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

The effective removal of Cu2+ 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 Cu2+ ions (10 ppm) can be decreased to reach the WHO drinking water standard in 10 min. When the concentration of Cu2+ 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 Cu2+ ions with the removal efficiency of 99.9 % in the mixed solution containing Na+, Mg2+, K+, Ca2+, Cu2+, Ni2+, Zn2+ and Co2+ ions. The adsorption mechanisms of PAN@LDH-Hpdc involved the coordination by the intercalated Hpdc anions and surface adsorption by the LDH laminate.