Application of response surface methodology for the adsorption optimization of reactive dyes onto recoverable magnetic carbon

Background and Aim: Discharging the effluents of textile wastewaters into potable water resources can endanger the ecosystem, due to their reactivity, toxicity, and chemical stability. In this research, the application of powder activated carbon modified with magnetite nanoparticles (PAC-MNPs ) as an adsorbent for removal of reactive dyes (Reactive black 5 (RB5)) and reactive red 120 (RR120)) was studied in a batch system.Method: The adsorption performance was evaluated as a function of temperature, contact time and different adsorbent and adsorbate concentrations. The levels of factors were statistically optimized using Box-Behnken Design (BBD) from the response surface methodology (RSM) to maximize the efficiency of the system. The adsorption process of both dyes was fit with the pseudo-second order kinetic and Langmuir isotherm models.Results: The identified optimum conditions of adsorption were 38.7 oC, 46.3 min, 0.8 g/L and 102 mg/L for temperature, contact time, adsorbent dose, and initial dyes concentration, respectively. According to the Langmuir isotherm, the maximum sorption capacities of 192.6 and 188.7 mg/g were obtained for RB5 and RR120, respectively. Thermodynamics studies indicated that the adsorption process of the reactive dyes was spontaneous, feasible, and endothermic in its nature. After five cycles, the adsorption efficiency was around 84 and 83 % for RB5 and RR120, respectively.Conclusion: A highly value of desorption was achieved suggesting that the PAC-MNPs have a good potential in regeneration and reusability; and also can be effectively utilized in industrial applications. PAC-MNPs also shows a good anti-interference potential for removal of reactive dyes in dye-industry wastewaters.

Keywords:

Reactive dyes , Response surface method , Box-Behnken design , Adsorption , Magnetic composite.