Pyrazole-3,5-dicarboxylic acid intercalated LDH: A highly selective structured adsorbents for Cu2+ ions removal

The effective removal of Cu 2+ ions from contaminated wastewater is greatly significant for environmental remediation. Herein, the PAN@LDH-Hpdc (PAN = polyacrylonitrile; LDH  = layered double hydroxide; Hpdc = pyrazole-3,5-dicarboxylate) was prepared using the “Seeds Embedded-Epitaxial Growth-Ion exchange” strategy. Benefiting from the high surface area and abundant exposed active sites, the PAN@LDH-Hpdc showed the removal efficiency of 99.6 % in 25 min, and the Cu 2+ ions (10 ppm) can be decreased to reach the WHO drinking water standard in 10 min. When the concentration of Cu 2+ ions was ∼ 1000 ppm, the adsorption capacity of PAN@LDH-Hpdc was as high as 200.0 mg/g. In addition, the PAN@LDH-Hpdc exhibited high selectivity for Cu 2+ ions with the removal efficiency of 99.9 % in the mixed solution containing Na + , Mg 2+ , K + , Ca 2+ , Cu 2+ , Ni 2+ , Zn 2+ and Co 2+ ions. The adsorption mechanisms of PAN@LDH-Hpdc involved the coordination by the intercalated Hpdc anions and surface adsorption by the LDH laminate.