Ion-selective adsorption of lead by a two-dimensional terbium oxalate framework

Nankawa, Takuya ; Sekine, Yurina   ; Yamada, Teppei*

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 Pb, Cd, Mn, Co, Ni, Cu, Na, K, Mg, and Ca showed that the TOF has high selectivity for Pb among other metal ions. The saturated adsorption capacity of the TOF for Pb was 276 mg g, which is higher than that of conventional adsorbents. Furthermore, the TOF exhibited reversible Pb adsorption/desorption and could be used for at least three cycles. The results showed that TOF has excellent potential as an adsorbent for removing Pb, and because of its reusability, it is also a promising material for wastewater clean-up.