Solehuddin Shuib

Separation and Characterization of the Vanillin Compound from Soda Lignin

The separation of vanillin from soda lignin that was extracted from black liquor of oil palm empty fruit bunches (EFB) using 20% sulfuric acid is presented in this paper. The degradation of soda lignin using alkaline nitrobenzene oxidation was carried out at 165 ° C for 3 hours in a 2 M NaOH and nitrobenzene solution. One of the major products obtained from the breakdown of lignin is vanillin. The crys- tallization process was used as a method to separate vanillin from other compounds. Based on the solubility of vanillin in acetone, 15 mL of acetone was added to the residue of the oxidized products. The mixture was slowly heated to 40 - 50 ° C for 15 minutes until the vanillin crystalline precipitated. A yield of about 1.6% vanillin was isolated from 50 mg sample of lignin. The isolated compound was analyzed utilizing high performance liquid chromatography, Fourier transform infrared spec- trophotometry (FTIR) and nuclear magnetic resonance ( 1 H-NMR). The results of the characterization studies proved that the isolated compound was vanillin.

Analysis of Stress on Inflation of Balloon Catheter using Finite Element Method

Urinary catheter has been widely used as a solution for urinary incontinence problem. But it can induce pressure stress at the human bladder neck. However, owing to the complexities in balloon geometries, material properties and interactions in bladder, analyses of the complete stress inflation of balloon are limited. This study describes some numerical simulations of the expansion phase of catheter balloon on bladder and to study the stress distribution at the balloon. In order to investigate the mechanical characteristics of inflation catheter balloon, a three-dimensional model of the complete catheter balloon were developed, which made the simulation well close to the real situation. Finite element analysis (FEA) ABAQUS 6.4-PR11 was used to simulate the balloon inflation and deflation. The hyperelastic behavior of the Mooney-Rivlin model is considered. Mechanical properties of the balloon have been taken from the literature. Simulated results showed that the stress distributed on the surface of the balloon. The maximum Von Mises stress for natural rubber from the analysis is 5.11 MPa. High stress concentrates on the center of it. In conclusion, FEM can help illustrate and quantify some mechanical characteristics of the balloon and it would be helpful for the general understanding of inflation of urinary catheter balloon.