Optimization of Dye Removal Efficiencies by Adsorbents

The affecting factors of dose (5–30 g/L), contact time (3–18 h), temperature (20–50 °C), pH (3–11), and concentration (30–90 mg/L) with the control condition of initial DR28 dye concentration of 50 mg/L, a sample volume of 100 mL, and a shaking speed of 150 rpm by using an incubator shaker (New Brunswick, Innova 42, USA)^{8 (link),9 (link),20 (link)} on DR28 dye removal efficiencies of SBB, SBBT, SBBM, SBBA, and SBBZ were investigated through a series of batch experiments which referred from the previous study of Praipipat et al.^{18 (link)} Their optimum conditions were chosen from the lowest dose or contact time or temperature or pH or concentration with obtaining the highest DR28 dye removal efficiencies^{9 (link)}. UV–VIS Spectrophotometer (UH5300, Hitachi, Japan) with a wavelength of 497 nm was used for analyzing dye concentrations, and the triplicate experiments were investigated to verify the results and report the average value. Dye removal efficiency in the percentage and dye adsorption capacity is calculated following Eqs. (1)–(2): $$\text{Dye removal efficiency}\left(\%\right)=\left(\left(C_0-C_{\text{e}}\right)/C_0\right)\times 100$$ $$\text{Dye adsorption capacity}\left(q_e\right)=(C_0-C_{\text{e}})V/m$$ where C_e is the dye concentration at equilibrium (mg/L), C₀ is the initial dye concentration (mg/L), q_e is the capacity of dye adsorption on adsorbent material at equilibrium (mg/g), V is the sample volume (L), and m is the amount of adsorbent material (g).