Abstract
The renewable, proteinaceous, marine biopolymer spongin is yet the focus of modern research. The preparation of a magnetic three-dimensional (3D) spongin scaffold with nano-sized Fe3O4 cores is reported here for the first time. The formation of this magnetic spongin–Fe3O4 composite was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential thermal analysis (DTA) (TGA-DTA), vibrating sample magnetometer (VSM), Fourier-transform infrared spectroscopy (FTIR), and zeta potential analyses. Field emission scanning electron microscopy (FE-SEM) confirmed the formation of well-dispersed spherical nanoparticles tightly bound to the spongin scaffold. The magnetic spongin–Fe3O4 composite showed significant removal efficiency for two cationic dyes (i.e., crystal violet (CV) and methylene blue (MB)). Adsorption experiments revealed that the prepared material is a fast, high-capacity (77 mg/g), yet selective adsorbent for MB. This behavior was attributed to the creation of strong electrostatic interactions between the spongin–Fe3O4 and MB or CV, which was reflected by adsorption mechanism evaluations. The adsorption of MB and CV was found to be a function of pH, with maximum removal performance being observed over a wide pH range (pH = 5.5–11). In this work, we combined Fe3O4 nanoparticles and spongin scaffold properties into one unique composite, named magnetic spongin scaffold, in our attempt to create a sustainable absorbent for organic wastewater treatment. The appropriative mechanism of adsorption of the cationic dyes on a magnetic 3D spongin scaffold is proposed. Removal of organic dyes and other contaminants is essential to ensure healthy water and prevent various diseases. On the other hand, in many cases, dyes are used as models to demonstrate the adsorption properties of nanostructures. Due to the good absorption properties of magnetic spongin, it can be proposed as a green and uncomplicated adsorbent for the removal of different organic contaminants and, furthermore, as a carrier in drug delivery applications.
Highlights
Adsorption-based techniques are considered to be among the most efficient technological options for water treatment, especially in industrial organic waste applications.Removal of organic dyes from wastewater using a broad array of adsorbents is still under extensive investigation [1]
The result revealed a gradual decrease in the methylene blue (MB) adsorption capacity and a slight decrease in the crystal violet (CV) adsorption capacity of the magnetic biosorbent with an increase in the NaCl concentration up to 0.2 M (Figure 7a)
Decreased adsorption capacity due to higher ionic strength caused by the addition of sodium chloride is because of the repulsion between Na+ and cationic MB and CV dyes
Summary
Adsorption-based techniques are considered to be among the most efficient technological options for water treatment, especially in industrial organic waste applications. Removal of organic dyes from wastewater using a broad array of adsorbents is still under extensive investigation [1]. Numerous industrially used dyes are highly toxic, resistant to natural degradation, and can seriously damage the environment [2]. MB is a cationic dye with high water and alcohol solubility that is commonly used in the textile industry. CV is a water-soluble cationic dye commonly used in the textile industry and in printing inks. Proper treatment techniques for removing these organic pollutants from wastewater are urgently needed in order to avoid environmental damage
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