Pristine and cerium-doped zinc oxides with a different dopant concentration between 1 and 5% were fabricated using the hydrothermal method. Prepared materials show direct bandgaps of comparable values. Cerium-doped materials show UV-Vis spectra with broad tails toward the visible light range. Pure zinc oxide displays the flower-like form, while cerium-doped materials possess rod-shaped morphologies. The materials were tested for the degradation performance of methylene blue under visible light irradiation. To elucidate the difference in their performance, further measurements and experiments were conducted. Overall, 3%-cerium doped zinc oxide shows the greatest photocatalytic performance. This is possibly attributed to its rod shape with good uniformity and to the enrichment of oxygen vacancies in its surface layers. Finally, trapping experiments reveal that positive holes and hydroxyl radicals were the predominant active species during the photocatalytic degradation process.

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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.

Vật liệu ZnO pha tạp Mn được tổng hợp với phương pháp thủy nhiệt. Các đặc trưng tính chất của vật liệu tổng hợp được nghiên cứu bằng bằng các phương pháp như XRD, FT-IR, UV-VIS, EDS, XPS và SEM. Các kết quả XRD, XPS và UV-VIS đã cho thấy ion Mn2+ đã pha tạp thành công vào ZnO. Sự pha tạp Mn đã làm giảm năng lượng vùng cấm, do đó làm tăng cường hấp thu quang vùng ánh sáng khả kiến của ZnO. Kết quả là vật liệu ZnO pha tạp Mn thể hện hoạt tính quang xúc tác cao hơn ZnO không pha tạp dưới ánh sáng khả kiến.

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