Application of a new metal-organic framework of [Ni2F2(4,4'-bipy)2(H2O)2](VO3)2.8H2O as an efficient adsorbent for removal of Congo red dye using experimental design optimization.

The new metal-organic framework of [Ni2F2(4,4'-bipy)2(H2O)2](VO3)2.8H2O was synthesized by a sonochemical method for the adsorptive removal of Congo red (CR) in a batch system. It was characterized by infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), thermogravimetric (TGA), and elemental analyses. Box-Behnken design (BBD) was applied to obtain an appropriate regression model for removal percent (R%) of CR dye. The optimized conditions for three effective factors: adsorbent dosage, temperature, and CR concentration were m = 0.0107 g, T = 45 °C, and Cd = 50 mg.L-1, respectively, while maximum removal percent is 96%. Langmuir isotherm shows that the maximum monolayer adsorption capacity (qmax) is 242.1 mg.g-1. The pseudo-second-order kinetic model better describes the adsorption kinetics behavior. Thermodynamic parameters illustrate that the adsorption process is endothermic and spontaneous chemisorption. The aim of this study is the introduction of a new metal-organic framework that can adsorb Congo red with high adsorption capacity. Therefore, due to synthesis of the new metal-organic framework as a high efficient adsorbent for Congo red removal, and also multivariate optimization of removal conditions, this study outright is novel.

Simultaneous removal of binary mixture of Brilliant Green and Crystal Violet using derivative spectrophotometric determination, multivariate optimization and adsorption characterization of dyes on surfactant modified nano-γ-alumina.

The present study deals with the simultaneous removal of Brilliant Green (BG) and Crystal Violet (CV) by surfactant-modified alumina. The utilization of alumina nanoparticles with an anionic surfactant (sodium dodecyl sulfate (SDS)) as a novel and efficient adsorbent is successfully carried out to remove two cationic dyes from aqueous solutions in binary batch systems. A first-order derivative spectrophotometric method is developed for the simultaneous determination of BG and CV in binary solutions. The linear concentration range and limits of detection for the simultaneous determination of BG and CV were found to be: 1-20, 1-15 mg/L, 0.3 and 0.5 mg/L, respectively. The influence of various parameters, such as contact time, initial concentration of dyes and sorbent mass on the dye adsorption is investigated. A response surface methodology achieved through performing the Box-Behnken design is utilized to optimize the removal of dyes by surfactant-modified nanoparticle alumina through a batch adsorption process. The proposed quadratic model resulting from the Box-Behnken design approach fitted very well with the experimental data. The optimal conditions for dye removal were contact time t=50 min, sorbent dose=0.036 g, CBG (Initial BG concentration)=215 mg/L and CCV (Initial CV concentration)=170 mg/L. Furthermore, FT-IR analysis, the isotherms and kinetics of adsorption were also explored.

Multi-response optimization using Taguchi design and principle component analysis for removing binary mixture of alizarin red and alizarin yellow from aqueous solution by nano γ-alumina.

The nanostructure of γ-alumina was used as an effective adsorbent for simultaneous removing of a mixture of alizarin red and alizarin yellow from aqueous solutions. The Taguchi design and principle component analysis were applied to explore effective parameters for achieving a higher adsorption capacity and removal percentage of the binary mixture containing alizarin red and alizarin yellow. Seven factors including temperature, contact time, initial pH value, the shaker rate, the sorbent dose, and initial concentrations of alizarin red and alizarin yellow in three levels were considered through the Taguchi technique. A L27 orthogonal array was used to determine the signal-to-noise ratio. Then, the removal percentage (R%) and adsorption capacity (q) of the above-mentioned dyes were transformed into an accurate S/N ratio. The Taguchi method indicates that the solution pH has the most contribution in controlling the removal percentage of alizarin red and alizarin yellow. Under optimal condition, the maximum removal percentages of 99% and 78.5%, and the capacity uptake of 54.4 and 39.0mg g(-1) were obtained for both alizarin red and alizarin yellow, respectively. Isotherm modeling and kinetic investigations showed that Langmuir, modified Langmuir, and pseudo-second-order models describe both the adsorption equilibrium and kinetic behavior well. The Fourier transform infrared analysis also firmly confirmed the involving active sites of nano γ-alumina in the adsorption process.