Unrefined Montmorillonite Nanoclay-Cinnamon Wood Biochar Composite for Simultaneous Removal of Hardness and Fluoride in Groundwater

Abstract

It was aimed to synthesize an adsorbent for fluoride and hardness removal using a nanoclay-biochar composite from unrefined Montmorillonite (MMT) clay from the Murunkan in Mannar, Sri Lanka. Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Scanning Electron Microscope (SEM), and Thermal Gravimetric Analysis (TGA) were employed to characterize the materials. FTIR, XRD, and TGA analyses indicated the presence of MMT clay mineral in the sample. The SEM image of the composite confirmed the successful binding of MMT onto the biochar through a flaky appearance along the porous morphology. Further, the surface texture of clay and biochar could support hardness and fluoride removal by enhancing adsorption. The results obtained from CHN analysis show that the biochar sample was rich in carbon, which helps in the sorption of hardness and fluoride. The adsorption isotherm data of all the adsorbents were well fitted to the Temkin isotherm model, suggesting that the removal of hardness and fluoride onto the adsorbent indicates a heat of sorption. The kinetic adsorption data of all the adsorbents were well fitted to the pseudo-first-order kinetic model, indicating the dominant contribution of the physisorption mechanism. However, since the measured adsorption was minimal, a modification to the nanoclay-biochar composite is required for higher sorption efficiency by enhancing the active sites on sorbents to purify groundwater that con