Ion-Selective Adsorption of Lead by a Two-Dimensional Terbium Oxalate Framework

Advances in hazardous metal ion removal are essential for wastewater clean-up to tackle the global water shortage crisis. Here, we report a Pb-selective adsorbent using a Tb oxalate framework (TOF) synthesized by a one-pot hydrothermal method. The TOF has a two-dimensional sheet structure, in which the interlayer space functions as an ion exchangeable site. Sorption tests using a mixed-ion solution containing Pb2+, Cd2+, Mn2+, Co2+, Ni2+, Cu2+, Na+, K+, Mg2+, and Ca2+ showed that the TOF has high selectivity for Pb2+ among other metal ions. The saturated adsorption capacity of the TOF for Pb2+ was 276 mg g−1, which is higher than that of conventional adsorbents. Furthermore, the TOF exhibited reversible Pb2+ adsorption/desorption and could be used for at least three cycles. The results showed that TOF has excellent potential as an adsorbent for removing Pb2+, and because of its reusability, it is also a promising material for wastewater clean-up.