Journal Articles - Natural Science - 2021

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Browsing Journal Articles - Natural Science - 2021 by Author "Dao Ngoc Nhiem"
  • Publication
    Electrochemical Determination of Diclofenac by Using ZIF-67/g-C3N4 Modified Electrode
    ( 2021)
    Dang Thi Ngoc Hoa
    ;
    Nguyen Thi Thanh Tu
    ;
    Le Van Thanh Son
    ;
    Le Vu Truong Son
    ;
    Tran Thanh Tam Toan
    ;
    Pham Le Minh Thong
    ;
    Dao Ngoc Nhiem
    ;
    Pham Khac Lieu
    ;
    Dinh Quang Khieu
    ;
    Thanh Son Le
    A facial differential pulse voltammetric procedure using a glassy carbon electrode modified with zeolite imidazolate framework-67/graphitic carbon nitride (ZIF-67/g-C3N4) for the diclofenac (DCF) determination is demonstrated. ZIF-67/g-C3N4 with different mass ratios of the components was synthesized in a self-assembly process. The obtained materials were characterized by using X-ray diffraction, scanning electron microscopy (SEM), EDX-mapping, and nitrogen adsorption/desorption isotherms. The peak current varies linearly with the DCF concentration in the range of 0.2–2.2 μmol·L−1 and has a detection limit of 0.071 μmol·L−1. The modified electrode exhibits acceptable repeatability, reproducibility, and selectivity towards DCF. The proposed electrode allows determining DCF in human urine without pretreatment, and the results are comparable with those determined with HPLC.
  • Publication
    Fluoride and Arsenite Removal by Adsorption on La2O3-CeO2/Laterite
    ( 2021)
    Duong Thi Lim
    ;
    Trinh Ngoc Tuyen
    ;
    Dao Ngoc Nhiem
    ;
    Dao Hong Duc
    ;
    Pham Ngoc Chuc
    ;
    Nguyen Quang Bac
    ;
    Dang Xuan Tung
    ;
    Ngo Nghia Pham
    ;
    Luu Thi Viet Ha
    ;
    Nguyen Thi Thanh Tu
    ;
    Vo Thang Nguyen
    ;
    Dinh Quang Khieu
    ;
    Dong kee Yi
    In the present article, the adsorbent prepared from laterite with lanthanum and cerium oxides (La2O3-CeO2/laterite (LCL)) was efficiently employed for the removal of arsenite and fluoride from an aqueous environment. The obtained materials were characterized by XRD, SEM, and nitrogen adsorption/desorption. The synthesized LCL exhibited a high adsorption capacity towards arsenite (As(III)) and fluoride. The adsorption of both analytes on LCL, which was well-fitted to a pseudo-second-order equation, was found to be kinetically fast in the first 20 minutes and reached equilibrium at around 180 minutes. Weber’s intraparticle diffusion model in multilinearity using the piecewise linear regression combined with Akaike’s criteria was addressed. The adsorption capacities of LCL calculated from Langmuir’s isotherm model were found to be 67.08 mg·g-1 for arsenite and 58.02 mg·g-1 for fluoride. Thermodynamic parameters presented an endothermic nature of arsenite adsorption but an exothermic nature for fluoride and a negative Gibbs free energy for the spontaneous process of arsenite or fluoride adsorption at the studied temperature range. The excellent adsorption performance and stability make the composite of laterite and La-Ce binary oxides an alternative efficient and cheap adsorbent for the removal of arsenite and fluoride in an aqueous solution.