Controlled synthesis of graphene oxide/silica hybrid nanocomposites for removal of aromatic pollutants in water

Abstract

The remarkable characteristics of graphene make it a model candidate for boosting the effectiveness of nano-adsorbents with high potential owing to its large surface area, π–π interaction, and accessible functional groups that interact with an adsorbate. However, the stacking of graphene reduces its influence adsorption characteristics and also its practical application. On the other hand, the widespread use of aromatic compounds in the industry has aggravated the contamination of the water environment, and how to effectively remove them has become a research hotspot. Herein, we develop the functionalization of silica nanoparticles on graphene oxide nanosheet (FGS) by a facile, cheap, and efficient synthesis protocol for adsorption of Trypan Blue (TB) and Bisphenol A (BPA). It was demonstrated that chemical activation with KOH at high autoclaving temperature successfully transformed rice husk ash (RHA) into FGS. The graphene oxide layered interlamination was kept open by using SiO2 to expose the interlayers' strong adsorption sites. XRD, EDX, FTIR, Raman spectroscopy, SEM, HR-TEM, and BET surface area are used to investigate the chemical composition, structure, morphology, and textural nature of the as-produced FGS hybrid nanocomposite. The various oxygen-containing functional groups of the hybrid nanocomposites resulted in a significantly increased adsorption capacity, according to experimental findings. In addition, FGS2, the best composite, has a specific surface area of 1768 m2g−1. Based on Langmuir isotherms, the maximal TB dye and BPA removal capacity attained after 30 min were 455 and 500 mg/g, respectively. The Langmuir isotherm model, a pseudo-second-order kinetic model, and an intraparticle diffusion model have all been used to provide mechanistic insights into the adsorption process. This suggests that BPA and TB adsorption on FGS2 is mostly chemically regulated monolayer adsorption. Due to its unique sp2-hybridized single-atom-layer structure, the exposed graphene oxide nanosheets' extremely hydrophobic effect, hydrogen bonding, and strong—electron donor–acceptor interaction contributed to their improved adsorption of BPA and TB. According to adsorption thermodynamics, FGS2 adsorption of TB and BPA is a spontaneous exothermic reaction that is aided by lowering the temperature. For adsorption-based wastewater cleanup, the produced nanocomposites with a regulated amount of carbon and silica in the form of graphene oxide and silica can be used. These findings suggest that functionalized GO/SiO2 hybrid nanocomposites could be a viable sorbent for the efficient and cost-effective removal of aromatic chemicals from wastewater.

The superior performance of silica gel supported nano zero-valent iron for simultaneous removal of Cr (VI)

“…The lines in Fig. 9 c did not pass through the origin affirming that the adsorption of Cr(VI) could be attained via intraparticle diffusion but it was not the only rate-governing step 56 . Moreover, the non-zero intercept in the case of the Boyd model in Fig.…”

Magnetic NH2-MIL-101(Al)/Chitosan nanocomposite as a novel adsorbent for the removal of azithromycin: modeling and process optimization

“…The high adsorption rate at the beginning of process may be explained by the high affinity of MIL/Cs@Fe 3 O 4 NCs for trapping pollutants due to the huge number of vacant sites (active sites) on adsorbent. Over time, the active sites in the adsorbent structure are occupied (filled) by pollutant molecules, which results in reduced efficiency and rate of AZT adsorption 58 , 59 . In the following, four conventional kinetic models including pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion, were employed to investigate the kinetics of AZT adsorption on MIL/Cs@Fe 3 O 4 NCs under optimized conditions (see Supplementary data, Fig.…”

“…The high adsorption rate at the beginning of process may be explained by the high affinity of MIL/Cs@Fe 3 O 4 NCs for trapping pollutants due to the huge number of vacant sites (active sites) on adsorbent. Over time, the active sites in the adsorbent structure are occupied (filled) by pollutant molecules, which results in reduced efficiency and rate of AZT adsorption 58,59 .…”

Green Synthesis via Eucalyptus globulus L. Extract of Ag-TiO2 Catalyst: Antimicrobial Activity Evaluation toward Water Disinfection Process

“…The wastewater treatment by photocatalysis has been intensely studied in the past decades [ 21 ], revealing new forms of synthesis methods for the catalysts [ 22 ] and ways to to remove persistent, emergent, and complex pollutants, such as aromatic compounds [ 23 ], dyes [ 24 ], endocrine disrupters [ 25 ], personal care products [ 26 ], and pharmaceuticals [ 27 , 28 ]. Even with the amount of knowledge and information regarding this topic, more studies are conducted to achieve a scaled-up application, and more studies show that TiO 2 can be modified with silver NPs to synergize antimicrobial activity, reducing the bandgap energy (3.2 eV) and activating the photocatalyst with visible light [ 29 , 30 , 31 , 32 , 33 ].…”