Nanoporous Alumina Membranes for Enhancing Hemodialysis

The nonuniformity of pore size and pore distribution of the current hemodialysis membrane results in low efficiency of uremic solute removal as well as the loss of albumin. By using nanotechnology, an anodic alumina membrane (ceramic membrane) with self-organized nanopore structure was produced. The objective of this study was to fabricate nanoporous alumina membranes and investigate the correlation between various anodization conditions and the pore characteristics in order to find its potential application in artificial kidney/hemodialysis. An aluminum thin film was oxidized in two electrolytes consisting of 3% and 5% sulfuric acid and 2.7% oxalic acid. The applied voltages were 12.5, 15, 17.5, and $20V$ for sulfuric acid and 20, 30, 40, and $50V$ for oxalic acid. Pore size and porosity were determined by analyzing Scanning Electron Microscopy (SEM) images and hydraulic conductivity was measured. Results show that pore size increased linearly with voltage. Acid concentration affected pore formation but not pore size and pore distribution. Hydraulic conductivity of the ceramic membrane was higher than that of the polymer dialysis membrane. The optimal formation conditions for self-organized nanopore structure of the ceramic membrane were $12.5-17.5V$ in 3–5% sulfuric acid at $0°C$⁠. Under these conditions, ceramic membranes with pores size of $∼10nm$ diameter can be produced. In conclusion, we used anodic alumina technology to reliably produce in quantity ceramic membranes with a pore diameter of $10-50nm$⁠. Because of more uniform pore size, high porosity, high hydraulic conductivity, and resistance to high temperature, the ceramic membrane has the potential application as a hemodialysis membrane.