Seminar khoa học của GS.TS Xavier Chateau và TS. Hoàng Lê Thụy Thùy Trang

Vào 9h00 ngày 17/7/2023, Viện IAST tổ chức buổi trao đổi học thuật tại phòng họp C với nội dung chi tiết như sau: 

GS.TS Xavier Chateau trình bày về "The origins of thixotropy in attractive colloidal suspensions"

Abstract:

The behavior of dense aqueous silica suspensions is investigated through a comprehensive experimental approach that considers the material’s properties at different length scales, from the contact level up to the overall properties. The first part of the study explores the ageing behavior of these suspensions and identifies a contact-controlled ageing process that governs both the shear modulus and yield strength ageing. Subsequently, the effect of a non-ionic surfactant on the yield stress and shear modulus of the same model suspension is studied. Results show that the addition of the surfactant significantly alters the interparticle contact properties, leading to modifications in the suspension’s storage modulus and overall yield stress. Importantly, we establish a relationship between the interparticle contact properties and the overall properties of the suspension for both systems

TS. Hoàng Lê Thụy Thùy Trang trình bày về "Magnetic Calcium Phosphate Composites: Preparation, Properties and the Application in the Removal of Cadmium"

Abstract:

To synthesize magnetic calcium phosphate composites in the presence of citric acid via one-pot synthesis and evaluate their cadmium removal efficiency. Materials & methods: The preparation of the calcium phosphates/Fe3O4 (CPs/Fe3O4) composites was conducted in three consecutive steps, including (1) the formation of Fe3O4 nanoparticles, (2) the complexation of citrate ions on Fe3O4 surface, and (3) the precipitation of CPs/Fe3O4. The materials were characterized using XRD, SEM, TEM, DSC, VSM, FT-IR, CHNS, and nitrogen adsorption-desorption analysis. The Cd2+ uptake was measured by ICP-OES. Results: The well-controlled syntheses are proved to be pH-dependent with the formation of two types of CPs, including hydroxyapatite (Hap) and amorphous calcium phosphates (ACP) in the composites. Hap/Fe3O4 is obtained at the pH higher than the pKa3 of citric acid (6.7–9.5), whereas ACP/Fe3O4 is observed at the pH lower than the pKa3 of citric acid (2.3–6.0). The ACP/Fe3O4 exhibits better performance in the removal of cadmium than Hap/Fe3O4. The cadmium adsorption of this composite is well-fitted with Langmuir isotherm giving a maximum capacity of 454.5 mg g-1 and shows a pseudo-second order kinetic behavior. The superior cadmium adsorption capacity of the composite is top ranked among previously reported adsorbents. Furthermore, the superparamagnetic nature of the composites allows a convenient separation of the materials after use. Conclusion: The synthesized composites are promising adsorbents possessing high Cd2+ removal capacity, facile preparation, low cost, and convenient separation