Experimental study and modelling of an azo colorant dynamic adsorption onto functional cross-linked chitosan/ ceramic particles in a fixed bed column

Abstract

The use of azo dyes in industrial activities generates a large volume ofcontaminated wastewater; these pollutants in water bodies affect aquatic biotaand human health. A functional biocomposite sorbent material was synthesizedusing cross-linked chitosan with oxalic acid that forms a coating on aluminaceramic particles (AOCh). The removal of Reactive Red 195, a reactiveazo dye, using a fixed-bed adsorption column filled with this material wastested. AOCh was physico-chemically characterized by Fourier transforminfrared spectroscopy?total attenuated reflection (FTIR-ATR), scanning electronmicroscopy?energy dispersion spectrometry X-ray (SEM-EDS), X-ray diffraction(XDR), thermo-gravimetric analysis (TGA), and Z-potential. Thedynamic adsorption performance was analyzed from experimental breakthroughcurves obtained in fixed-bed columns by modifying different operatingconditions (bed depth, volumetric flow rate, and dye inlet concentration).Equilibrium adsorption isotherms were determined under dynamic conditionsand compared with batch results. The maximum adsorption capacity of thedynamic equilibrium isotherm obtained from the continuous assays was331 mg/g; this value was the highest in comparison to other tested materialsreported in the literature. Different dynamic adsorption models were appliedto fit experimental data, including Thomas, Bohart?Admas, Yoon?Nelson,logistic general model, bed depth surface time (BDST), and modified doseresponse (Yan) models. A critical analysis of these equations was presented,showing the equivalences and the relationship among the coefficients. TheYan model achieved the highest level of agreement between the experimentaland predicted values of the breakthrough curves. The use of this model enablesscaling-up the industrial process for dye removal. The present work proposed anovel biosorbent material and contributes to the analysis of industrial dyeremoval under dynamic conditions.