Novel amidinothiourea-modified chitosan microparticles for selective removal of Hg(II) in solution

Glutaraldehyde-crosslinked chitosan microparticles (CGP) prepared via the inversed-phase emulsification were successively modified by epichlorohydrin (ECH) and amidinothiourea (AT) as novel adsorbent (CGPET) for selective removal of Hg(II) in solution. FTIR, EA, XPS, SEM-EDX, TG, DTG, and XRD results indicated that CGPET had ample -NH2 and C-S, relative rough surface, mean diameter of similar to 40 mu m, great thermal stability, and crystalline degree of 2.4%, beneficial to the uptake of Hg(II). The optimum parameters (pH 5, dosage 1 g/L, contact time 4 h, and initial concentration 150 mg/L) were acquired via batches of adsorption experiments. Adsorption behavior was well described by the Liu isothermal and pseudo-second-order kinetics models, and the maximum adsorption capacity was 322.51 mg/g, surpassing many reported adsorbents. Regeneration and coexisting-ion tests demonstrated that CGPET had outstanding reusability (Rr > 86.89% at the fifth cycle) and selectivity (Rs > 93%). Besides, its potential adsorption sites and mechanisms were proposed.

Automated summary

CGPET, a novel adsorbent, was prepared by modifying glutaraldehyde-crosslinked chitosan microparticles with epichlorohydrin and amidinothiourea for selective removal of Hg(II) in solution. Characterization techniques revealed its unique surface properties, thermal stability, and high adsorption capacity surpassing many reported adsorbents. Adsorption behavior was well described by isothermal and pseudo-second-order kinetics models, highlighting its outstanding reusability and selectivity.