanocomposites membrane decreased its stability in aqueous medium. The adsorption characteristics of the membranes were evaluated by the adsorption of Congo red (CR) dye from aqueous medium. The adsorbent can remove 80% of CR from aqueous medium and follows second order kinetics. This study outlines the possibility of exploring green membranes which can be easily fit in various flow systems.

Introduction

During the last decade Graphene oxide (GO) has emerged as an interesting material for polymer composites and in particular, has markedly increased the efficiency of wastewater treatment in many cases [[1], [2], [3]]. The presence of carboxyl and hydroxyl groups on the surface of GO renders it hydrophilic, and quite reactive towards adsorbents [4,5]. Another important advantage of GO is its potential for interaction through strong π-π interactions [[6], [7], [8]]. Congo red (CR) is a benzidine-based anionic dye which is discharged [9] into water courses from the printing, dyeing, paper and textile industries [10,11]. CR is believed to metabolize into benzidine, a known human carcinogen [12,13], so its removal from waste resources is very important. The potential advantages of GO led Debnath et al. [14] to investigate the adsorption of CR by powdered GO. Their results showed good adsorption, but handling GO and its removal from water requires extra time and effort and traces of the material may be left behind. To address this issue, GO supported material can be used. Using a biopolymer-based support would offer a more environmentally benign, and greener approach [15,16].

Chitosan extracted from the exoskeletons of shellfish [17]or Fungi [18], is a natural polysaccharide which shows good biocompatibility and biodegradability [19]. It is non-toxic and can be easily functionalized with other materials. Chitosan is also a strongly adsorbed material due to the presence of large numbers of amino and hydroxyl groups [20]. Its cationic nature could give additional benefit for the removal of anionic dyes such as CR [21,22]. Chitosan readily forms thin membranes or films [23] and can also be blended with other polymers to enhance its mechanical properties [24], an example being PVP. Ch-PVP blends which are miscible [25,26] due to the interactions between the hydroxyl groups in Ch and the carbonyl groups in PVP.

In this paper, we report efforts to improve the adsorptive performance of Ch/PVP membranes by incorporating GO as a nanofiller. Ch/PVP/GO nanocomposite membranes were prepared using a simple solution-casting technique. The swelling, oxidative and hydrolytic constancy and adsorptive performance of membranes have been determined.

Section snippets

Materials and methods

Chitosan (C3646, 75% de-acetylated), 3-(aminopropyl)triethoxysilane (3-APTES), PVP (average MW: 40,000), sulphuric acid, phosphoric acid, congo red, acetic acid, ethanol, potassium permanganate, and hydrochloric acid (HCl) were purchased from Sigma Aldrich. Ferrous sulphate and hydrogen peroxide were purchased from Merck. All chemicals were analytical grade and used without further purification.

Synthesis of graphene oxide (GO)

Expanded graphite was prepared [27] from commercial graphite by treating it with 25 mL of

Morphological analysis

Fig. 1 shows SEM micrographs of Ch/PVP/GO, Ch/PVP and CR-adsorbed nanocomposites membranes. Graphene sheets are visible in the micrographs of the GO containing membranes (the inset (Fig. 1a) shows a TEM of GO dispersed in ethanol) and also indicate homogeneous blending of PVP with the chitosan. Uniform dispersion of filler throughout the polymer matrices is shown in Fig. 1b. Fig. 1c shows the SEM image of Ch/PVP film while Fig. 1d represents the surface morphology of films after dye uptake.

Structural analysis

In

Conclusion

This work describes the fabrication and adsorptive characteristics of nanocomposite membranes consisting of GO dispersed in a Ch/PVP matrix. These combinations not only improve the adsorptive properties but also enhanced the thermal ability of the chitosan. Swelling, as well as hydrolytic results, confirmed that level of GO of 2%-Ch/PVP gave the most stable membrane while increasing the amount of 3-APTES crosslinker reduced the stability towards aqueous media due to the increased amount of

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

The authors would like to extend their sincere appreciation to the Deanship of Scientific Research at King Saud University for its funding of this research through the Research Group Project no. RGP-293.

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