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a b s t r a c tThe molecular structures and electron affinities of the SeO n /SeO n À (n = 1-5) species were examined using hybrid Hartree-Fock/density functional theory(DFT). The basis set used in this work was of double-f plus polarization quality with additional diffuse s-and p-type functions, denoted DZP++. Seven different density functionals (B3LYP, BLYP, BHLYP, BP86, B3P86, BPW91, and B3PW91) were used in this work. The ground state structures of the SeO n (n = 1-5) was explored in this work. The SeO have a 3 Rg À ground state, the SeO 2 have an open C 2V (ozone-like) structure. For the SeO 3 , D 3h structure is turn to be ground state. The SeO 4 has C 2V (ozone-like) structure, and The SeO 5 has C 2 structure. The most reliable adiabatic electron affinities, obtained at the DZP++ BLYP and DZP++ BPW91 level of theory, are be1.38 or 1.40 eV (SeO), 1.87 or 1.89 eV (SeO 2 ), 3.28 or 3.23 eV (SeO 3 ), 4.98 or 4.79 eV (SeO 4 ), 6.15-6.12 eV (SeO 5 ). The BHLYP bond length of the SeO atom, SeO 2 molecules predicted by this work are in reasonable agreement with the experimental results. The dissociation energies predicted by the B3P86 method are the most reliable. For the vibrational frequencies of Selenium Oxygen, the B3LYP methods produce good predictions compared with the limited experiments.

Heavy-metal ions are common pollutants in wastewater and are thus attracting considerable attention. Herein, an eco-friendly biodegradable adsorbent, iminodisuccinic acid (IDS) modified attapulgite (ATP) is prepared by graft-polymerization to reduce Cu(II) in water, referred as IDS-ATP. The equilibrium adsorption capacity of IDS-ATP for Cu(II) is increased by 329.5% and 272% compared with raw ATP and non-degradable chelator ethylenediaminetetraacetic acid-modified ATP (EDTA-ATP), respectively. Moreover, the adsorption capacities for Cu(II) in combined system increased by 186% compared with in single system. The structure and surface properties of IDS-ATP are characterized, demonstrating that the IDS moieties are anchored on the surface of ATP without structural damage. In the aqueous Cu(II) (64 mg /L), the best adsorption pH is 5.0, the best dosage is 800 mg/L, and the adsorption equilibrium time is 4 h. The adsorption of IDS-ATP is chemical adsorption and regenerated adsorbent still exhibits high adsorption capacity. The adsorption mechanism includes the coordination of amino groups with Cu(II), the chelation of -COOH on heavy metals (HMs), and the ion exchange. Taking Cu(II) as an example to study the process of IDS-ATP in water, it is beneficial to apply this degradable material to reduce the other HMs.

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