Dang Viet Quang

Trong nghiên cứu này, TiO2 được biến tínhbằng phương pháp tẩm ướt với dung dịch AgNO3 và Na2WO4 theo tỉ lệ mol của từng nguyên tố Ag/Ti và W/Ti từ 0,01 đến 0,5%. Mẫu sau tẩm được sấy khô và nung ở 500 oC để tăng cường liên kết giữa Ag và W với TiO2. Các phương pháp chụp ảnh hiển vi điện tử quét, nhiễu xạ tia X, quang phổ hồng ngoại biến đổi Fourier và quang phổ phản xạ khuếch tán tử ngoại – khả kiến được sử dụng để nghiên cứu đặc tính của vật liệu. Khả năng quang xúc tác của vật liệu được nghiên cứu thông qua sự phân hủy dung dịch xanh methylene dưới ánh sáng tử ngoại. Kết quả nghiên cứu cho thấy, cấu trúc tinh thể và năng lượng vùng cấm của TiO2 không thay đổi đáng kể, tuy nhiên, khả năng quang xúc tác của TiO2 tăng lên một cách rõ rệt. TiO2 xử lý bằng dung dịch AgNO3 và Na2WO4 với tỉ lệ số mol 0,05% cho hiệu quả phân hủy xanh methylene tốt nhất, đạt 68% so với vật liệu TiO2 ban đầu là 62%. Kết quả này cho thấy tẩm ướt là phương pháp đơn giản và hiệu quả trong biến tính TiO2.

In this study, sugarcane bagasse was pyrolyzed at 600 oC in N2 to generate biochar following by modification with sodium dodecyl sulfate (SDS) solution. The adsorption ability of both biochar and SDS modified biochar was examined with methyl violet. Adsorption experiments were conducted with dye solution having a different concentration at the adsorbent dose of 5 g/L. Obtained results indicated that the removal efficiency of biochar increased from 64.30% to 97.54% as the concentration of SDS modifying solution increased from 0 to 0.4 g/L, respectively. The adsorption on biochar and modified biochar fits well to Langmuir model. The maximum adsorption capacity of biochar without modification was 10.58 mg/g, but increased 14.68 mg/g after being modifying with SDS solution 0.3 g/L. The adsorption fitted well to pseudo second order kinetic model with rate constants of 0.077 and 0.161 (g/mg·min) The success of study demonstrated that the dye adsorption on sugarcane bagasse-based biochar can be significantly improved by treatment biochar with SDS solution. This suggests a facile and cost-effective way to modify biochar for dye adsorption.

TiO₂ nanoparticles have emerged as a great photocatalyst to degrade organic contaminants in water; however, the nanoparticles dispersed in water could be difficult to be recovered and potentially become contaminant. Herbicide like 2,4-dichlorophenoxyacetic acid (2,4-D) used in agriculture usually ends up with a large fraction remaining in water and sediment, which may cause potential risk to human health and the ecosystem. This study proposes a greener method to utilize TiO₂ as photocatalyst to remove 2,4-D from water. Accordingly, TiO₂ nanoparticles (1045nm) were synthesized and grafted on lightweight fired clay to generate a TiO₂-based floating photocatalyst. Experimental testing revealed that 60.2 of 2,4-D (0.1mM) can be decomposed in 250min under UV light with TiO₂-grafted lightweight fired clay floating on water. Degradation fits well into the pseudo-first-order kinetic model. The floating photocatalysts can degrade approximately 50 2,4-D in 250min under sunlight and the degradation efficiency is stable for cycles. The results revealed that the fabrication of floating photocatalyst could be a promising and greener way to remove herbicide contaminants in water using TiO₂.

Dengue fever pandemic caused by dengue virus has been claimed for many lives, however, no specific treatment is available. Prevention based on vector control posed to be the most effective measure so far. The application of chitosan stabilized silver nanoparticle (AgNPs) to control larvae and adult mosquitoes has recently discovered, but their ability to inhibit Dengue virus has scarcely discussed. In this study, chitosan stabilized AgNPs have been prepared and tested against dengue virus type 1. The results showed that chitosan stabilized AgNPs can inhibit 96.66% and 98.33% dengue virus type 1 at 12.50 ppm and 25.00 ppm, respectively, without any toxicity to BHKFcɣ cells. This study confirms that chitosan stabilized AgNPs have a highly antiviral ability against dengue virus in addition to its mosquitocidal properties. This allows one to control both virus and vector simultaneously. The study suggested that chitosan stabilized AgNPs could be an effective tool to prevent the dengue epidemic.

Jute fibres (JFs) and polyamide 11 (PA11) are naturally originated materials that, individually, have been widely employed for the manufacture of biocomposites. However, their simultaneous use in an environmentally friendly JFs/PA11 biocomposite that combines the advantages of both materials has received little attention. Therefore, this study investigated the possible fabrication of a biocomposite based on JFs and PA11. Since the dispersion, adhesion and interfacial interaction between JFs and resin matrix are usually poor, the possibility of improving those characteristics was explored via chemical modification. Accordingly, two modification routes were used: alkali treatment and SiO₂ nanoparticle deposition. Both modified and unmodified fibres were blended with PA11 for biocomposite production. Various techniques including Fourier transform infrared spectroscopy, thermogravimetry, mechanical property analysis and scanning electron microscopy were used to characterize fibre and biocomposite samples. The results indicated that thermal and mechanical stability of JFs were considerably improved as a result of modification. The tensile strength and Young's modulus of unmodified fibres was 303.75 MPa and 12.32 GPa, which then increased to 483.66 MPa and 483.66 GPa, respectively, as a result of SiO₂ nanoparticle deposition on the fibre surface. Because of SiO₂ nanoparticle modification, the interaction and adhesion between JFs and PA11 matrix were improved, which led to increases of 58.3%, 11.7% and 45.9% in tensile strength, impact strength and Young's modulus. The success of this study provides a novel route to produce a complete biocomposite from JFs and PA11, which could become a promising alternative to conventional synthetic polymer composites. © 2021 Society of Industrial Chemistry.

The influence of firing temperature on characteristics and bacterial filtration of the porous ceramic membrane prepared from rice husk (20wt) and kaolin has been investigated. As firing temperatures increased from 900 to 1100C, the compressive strength of membrane increased from 555.3N/cm² to 2992.3N/cm², whereas the porosity decreased from 49.4 to 30.2 due to structural condensation and mullite formation. The condensation caused pore contraction that finally improved bacterial removal efficiency from 90 to 99. The results suggested that the porous ceramic membrane prepared from rice husk and kaolin should be fired at 1050C to attain both strength and filtration efficiency.