Modification of alginic acid for the removal of dyes from aqueous solutions by solid-phase extraction

Industrial waste consisting of dyes has emerged as a major waterbody pollutant in these modern times. Therefore, an efficient method is required to remove and address these water contaminant concerns. The current study reported the fabrication of a new hybrid type carboxylatedalginic acid (CAA) coordinated with Sn-metal (Sn-CAA) green composite absorbent for the removal of toxic dyes such as Acid Red (AR.) and Brilliant Green (BG). To obtain CAA, alginic acid was chemically oxidised via KMnO₄ and it was subsequently used to coordinate with Sn²⁺ metal ion. The characterisation such as field emission-scanning electron microscope, X-ray powder diffraction technique and Fourier-transform-infrared spectroscopy was carried out to confirm the fabrication of CAA and Sn-CAA adsorbents. Several parameters including shaking time, pH, heating and concentration-effect were employed to conduct solid-phase extraction and UV-vis spectroscopy experiments were conducted to confirm the successful removal of toxic dyes from the aqueous media. The dye removal results established the spontaneous and endothermic nature of dye removal process as assessed through obtained thermodynamic and kinetic parameters. Furthermore, for the removal of BG and AR, the fabricated Sn-CAA-based adsorbent found to be more proficient than pristine CAA.