Multi-active-site-engineered hierarchical porous silicate synthesized from graphite tailings for exceptional pollutant removal

A sustainable strategy was developed to convert graphite tailings (GT), a solid waste, into a hierarchical porous silicate adsorbent with engineered multiple active sites (denoted as GTPM12h) through an integrated mechanochemical-hydrothermal route for efficient decontamination of organic dye wastewater. The reconstructed silicate phases are enriched with oxygen-containing functional groups and metal active sites, resulting in remarkably enhanced adsorption performance. GTPM12h exhibits superior adsorption capacities of 379.76 mg·g −1 for methylene blue and 487.57 mg·g −1 for methyl violet over a broad pH range (5–9), outperforming most commercial activated carbons. At a low dosage (0.6 g·L −1 ), the removal efficiency of dyes exceeds 99.9 % in both single and ternary mixed dye systems and remains at 92.4 % after five cycles. The adsorption process follows a chemisorption-dominated monolayer mechanism driven by synergistic electrostatic attraction, hydrogen bonding, and ion exchange. This study presents an eco-friendly strategy addressing dual environmental challenges: upcycling industrial waste and remediating water pollution.