Carbon disulfide-modified turmeric powder-incorporated silica gel for removal of Hg2+ in aqueous media

The application of turmeric powder as a natural product-based material for removing Hg2+ from water was demonstrated. In this study, carbon disulfide-modified turmeric (MT) was synthesized and incorporated into silica gel to create a selective sorbent (SiO2-MT). Infrared spectroscopy and energy-dispersive X-ray spectroscopy confirmed that MT was successfully incorporated into the silica gel matrix. Morphological studies revealed that SiO2-MT was porous with a pore size of 1.87 nm. SiO2-MT exhibited selectivity for the adsorption of Hg2+. The overall performance of SiO2-MT in adsorbing Hg2+ significantly improved with increasing SiO2-MT dosage, ranging from 5 to 20 mg. After reaching a dosage of 20 mg of SiO2-MT, no further significant improvement was observed. The optimal pH for Hg2+ removal ranged from four to five, with approximately 90% Hg2+ removal, and the adsorption process reached equilibrium at 180 min. The adsorption data were well-fitted to the Langmuir isotherm and pseudo-second-order kinetics models, indicating that SiO2-MT adsorbed Hg2+ through monolayer adsorption and chemisorption. The maximum adsorption capacity of the synthesized SiO2-MT was 37.6 mg g−1, which is higher than that of other reported biomasses, including bamboo leaves and garlic powder. In conclusion, this study demonstrates the potential use of turmeric powder, a natural product, for effective Hg2+ removal during water treatment.