Nano-structured surface modification of micro-porous ceramic membrane with positively charged nano-Y2O3 coating for organic dyes removal
Abstract
The purpose of this study is to develop a kind of positively charged microporous ceramic membrane which works on the electrostatic adsorption principle to promote adsorption of organic dyes with negative charge. The nano-Y2O3 coating which played the role of charged agent was obtained through colloid reaction and a thermal decomposition process. Firstly, the precursor colloid was synthesized by chemical reaction of urea and YCl3, and subsequently the precursor colloid was calcined in air to transform into nano-Y2O3, which was fixed on the surface of a base membrane. The specific surface area of positively charged ceramic membrane increased 36.72% through the coating process, and the nano-Y2O3 was evenly attached to the base membrane surface with an isoelectric point of 8.18. The EDS and XPS results demonstrated that there were new chemical bonds formed with Y element between the base membrane and the Y2O3 coating, which meant the Y2O3 coating did not easily fall off. The positively charged ceramic membrane prepared in this study removed approximately 99.6% of titan yellow and 98.3% of eriochrome black T, which were both small molecule dyes with negative charges in water, and which indicates a potential manufacturing process to yield effective dye filters superior to those of current dye filtration techniques.