Hybrid central composite design for simultaneous optimization of removal of methylene blue and alizarin red S from aqueous solutions using Vitis tree leaves

Vitis tree leaves powder was used for efficient removal of dyes (eg, alizarin red and methylene blue) from water samples in binary batch systems. The influence of various parameters such as initial pH, initial dye concentration, and sorbent mass on the biosorption process was investigated. Statistical experimental design was utilized to optimize this biosorption process. A regression model was derived using a response surface methodology through performing the 416B model of hybrid central composite design. Model adequacy was checked by means of tests such as analysis of variance, a lack of fit test, and residual distribution consideration. The proposed quadratic model resulted from the hybrid design approach fitted very well to the experimental data. The optimal conditions for dye biosorption were as follows: pH=3.0, sorbent mass=0.05g, initial alizarin red concentration (C-AR)=999.6mgL(-1) and initial methylene blue concentration (C-MB)=878.5mgL(-1). Evaluation of biosorption data with Langmuir and Freundlich isotherms shows that the Langmuir model indicated the best fit to the equilibrium data with maximum adsorption capacity of 66.4 and 53.5mg g(-1) in single system and 54.6 and 43.9mg g(-1) in binary system for AR and MB, respectively. Moreover, kinetics of the biosorption process was also investigated. Vitis tree leaves powder was used for efficient removal of dyes (eg, alizarin red and methylene blue) from water samples in binary batch systems. The influence of various parameters such as initial pH, initial dye concentration and sorbent mass on the biosorption process was investigated. Statistical experimental design was utilized to optimize this biosorption process.