Application of Chemically Modified Coal Mine Waste for the Sustainable Management of Fluoride in Drinking Water

Waste rocks obtained from mining operations are typically stockpiled due to the lack of their economic value. This practice resulted in significant land occupation and potential for secondary pollution risks due to the lack of probability of leaching. The present study explores the possible utilization of waste rocks as a novel adsorbent for treating F⁻ enriched groundwater. Shale, a coal mine waste was chemically modified by ferrous chloride in a 3 : 1 ratio. Optimization of the adsorption process was done by performing batch adsorption. Surface morphological characterization of the adsorbent was performed by scanning electron microscopy (SEM), energy-dispersive X-ray (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectrophotometer (FTIR). The best results were obtained when 100 mg/L was used to defluoridate contaminated water for 60 min at neutral pH. The efficiency of management was 32% removal at 10 ppm fluoride contamination. Post-treatment adsorbent can be utilized in brick formation to rule out any possibility of secondary/tertiary contamination.