Reduction in Chemical Oxygen Demand of TNT Red Water Using Layered Double Hydroxide Prepared from Red Mud and Brucite

A low-cost organolayered double hydroxide adsorbent prepared under alkali conditions with red mud (waste tailings from alumina production) and brucite is modified by anionic surfactant, sodium dodecyl benzene sulfonate (SDBS), by ion exchange to produce a layered double hydroxide adsorbent (LDH-SDBS). LDH-SDBS was used to treat 2,4,6-trinitrotoluene (TNT) red water that had high toxicity, contained persistent compounds, and had a high chemical oxygen demand (COD). Removal efficiency reached 46% at 20-fold dilution (COD, 4024 mg/L) and kinetics showed that adsorption processes followed a pseudo-second-order model. Negative ΔG and positive ΔH indicated adsorption was spontaneous and endothermic and Gas Chromatography-Mass Spectrometer (GC/MS) revealed that amounts of organic compounds in TNT red water were reduced significantly.