Study on Adsorption Performance of MgO/Calcium Alginate Composite for Congo Red in Wastewater

This research prepared a poly-functional material which has outstanding adsorption performance and easily recyclable for Congo red dye removal. The multifunctional gel yarn composed of calcium alginate and nano-magnesium oxide was prepared by wet spinning. For the morphology and structure of MgO/CA composite, the compound product was characterized by Field Emission Scanning Electron Microscope (FE-SEM), Fourier Transform infrared spectroscopy (FTIR) and Thermogravimetric analysis (TGA). Then, the adsorption performance of MgO/CA aerogel for Congo red was studied, including the influence of four factors (adsorbent dosage, pH, initial concentration, contact time), adsorption isotherm, adsorption kinetics and adsorption thermodynamics. The results show that the adsorption properties of MgO/CA aerogel on Congo red largely depend on these factors. The best contact time for MgO/CA aerogel to remove Congo red is 24 h. Besides, the maximum adsorption capacity of the adsorbents is usually very high (312.5, 322.6 and 344.8 mg/g at 303, 313 and 323 K, respectively). The adsorption kinetics can be best described by a pseudo second-order reaction, and the adsorption data agree well with the Langmuir model. Thermodynamic parameters including the changes in entropy (ΔS0), free energy (ΔG0) and enthalpy (ΔH0), and stated that adsorption by the MgO/CA aerogel was endothermic and spontaneous.