Super rapid removal of copper, cadmium and lead ions from water by NTA-silica gel

摘要

Copper (Cu ~(2+) ), cadmium (Cd ~(2+) ) and lead ions (Pb ~(2+) ) are toxic to human beings and other organisms. In this study, a silica gel material modified with nitrilotriacetic acid (NTA-silica gel) was sensibly designed and prepared via a simple amidation procedure for the removal of Cu ~(2+) , Cd ~(2+) and Pb ~(2+) from water. The NTA-silica gels showed rapid removal performances for the three metal ions (Pb ~(2+) (<2 min), Cu ~(2+) and Cd ~(2+) (<20 min)) with relatively high adsorption capacities (63.5, 53.14 and 76.22 mg g ~(?1) for Cu ~(2+) , Cd ~(2+) and Pb ~(2+) , respectively). At the same concentration of 20 mg L ~(?1) , the removal efficiencies of the three metals by the adsorbent ranged from 96% to 99%. The Freundlich and Langmuir models were utilized to fit the adsorption isotherms. The adsorption kinetics for the three metal ions was pseudo-second-order kinetics. The removal performance of the NTA-silica gels increased in a wide pH range (2–9) and maintained in the presence of competitive metal ions (Na ~(+) , Mg ~(2+) , Ca ~(2+) and Al ~(3+) ) with different concentrations. In addition, the NTA-silica gels were easily regenerated (washed with 1% HNO _(3) ) and reused for 5 cycles with high adsorption capacity. This study indicates that the NTA-silica gel is a reusable adsorbent for the rapid, convenient, and efficient removal of Cu ~(2+) , Cd ~(2+) , and Pb ~(2+) from contaminated aquatic environments.