Methyl Orange Removal from Aqueous Solution by Sorption onto Porous Polysaccharide-Based Adsorbents: Optimization by Taguchi Design

The removal of methyl orange (MO) dye using porous chitosan (CS) gel beads was investigated in a batch mode. The newly formed porous CS gel beads were synthesized by using a solidification bath containing mixture of NaOH-Na₂CO₃ at ratio of 1:1. Orthogonal array of L9 (3³) was used to generate nine sets of experiments based on three controlling factors: initial dye concentration (30 ppm, 50 ppm, 90 ppm), adsorbent dosage (0.35 g, 0.5 g, 1 g) and pH of MO (pH 3, 7, 11).The highest mean of Signal to Noise (S/N) ratio was chosen to obtain maximum adsorption capability of newly formed porous CS gel beads. The optimum operating conditions to maximise the removal percentage (R% ) were identified as 1 g of adsorbent dosage, 30 mg/L of initial MO concentration at pH 3, whereas maximum equilibrium uptake capacity (qe) of 10.41 mg/g was achieved by dosing 0.35 g of adsorbent dosage into 90 mg/L of initial MO concentration at pH 3. ANOVA studies were also carried out to study the contribution percentage of each designed parameter. The results indicated that the initial concentration and pH of MO dye solution have the biggest contribution to R% and qe, respectively.