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.