Design and fabrication of sulfonic acid functionalized graphene oxide for enriched fluoride adsorption

In this research paper, sulfonic acid functionalized graphene oxide namely sulfonated GO (SGO) was utilized as an adsorbent material for defluoridation from water environment. Fluoride adsorption experimentations were employed under batch scale to optimize the diverse influencing factors such as contact time (10-60 min), SGO dosage (0.025 to 0.25 g), initial fluoride concentrations (2-14 mg/L), temperature (303, 313 and 323 K) and adsorbate pH (3-11). The defluoridation capacity (DC) of SGO was identified to be 4260 mgF- kg- 1 for 10 mg/L of initial fluoride solution using 0.1 g SGO dosage. The contact time and adsorbate pH for enhanced defluoridation was noted at 40 min and pH 6 respectively. The sophisticated instrumental methods like TEM, FTIR, XPS, SEM, and TGA were performed to evaluate the physiochemical properties of adsorbent material. The experimentally obtained equilibrium data of SGO were applied to three adsorption isotherm models viz., Langmuir, Dubinin-Radushkevich (D-R) and Freundlich isotherms. In kinetic models, the obtained equilibrium data follows intraparticle diffusion and pseudo-second-order models for fluoride adsorption by SGO. Thermodynamic investigation shows that the defluoridation process of SGO was spontaneous and endothermic in nature. Regeneration studies of SGO material was carried out and its results exhibit that SGO was regenerable one. Moreover, field sample taken from fluoride endemic village was also investigated using synthesized SGO material.