Alginate-based hydrogels are attracted much attention in biomedical and chemical field, and their size and shape are significant to their applications like drug delivery and cell encapsulation. Monodisperse sodium alginate microdroplets are produced using a flow-focusing microfluidic device (MFFD) by adjusting the flow rate on the continuous phase (soybean oil) and the dispersed phase (sodium alginate solution). The external gelation process of sodium alginate microdroplets occurs outside the chanel in a calcium chloride solution to form calcium alginate hydrogel particales. The shape, size and size distribution of these calcium alginate hydrogel particles depend strongly on the flow rate inside the MFFD. By optimizing the parameters, the hydrogel microparticles were obtained with diameters ranging from 70 µm to 100 µm with size distribution under 10%, depending on experimental conditions. The removal of Cu2+ ions by the absorption of hydrogel microparticles was also demonstrated.

TiO2 thin films were synthesized by using Chemical Vapor Deposition (CVD) method on different substrates, such as glass, aluminium foil , and ceramic. The samples had been characterized by microscopy analysis, SEM, and EDS. The results show that TiO2 thin films were successfully fabricated and TiO2 nanocrystals with size of 50-100 nm loaded uniformly on surface of different substrates. The photocatalytic activities of all samples were investigated in photo-degradation of methyl orange (MO) under UV light irradiation and was followed by the UV-Vis diffuse reflectance spectroscopy, showing that the conversion of methyl orange achieved the highest percentage of 91% with TiO2 thin film synthesized on the ceramic substrate over 270 minutes of reaction. The hypothetical mechanism explaining this observation is that the surface morphology of ceramic plays a major role in the augmentation of MO molecules adsorption onto the surface of material, thus, improves the dye degradation process.