Preparation of graphene oxide-doped silica aerogel using supercritical method for efficient removal of emerging pollutants from wastewater

Abstract

Emerging pollutants and a large volume of unused dyes from the textile industry have been contaminating water bodies. This work introduces a scalable approach to purifying water by the adsorption of Acid green 25 (AG), Crystal Violet (CV), and Sulfamethoxazole (SMA) from an aqueous solution by graphene oxide (GO) doped modified silica aerogel (GO-SA) with supercritical fluid deposition (SFD) method. Characterization of GO-SA using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), high-resolution scanning electron microscopy (HR-SEM), thermogravimetric analysis (TGA), and Brunauer–Emmett–Teller (BET) adsorption isotherms revealed the improvement in the adsorbent surface area, and its textural properties. The high removal percentages observed in most of the experimental runs provide evidence of the excellent performance of the adsorbent towards the anionic and cationic dyes along with the antibiotic. The adsorption isotherm and kinetics showed that the Langmuir isotherm and pseudo-second-order kinetic models could explain adsorption. The adsorbent holds a higher adsorption capacity for SMA (67.07 mg g−1) than for CV (41.46 mg g−1) and AG (20.56 mg g−1) due to the higher hydrophobicity that interacts with the hydrophobic adsorbent. The GO-SA successfully removed AG, CV, and SMA with removal percentages of 98.23%, 98.71%, and 94.46%, respectively. The parameters were optimized using Central Composite Design (RSM-CCD). The prepared aerogel showed excellent reusability with a removal efficiency of > 85% even after 5 cycles. This study shows the potential of GO-SA adsorbent in textile and other wastewater purification.

Biomass-based graphene aerogel for the removal of emerging pollutants from wastewater

“…The doping of GO in silica aerogel was done in a customized high vacuum using a supercritical method. 3 The emerging contaminant removal studies were performed in 100 mL of solution, as demonstrated in Fig. 2a.…”

“…2d. 3 Shukla et al reported efficient adsorptive removal of histamine from red wine using a crude biomass derived graphene aerogel. The designed setup could contain a contaminated liquid sample and the flow rate of liquid can be regulated by N 2 pressure.…”

“…10c shows the negative zeta potential of the GO SA at different pH values, which was due to the presence of partially negatively charged silanol groups (–Si–OH) on its surface. 3 The adsorption of sulfamethoxazole (SMA) onto the GO SA occurred via weak intermolecular forces. These forces do not depend on pH.…”

“…2 These compounds have diverse chemical nature including endocrine disruptors, pharmaceuticals and personal care products (PPCPs), microplastics, antibiotics, ionic liquids, polycyclic aromatic hydrocarbon derivatives and engineered nanoparticles. 3–5 Emerging pollutants can enter the water through various sources such as industrial activity, agricultural waste, hospitals and household activities, as well as from the improper disposal of pharmaceuticals, expired medicine and other chemicals. 3 Various reports on adverse effects of these emerging pollutants on the ecosystem as well as the methods for their detection and removal have been reported.…”

“…3–5 Emerging pollutants can enter the water through various sources such as industrial activity, agricultural waste, hospitals and household activities, as well as from the improper disposal of pharmaceuticals, expired medicine and other chemicals. 3 Various reports on adverse effects of these emerging pollutants on the ecosystem as well as the methods for their detection and removal have been reported. 6,7 Conventional wastewater treatment processes such as reverse osmosis, flotation, electro-precipitation, membrane separation, flocculation, ion exchange, etc.…”