Synthesis of poly(N1,N1,N6,N6-tetraallylhexane-1,6-diammonium dichloride) microparticles for removing Mo(VI) in aqueous solution

Abstract

A novel poly(N1,N1,N6,N6-tetraallylhexane-1,6-diammonium dichloride) (PTAHDADC) microparticle was prepared via inverse emulsion polymerization. The adsorption characteristics and mechanism for Mo(VI) in an aqueous solution were investigated systemically. Results showed that PTAHDADC had a high positively charge density with a positive charge at every six CH2 (or CH) units and presented a coral-like morphology, with macropores distributed in 30–130 μm, and a porosity of up to 46.52%. The Mo(VI) removal efficiency was >99% at pH = 3.0–4.0. The adsorption data could be effectively described using the Langmuir and pseudo-second-order kinetic models. The maximum adsorption capacity was up to 394.11 mg·g−1 at 293 K. The adsorption process was rapid, and reached equilibrium within 120 min with an adsorption activation energy Ea of 41.15 kJ·mol−1. The adsorption process of Mo(VI) by PTAHDADC was accompanied by the partial ion exchange of counterion Cl−, the partial deprotonation of functional groups (CH2)3N+H on PTAHDADC, and the new interaction and bond formation between Mo(VI) and PTAHDADC. Mo(VI) removal by PTAHDADC was a process of spontaneously endothermic entropy increment, which involves physisorption, electrostatic attraction, ion exchange, and chemisorption. PTAHDADC offers a simple synthesis and excellent adsorption performance and recyclability. Therefore, PTAHDADC is a highly potential adsorbent for removing Mo(VI) ions from wastewater and has a broad application prospect.