Application of Taguchi experimental design in optimization of desalination using purified carbon nanotubes as adsorbent

Carbon nanotubes (CNTs) were synthesized by chemical vapor deposition of cyclohexanol and ferrocene in nitrogen atmosphere at 750 °C, and purified by thermal oxidation and acid treatment. Desalination using purified CNTs as adsorbent was performed. Effects of purification (treatment with HNO3 (8 M), HNO3/H2SO4 (1/1) and HNO3/H2SO4 (1/3)), initial salt concentration (10,000, 20,000 and 30,000 mg/l), temperature (25, 35 and 45 °C) and initial pH (3, 7 and 11) on adsorption uptake (mg/g) of the purified CNTs in desalination process were investigated using Taguchi experimental design (L9 orthogonal array). Optimum conditions were predicted, and confirmed by carrying out some new experiments. Relative importance of the effects of various factors was evaluated using analysis of variance (ANOVA). Langmuir and Freundlich isotherm models were applied to fit the experimental data.