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Abstract:
In this study, a hybrid composite material was synthesized using waste tire (WT) rubber based activated carbon (WTAC) with functionalized graphene nanoplates (FGNPs). The precursor WT was activated using two steps of physical activation under nitrogen flow (N2) to ensure inert atmosphere. Prior to integration with WTAC, Graphene Nanoflakes (GNPs) were refluxed with KOH and further subjected to secondary pyrolysis at 650ºC for 1 hour under nitrogen (N2) flow. Prior to the second phase of activation base catalytic approach was undertaken to enhance the surface area of WTAC as well as functionalize the GNPs to improve the adsorption capacity of Malachite Green (MG) from waste water, The synthesized composite and its’ initial precursor of WT were analyzed using various techniques, including field emission scanning electron microscopy (FESEM), BET surface area measurement, thermogravimetric analysis (TGA), ultimate analysis (CHNOS), and X-ray diffraction analysis. Bulk density along with Methylene Blue number of the hybrid composite was determined. The nanocomposite demonstrated superior performance compared to the respective activated carbon of WTAC in terms of removal efficiency (%R) and equilibrium time. The adsorption data were analyzed using Langmuir, Freundlich, and Temkin isotherm models, while the kinetics data were evaluated through linear regression analysis of pseudo first-order, pseudo second-order, and intra-particle diffusion models for the composite samples. Equilibrium kinetics analysis was conducted at room temperature for both samples, while isotherm analysis was performed at 30, 50, and 70 ºC to examine the impact of temperature on removal efficiency. The Langmuir separation factor (RL) and the Freundlich factor (1/n) were both below one, indicating a favorable sorption process. The WT/FGNPs sample exhibited a higher surface area after secondary pyrolysis, compared to WTAC. Thermodynamics parameters like Gibb’s Free energy, Enthalpy and Entropy were calculated along with activation energy. These results highlight the potential of WT materials for carbon based composite formation as effective adsorbents for MG removal from wastewater.
Keywords: Graphene Nanoplates (FGNPs), Waste Tyre Rubber (WT), Kinetics, Isotherm, Thermodynamics
