Synergistic effect of a triethanolamine-modified carbon-based layered double hydroxide for efficient removal of nitrate from micro-polluted water.

Owing to the ubiquitous existence and low concentrations of detrimental nitrogen pollutants in micro-polluted water, simple adsorption-oriented approaches are becoming increasingly appealing for the effective removal of NO from wastewater. Triethanolamine (TDA) modified carbon-based layered double hydroxide (LDH) composites (TDA@LDH/CS) were synthesized by a supersaturated co-precipitation method for efficient NO adsorption. The characterization results showed that TDA@LDH/CS, formed by the stacking of irregular nanosheets and lamellar aggregates, has a mesoporous structure and a specific surface area of 67.15 m g. The Langmuir and pseudo-second-order kinetic models were well fitted with the adsorption of NO by TDA@LDH/CS, with the maximum adsorption capacity reaching 14.45 mg g, and the adsorption process was consistent with the spontaneous exothermic entropy increasement. Furthermore, the synergistic adsorption mechanism of NO by the TDA-modified materials was proposed using XPS analysis, which indicated that TDA modification greatly enriched the surface of TDA@LDH/CS with tertiary amine groups (RN) and hydroxyl groups (-OH), providing more adsorption sites and active sites. After five cycles, the NO removal rate could still reach 64.2%, which exhibited its high potential to be utilized as an adsorbent for the removal of nitrogen pollutants from micro-polluted water.