Molecular imprinting technology(MIT) is known as a technology for creation of tailor-made binding sites with memory of the shape, size and functional groups of the template molecules. Ion imprinting technology is the technology that creating three-dimensional cavity structures in a polymer matrix, i.e., ion imprinting polymers (IIPs) by the copolymerization of functional monomers and cross-linkers in the presence of target ion that act as template molecules based on coordination or electrostatic interactions. After removal of the template ion with acidic reagent, recognition cavities complementary to the template ion were formed in the highly cross-linked polymer matrix. Owing to the special coordination, ion imprinting technology, as an important branch of MIT, obtained the rapid development. Heavy metal ion as the most typical water-soluble ion, has gained increasing concerns. So, effective identification and quantification of heavy metal ions by using ion imprinting polymers are highly crucial. The principles, synthesis strategies of ion imprinting and advantages on analysis of trace and ultra-trace metal are introduced in the review.Then, the applications of ion imprinted polymers for typical heave metal ions from environmental monitoring including lead, mercury, copper, cadmium, chromium and arsenic ions are summarized. Finally, the challenges and possible solution strategies, and future trends are proposed.

Contents
1 Introduction
2 Ion imprinting technology
2.1 Principles of ion imprinting
2.2 Preparation of ion imprinting
2.3 Superiority
3 Typical heave metal ion imprinted polymers and their applications
3.1 Pb-IIPs
3.2 Hg-IIPs and CH₃Hg-IIPs
3.3 Cu-IIPs
3.4 Cd-IIPs
3.5 Cr-IIPs
3.6 As-IIPs
4 Conclusion and outlook