Optimization of the Retardance in Citric Acid Coated Ferrofluids

The citric acid (CA) coated Fe₃O₄ ferrofluids (FFs) were prepared by a co-precipitation method and the magneto-optical retardance was measured by a Stokes polarimeter. Using Taguchi method with nine tests for four parameters, including pH of suspension, molar ratio of CA to Fe₃O₄, CA volume, and coating temperature, the influence sequence between parameters and excellent program for maximum retardance were found. The relationship between dependent and independent variables was found by the regression analysis and the model had statistically significant predictive ability. Further, three optimization techniques, including evolution algorithm (in Excel), fmincon and genetic algorithm solver (in MATLAB® Optimization Toolbox) are used to find out the optimized parametric combination and the maximum retardance in CA coated FFs.