Enhanced Selective Removal of Cd(II) by an Amino-Functional Water-Retaining Agent Incorporating Nano Hydrous Manganese Oxide

An amino-functionalized water-retaining agent (PPM40-NH(2)) and a water-retaining agent lacking functionalization (PPM40) were prepared to investigate their selective Cd(II) removal properties. The affinity for Cd(II) was increased after introducing the amino functional group. The SFCd/Ca of PPM40-NH(2) was 3-7 fold higher than that of PPM40 although the CCa was 100-1000 times higher than that of CCd. The chelating effect of -COOH and -NH(2) in PPM40-NH(2) corresponded well with the selective adsorption of Cd(II), as confirmed by simulations. A seed germination experiment demonstrated that PPM40-NH(2) could act as a filter of heavy metals to supply "clean" water for the roots of the pakchoi plant. The leaching experiment indicated that PPM40-NH(2) is an efficient in situ fixation agent for the remediation of agricultural soil contaminated with Cd(II) in the presence of high concentrations of Ca(II) salts.