Large-pore diameter nano-adsorbent and its application for rapid lead(II) detection and removal from aqueous media

The detection and removal of lead (Pb(II)) ions in water is essential for both human health and the natural environment. This study reported the feasibility of the large-pore diameter nano-adsorbent for capturing low level Pb(II) ions from aqueous solutions in a batch system, in order to comply with the toxicity limit for discharging wastewaters. The nano-adsorbent was prepared by incorporating organic ligand onto the mesoporous silica. The proposed Pb(II) detection system has good characteristics with high sensitivity and selectivity, robustness, easy operation, portability and use of a small sample volume. The sensitive detection was determined under specific optimum conditions and the limit of detection was 0.29. μg/L. The competing ions effect was assessed with spiked samples and the nano-adsorbent exhibited high selectivity to Pb(II) ions with optimum color formation and the detection procedure can be easily applied to rapid on-site Pb(II) ions monitoring. The sorption results clarified that the Pb(II) sorption increased as the initial Pb(II) ion concentration increased. Also the solution pH played an important role for selective uptake of Pb(II) ions. Isotherm data fitted well to the Langmuir isotherm model, indicated as monolayer and spontaneous processes and the maximum sorption capacity was 169.34. mg/g. The sorption results of the nano-adsorbent were compared with the other forms of different adsorbents. In addition, the adsorbent displayed an excellent selectivity to Pb(II) ions over diverse ions in the multi-mixtures metal species system. The adsorbent exhibited reusability and can work for many cycles of Pb(II) detection and removal without significant deterioration of the nano-adsorbent functionality. The results showed that the nano-adsorbent developed in this work has excellent performance to be applied for selective Pb(II) detection and removal from water samples.