Effect of synthesis process on the properties of GO/Ca(OH)2 nanocomposite and dye removal efficiency

In this study, graphene oxide (GO) was synthesized by modified Hummer method and Ca(OH)₂ was synthesized using a hydrothermal route at 180°C for 24 hours. After the synthesis of graphene oxide (GO) and Ca(OH) 2 , the nanocomposites of GO/Ca(OH) 2 were synthesized using two different methodologies, first was chemical-precipitation method (CP) and second was hydrothermal method (HT). The synthesized samples were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-visible spectroscopy, Brunauer-Emmett-Teller (BET) and Field emission scanning electron microscopy (FESEM) to analyze their crystalline structure, chemical composition, optical properties, surface area and surface morphological study, respectively. The average crystal size was obtained as 100.47, 102.71, and 104.25 nm for Ca(OH)₂, GO/Ca(OH)₂-CP, and GO/Ca(OH)₂-HT, respectively. The optical bandgap for Ca(OH)₂ was found to be 5.726 eV, while the bandgap energy increased for the GO/Ca(OH)₂ nanocomposite material. Morphological studies revealed wrinkled GO sheets, nanoscale Ca(OH) 2 particles, and a well-integrated composite structure with uniformly dispersed Ca(OH) 2 nanoparticles on the GO surface. Further, two types of dyes were selected for the study of wastewater treatment, one of which was a cationic dye Rhodamine-6G (Rh6G) and another was anionic dye Methyl Orange (MO). Rh6G was 97% removed by all the samples due to attractive electrostatic interaction between nanomaterials and Rh6G, and methyl orange was less removed due to repulsive electrostatic interaction. This work uniquely mixed GO and Ca(OH) 2 to develop a hybrid nanocomposite material for cost effective treatment of wastewater. GO, Ca(OH)₂, and GO/Ca(OH)₂ nanomaterials were synthesized using the modified Hummer’s method, co-precipitation method, and hydrothermal method. The crystal size is obtained between 100 to 104 nm for Ca(OH)₂ and GO/Ca(OH)₂ nanocomposites. Further, all synthesized materials were tested for wastewater treatment. As a result, the present materials are best suitable for cationic dye adsorption.