A mesoporous poly-melamine-formaldehyde polymer as a solid sorbent for toxic metal removal

A mesoporous poly-melamine-formaldehyde (mPMF) polymer with a high surface area, good porosity and high density of amine and triazine functional groups has been designed and synthesized. This porous organic polymer (POP) was found to be highly effective in removing toxic lead ions from water. Of particular interest was the ability of mPMF to reduce lead ions in water to trace levels (ppt) within seconds. Adsorption over mPMF was found to be highly selective towards lead ions in the presence of main group cations, such as Na⁺, K⁺ and Ca²⁺, which are commonly found in water. The presence of a hexadentate ligand, ethylenediaminetetraacetic acid (EDTA), did not affect the binding of lead ions to mPMF. The feasibility of lead ion removal by mPMF from water in dynamic flow was successfully demonstrated. mPMF also displayed good affinity towards other toxic metals, including cadmium, copper and palladium. The adsorbed metal ions could be easily recovered, and the mPMF sorbent was recycled for reuse. The ease of synthesis and low cost, coupled with the efficient and rapid removal of toxic lead ions, make mPMF an attractive adsorbent for the purification of waste and contaminated water.